beyond polyphagy and opportunism: natural prey of hunting ...beyond polyphagy and opportunism:...

Beyond polyphagy and opportunismnatural prey of hunting spiders in thecanopy of apple treesLaacuteszloacute Mezőfi1 Gaacutebor Markoacute23 Csaba Nagy4 Daacutevid Koraacutenyi56 andViktor Markoacute1

1 Department of Entomology Szent Istvaacuten University Budapest Hungary2 Department of Plant Pathology Szent Istvaacuten University Budapest Hungary3 Behavioural Ecology Group Department of Systematic Zoology and Ecology Eoumltvoumls LoraacutendUniversity Budapest Hungary

4 Research Institute for Fruitgrowing and Ornamentals National Agricultural Research andInnovation Centre Uacutejfeheacutertoacute Hungary

5 Institute of Ecology and Botany ldquoLenduumlletrdquo Landscape and Conservation Ecology Centre forEcological Research Vaacutecraacutetoacutet Hungary

6 GINOP Sustainable Ecosystems Group Centre for Ecological Research Tihany Hungary

ABSTRACTSpiders (Araneae) form abundant and diverse assemblages in agroecosystems such asfruit orchards and thus might have an important role as natural enemies of orchardpests Although spiders are polyphagous and opportunistic predators in generallimited information exists on their natural prey at both species and communitylevels Thus the aim of this study was to assess the natural prey (realized trophicniche) of arboreal hunting spiders their role in trophic webs and their biologicalcontrol potential with direct observation of predation events in apple orchardsHunting spiders with prey in their chelicerae were collected in the canopy of appletrees in organic apple orchards in Hungary during the growing seasons between 2013and 2019 and both spiders and their prey were identified and measured Amongothers the composition of the actual (captured by spiders) and the potential(available in the canopy) prey was compared trophic niche and food web metricswere calculated and some morphological dimensional data of the spider-preypairs were analyzed Species-specific differences in prey composition or pest controlability were also discussed By analyzing a total of 878 prey items captured by spiderswe concluded that arboreal hunting spiders forage selectively and consume a largenumber of apple pests however spidersrsquo beneficial effects are greatly reduced by theirhigh levels of intraguild predation and by a propensity to switch from pests toalternative prey In this study arboreal hunting spiders showed negative selectivityfor pests no selectivity for natural enemies and positive selectivity for neutralspecies In the trophic web the dominant hunting spider taxagroups (Carrhotusxanthogramma Philodromus cespitum Clubiona spp Ebrechtella tricuspidataXysticus spp and lsquoOther salticidsrsquo) exhibit different levels of predation on differentprey groups and the trophic webrsquos structure changes depending on the time of yearHunting spiders show a high functional redundancy in their predation butcontrary to their polyphagous nature the examined spider taxa showed differences intheir natural diet exhibited a certain degree of prey specialization and selected preyby size and taxonomic identity Guilds (such as stalkers ambushers and foliage

How to cite this article Mezőfi L Markoacute G Nagy C Koraacutenyi D Markoacute V 2020 Beyond polyphagy and opportunism natural prey ofhunting spiders in the canopy of apple trees PeerJ 8e9334 DOI 107717peerj9334

Submitted 20 January 2020Accepted 19 May 2020Published 19 June 2020

Corresponding authorLaacuteszloacute Mezőfimezofilaszlokertksziehu

Academic editorAnn Hedrick

Additional Information andDeclarations can be found onpage 29

DOI 107717peerj9334

Copyright2020 Mezőfi et al

Distributed underCreative Commons CC-BY 40

runners) did not consistently predict either prey composition or predation selectivityof arboreal hunting spider species From the economic standpoint Ph cespitumand Clubiona spp were found to be the most effective natural enemies of apple pestsespecially of aphids Finally the trophic niche width of C xanthogramma and Phcespitum increased during ontogeny resulting in a shift in their predation Theseresults demonstrate how specific generalist predators can differ from each other inaspects of their predation ecology even within a relatively narrow taxonomic group

Subjects Agricultural Science EcologyKeywords Araneae Beneficial arthropods Natural diet Intraguild predation Food webTrophic niche Biocontrol potential Ontogenetic shift Carrhotus xanthogrammaPhilodromus cespitum

INTRODUCTIONSpiders play an important role in ecosystems as predators of various invertebrate groupsIn certain habitats according to the highest realistic estimates spiders might kill up toapproximately 200 kg prey haminus1 yearminus1 (Nyffeler 2000) which by extrapolation suggeststhat the global spider community might consume up to 400ndash800 million tons of preyannually (Nyffeler amp Birkhofer 2017) Generally spiders are regarded as polyphagous(preying on a wide variety of prey) and opportunistic (taking their prey as a function ofeach prey speciesrsquo availability) although some degree of selectivity in foraging is oftenobserved (Nentwig 1980 Whitney et al 2018 Eitzinger et al 2019) Moreoverstenophagy has evolved in certain groups of spiders eg myrmecophagy in Zodariidae oraraneophagy in Salticidae (Pekaacuter Coddington amp Blackledge 2012 Pekaacuter amp Toft 2015)Spiders mainly prey on insects of which the preferred size is primarily ~50ndash80 of thespidersrsquo size (Nentwig amp Wissel 1986 Foelix 2011) but they can also feed on otherinvertebrates (Nyffeler amp Symondson 2001 Nyffeler et al 2017) or vertebrates (Nyffeler ampKnoumlrnschild 2013 Nyffeler amp Pusey 2014 Nyffeler Edwards amp Krysko 2017) eggs ofvarious arthropods (Nyffeler et al 1990 Ahmed et al 2018) or even on plant nectar andpollen (Nyffeler 2016 Nyffeler Olson amp Symondson 2016)

In agroecosystems spiders can contribute significantly to pest control by consuming alarge number of various insect pests (Nyffeler amp Benz 1988 Young amp Edwards 1990Marc Canard amp Ysnel 1999 Nyffeler amp Sunderland 2003 Birkhofer et al 2008 Liu et al2015 Suenaga amp Hamamura 2015 Lefebvre et al 2017) A recent meta-analysis(Michalko et al 2019) of 58 studies found that spiders suppressed agricultural insect pestsin 79 of the cases although their efficacy varied among crops From an economic point ofview hunting spiders have special importance as they collect their prey directly fromthe surface of the crop and thus they more frequently consume less mobile stages(eg eggs larvae nymphs) of various arthropods than web-building spiders (MarcCanard amp Ysnel 1999 Nyffeler 1999) Also hunting spiders have a wider trophic nichecompared to web-builders (Nyffeler 1999 Michalko amp Pekaacuter 2016) Furthermorebesides direct predation hunting spiders have several other non-consumptive effects onpestsherbivores (Mansour Rosen amp Shulov 1981 Sunderland 1999 Beleznai et al 2015

Mezofi et al (2020) PeerJ DOI 107717peerj9334 238

Bucher Menzel amp Entling 2015 Tholt et al 2018) and due to the consumptive andnon-consumptive effects hunting spiders can also improve crop performance indirectly(Schmitz Beckerman amp OrsquoBrien 1997 Schmitz amp Suttle 2001 Schmitz 2008)

Trophic niche width (or diet breadth) of spider species varies along a continuum fromextremely narrow (feeding on a single prey taxon) to extremely wide (feeding on allavailable prey taxa) diet range although some differences may exist even at the morepolyphagic end of the continuum (Pekaacuter Coddington amp Blackledge 2012 Pekaacuter ampToft 2015) Although these generalist predators can effectively reduce pest numbers(Symondson Sunderland amp Greenstone 2002 Nyffeler amp Sunderland 2003) many factorscan influence their role in pest suppression and food-web dynamics at both communityand individual levels (Michalko Pekaacuter amp Entling 2019) Several environmental factorsand functional traits can be directly or indirectly involved including the presence orabsence of alternative prey (Madsen Terkildsen amp Toft 2004 Kuusk amp Ekbom 2010)the intensity of intraguild predation or predator interference (Snyder amp Wise 1999Wise 2006 Petraacutekovaacute et al 2016 Michalko et al 2017) the season of the year (Snyder ampWise 2001) hunting strategy or guild (Schmitz 2008 Miller Ament amp Schmitz 2014 Liuet al 2015 Michalko amp Pekaacuter 2016) or ontogenetic differences (Bartos 2011)

It is hard to assess what spidersrsquo diets consist of or what role various species play in foodwebs or trophic cascades In laboratory experiments spiders might accept more prey typesthan in their natural environment (Liacuteznarovaacute amp Pekaacuter 2019) and thus these studiesprovide only limited insight into the natural diet of spiders (Greenstone 1999) In thefield there are many methods to obtain information about the realized trophic nicheof invertebrate predators (Sunderland 1988 Symondson 2002 Birkhofer et al 2017Maciacuteas-Hernaacutendez et al 2018) Although they are labor-intensive direct in situobservations can provide the most reliable data about the natural diet of a focal predatorspecies (Greenstone 1999 Birkhofer et al 2017 Pekaacuter Garciacutea amp Viera 2017) so it is notsurprising that this method is widely used to assess diet concerning different species ofspiders (Yeargan 1975 Lockley amp Young 1987 Morse 1981 Nyffeler Dean amp Sterling1992 Huseynov 2005 2007) Many studies on the natural diet of spiders have focused onweb-building spiders because the observation of sedentary species is easier than trackingmobile hunters and in case of web-builders there is an opportunity to collect preycarcasses from their web In many studies investigating hunting spiders the diet ofonly one species or species-pair was examined without comparing the composition ofpotential and actual prey (see the references in Pekaacuter Coddington amp Blackledge (2012)Michalko amp Pekaacuter (2016) and Pekaacuter Garciacutea amp Viera (2017)) Thus very little is knownabout the field diet of hunting spider assemblages especially in the canopy layer andlimited information is available on how actual prey relates to potential prey and how onespeciesrsquo diet relates to another

Spiders form abundant and diverse assemblages in apple orchards and can contributeto the suppression of various apple pests (Bogya Szinetaacuter amp Markoacute 1999 BogyaMarkoacute amp Szinetaacuter 2000 Michalko amp Pekaacuter 2015 Lefebvre et al 2017) although theirfunction in biological control has been less studied in orchards (Michalko et al 2019)In the light of the above the aim of this study was to assess the natural prey (realized


trophic niche) of arboreal hunting spiders their role in trophic webs and their biologicalcontrol potential using direct observation of predation events in apple orchards Morespecifically our objectives were (1) to evaluate the natural prey and (2) predationselectivity of the hunting spider assemblage in the canopy of apple trees (3) to compare thepreferred prey of the most abundant hunting spider species or groups (4) concerningtheir hunting guild We also aimed to determine how (5) size and (6) the life stage ofhunting spiders affect the composition and size of their prey

MATERIALS AND METHODSData collectionData on the natural diet (actual prey) of the arboreal hunting spider assemblage wascollected between 2013 and 2019 in apple orchards in Hungary For this apple trees werevisually inspected regularly in organic orchards and hunting spiders with prey in theirchelicerae were collected during the growing season (from the beginning of April to theend of October) The vast majority of the observations (N = 788 almost 90 of the data)came from one organic apple orchard located at Uacutejfeheacutertoacute (an experimental orchardof the Research Institute for Fruitgrowing and Ornamentals National AgriculturalResearch and Innovation Centre) in Szabolcs-Szatmaacuter-Bereg County eastern HungaryA further 37 31 and 22 observations on the hunting spidersrsquo natural prey (for a total of878 observations) were collected in apple orchards of the Szent Istvaacuten University in thevicinity of Uacutejfeheacutertoacute (Szabolcs-Szatmaacuter-Bereg County) in Pest County and Baacutecs-KiskunCounty respectively The orchard located in Uacutejfeheacutertoacute (~33 ha 4749prime115PrimeN 2139prime569PrimeE) was planted on flat land on a fine sandy soil in autumn 2002 and contained thecultivars lsquoFlorinarsquo lsquoPrimarsquo lsquoRajkarsquo lsquoReleikarsquo lsquoRewenarsquo lsquoRubinolarsquo and lsquoTopazrsquo on lsquoM9rsquoand lsquoRemorsquo and lsquoResirsquo on lsquoM26rsquo rootstocks It had 32 rows each consisting of ~90ndash135trees Rows were spaced 5 m apart and apple trees were spaced 15 and 225 m apart withinrows The orchard was surrounded by other orchards (cherry apple) as well as otheragricultural areas

Our in situ observations were conducted both day and night (approximate ratio 73)to get information not only on the prey of the diurnal hunting spiders but also on thenocturnal ones Apple trees were examined mainly between 900 and 1200 between1400 and 1800 and between 2000 and 2300 (after sunset) Spiders with prey in theirchelicerae were collected (with a glass vial) and the prey was taken from the spiders toprevent any further degradation In some cases just the prey was collected because thespider escaped or because we did not want to influence other trials conducted in theorchard After collecting the spiders with their prey the material was taken to thelaboratory of the Department of Entomology Szent Istvaacuten University (BudapestHungary) and both the spider and the prey were identified (with a binocular stereomicroscope Leica MZ6) to the lowest taxonomic level possible Moreover in spiders thewidth of the prosoma and in case of the preys (if their conditions allowed) the widthof the thorax were measured with 01 mm accuracy using an ocular micrometer calibratedwith a stage micrometer In juvenile spiders where the species-level identification wasnot possible (eg in Philodromus species) spiders were raised to the adult stage


(on Drosophila hydei Sturtevant) in the laboratory Spiders were identified after Nentwiget al (2019) and the taxonomic names follow the nomenclature of the WSC (2019)The spiders were stored in 70 ethanol while the prey items were stored mainly dry inglass vials Approximately 4ndash5 of the prey items collected were unidentifiable dueto the high level of degradation and were excluded from the analyses The dataset(see Data S1) contains only the cases where both the spider and its prey were identifiable(878 observations)

To obtain information on the potential prey community of arboreal hunting spidersa D-VAC sampler was used In the organic apple orchard located at Uacutejfeheacutertoacute suctionsamples were taken at monthly intervals between April and October in 2016 and 2017(on 14 sampling dates) On each sampling date five samples were taken Each sampleconsisted of suction samples collected from one (left or right) side of the canopy of fourrandomly selected apple trees in a randomly selected row For the samplings a ~25 cmlong tapering gauze bag (mesh lt 05 mm) was inserted into the 12 cm diameter intakenozzle of the D-VAC sampler Suction sampling was carried out during dry weatherapproximately between 900 and 1400 The collected material was sorted and identified(mainly to order suborder family or genus level) in the laboratory

Preparation of data for analysisFor most analyses the spiders were classified into six groups (1) Carrhotus xanthogramma(Latreille) (2) Other salticids (3) Philodromus cespitum (Walckenaer) (4) Ebrechtellatricuspidata (Fabricius) (5) Xysticus spp s lat and (6) Clubiona spp The main criterionfor group formation was that the number of records in a particular group shouldexceed 5 of the total sample (ie a group must contain at least 44 observations) atthe lowest possible taxonomic level Thus while C xanthogramma Ph cespitum andE tricuspidata were collected in sufficiently large numbers (44 lt n) for analyses the otherspecies had to be placed in genus- (Xysticus spp and Clubiona spp) or family-level (Othersalticids) groups The group lsquoOther salticidsrsquo comprises the data on other spider speciesbelonging to the family Salticidae mainly three species (1) Heliophanus auratus C LKoch (2) H cupreus (Walckenaer) (3) Salticus scenicus (Clerck) but not includingC xanthogramma The group lsquoXysticus spp s latrsquo (hereafter Xysticus spp) comprises thefollowing seven species (1) Xysticus acerbus Thorell (2) X cristatus (Clerck) (3) X kochiThorell (4) X lanio C L Koch (5) X striatipes L Koch (currently Spiracme striatipessee Breitling 2019) (6) X ulmi (Hahn) and (7) unidentified juveniles of Xysticus sppFinally the group lsquoClubiona spprsquo consists of C frutetorum L Koch and unidentifiedjuveniles of Clubiona spp (Tables S1 and S2) To compare the hunting strategies of thespecies collected they were classified using two different guild classification systems(Uetz Halaj amp Cady 1999 Cardoso et al 2011) According to Uetz Halaj amp Cady (1999)hunting spider guilds included (1) stalkers (C xanthogramma and Other salticids)(2) ambushers (Ph cespitum E tricuspidata and Xysticus spp) and (3) foliage runners(Clubiona spp) Based on a more recent guild classification by Cardoso et al (2011)our hunting spider groups could be grouped into just two guilds ambush hunters


(E tricuspidata and Xysticus spp) and other hunters (C xanthogramma Other salticidsPh cespitum and Clubiona spp)

Using the slightly modified prey classification system ofMichalko amp Pekaacuter (2015) preyitems retrieved from spiders or collected by D-VAC sampling were classified into thefollowing 16 taxonomic groups Acari Araneae Coleoptera Lepidoptera FormicidaeOther (non-formicid) Hymenoptera Brachycera Nematocera (ie all non-Brachyceradipterans) Auchenorrhyncha Heteroptera Sternorrhyncha Ephemeroptera NeuropteraPsocoptera Thysanoptera and Trichoptera The prey categories that had relativeabundances of less than 1 in the total actual prey of the whole arboreal hunting spiderassemblage namely Acari Ephemeroptera Neuroptera Psocoptera Thysanoptera andTrichoptera were pooled into the group of lsquoOther preyrsquo in certain statistical analyses

To evaluate the biological control potential of the hunting spiders the prey items werecategorized according to their economic status in apple orchards in Central Europe aspests natural enemies and neutral arthropod groups A prey species was considered tobe a pest if at least one of its life stages is known to feed on any parts of the apple treeThe pest category included some beetles (mainly weevils) some moths (both adult andlarva of for example leaf miners tortrix moths) some leafhoppers and planthopperslace bugs and all aphid and psyllid (Sternorrhyncha) species Natural enemies aredefined as species that can feed (at least in one of their life stages) on any stage ofarthropods that were previously categorized as pests This category includes red velvetmites (Trombidiidae) spiders predatory beetles (eg coccinellids carabids) parasitoidwasps hoverflies zoophagous bugs (eg some mirids and anthocorids) and lacewingsFinally the neutral category was comprised of other (non-pest and non-natural enemy)prey species For prey that could be identified only to suborder such as Nematocera theclassification was made according to the dominant characteristics of the taxon (ie thevast majority of Nematocera occurring in apple orchard are neutral species (Alford 2014))

Only a few species of Diptera cause damage on apple in Europe (Dasineura mali(Keifer) Resseliella oculiperda (Ruumlbsaamen) (Nematocera) and Phytomyza heringianaHendel (Brachycera)) and they are of minor importance (Alford 2014) None of thesespecies or their damage were found in the orchard (Uacutejfeheacutertoacute) Drosophila suzukii(Matsumura) (and other Drosophila species Brachycera) can breed exclusively onoverripe bruised and rotten apples and usually infests fallen fruits Therefore in appleorchards this species considered to be as a decomposer (Alford 2014) Based on theseconsiderations Nematocera and Brachycera dipterans (excluding hoverflies) wereclassified as neutral species The role of ants could change seasonally depending on the sizeof the aphid colonies In apple orchards ants act as mutualists in the early phase of theaphid population development (Nagy Cross amp Markoacute 2015) However later when theaphid abundance is already high ants follow rather than drive aphid abundances(Markoacute et al 2013) Because of the above criteria and because of vast majority of antscaptured by spiders were dispersing males or workers at the peak of aphid abundance antswere also classified as neutral prey Economic classification can be seen in Data S1 in moredetail


Data analysisAll statistical analyses were performed within the R (v353) statistical environment(R Core Team 2019) For all analyses the natural prey data were pooled across orchardsand years (see later) except for the comparison of actual and potential prey where only thedata collected at the same place (Uacutejfeheacutertoacute) and in the same years (2016ndash2017) wereanalyzed

Comparison of actual versus potential preyGeneralised Linear Mixed Models with binomial error structure (GLMM-b) (Pekaacuter ampBrabec 2016) were used to compare the relative frequency of prey taxa or economic groupsbetween the actual and potential prey For these analyses abundance data in each preycategory were pooled for each season (spring summer and fall) regarding the givenyear (2016 or 2017) In the model the response variable was a matrix (Pekaacuter amp Brabec2016) containing the abovementioned seasonal counts of a given prey category and thedifference of these seasonal counts and the seasonal sums of all actual or potential preycounts for the given year Prey taxa their economic status prey type (actual vs potential)season and year were entered in the model as fixed factors and the interactions werecalculated (Prey taxaEconomic status times Prey type Prey taxaEconomic status times Seasonand Prey taxaEconomic status times Year) The model included an observation level randomeffect to avoid overdispersion Significant interaction (eg between Prey taxa and Preytype) implies that hunting spiders select prey disproportionately Model contrasts for theprey types within each prey categories were computed separately using the R packageldquoemmeansrdquo (Lenth et al 2020) For the raw data of the previous analyses see Data S2

To assess the degree of selectivity shown by spiders Ivlevrsquos electivity indices (IE) werecomputed based on the relative abundances of the actual and potential prey categories(collected in Uacutejfeheacutertoacute 2016ndash2017) To filter out the effect of year first the index valueswere calculated for each year and prey category (taxonomic or economic) and thenmean index values were calculated For economic categories the abundances werecalculated as sums of all prey items belonging to the given category The IE values rangebetween minus1 and +1 where negative and positive values indicate negative and positive preyselection relative to prey availability in the environment respectively (Cock 1978)

Comparison of spider and prey composition on temporal and spatialscaleThe accuracy of our hand sampling method was evaluated and the selectivity in spiderpredation was examined from another perspective as well For this a Mantel test based onMorisita dissimilarity distance was performed to calculate the correlation between thematrices of monthly abundance of the six spider groups in hand-collected versus suctionsamples (Uacutejfeheacutertoacute 20162017 see Table S3) and between the matrices of monthlyabundance of actual versus potential prey groups (Uacutejfeheacutertoacute 20162017 see Table S4)using the ldquovegdistrdquo function of the R package ldquoveganrdquo (Oksanen et al 2019) and theldquomantelrdquo function of the R package ldquoecodistrdquo (Goslee amp Urban 2019) The same methodwas used to compare the abundances of the actual prey groups for the six most abundant


spider taxa in Uacutejfeheacutertoacute 20162017 with those from other sites or years (see Table S5)For further statistics the data from Uacutejfeheacutertoacute 20162017 were pooled with the rest of theobservations (as noted in ldquoResultsrdquo)

Food web metrics niche width and niche overlapTo compare the trophic characteristics of the six most abundant spider taxa specializationmetrics (a measure of stenophagy) trophic niche width and degree of niche overlapwere calculated based on the taxonomic composition of the spidersrsquo prey (see the upperpart of the Table S6) Food web specialization was calculated at both the network andspecies level (Bluumlthgen Menzel amp Bluumlthgen 2006) Web specialization (H2prime) was calculatedusing ldquoH2funrdquo function while species-level specialization (dprime) was calculated for the sixspider taxa using the ldquodfunrdquo function of the R package ldquobipartiterdquo (Dormann Fruend ampGruber 2020) The values of these quantitative frequency-based specialization metricsrange from 0 to 1 where 0 corresponds to total generalization and 1 corresponds toextreme specialization (Bluumlthgen Menzel amp Bluumlthgen 2006) To estimate the trophicniche breadth Levinsrsquo index (B) (Krebs 1999) was calculated using the R package ldquospaardquo(Zhang 2016) Niche overlap indices (NOs) between the six spider taxa based on preytaxonomic composition (categorical data) and prey size (log-transformed continuous data)were calculated using the script provided by Geange et al (2011) Null models with10000 permutations were used for each niche dimension (taxonomic size and overall)to test the possible differences between the occupied niches of the hunting spider groups(Geange et al 2011) Bonferroni correction was used to avoid the errors of multiplecomparisons 1 ndash NOs as a distance measures were used to visualize differences amongspider groups in their niches with multidimensional scaling (MDS) (Geange et al 2011)using ldquomonoMDSrdquo function of the R package ldquoveganrdquo (Oksanen et al 2019) Levinsrsquo Branges from 1 to n where n is the total number of resource states and 1 correspondswith maximum specialization while NO ranges from 0 to 1 where 1 corresponds withcomplete overlap (Krebs 1999 Geange et al 2011) As prey availability data were notavailable for every year and orchard they were not involved in the above-mentionedmeasures

Comparison of prey composition of spider groups using fourth-corneranalysisThe ldquofourth-corner analysisrdquo is an adequate multivariate technique for testingrelationships between abundance data and species or other environmental trait matrices(Dray amp Legendre 2008 Brown et al 2014 Comay amp Dayan 2018) The analysis providescoefficients indicating the strength of the association between each pair of traits andtests for significance using a permutation test (Dray amp Legendre 2008 Brown et al 2014)In the analyses the response variable was the abundance of the observed prey taxawhile the environmental components included species composition of the predators(ie spider groups) and seasonality (ie spring summer and fall) To calculatethese coefficients a LASSO-penalised regression model assuming a negative binomialdistribution for model errors was applied by the ldquomvabundrdquo R package (Wang et al 2012)


The size of a coefficient reflects the relative importance of the given interaction that ishow a coefficient changes the slope of the relationship between abundance and agiven environmental variable A spider group (or season) and a prey taxon was consideredas either negatively or positively associated if the absolute value of the coefficient wasgreater than 003

Analyses of the predatorndashprey size relationship and the variation inbody sizeTo analyze the spider-prey size relationship GLMs with gamma error structure andlog-link (GLM-g) were used due to the Gamma distribution of the prey thorax widths(Michalko amp Pekaacuter 2015 Pekaacuter amp Brabec 2016) As a new variable the thorax-prosoma(ie preyndashpredator) size ratio (prey thorax width divided by spider prosoma width)was computed in each possible spider-prey pair (if data was available) After that thevariation of the taxa-specific body traits the predator prosoma width prey thorax widthand thorax-prosoma ratio were analyzed separately by Linear Models (LMs) In all modelsthe body trait was the response variable while the spider group season and prey taxawere entered as predictor variables The body size variables were log-transformed toapproach normal distribution Special attention was paid to the life-stage-specificdifferences in two spider species (C xanthogramma and Ph cespitum) given bothspecies were collected in large numbers Within both species the individuals were groupedinto two life-stages juveniles and adults (ie adult and subadult individuals) In adultsthe data of different sexes were pooled for both species because there were nosex-specific differences in the investigated morphological traits (ie prey thorax widthC xanthogramma t = minus0315 df = 75406 P = 0753 Ph cespitum t = 1646 df = 45803P = 0107 thorax-prosoma ratio C xanthogramma t = minus0878 df = 65904 P = 0383Ph cespitum t = 0973 df = 39225 P = 0337) The following model structure was runin both species separately the log-transformed thorax-prosoma ratio was the responsevariable while the Life-stage (ie juvenile and adult) Prey taxa and Season (spring summerand fall) were the predictor variables (as factors) For testing the post-hoc contrasts Welchrsquost-test with the Holmrsquos correction (to avoid the errors of multiple comparisons) was used

To compare the widths of the niches with respect to prey size between the differentarboreal hunting spider groups or between the life stages of C xanthogramma and Phcespitum the variances (S2) in preyndashpredator size ratios were computed (as Michalko ampPekaacuter 2015) To compare variances Levenersquos test was used This test tolerates a slightdeviation from a normal distribution (Reiczigel Harnos amp Solymosi 2018) and thusthe data were not transformed to avoid the false interpretation of the results becausetransformation might have affected the variability of our data (Feng et al 2014) In the caseof multiple comparisons the P-values of Levenersquos test were adjusted using Holmrsquoscorrection

RESULTSA total of 878 hunting spider individuals belonging to 29 species and seven families werecollected with identifiable prey in their chelicerae from the canopy of apple trees between


2013 and 2019 (Table S1) The most abundant spider taxagroups in decreasing orderwere C xanthogramma Ph cespitum Clubiona spp Other salticids E tricuspidataand Xysticus spp which accounted for 89 of all spiders in the dataset (Table S2)Approximately 08ndash12 spiders with a prey item in the chelicerae were collected perperson-hour and 34 46 and 20 of the individuals were collected in the morningafternoon and after sunset respectively Species of Sternorrhyncha Brachycera andNematocera together accounted for 665 of the total prey of the hunting spiderassemblage and spiders most frequently (54) preyed upon arthropods that wereirrelevant to pest management (neutral prey) (Fig 1 Table S7) Aphids and spiderswere preyed upon to the greatest extent within the pest and natural enemy groupsrespectively (Tables S8 and S9) In contrast none of the hunting spiders collected in thisstudy preyed on larvae or adults of codling moth (Cydia pomonella (L)) the key pestof apple in Europe Two salticid individuals (one each of C xanthogramma andHeliophanus sp) were observed to feed on lacewing eggs For the monthly abundancecount of spider and prey groups see Tables S3 and S4 For the total hunting spiderassemblage prey size was significantly related to spider size (GLM-g F1 647 = 23574P lt 0001 R2 = 023) with the average prey thorax width and spider prosoma width being

Araneae65

Coleoptera44

Lepidoptera17

Formicidae79

Other Hymenoptera23

Brachycera193

Nematocera234

Auchenorrhyncha34

Heteroptera48

Sternorrhyncha238

Acari03

Ephemeroptera03

Neuroptera09

Psocoptera06

Thysanoptera03

Trichoptera01

Other26

0 10 20 30 40 50 60 70 80 90 100

Economic composition

Natural enemy15 (128)

Neutral54 (473)

Pest31 (277)

Natural prey of arboreal hunting spiders (N=878)

Taxonomic compositionA

B

Figure 1 Natural prey (N = 878) of arboreal hunting spiders collected in apple orchards Taxonomic(A) and economic (B) composition Full-size DOI 107717peerj9334fig-1


113 and 172 mm respectively while the average preyndashpredator size ratio was 067(SD 034) (see Fig S1)

Comparison of actual and potential preyIn the apple orchard located in Uacutejfeheacutertoacute in 2016 and 2017 the seasonal composition ofhand-collected spiders (with prey) and suction-sampled spiders correlated (Mantelrsquosr = 0605 P = 0004) which showed that our hand-collected sample represented wellthe total hunting spider assemblage in the canopy However the Mantel test showed nocorrelation between the seasonal composition of actual (held in the chelicerae) andpotential (suction-sampled) prey groups (r = 0013 P = 0957) (for the raw matricessee Tables S3 and S4) This suggests that the composition of actual prey was not stronglydriven by the composition of potential prey In accordance with this finding the relativefrequencies of actual prey groups differed significantly from those of potential prey(GLMM-b Prey taxa vs Prey type (actual vs potential) interaction LRT10 = 37680P lt 0001) demonstrating that hunting spiders as a community showed selectivity in theirdiet Brachycera and Nematocera were captured significantly more (GLMM-b contrastsP = 0002 and P = 0025 respectively) while Coleoptera was captured significantly less(GLMM-b contrast P lt 0001) frequently than their abundance would suggest (Figs 2and 3 Table S10) Lepidoptera Other Hymenoptera and Sternorrhyncha were marginally

Figure 2 Trophic link structure for the arboreal hunting spider assemblage (middle bar) and its prey(upper and lower bars) at Uacutejfeheacutertoacute Hungary 2016ndash2017 Trapezoids connecting the bars show thefrequency of prey categories in the natural diet of the spider assemblage (actual prey N = 452 center ofconnector) and in the canopy of apple trees (potential prey N = 11421 upper and lower end of con-nectors) Non‐parallel sides in a trapezoid suggest selectivity in spiders predation on the focal preycategory with an outward tapering trapezoid suggesting an overrepresentation and an outward wideningtrapezoid suggesting underrepresentation of the given taxon or economic group in the diet of spidersNote that the figure based on the 2 years sum of actual and potential prey items Numbers refer tofollowing prey taxa (1) Acari (2) Araneae (3) Coleoptera (4) Lepidoptera (5) Formicidae (6) OtherHymenoptera (7) Brachycera (8) Nematocera (9) Auchenorrhyncha (10) Heteroptera (11) Sternor-rhyncha (12) Ephemeroptera (13) Neuroptera (14) Psocoptera (15) Thysanoptera (16) Other preyitems Full-size DOI 107717peerj9334fig-2


significantly positively selected and Auchenorrhyncha was marginally significantlynegatively selected by spiders while Araneae Formicidae Heteroptera and Other prey taxawere preyed proportionally to their availability (Figs 2 and 3 for GLMM-b contrastssee Table S10) Brachycera had the highest Ivlevrsquos index value while Coleoptera hadthe lowest value of the Ivlevrsquos index being our measure of selective predation (Fig 3Table S10) The relative frequencies of prey groups differed significantly among seasons(GLMM-b Prey taxa times Season interaction LRT20 = 83765 P lt 0001) but not amongyears (GLMM-b Prey taxa times Year interaction LRT10 = 12846 P = 0232)

Considering the economic status of prey species the proportions of the categories in theactual prey differed significantly from the potential prey (GLMM-b Prey status times Prey type(actual vs potential) interaction LRT2 = 15286 P lt 0001 Figs 2 and 3 Table S10)We found that the actual prey of arboreal hunting spiders consisted of proportionallymore neutral prey and fewer pest individuals (GLMM-b both contrast P = 0002) ascompared with the relative abundance of potential prey (Fig 3 Table S10) Naturalenemies were preyed proportionally to their availability (Fig 3 Table S10) The diets of allhunting spider groups show a similar pattern (Fig 4) Based on the Ivlevrsquos index four outof the six spider taxa selected natural enemies positively (Fig 4) The proportions ofthe economic categories differed marginally between seasons (GLMM-b Prey status times

Pest

Neutral

Natural enemy

Other prey

Sternorrhyncha

Heteroptera

AuchenorrhynchaNematocera

Brachycera

Other HymenopteraFormicidae

Lepidoptera

Coleoptera

Araneae

-05 00 05

axaT

Ivlev index of electivity(and results of comparison of proportion of prey

types between the actual and potential prey)

+

+

+

+

Figure 3 Ivlevrsquos electivity index for the arboreal hunting spider assemblage Uacutejfeheacutertoacute Hungary2016ndash2017 A total of 2-year means of the index values In the given group asterisks indicate sig-nificant (P lt 005 P lt 001 P lt 0001) or marginally significant (+P lt 01) deviation between spiderdiet and relative abundance of potential prey based on model contrasts For the indices and P values seeTable S10 Full-size DOI 107717peerj9334fig-3


Season interaction LRT4 = 9427 P = 0051) without difference between years(GLMM-b Prey status times Year interaction LRT2 = 3284 P = 0194)

Food web metrics niche width and niche overlapFor further analyses we focused only on the most abundant hunting spider groups As theabundances of the actual prey groups for the six most abundant spider taxa at Uacutejfeheacutertoacute20162017 were correlated (Mantelrsquos r = 0515 P = 0003) with those from other sitesor years (see Table S5) the data were pooled across all sites and years Figure 5 shows thetrophic interactions between the spider groups and the canopy-dwelling arthropodcommunity for the whole growing season Overall considering each grouprsquos abundancethe highest predation pressure for most prey groups (Araneae Formicidae Other

Figure 4 Ivlevrsquos electivity index for arboreal hunting spider groups Uacutejfeheacutertoacute Hungary 2016ndash2017A total of 2-year means of the index values N = 214 26 73 24 22 and 57 for (A) C xanthogramma(B) Other salticids (C) Ph cespitum (D) E tricuspidata (E) Xysticus spp and (F) Clubiona spprespectively Full-size DOI 107717peerj9334fig-4


Hymenoptera Brachycera Auchenorrhyncha Heteroptera and Sternorrhyncha) wasimposed by C xanthogramma Most nematoceran prey were consumed by Ph cespitumwhile coleopterans were preyed on mainly by Xysticus spp In addition Ph cespitum andClubiona spp exerted a high predation pressure on Sternorrhyncha and Xysticus sppdid so on Formicidae (Fig 5) The majority of natural enemies were consumed byC xanthogramma and the diets of Ph cespitum and Clubiona spp had the highest numberof pests relative to the number of captured natural enemies (Fig 5 for the raw data ofthe food-web see Table S6) The seasonal abundance of the spider and potential preygroups and therefore the food web structure showed significant seasonal change(Figs S2ndashS4) While Ph cespitum was the most abundant hunting spider species in springC xanthogramma dominated in summer and fall Brachycera Nematocera andSternorrhyncha were the most abundant prey groups in spring summer and fallrespectively (Figs S2ndashS4)

Food web specialization (H2prime) was the highest in spring and the lowest in summer(Table 1) In general hunting spiders were found to be generalists as their species-levelspecialization (dprime) was low (values are mostly close to 0) and their trophic niche breadth(B) was wide Xysticus spp followed by Ph cespitum was the most specialized (moststenophagous) group and in accordance with this had the narrowest niche breadth(Table 1)

Figure 5 Trophic interactions between the most abundant hunting spider groups and the arthropodcommunity in the canopy of apple trees Whole growing season N = 784 The middle bars representspider groups and upper and bottom bars represent the spidersrsquo prey divided taxonomically andaccording their economic status The width of the links between the trophic levels depict the frequency ofinteractions and bar widths indicate the relative abundance of each category Numbers refer to followingprey taxa (1) Acari (2) Araneae (3) Coleoptera (4) Lepidoptera (5) Formicidae (6) Other Hyme-noptera (7) Brachycera (8) Nematocera (9) Auchenorrhyncha (10) Heteroptera (11) Sternorrhyncha(12) Ephemeroptera (13) Neuroptera (14) Psocoptera (15) Thysanoptera (16) Trichoptera SpidersC xanth = Carrhotus xanthogramma O salt = Other salticids Ph cesp = Philodromus cespitumE tri = Ebrechtella tricuspidata Xys = Xysticus spp Club = Clubiona spp

Full-size DOI 107717peerj9334fig-5


Considering the taxonomic composition of their prey spider groups exhibited arelatively high level of trophic niche overlap (061 lt NO in all comparisons) exceptfor Xysticus spp which had a relatively distinct prey composition (NO lt 039 in allcomparisons) (Fig 6A Table S11) The highest levels of niche overlap (073 le NO)were observed between the following group pairs C xanthogramma and Other salticidsClubiona spp and Other salticids and E tricuspidata and Other salticids (Fig 6ATable S11) Spider groups displayed significant clustering in their distribution acrossniche space with respect to taxonomic composition of their prey (null model 10000permutations P lt 0001 Fig 6A Table S11) In contrast spider groups exhibited a highlevel of niche overlap (072 le NO in all comparisons) without significant clusteringacross niche space with respect to size of their prey (null model 10000 permutationsP = 0135 Table S11) When we considered both niche dimensions combined (taxonomicidentity and prey size) the realized niches of the spider groups clustered in niche space(null model 10000 permutations P lt 0001 Fig 6C Table S11) Although the overallniche overlap between spider groups remained relatively high (between 051 and 085Table S11) we found significant differences in 11 out of 15 pairwise comparisons (Fig 6C)For the detailed NOs and pairwise comparisons see Tables S11 and S12

Fourth-corner analysis of spider-prey associationsFourth-corner analysis revealed that the variables Spider groups (GLM-nbDev12 5 = 14895 P = 001) and Season (GLM-nb Dev10 2 = 8201 P = 0005) significantlycontributed to the prey selection by spiders Furthermore the interaction between Spidergroups and Season also explained a significant amount of variance in prey abundance(GLM-nb Dev0 10 = 21697 P = 0001) Coefficients for the significant predictors ofprey abundance are depicted in Fig 7 and the exact values are shown in Table S13 Preytaxa varied in their abundance across spider groups and within the growing season Taking

Table 1 Trophic niche width (B) and specialization metrics (dprimeand H2prime) for hunting spider groups

Carrhotusxanthogramma

Othersalticids

Philodromuscespitum

Ebrechtellatricuspidata

Xysticusspp

Clubionaspp

Levinsrsquo niche breadth (B)

Whole season 6512 5158 3275 5231 3842 4183

Predator specialization (dprime)

Whole season 0074 0045 0186 0065 0397 0066

Spring 0262 0075 0211 0048 0582 0186

Summer 0043 0157 0139 0094 0326 0060

Fall 0142 0161 0200 0212 0449 0097

Food web specialization (H2prime)

Whole season 0142

Spring 0256

Summer 0130

Fall 0190

Note Specialization indices range from 0 for extreme generalization to 1 for extreme specialization


Club

Cxanth adults

Cxanth juvs

Etri

Osalt

Phcesp adults

Phcesp juvs

Xys

MDS-1

MD

S-2

DStress = 0089

Cxanth

Club

Etri

Osalt

PhcespXys

MDS-1

MD

S-2

CStress lt 0001

Overall niche overlap

Club

Cxanth adultsCxanth juvs

Etri

Osalt

Phcesp adults

Phcesp juvs

Xyst

MDS-1

MD

S-2

BStress = 0071

Cxanth

Club

Etri

Osalt

Phcesp

Xyst

MDS-1

MD

S-2

AStress lt 0001

Niche overlap based on prey taxonomic composition

Figure 6 Trophic niche overlap between the most abundant arboreal hunting spider groups in appleorchards Interspecific similarities in niche overlap based on taxonomic composition of spidersrsquo naturalprey (A and B) and on two functional traits (C and D) (1) taxonomic composition of natural prey and(2) prey size (A and C) the six most abundant spider groups (B and D) the same but C xanthogrammaand Ph cespitum were split to juveniles (all juvenile stages) and adults (subadults and adults) Similaritiesare represented graphically as multi-dimensional scaling Ellipses encircle species occupying niches thatwere not identified as significantly different using null model tests Different marks and fill indicatedifferent guilds circle stalkers triangle ambushers square foliage runners (based on guild classificationby Uetz Halaj amp Cady (1999)) empty marks ambush hunters solid marks other hunters (based on guildclassification by Cardoso et al (2011)) Spiders C xanth = Carrhotus xanthogramma O salt = Othersalticids Ph cesp = Philodromus cespitum E tri = Ebrechtella tricuspidata Xys = Xysticus sppClub = Clubiona spp Full-size DOI 107717peerj9334fig-6


into account the differences in total and seasonal abundances we found that as comparedto the other spiders C xanthogramma was positively associated (PA) with the prey groupsFormicidae (almost exclusively winged males) and Coleoptera and negativelyassociated (NA) with Nematocera Lepidoptera and Heteroptera Similar selectivity wasobserved in other spider groups as well Other salticids (PA Other HymenopteraSternorrhyncha NA Formicidae Nematocera) Ph cespitum (PA NematoceraSternorrhyncha Auchenorrhyncha NA Formicidae Coleoptera Lepidoptera)E tricuspidata (PA Other Hymenoptera Heteroptera Lepidoptera NA AraneaeAuchenorrhyncha) Xysticus spp (PA Formicidae Coleoptera Heteroptera NASternorrhyncha Brachycera Nematocera) Clubiona spp (PA SternorrhynchaLepidoptera NA Coleoptera) (Fig 7) The coefficient matrix also indicates significantseasonal variation in predation of certain prey taxa (eg Araneae Coleoptera NematoceraAuchenorrhyncha) throughout the season (Fig 7)

Intraguild differences and interguild similaritiesBased on the guild classification of Uetz Halaj amp Cady (1999) marked intraguilddifferences (Ph cespitum vs Xysticus spp and E tricuspidata vs Xysticus spp (null model10000 permutations P lt 0001 in both comparisons)) and high interguildsimilarities (E tricuspidata vs Other salticids Other salticids vs Clubiona spp and

Predator groups and seasons

xat yerPa

Other prey

Sternorrhyncha

Heteroptera

Auchenorrhyncha

Nematocera

Brachycera

Other Hymenoptera

Formicidae

Lepidoptera

Coleoptera

Araneae

-03

-02

-01

00

01

02

03

Figure 7 Fourth-corner analysis including standardized coefficients of prey taxa vs spider groupsand seasonal predictors (GLM model-based approach with LASSO penalty) Darker colors indicatestronger associations than paler ones positive associations are indicated by red negative associations areindicated by blue color For the coefficients see Table S13 Full-size DOI 107717peerj9334fig-7


E tricuspidata vs Clubiona spp) were found in the composition (taxonomic or taxonomic+ size) of natural prey (Figs 5 and 6 Table S11) Prey preferences could also differ within aguild (eg in ambushers (Ph cespitum vs E tricuspidata vs Xysticus spp) Fig 7)Based on the guild classification of Cardoso et al (2011) certain species also showedsignificant differences in their diet (Ph cespitum vs Clubiona spp C xanthogramma vsPh cespitum C xanthogramma vs Clubiona spp and E tricuspidata vs Xysticus spp (nullmodel 10000 permutations P lt 0001 in all comparisons Fig 6 Table S11)) orpreferences (eg C xanthogramma vs Ph cespitum or E tricuspidata vs Xysticus spprespectively Fig 7) within the guilds of other hunters or ambush hunters Furthermoredespite belonging to different guilds E tricuspidata and Other salticids or E tricuspidataand Ph cespitum showed no difference in trophic niche occupancy (Fig 6 Table S11)

Predatorndashprey size relationshipsA moderately strong exponential relationship was found between the spider and prey sizefor all six hunting spider groups (Fig 8) Spider size differed between spider groups(F5 553 = 31543 P lt 0001) seasons (F2 553 = 67337 P lt 0001) and also between preytaxa (F10 553 = 8703 P lt 0001) On average C xanthogramma and Xysticus spp had thewidest while Clubiona spp had the narrowest prosoma (Table 2) Prey size differedbetween spider groups (F5 553 = 8499 P lt 0001) seasons (F2 553 = 20554 P lt 0001) andbetween prey taxa (F10 553 = 30946 P lt 0001) Xysticus spp had prey with the widestwhile Clubiona spp had prey with the narrowest thorax (Table 2) The thorax-prosomaratio differed among the spider groups (F5 553 = 5014 P lt 0001) among the seasons(F2 553 = 13176 P lt 0001) and among the different prey groups (F10 553 = 24222P lt 0001) Compared to their own size Ph cespitum and C xanthogramma caught thesmallest whereas Xysticus and Clubiona spp caught the relatively largest prey items andthe difference between the first two species and Clubiona spp was significant (Fig 9Table 2) Furthermore C xanthogramma differed significantly from Xysticus spp in nichewidth with respect to prey size (S2 of thorax-prosoma ratios Fig 9)

The size of spiders and prey items decreased from spring to summer Spider sizeincreased afterwards whereas prey size remained low (Table 2 Fig S5) As a consequencethe thorax-prosoma ratio was identical in spring and summer (P = 0834) and decreasedin fall (compared to spring P = 0054 or summer P = 0020) (Table 2 Fig S5)Analysed separately the prey size was significantly related to spider size for all threemain prey groups (Brachycera Nematocera Sternorrhyncha) (Fig 10) However thepreyndashpredator (thorax-prosoma) size ratio was significantly different (P lt 0001 in allcomparisons) with Brachycera being the largest prey caught by a same-sized spiderindicating that the taxonomic identity of the prey influenced the preyndashpredator ratio(Fig 10)

Life stages of C xanthogramma and Ph cespitumOnly C xanthogramma and Ph cespitum were collected in numbers high enough toanalyze their prey in more detail Comparing the prey of the spider life stages the followingresults were obtained C xanthogramma adults had the widest trophic niche breadth


(B = 676) followed by C xanthogramma juveniles (B = 585) Ph cespitum adults(B = 432) and Ph cespitum juveniles (B = 251) (Table S14) Considering the taxonomiccomposition of their prey (Table S15) these four groups showed a high level of nicheoverlap (070 lt NO) except for the lower overlap (NO lt 054) between Ph cespitumjuveniles and both adults and juveniles of C xanthogramma (Fig 6B Table S12) WhenC xanthogramma and Ph cespitum were split to juveniles and adults spider groupsdisplayed significant clustering across niche space regarding taxonomic composition(null model 10000 permutations P lt 0001 Fig 6B) and size of the prey (null model10000 permutations P = 0008) and across niche space incorporating these two functionaltraits (null model 10000 permutations P lt 0001 Fig 6D) Ph cespitum adults occupieda trophic niche different from that of juvenile conspecifics (null model 10000permutations P = 0001) indicating an ontogenetic niche shift (Fig 6B) Taking intoaccount both niche dimensions (taxonomic identity and prey size) adults and juveniles of

Figure 8 Relationship between spider and prey size (spider prosoma and prey thorax widths jittered) for the most abundant arboreal huntingspider groups (AndashF) in apple orchards On the marginal boxplots red squares indicate means see Table 2



both species differed from each other in niche occupancy (C xanthogramma null model10000 permutations P lt 0001 Ph cespitum null model 10000 permutations P = 0001Fig 6D Table S12)

Although prey size was significantly related to spider size in both species (Fig 8)different results were obtained when life stages were taken into consideration (Fig 11)A significant relationship was found between predator and prey size for juveniles but notfor adults (Fig 11) However the thorax-prosoma size ratio was similar for the two lifestage groups (C xanthogramma F1 260 = 2814 P = 0095 Ph cespitum F1 91 = 1288P = 0259 Fig S6) while it was different among the various prey groups

Figure 9 Prey-spider (prey thorax vs spider prosoma) size ratios (jittered) for the arboreal huntingspider groups Red squaremdashmean black horizontal solid linemdashmedian black vertical rectanglemdashinterquartile range Different capital letters indicate significant differences among means while differentlowercase letters indicate significant differences among variances at P lt 005 level Letters in parenthesesrefer to pairwise comparisons with unadjusted P values Full-size DOI 107717peerj9334fig-9

Table 2 Spider prosoma and prey thorax widths and thorax-prosoma ratios (mean plusmn SD) for hunting spider groups and seasons

Spider taxa Pooled Season


Othersalticids

Philodromuscespitum


Xysticus spp Clubionaspp

Spring Summer Fall

N

275 46 105 44 46 55 571 161 293 117

Spider prosoma width (mm)

186 (056) C 153 (036) B 159 (042) B 178 (035) C 186 (068) BC 120 (043) A 171 (055) 192 (059) b 153 (039) a 189 (066) b

Prey thorax width (mm)

118 (064) B 099 (049) AB 097 (061) A 128 (085) AB 139 (088) B 088 (039) A 112 (066) 130 (069) b 106 (066) a 103 (056) a

Thorax-prosoma ratio

064 (028) A 066 (029) AB 062 (036) A 070 (041) AB 077 (050) AB 077 (030) B 066 (033) 068 (033) ab 069 (035) b 059 (027) a

Notes Spiders with no prosoma or prey thorax width data were excludedDifferent capital letters indicate significant differences between spider groups while different lowercase letters indicate significant differences between seasons at P lt 005level


(C xanthogramma F10 260 = 24133 P lt 0001 Ph cespitum F8 91 = 6338 P lt 0001)The three most abundant prey groups (Brachycera Nematocera Sternorrhyncha) differedfrom each other (1) C xanthogramma Brachycera vs Nematocera (P lt 0001) Brachyceravs Sternorrhyncha (P lt 0001) Nematocera vs Sternorrhyncha (P = 0001) and(2) Ph cespitum Brachycera vs Nematocera (P lt 0001) Brachycera vs Sternorrhyncha(P lt 0001) Nematocera vs Sternorrhyncha (P = 0019) in relation to thorax-prosomaratio that is a spider of a given size mostly caught larger Brachycera prey items than thoseof Nematocera or Sternorrhyncha (Fig S7) Among seasons the size ratio was different forC xanthogramma (F2 260 = 9776 P lt 0001) but not for Ph cespitum (F2 91 = 0358P = 07)

Figure 10 Relationship between spider and prey size (prosoma and thorax widths jittered N = 352)for the arboreal hunting spider groups and their main prey taxa Brachycera Nematocera andSternorrhyncha On the marginal boxplots red squares indicate the mean Pie charts show the relativefrequency of the three main prey groups for three different spider size categories (N = 135 117 and 100respectively) Full-size DOI 107717peerj9334fig-10


We found that C xanthogramma adults had numerically lower size variance whilePh cespitum adults had significantly greater variance (S2) in their size (prosoma width)compared to that in juveniles (Levenersquos tests C xanthogramma F1 272 = 3319 P = 007Ph cespitum F1 101 = 52 P = 0025) Adults of both species had significantly greatervariance in the size of their prey (thorax width) than juveniles (Levenersquos testsC xanthogramma F1 277 = 19282 P lt 0001 Ph cespitum F1 181 = 6745 P = 001)However the variance of thorax-prosoma ratio (niche width with respect to prey size) wasnot different between the life stages (Levenersquos tests C xanthogramma F1 272 = 0166P = 0685 Ph cespitum F1 101 = 0252 P = 0617) For detailed data see Table S14

Figure 11 Relationship between spider prosoma and prey thorax widths (jittered) for juveniles andadults of Carrhotus xanthogramma (A and B) and Philodromus cespitum (C and D) Adults (B and D)comprise both subadult and adult individuals On the marginal boxplots red squares indicate the meanvalues Full-size DOI 107717peerj9334fig-11


DISCUSSIONBased on 878 predator-prey records we analyzed the prey composition biologicalcontrol potential and trophic interactions of arboreal hunting spiders in apple orchardsAlthough they were found to be polyphagous predators in general hunting spidersselectively preyed upon canopy arthropods and the different spider speciesgroups differedfrom each other either in their diet composition or their prey size selection

Prey composition selectivity and efficiency in biological controlTwo-thirds of the hunting spidersrsquo prey were Sternorrhyncha Brachycera or Nematocera(Fig 1) Interestingly these are also the main prey groups of the web-building spidersin agricultural ecosystems (Birkhofer et al 2018) and are the groups most often consumedby spiders in general (Birkhofer amp Wolters 2012 Michalko amp Pekaacuter 2016) MostSternorrhyncha prey were aphids (mainly Dysaphis plantaginea (Passerini) and Aphispomi De Geer) Although aphids are regarded as a low-quality food (Toft 1995 2005Bilde amp Toft 2001) they appear relatively frequently among the prey of spiders(Alderweireldt 1994 Harwood Sunderland amp Symondson 2005 Kerzicnik et al 2012)What is more hunting spiders can contribute to aphid suppression in various agriculturalhabitats (Birkhofer et al 2008 De Roinceacute et al 2013 Lefebvre et al 2017) Ants (mainlyLasius niger (L)) made up almost 8 of the prey of hunting spiders and comprisedof both ant workers and winged malesqueens The fifth most frequent prey taxonwas Araneae (eg theridiid or linyphiid males or other hunting spiders such asC xanthogramma Ph cespitum) which comprised 65 of the total prey (Fig 1)Intraguild predation is very common among hunting spiders (Hodge 1999 Birkhofer ampWolters 2012 Mestre et al 2013) and spiders can make up to a quarter or a third ofthe hunting spidersrsquo diet (Michalko amp Pekaacuter 2016) Furthermore in this study weobserved two unusual predation events a C xanthogramma and a Heliophanus sp thatboth fed on stalked chrysopid eggs Oophagy although uncommon has been found insalticids (Nyffeler et al 1990 Ahmed et al 2018) and predation on lepidopteran eggs byC xanthogramma was observed by Hirose et al (1980)

Some prey types were consumed significantly more or less often by the arborealhunting spiders than expected from their respective abundances in the environment(Figs 2 and 3 Tables S7 and S10) indicating that these spiders are not strict opportunistsand do not feed in a frequency-dependent manner In general the groups Brachyceraand Nematocera (and possibly Other Hymenoptera Lepidoptera and Sternorrhyncha)were overrepresented while Coleoptera (and possibly Auchenorrhyncha) wereunderrepresented in the actual prey of the hunting spider community Selective foragingwas found both in epigeal (eg lycosids) and arboreal (eg philodromids) hunting spiders(Michalko amp Pekaacuter 2015 Whitney et al 2018 Eitzinger et al 2019)

Hunting spiders preyed mostly (54 of the diet) on arthropods irrelevant to pestmanagement in apple orchards in Central Europe such as Brachycera (excludinghoverflies) Nematocera and Formicidae (Fig 1) They also consumed a significant number(31) of pests eg aphids Phyllobius spp (Coleoptera Curculionidae)Metcalfa pruinosa(Say) (Auchenorrhyncha Flatidae) and psyllids (Table S8) although some of these


apple-feeding arthropods are considered only minor pests of apple in Hungary(eg M pruinosa) The rest of the prey (15 of the diet) was made up of natural enemiessuch as spiders zoophagous bugs parasitic wasps hoverflies and lacewings (Table S9)

The hunting spider assemblage showed the highest selectivity (positive preference) forneutral prey species and spiders preyed on pests less than would be expected based ontheir availability in the canopy of apple trees (Figs 2ndash4) Natural enemies were caughtmore often (but not significantly so) than their abundance would suggest This impliesthat hunting spiders exerted a relatively lower predation pressure on pests than on neutralprey or even on natural enemies The presence of alternative prey has been shown todisrupt biological control provided by generalist predators (Koss amp Snyder 2005) and inagreement with these findings our results suggest that hunting spiders can easily switchfrom pests to neutral (or beneficial) prey hampering the effectiveness of conservationbiological control in apple orchards Although generalist predators (single species orassemblages) can reduce pest numbers (Symondson Sunderland amp Greenstone 2002)intraguild predation often disrupts their action as biological control agents of herbivores(Rosenheim et al 1995 Rosenheim 1998) for example in the case of unidirectionalintraguild predation where the intermediate predators (eg zoophagous bugs parasiticwasps hoverflies and lacewings) are more effective at suppressing the target prey(aphids) than the top predators (spiders) (Vance-Chalcraft et al 2007) As spiders madeup almost 45 of the spider-consumed natural enemies (Table S9) it would be difficultto calculate their negative effect on the biological control of pests Nevertheless ourresults suggest that similar to several multi-enemy systems hunting spider assemblages ingeneral may often be unable to augment the pest suppression ability of local naturalenemies but instead reduce the overall predation pressure on pests via intraguildpredation (Rosenheim Wilhoit amp Armer 1993 Yasuda amp Kimura 2001 Finke amp Denno2003 2004 2005) However there are some examples where presence of alternative preyhas reduced the intensity of intraguild predation (eg Rickers Langel amp Scheu 2006)

Specific differences in the diet and in the pest control abilityWe found that different spider species exerted different levels of predation on a given preytaxon (Fig 5 Table S6) Although these trophic interactions strongly depended on boththe abundances of predator and prey species and on the season (Figs S2ndashS4) thefourth-corner analysis indicated an inherent species-specific prey selection pattern amonghunting spiders (Fig 7 Table S13) This suggests some selectivity in foraging behavior(Nentwig 1980 Whitney et al 2018 Eitzinger et al 2019) but the influence of otherspecies-specific factors such as microhabitat preference (Schmitz amp Suttle 2001) huntingstrategy (Schmitz 2008 Liu et al 2015 Sanders Vogel amp Knop 2015) or temporalniche (Morse 1981Herberstein amp Elgar 1994Mezőfi et al 2019) on the prey compositionalso cannot be excluded

We observed relatively high levels of niche overlap which indicates a functionalredundancy (Roubinet et al 2018) within hunting spiders in the canopy of apple trees(Fig 6 Tables S11 and S12) Food web specialization was the highest in spring and thelowest in summer (Table 1) and was mainly driven by the prey groups Brachycera


Nematocera and Sternorrhyncha (Figs S2ndashS4) Similarly food web specialization washigher in the early than in the late period of the growing season in barley fields and thisvariation was suggested to be explained by prey availability dynamics (Roubinet et al2018) Species-level specialization was also the highest in spring in four out of six spidergroups (Table 1) Overall Ph cespitum and Xysticus spp showed the highest level ofstenophagy and in accordance with that the narrowest niche breadth (Table 1) becausePh cespitum mainly preyed on Nematocera and Sternorrhyncha while the diet of Xysticusspp was comprised mostly of Formicidae and Coleoptera (Fig 5 Table S6)

The prey composition of Xysticus spp was very different from that of the other spidergroups (Fig 6 Table S11) Brachycera Nematocera and Sternorrhyncha were allconsumed by Xysticus spp in much lower proportions (16) than by the other spiders(60ndash88) (Fig 5 Table S6) In contrast to our findings Xysticus spp was reported to preyintensively on Diptera in hay meadows X cristatus on aphids in winter wheat and X kochion thrips pests in greenhouse pepper (Nyffeler amp Breene 1990 Birkhofer et al 2008Zrubecz Toth amp Nagy 2008) Based on these findings it seems that although we foundXysticus spp to be the most stenophagous hunting spider group it had a high level ofplasticity in its use of available resources

Fourth-corner analysis showed that spider groups discriminated among prey taxaand each spider group had a certain degree of prey preference and avoidance On acommunity level different species of spiders partly complement each other via resourcepartitioning if a particular prey group was avoided by one spider group it was usuallypreferred by another (Fig 7 Table S13) For example compared to the other spidersColeoptera and Formicidae prey was rejected by Ph cespitum but preferred byC xanthogramma and Xysticus spp Similar to our results Michalko amp Pekaacuter (2015)found that the Philodromus species they studied rejected these two types of preyThe formicid prey of C xanthogramma consisted almost exclusively of winged males assalticids usually refuse dangerous ant workers as prey (Richman amp Jackson 1992Huseynov 2005) but Xysticus species as in our case consume workers frequently(Nyffeler amp Breene 1990 Huseynov 2014)

It would be expected that spider species within the same guild would exhibit more orless uniform resource utilization patterns (eg Luiselli Akani amp Capizzi 1998Michalko ampPekaacuter 2016) but our results do not support this view In the canopy level of thestudied apple orchards we found marked intraguild differences and interguild similaritiesin the taxonomic composition of hunting spidersrsquo prey or in their prey preferences (Figs 6and 7) These results agree with Mestre et al (2013) who reported trophic differencesbetween spider species belonging to the same family Overall we found no evidence thathunting guild consistently determines prey composition Possibly the guild approach failsto identify finer trophic dynamics and thus for a more accurate understanding ofspider-prey community patterns the use of (species-specific) functional traits is needed(Fountain-Jones Baker amp Jordan 2015 Sanders Vogel amp Knop 2015)

Hunting spiders among prey designated as pest most frequently consumed aphids(Table S8) Among hunting spiders Ph cespitum caught the most aphids in spring(Fig S2) and possibly contributed to aphid control especially in the early season by


preying upon fundatrices and their larvae (De Roinceacute et al 2013Michalko amp Pekaacuter 2015Lefebvre et al 2017) In addition Ph cespitum also feeds on other pests (Klein 1988Wisniewska amp Prokopy 1997 Ghavami 2008 Michalko et al 2017) This spider remainsactive during winter when other predators are dormant and consequently it can alsoreduce for example overwintering psyllid populations (Pekaacuter et al 2015 Petraacutekovaacute et al2016) Ph cespitum is among the most abundant hunting spiders in the canopy ofapple orchards both in Europe (Bogya Szinetaacuter amp Markoacute 1999 Pekaacuter 1999 Pekaacuter ampKocourek 2004Markoacute et al 2009) and North America (Miliczky Horton amp Calkins 2008Sackett Buddle amp Vincent 2008) and in our study it consumed the second-highestnumber of pests (following Clubiona spp) compared to the number of natural enemies itconsumed (Fig 5 Table S6) Based on the above facts this species could possibly be oneof the most effective araneid biological control agents in the canopy of fruit trees intemperate regions especially in the orchards with reduced use of insecticides (ŘezaacutečPekaacuter amp Staraacute 2010Michalko amp Košulič 2016 Řezaacuteč Řezaacutečovaacute amp Heneberg 2019) BesidePh cespitum Clubiona spp (mostly C frutetorum) exerted considerable predationpressure on aphids especially in autumn (Fig 5 Fig S4) There are some examples wherespiders reduced aphid infestation by catching aphids immigrating back to the orchard inautumn (Wyss Niggli amp Nentwig 1995 Cahenzli Pfiffner amp Daniel 2017) and possiblyclubionids also have a high predation potential in this context Furthermore accordingtoMadsen Terkildsen amp Toft (2004) the level of predation on aphids by Clubiona lutescensWestring is not affected by the presence of alternative prey Clubionids may also contributeto early season aphid control (Fig S2 De Roinceacute et al 2013) and they may reducepopulations of lepidopteran pests by consuming both larvae and adults (Fig 7 Bogya1999) The diet of Clubiona spp had the lowest proportion of natural enemies (Figs 4and 5 Table S6) which suggests that clubionids are more compatible with biologicalcontrol than several other hunting spiders Meanwhile C xanthogramma is one of themost common species of spiders in the canopy of pome fruit orchards in Hungary where itcan dominate the arboreal spider assemblage (Bogya Szinetaacuter amp Markoacute 1999 BogyaMarkoacute amp Szinetaacuter 2000 Markoacute amp Keresztes 2014) Due to its high abundance it exertsstrong predation pressure on several prey taxa (Fig 5 Table S6) but as Markoacute ampKeresztes (2014) previously supposed in this study C xanthogramma was found to be asignificant intraguild predator of natural enemies especially spiders (Fig 5) Beside pestsits diet was comprised of a great number of beneficial prey as well (32 vs 19respectively) and according to the fourth-corner analyses it proved to be the mostaraneophagic species compared to the other spider taxa examined (Fig 7 Table S13)Due to its high level of intraguild predation and low abundance in springC xanthogramma is possibly not an effective biological control agent As intraguildpredation on spiders is widespread among generalist salticids (Markoacute amp Keresztes 2014)the arboreal spider assemblage presumably has higher pest suppression potential in appleorchards in northern Europe where the proportion of salticid spiders in the spiderassemblages is lower than in central or southern Europe where the proportion of salticidspiders is higher (Bogya Markoacute amp Szinetaacuter 1999)


Although spiders are characterized as polyphagous predators with a high level offunctional redundancy (Figs 5 and 6 Foelix 2011 Roubinet et al 2018) they exertdifferent predation pressure on different arthropod groups (Fig 5 Figs S2ndashS4) and havetheir own preferences towards certain prey taxa (Fig 7 Nentwig 1986) which means thatthe degree of pest suppression depends on the taxonomic composition of the huntingspider assemblage and on the taxonomic identity of the key pests In other way asBirkhofer et al (2008) suggested promoting particular species (in our context Ph cespitumand Clubiona spp) or particular pest-consuming functional groups might be moreeffective in biological control rather than enhancing predator biodiversity as the effect ofincreased diversity is highly context-dependent (Markoacute amp Keresztes 2014Michalko et al2019)

Predatorndashprey size relationshipsThe size of the prey was strongly related to the size of the hunting spiders and on averageprey size was 67 that of the spider (see Fig S1) Analysed separately there was asignificant exponential relationship between the six most abundant spider taxa and theirprey with prey size being 62ndash77 of predator size (Fig 8 Table 2) Prey size relates topredator size in both hunting spiders (Nentwig 1982 Bartos 2011) web-builders (Brown1981 Murakami 1983) but many other animals (Luiselli Akani amp Capizzi 1998Amundsen et al 2003) This relationship suggests that the size of the prey has animportant role in prey selection especially in active hunters Hunting spiders have tooptimize their energy and nutritional intake while minimizing risk and therefore preferprey items in the 60ndash80 range of their own size However they regularly capturedprey that are larger or smaller than the preferred size (Fig 8) Furthermore without takinginto account the shape of the spider prosoma different species of spiders can preferdifferent prey size (thorax width) relative to their own size (prosoma width) Ph cespitumcaught the smallest prey items compared to their body size followed by C xanthogrammawhile clubionids caught the largest prey (Fig 9 Table 2) We also found a significantdifference in niche width with respect to prey size relative to their own sizeC xanthogramma caught prey from the narrowest prey size range while Xysticus sppcaught prey from the broadest size range suggesting that the size of the prey is not equallyimportant for different hunting spider species (or for different hunting strategies)when choosing prey (Fig 9) Preyndashpredator size ratios differed not only between spidergroups but also between prey taxa (Fig 10 Fig S7) This shows that size and taxonomicidentity of the prey are not independent factors In this study spiders of the same sizecaught larger Brachycera than they did Nematocera prey Finally the preyndashpredatorsize ratio differed between summer and fall This seasonal difference could be partlyexplained by prey availability dynamics or by the fact that both the spiders and their preydiffered in size between seasons (Table 2 Fig S5) Nevertheless the preyndashpredator sizeratios observed were possibly determined not only by the preferences of spiders but tosome extent by the available range of prey size in the environment (Tsai Hsieh ampNakazawa 2016) Overall beside taxonomic identity the size of the prey also matters in


prey selection though its importance may vary depending on the hunting strategy orspider species

Ontogenetic niche shifts in C xanthogramma and Ph cespitumOntogenetic niche shifts are common in the animal kingdom (Nakazawa 2015) Suchshifts are well documented for example in aquatic systems (Amundsen et al 2003) but arelargely understudied in spiders In general we observed that the diet of C xanthogrammaadults included more Coleoptera and Auchenorrhyncha and fewer Formicidae andNematocera while the diet of Ph cespitum adults comprised more Brachycera andAuchenorrhyncha and fewer Nematocera than did the diet of the juveniles (Table S15)However an ontogenetic niche shift in prey type and size was observed only forPh cespitum even though the sesonal occurrence of juveniles overlapped with that of theadults (Figs 6B and 11) In contrast C xanthogramma exhibited ontogenetic shift only inprey size despite little seasonal overlap between the two life stages (Figs 6D and 11)There was no difference between the life stages in preyndashpredator size ratio (Fig S6Table S14) However we found an ontogenetic shift in the niche breadth the adults ofC xanthogramma and Ph cespitum preyed upon a wider taxonomic and size range of preythan did their juveniles (Table S14) Bartos (2011) studied the natural prey of anothersalticid Yllenus arenarius Simon and obtained similar results the prey size whenstandardized relative to spider size did not differ between life stages but the trophic nichewidth increased during the course of the predatorrsquos development A similar increase introphic niche width with ontogeny was reported for the philodromid Ph disparWalckenaer (Sanders Vogel amp Knop 2015) In connection to the larger variance in preysize for adults we found significant relationship between predator and prey size only injuveniles but not in adults (Fig 11 but see the marginally significant relationship inPh cespitum adults) In a web-builder spider Argiope amoena L Koch Murakami (1983)found a similar relationship both prey size and prey size range increased with the increaseof the prosoma width A simple explanation for these findings would be that the preysize of spiders is (size-specifically) upper-bounded but not lower-bounded and thereforethe larger spiders can choose from a wider size and taxonomic range of prey

CONCLUSIONSBy analyzing a total of 878 hunting spider prey items collected from the canopy of appletrees in apple orchards in Hungary we concluded that (1) although highly polyphagousarboreal hunting spiders forage selectively and therefore cannot be considered asentirely opportunistic predators We found that more Brachycera Nematocera (andpossibly Other (non-formicid) Hymenoptera Lepidoptera and Sternorrhyncha) andless Coleoptera (and possibly Auchenorrhyncha) were consumed by the hunting spiderassemblage than would be expected from their abundance in the canopy of apple trees(2) Hunting spider assemblages consume a large number of pests However this beneficialeffect is strongly constrained by the high predation levels on natural enemies (intraguildpredation) and on neutral insects (propensity to switch from pests to alternative prey)


In this study the hunting spider assemblage showed positive selection for neutral preyneutral selection for natural enemies and negative selection for pests (3) In trophic websdifferent hunting spider taxagroups mediate different strengths of trophic effects ondifferent prey taxa and the web structure changes considerably with the season(4) The natural prey of hunting spider species is highly overlapped showing functionalredundancy in their predation (5) Nevertheless hunting spider species show differenttrophic niche occupancy also exhibit a certain level of stenophagy (species-specific preypreference) and select prey by its taxonomic identity and size (6) The guilds do notdetermine the preferred or rejected prey types consistently thus the diet of huntingspiders classified into the same guild can be considerably different (7) From an economicpoint of view Ph cespitum and Clubiona spp were found to be the most effective naturalenemies because of their high level of aphid (Ph cespitum and Clubiona spp) andLepidoptera (Clubiona spp) consumption and low level of intraguild predation(8) The trophic niche width of C xanthogramma and Ph cespitum increased duringontogeny where adults prey upon a wider taxonomic and size range of arthropods thanjuveniles Ph cespitum exhibited an ontogenetic shift in prey type whereas no such patternwas observed for C xanthogramma

ACKNOWLEDGEMENTSThe authors would like to thank Kristoacutef Baacutersony Rebeka Saliga Csaba Borbeacutely and SzilviaMezőfi for their assistance in collecting spiders and Petr Dolejš and Theo Blick forproviding literature The authors are grateful to Radek Michalko and an anonymousreviewer for their valuable comments on the previous version of the manuscript

ADDITIONAL INFORMATION AND DECLARATIONS

FundingThis study was supported by the National Research Development and Innovation Officeof Hungary (K112743) and by the Ministry for Innovation and Technology within theframework of the Higher Education Institutional Excellence Program (NKFIH-1159-62019) in the scope of plant breeding and plant protection researches of Szent IstvaacutenUniversity The funders had no role in study design data collection and analysis decisionto publish or preparation of the manuscript

Grant DisclosuresThe following grant information was disclosed by the authorsNational Research Development and Innovation Office of Hungary K112743Ministry for Innovation and Technology within the framework of the Higher EducationInstitutional Excellence Program NKFIH-1159-62019

Competing InterestsThe authors declare that they have no competing interests


Author Contributions Laacuteszloacute Mezőfi performed the experiments analyzed the data prepared figures andortables authored or reviewed drafts of the paper and approved the final draft

Gaacutebor Markoacute analyzed the data authored or reviewed drafts of the paper and approvedthe final draft

Csaba Nagy conceived and designed the experiments performed the experimentsauthored or reviewed drafts of the paper and approved the final draft

Daacutevid Koraacutenyi performed the experiments authored or reviewed drafts of the paper andapproved the final draft

Viktor Markoacute conceived and designed the experiments authored or reviewed drafts ofthe paper and approved the final draft

Data AvailabilityThe following information was supplied regarding data availability

The raw data is available in the Supplemental Files

Supplemental InformationSupplemental information for this article can be found online at httpdxdoiorg107717peerj9334supplemental-information

REFERENCESAhmed J Hill DE Pearce RJ Kumar ANS Khalap R Mohan K 2018 Oophagy by

Hyllus semicupreus (Araneae Salticidae Plexippina) Peckhamia 171(1)1ndash6

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Birkhofer K Gavish-Regev E Endlweber K Lubin YD Von Berg K Wise DH Scheu S 2008Cursorial spiders retard initial aphid population growth at low densities in winter wheatBulletin of Entomological Research 98(3)249ndash255 DOI 101017S0007485308006019

Birkhofer K Wolters V 2012 The global relationship between climate net primary productionand the diet of spiders Global Ecology and Biogeography 21(2)100ndash108DOI 101111j1466-8238201100654x

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Bogya S Markoacute V Szinetaacuter C 1999 Comparison of pome fruit orchard inhabiting spiderassemblages at different geographical scales Agricultural and Forest Entomology 1(4)261ndash269DOI 101046j1461-9563199900035x

Bogya S Markoacute V Szinetaacuter C 2000 Effect of pest management systems on foliage- andgrass-dwelling spider communities in an apple orchard in Hungary International Journal of PestManagement 46(4)241ndash250 DOI 10108009670870050206000

Bogya S Szinetaacuter C Markoacute V 1999 Species composition of spider (Araneae) assemblages inapple and pear orchards in the Carpathian Basin Acta Phytopathologica et EntomologicaHungarica 3499ndash121

Breitling R 2019 A barcode-based phylogenetic scaffold for Xysticus and its relatives (AraneaeThomisidae Coriarachnini) Ecologica Montenegrina 20198ndash206 DOI 1037828em20192016

Brown KM 1981 Foraging ecology and niche partitioning in orb-weaving spiders Oecologia50(3)380ndash385 DOI 101007BF00344980

Brown AM Warton DI Andrew NR Binns M Cassis G Gibb H 2014 The fourth-cornersolutionmdashusing predictive models to understand how species traits interact with theenvironment Methods in Ecology and Evolution 5(4)344ndash352 DOI 1011112041-210X12163

Bucher R Menzel F Entling MH 2015 Risk of spider predation alters food web structure andreduces local herbivory in the field Oecologia 178(2)571ndash577 DOI 101007s00442-015-3226-5

Cahenzli F Pfiffner L Daniel C 2017 Reduced crop damage by self-regulation of aphids in anecologically enriched insecticide-free apple orchard Agronomy for Sustainable Development37(6)65 DOI 101007s13593-017-0476-0

Cardoso P Pekaacuter S Jocqueacute R Coddington JA 2011 Global patterns of guild composition andfunctional diversity of spiders PLOS ONE 6(6)e21710 DOI 101371journalpone0021710

Cock MJW 1978 The assessment of preference Journal of Animal Ecology 47(3)805ndash816DOI 1023073672

Comay O Dayan T 2018What determines prey selection in owls Roles of prey traits prey classenvironmental variables and taxonomic specialization Ecology and Evolution 8(6)3382ndash3392DOI 101002ece33899

De Roinceacute CB Lavigne C Mandrin JF Rollard C Symondson WOC 2013 Early-seasonpredation on aphids by winter-active spiders in apple orchards revealed by diagnostic PCRBulletin of Entomological Research 103(2)148ndash154 DOI 101017S0007485312000636

Dormann CF Fruend J Gruber B 2020 R Package lsquobipartitersquo 214 Available athttpsCRANR-projectorgpackage=bipartite (accessed 3 March 2020)

Dray S Legendre P 2008 Testing the species traits-environment relationships the fourth-cornerproblem revisited Ecology 89(12)3400ndash3412 DOI 10189008-03491


Eitzinger B Abrego N Gravel D Huotari T Vesterinen EJ Roslin T 2019 Assessing changes inarthropod predatorndashprey interactions through DNA-based gut content analysismdashvariableenvironment stable diet Molecular Ecology 28(2)266ndash280 DOI 101111mec14872

Feng C Wang H Lu N Chen T He H Lu Y Tu XM 2014 Log-transformation and itsimplications for data analysis Shanghai Archives of Psychiatry 26105ndash109DOI 103969jissn1002-0829201402009

Finke DL Denno RF 2003 Intra-guild predation relaxes natural enemy impacts on herbivorepopulations Ecological Entomology 28(1)67ndash73 DOI 101046j1365-2311200300475x

Finke DL Denno RF 2004 Predator diversity dampens trophic cascades Nature429(6990)407ndash410 DOI 101038nature02554

Finke DL Denno RF 2005 Predator diversity and the functioning of ecosystems the role ofintraguild predation in dampening trophic cascades Ecology Letters 8(12)1299ndash1306DOI 101111j1461-0248200500832x

Foelix RF 2011 Biology of spiders Third Edition Oxford Oxford University Press

Fountain-Jones NM Baker SC Jordan GJ 2015 Moving beyond the guild concept developing apractical functional trait framework for terrestrial beetles Ecological Entomology 40(1)1ndash13DOI 101111een12158

Geange SW Pledger S Burns KC Shima JS 2011 A unified analysis of niche overlapincorporating data of different types Methods in Ecology and Evolution 2(2)175ndash184DOI 101111j2041-210X201000070x

Ghavami S 2008 The potential of predatory spiders as biological control agents of cotton pests inTehran provinces of Iran Asian Journal of Experimental Sciences 22303ndash306

Goslee S Urban D 2019 R Package lsquoecodistrsquo 203 Available athttpsCRANR-projectorgpackage=ecodist (accessed 3 March 2020)

Greenstone MH 1999 Spider predation How and why we study it Journal of Arachnology27333ndash342

Harwood JD Sunderland KD Symondson WOC 2005 Monoclonal antibodies reveal thepotential of the tetragnathid spider Pachygnatha degeeri (Araneae Tetragnathidae) as an aphidpredator Bulletin of Entomological Research 95(2)161ndash167 DOI 101079BER2004346

Herberstein ME Elgar MA 1994 Foraging strategies of Eriophora transmarina and Nephilaplumipes (Araneae Araneoidea) Nocturnal and diurnal orb-weaving spidersAustralian Journal of Ecology 19(4)451ndash457 DOI 101111j1442-99931994tb00511x

Hirose Y Suzuki Y Takagi M Hiehata K Yamasaki M Kimoto H Yamanaka M Iga MYamaguchi K 1980 Population dynamics of the citrus swallowtail Papilio xuthus Linneacute(Lepidoptera Papilionidae) Mechanisms stabilizing its numbers Population Ecology21(2)260ndash285 DOI 101007BF02513625

Hodge MA 1999 The implications of intraguild predation for the role of spiders in biologicalcontrol Journal of Arachnology 27351ndash362

Huseynov EF 2005 Natural prey of the jumping spider Menemerus taeniatus (AraneaeSalticidae) European Journal of Entomology 102(4)797ndash799 DOI 1014411eje2005109

Huseynov EF 2007 Natural prey of the lynx spider Oxyopes lineatus (Araneae Oxyopidae)Entomologica Fennica 18(3)144ndash148 DOI 1033338ef84391

Huseynov EF 2014 Natural prey of the crab spider Xysticus marmoratus (Araneae Thomisidae)on Eryngium plants Journal of Arachnology 42(1)130ndash132 DOI 101636P13-861


Kerzicnik LM Chapman EG Harwood JD Peairs FB Cushing PE 2012 Molecularcharacterization of Russian wheat aphid consumption by spiders in winter wheatJournal of Arachnology 40(1)71ndash77 DOI 101636P11-761

Klein W 1988 Erfassung und bedeutung der in den apfelanlagen aufgetretenen spinnen (Araneae)als nuumltzlinge im grossraum Bonn D Phil thesis Rheinischen Friedrich-Wilhelms-UniversitaumltBonn

Koss AM Snyder WE 2005 Alternative prey disrupt biocontrol by a guild of generalist predatorsBiological Control 32(2)243ndash251 DOI 101016jbiocontrol200410002

Krebs CJ 1999 Ecological methodology Second Edition Menlo Park Benjamin Cummings

Kuusk AK Ekbom B 2010 Lycosid spiders and alternative food feeding behavior andimplications for biological control Biological Control 55(1)20ndash26DOI 101016jbiocontrol201006009

Lefebvre M Franck P Olivares J Ricard J-M Mandrin J-F Lavigne C 2017 Spider predation onrosy apple aphid in conventional organic and insecticide-free orchards and its impact on aphidpopulations Biological Control 10457ndash65 DOI 101016jbiocontrol201610009

Lenth R Singmann H Love J Buerkner P Herve M 2020 R Package lsquoemmeansrsquo 144Available at httpsCRANR-projectorgpackage=emmeans (accessed 3 March 2020)

Liu S Li Z Sui Y Schaefer DA Alele PO Chen J Yang X 2015 Spider foraging strategiesdominate pest suppression in organic tea plantations BioControl 60(6)839ndash847DOI 101007s10526-015-9691-2

Lockley TC Young OP 1987 Prey of the striped lynx spider Oxyopes salticus (AraneaeOxyopidae) on cotton in the delta area of Mississippi Journal of Arachnology 14395ndash397

Luiselli L Akani GC Capizzi D 1998 Food resource partitioning of a community of snakes in aswamp rainforest of south-eastern Nigeria Journal of Zoology 246(2)125ndash133DOI 101111j1469-79981998tb00141x

Liacuteznarovaacute E Pekaacuter S 2019 Trophic niche and capture efficacy of an ant-eating spiderEuryopis episinoides (Araneae Theridiidae) Journal of Arachnology 47(1)45ndash51DOI 1016360161-8202-47145

Maciacuteas-Hernaacutendez N Athey K Tonzo V Wangensteen OS Arnedo M Harwood JD 2018Molecular gut content analysis of different spider body parts PLOS ONE 13(5)e0196589DOI 101371journalpone0196589

Madsen M Terkildsen S Toft S 2004 Microcosm studies on control of aphids by generalistarthropod predators effects of alternative prey BioControl 49(5)483ndash504DOI 101023BBICO00000364427017166

Mansour F Rosen D Shulov A 1981 Disturbing effect of a spider on larval aggregations ofSpodoptera littoralis Entomologia Experimentalis et Applicata 29(2)234ndash237DOI 101111j1570-74581981tb03063x

Marc P Canard A Ysnel F 1999 Spiders (Araneae) useful for pest limitation and bioindicationAgriculture Ecosystems amp Environment 74(1ndash3)229ndash273 DOI 101016S0167-8809(99)00038-9

Markoacute V Jenser G Kondorosy E Aacutebrahaacutem L Balaacutezs K 2013 Flowers for better pest controlThe effects of apple orchard ground cover management on green apple aphids (Aphis spp)(Hemiptera Aphididae) their predators and the canopy insect community Biocontrol Scienceand Technology 23(2)126ndash145 DOI 101080095831572012743972

Markoacute V Keresztes B 2014 Flowers for better pest control Ground cover plants enhance appleorchard spiders (Araneae) but not necessarily their impact on pests Biocontrol Science andTechnology 24(5)574ndash596 DOI 101080095831572014881981


Markoacute V Keresztes B Fountain MT Cross JV 2009 Prey availability pesticides and theabundance of orchard spider communities Biological Control 48(2)115ndash124DOI 101016jbiocontrol200810002

Mestre L Pintildeol J Barrientos JA Espadaler X Brewitt K Werner C Platner C 2013 Trophicstructure of the spider community of a Mediterranean citrus grove a stable isotope analysisBasic and Applied Ecology 14(5)413ndash422 DOI 101016jbaae201305001

Mezőfi L Markoacute G Kovaacutecs P Markoacute V 2019 Circadian rhythms in the locomotor activity of thespiders Carrhotus xanthogramma (Salticidae) and Philodromus cespitum (Philodromidae)temporal patterns and sexual differences European Journal of Entomology 116(9)158ndash172DOI 1014411eje2019017

Michalko R Košulič O 2016 Temperature-dependent effect of two neurotoxic insecticides onpredatory potential of Philodromus spiders Journal of Pest Science 89(2)517ndash527DOI 101007s10340-015-0696-5

Michalko R Pekaacuter S 2015 The biocontrol potential of Philodromus (Araneae Philodromidae)spiders for the suppression of pome fruit orchard pests Biological Control 8213ndash20DOI 101016jbiocontrol201412001

Michalko R Pekaacuter S 2016 Different hunting strategies of generalist predators result in functionaldifferences Oecologia 181(4)1187ndash1197 DOI 101007s00442-016-3631-4

Michalko R Pekaacuter S Dulrsquoa M Entling MH 2019 Global patterns in the biocontrol efficacy ofspiders a meta-analysis Global Ecology and Biogeography 28(9)1366ndash1378DOI 101111geb12927

Michalko R Pekaacuter S EntlingMH 2019 An updated perspective on spiders as generalist predatorsin biological control Oecologia 189(1)21ndash36 DOI 101007s00442-018-4313-1

Michalko R Petraacutekovaacute L Sentenskaacute L Pekaacuter S 2017 The effect of increased habitat complexityand density-dependent non-consumptive interference on pest suppression by winter-activespiders Agriculture Ecosystems amp Environment 24226ndash33 DOI 101016jagee201703025

Miliczky ER Horton DR Calkins CO 2008 Observations on phenology and overwintering ofspiders associated with apple and pear orchards in south-central WashingtonJournal of Arachnology 36(3)565ndash573 DOI 101636T07-291

Miller JRB Ament JM Schmitz OJ 2014 Fear on the move predator hunting mode predictsvariation in prey mortality and plasticity in prey spatial response Journal of Animal Ecology83(1)214ndash222 DOI 1011111365-265612111

Morse DH 1981 Prey capture by the crab spider Misumena vatia (Clerck) (Thomisidae) on threecommon native flowers American Midland Naturalist 105(2)358ndash367 DOI 1023072424754

Murakami Y 1983 Factors determining the prey size of the orb-web spider Argiope amoena(L Koch) (Argiopidae) Oecologia 57(1ndash2)72ndash77 DOI 101007BF00379564

Nagy C Cross JV Markoacute V 2015 Can artificial nectaries outcompete aphids in ant-aphidmutualism Applying artificial sugar sources for ants to support better biological control of rosyapple aphid Dysaphis plantaginea Passerini in apple orchards Crop Protection 77127ndash138DOI 101016jcropro201507015

Nakazawa T 2015 Ontogenetic niche shifts matter in community ecology a review and futureperspectives Population Ecology 57(2)347ndash354 DOI 101007s10144-014-0448-z

Nentwig W 1980 The selective prey of linyphiid-like spiders and of their space webs Oecologia45(2)236ndash243 DOI 101007BF00346464

Nentwig W 1982 Epigeic spiders their potential prey and competitors relationship between sizeand frequency Oecologia 55(1)130ndash136 DOI 101007BF00386728


Nentwig W 1986 Non-webbuilding spiders prey specialists or generalists Oecologia69(4)571ndash576 DOI 101007BF00410365

Nentwig W Blick T Gloor D Haumlnggi A Kropf C 2019 Araneae spiders of EuropeVersion 092019 Available at httpwwwaraneaenmbech (accessed 5 September 2019)

Nentwig W Wissel C 1986 A comparison of prey lengths among spiders Oecologia68(4)595ndash600 DOI 101007BF00378777

Nyffeler M 1999 Prey selection of spiders in the field Journal of Arachnology 27317ndash324

Nyffeler M 2000 Ecological impact of spider predation a critical assessment of Bristowersquos andTurnbullrsquos estimates Bulletin of the British Arachnological Society 11367ndash373

Nyffeler M 2016 Phytophagy in jumping spiders the vegetarian side of a group of insectivorouspredators Peckhamia 137(1)1ndash17

Nyffeler M Benz G 1988 Feeding ecology and predatory importance of wolf spiders(Pardosa spp) (Araneae Lycosidae) in winter wheat fields Journal of Applied Entomology106(1ndash5)123ndash134 DOI 101111j1439-04181988tb00575x

Nyffeler M Birkhofer K 2017 An estimated 400-800 million tons of prey are annually killed bythe global spider community Science of Nature 104(3ndash4)30 DOI 101007s00114-017-1440-1

Nyffeler M Breene RG 1990 Spiders associated with selected European hay meadows and theeffects of habitat disturbance with the predation ecology of the crab spiders Xysticus spp(Araneae Thomisidae) Journal of Applied Entomology 110(1ndash5)149ndash159DOI 101111j1439-04181990tb00108x

Nyffeler M Breene RG Dean DA Sterling WL 1990 Spiders as predators of arthropod eggsJournal of Applied Entomology 109(1ndash5)490ndash501 DOI 101111j1439-04181990tb00080x

Nyffeler M Dean DA Sterling WL 1992 Diets feeding specialization and predatory role of twolynx spiders Oxyopes salticus and Peucetia viridans (Araneae Oxyopidae) in a Texas cottonagroecosystem Environmental Entomology 21(6)1457ndash1465 DOI 101093ee2161457

Nyffeler M Edwards GB Krysko KL 2017 A vertebrate-eating jumping spider (AraneaeSalticidae) from Florida USA Journal of Arachnology 45(2)238ndash241DOI 101636JoA-17-0111

Nyffeler M Knoumlrnschild M 2013 Bat predation by spiders PLOS ONE 8(3)e58120DOI 101371journalpone0058120

Nyffeler M Lapinski W Snyder A Birkhofer K 2017 Spiders feeding on earthworms revisitedconsumption of giant earthworms in the tropics Journal of Arachnology 45(2)242ndash247DOI 101636JoA-17-0131

Nyffeler M Olson EJ Symondson WOC 2016 Plant-eating by spiders Journal of Arachnology44(1)15ndash27 DOI 101636P15-451

Nyffeler M Pusey BJ 2014 Fish predation by semi-aquatic spiders a global pattern PLOS ONE9(6)e99459 DOI 101371journalpone0099459

Nyffeler M Sunderland KD 2003 Composition abundance and pest control potential of spidercommunities in agroecosystems a comparison of European and US studiesAgriculture Ecosystems amp Environment 95(2ndash3)579ndash612 DOI 101016S0167-8809(02)00181-0

Nyffeler M Symondson WOC 2001 Spiders and harvestmen as gastropod predatorsEcological Entomology 26(6)617ndash628 DOI 101046j1365-2311200100365x

Oksanen J Blanchet FG Friendly M Kindt R Legendre P McGlinn D Minchin PROrsquoHara RB Simpson GL Solymos P Stevens MHH Szoecs E Wagner H 2019 R Packagelsquoveganrsquo 25-6 Available at httpsCRANR-projectorgpackage=vegan (accessed 3 March 2020)


Pekaacuter S 1999 Effect of IPM practices and conventional spraying on spider population dynamics inan apple orchard Agriculture Ecosystems amp Environment 73(2)155ndash166DOI 101016S0167-8809(99)00024-9

Pekaacuter S Brabec M 2016 Modern analysis of biological data generalized linear models in RBrno Masaryk University Press

Pekaacuter S Coddington JA Blackledge TA 2012 Evolution of stenophagy in spiders (Araneae)evidence based on the comparative analysis of spider diets Evolution 66(3)776ndash806DOI 101111j1558-5646201101471x

Pekaacuter S Garciacutea LF Viera C 2017 Trophic niches and trophic adaptations of prey-specializedspiders from the Neotropics a guide In Viera C Gonzaga MO eds Behaviour and Ecology ofSpiders Cham Springer 247ndash274

Pekaacuter S Kocourek F 2004 Spiders (Araneae) in the biological and integrated pest management ofapple in the Czech Republic Journal of Applied Entomology 128(8)561ndash566DOI 101111j1439-0418200400884x

Pekaacuter S Michalko R Loverre P Liacuteznarovaacute E Černeckaacute L 2015 Biological control in winternovel evidence for the importance of generalist predators Journal of Applied Ecology52(1)270ndash279 DOI 1011111365-266412363

Pekaacuter S Toft S 2015 Trophic specialisation in a predatory group the case of prey-specialisedspiders (Araneae) Biological Reviews 90(3)744ndash761 DOI 101111brv12133

Petraacutekovaacute L Michalko R Loverre P Sentenskaacute L Korenko S Pekaacuter S 2016 Intraguild predationamong spiders and their effect on the pear psylla during winter Agriculture Ecosystems ampEnvironment 23367ndash74 DOI 101016jagee201608008

R Core Team 2019 R a language and environment for statistical computing Vienna RFoundation for Statistical Computing Available at httpswwwR-projectorg

Reiczigel J Harnos A Solymosi N 2018 Biostatisztika nem statisztikusoknak Second EditionBudapest Pars Kft

ŘezaacutečM Pekaacuter S Staraacute J 2010 The negative effect of some selective insecticides on the functionalresponse of a potential biological control agent the spider Philodromus cespitum BioControl55(4)503ndash510 DOI 101007s10526-010-9272-3

Řezaacuteč M Řezaacutečovaacute V Heneberg P 2019 Contact application of neonicotinoids suppresses thepredation rate in different densities of prey and induces paralysis of common farmland spidersScientific Reports 9(1)5724 DOI 101038s41598-019-42258-y

Richman DB Jackson RR 1992 A review of the ethology of jumping spiders (Araneae Salticidae)Bulletin of the British Arachnological Society 933ndash37

Rickers S Langel R Scheu S 2006 Stable isotope analyses document intraguild predation in wolfspiders (Araneae Lycosidae) and underline beneficial effects of alternative prey andmicrohabitat structure on intraguild prey survival Oikos 114(3)471ndash478DOI 101111j20060030-129914421x

Rosenheim JA 1998 Higher-order predators and the regulation of insect herbivore populationsAnnual Review of Entomology 43(1)421ndash447 DOI 101146annurevento431421

Rosenheim JA Kaya HK Ehler LE Marois JJ Jaffee BA 1995 Intraguild predation amongbiological-control agents theory and evidence Biological Control 5(3)303ndash335DOI 101006bcon19951038

Rosenheim JA Wilhoit LR Armer CA 1993 Influence of intraguild predation among generalistinsect predators on the suppression of an herbivore population Oecologia 96(3)439ndash449DOI 101007BF00317517


Roubinet E Jonsson T Malsher G Staudacher K Traugott M Ekbom B JonssonM 2018Highredundancy as well as complementary prey choice characterize generalist predator food webs inagroecosystems Scientific Reports 8(1)8054 DOI 101038s41598-018-26191-0

Sackett TE Buddle CM Vincent C 2008 Comparisons of the composition of foliage-dwellingspider assemblages in apple orchards and adjacent deciduous forest Canadian Entomologist140(3)338ndash347 DOI 104039n07-048

Sanders D Vogel E Knop E 2015 Individual and species-specific traits explain niche size andfunctional role in spiders as generalist predators Journal of Animal Ecology 84(1)134ndash142DOI 1011111365-265612271

Schmitz OJ 2008 Effects of predator hunting mode on grassland ecosystem function Science319(5865)952ndash954 DOI 101126science1152355

Schmitz OJ Beckerman AP OrsquoBrien KM 1997 Behaviorally mediated trophic cascades effects ofpredation risk on food web interactions Ecology 78(5)1388ndash1399DOI 1018900012-9658(1997)078[1388BMTCEO]20CO2

Schmitz OJ Suttle KB 2001 Effects of top predator species on direct and indirectinteractions in a food web Ecology 82(7)2072ndash2081DOI 1018900012-9658(2001)082[2072EOTPSO]20CO2

Snyder WE Wise DH 1999 Predator interference and the establishment of generalist predatorpopulations for biocontrol Biological Control 15(3)283ndash292 DOI 101006bcon19990723

Snyder WE Wise DH 2001 Contrasting trophic cascades generated by a communityof generalist predators Ecology 82(6)1571ndash1583DOI 1018900012-9658(2001)082[1571CTCGBA]20CO2

Suenaga H Hamamura T 2015 Effects of manipulated density of the wolf spider Pardosaastrigera (Araneae Lycosidae) on pest populations and cabbage yield a field enclosureexperiment Applied Entomology and Zoology 50(1)89ndash97 DOI 101007s13355-014-0310-y

Sunderland KD 1988 Quantitative methods for detecting invertebrate predation occurring in thefield Annals of Applied Biology 112(1)201ndash224 DOI 101111j1744-73481988tb02056x

Sunderland K 1999 Mechanisms underlying the effects of spiders on pest populationsJournal of Arachnology 27308ndash316

Symondson WOC 2002 Molecular identification of prey in predator diets Molecular Ecology11(4)627ndash641 DOI 101046j1365-294X200201471x

Symondson WOC Sunderland KD Greenstone MH 2002 Can generalist predators be effectivebiocontrol agents Annual Review of Entomology 47(1)561ndash594DOI 101146annurevento47091201145240

Tholt G Kis A Medzihradszky A Szita Eacute Toacuteth Z Havelda Z Samu F 2018 Could vectorsrsquo fearof predators reduce the spread of plant diseases Scientific Reports 8(1)8705DOI 101038s41598-018-27103-y

Toft S 1995 Value of the aphid Rhopalosiphum padi as food for cereal spiders Journal of AppliedEcology 32(3)552ndash560 DOI 1023072404652

Toft S 2005 The quality of aphids as food for generalist predators implications for natural controlof aphids European Journal of Entomology 102(3)371ndash383 DOI 1014411eje2005054

Tsai CH Hsieh CH Nakazawa T 2016 Predator-prey mass ratio revisited does preference ofrelative prey body size depend on individual predator size Functional Ecology30(12)1979ndash1987 DOI 1011111365-243512680

Uetz GW Halaj J Cady AB 1999 Guild structure of spiders in major cropsJournal of Arachnology 27270ndash280


Vance-Chalcraft HD Rosenheim JA Vonesh JR Osenberg CW Sih A 2007 The influence ofintraguild predation on prey suppression and prey release A meta-analysis Ecology88(11)2689ndash2696 DOI 10189006-18691

Wang Y Naumann U Wright ST Warton DI 2012 mvabundmdashan R package for model-basedanalysis of multivariate abundance data Methods in Ecology and Evolution 3(3)471ndash474DOI 101111j2041-210X201200190x

Whitney TD Sitvarin MI Roualdes EA Bonner SJ Harwood JD 2018 Selectivity underlies thedissociation between seasonal prey availability and prey consumption in a generalist predatorMolecular Ecology 27(7)1739ndash1748 DOI 101111mec14554

Wise DH 2006 Cannibalism food limitation intraspecific competition and the regulation ofspider populations Annual Review of Entomology 51(1)441ndash465DOI 101146annurevento51110104150947

Wisniewska J Prokopy RJ 1997 Do spiders (Araneae) feed on rose leafhopper (Edwardsianarosae Auchenorrhyncha Cicadellidae) pests of apple trees European Journal of Entomology94243ndash251

WSC 2019 World spider catalog version 205 natural history museum Bern Available athttpwscnmbech (accessed 5 September 2019)

Wyss E Niggli U Nentwig W 1995 The impact of spiders on aphid populations in astrip-managed apple orchard Journal of Applied Entomology 119(1ndash5)473ndash478DOI 101111j1439-04181995tb01320x

Yasuda H Kimura T 2001 Interspecific interactions in a tri-trophic arthropod system effects of aspider on the survival of larvae of three predatory ladybirds in relation to aphidsEntomologia Experimentalis et Applicata 98(1)17ndash25 DOI 101046j1570-7458200100752x

Yeargan KV 1975 Prey and periodicity of Pardosa ramulosa (McCook) in alfalfaEnvironmental Entomology 4(1)137ndash141 DOI 101093ee41137

Young OP Edwards GB 1990 Spiders in United States field crops and their potential effect oncrop pests Journal of Arachnology 181ndash27

Zhang J 2016 R Package lsquospaarsquo 022 Available at httpsCRANR-projectorgpackage=spaa(accessed 3 March 2020)

Zrubecz P Toth F Nagy A 2008 Is Xysticus kochi (Araneae Thomisidae) an efficient indigenousbiocontrol agent of Frankliniella occidentalis (Thysanoptera Thripidae) BioControl53(4)615ndash624 DOI 101007s10526-007-9100-6


Beyond polyphagy and opportunism natural prey of hunting spiders in the canopy of apple trees

Introduction

Materials and Methods

Results

Discussion

Conclusions

flink6

References

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ltFEFF004b00e40079007400e40020006e00e40069007400e4002000610073006500740075006b007300690061002c0020006b0075006e0020006c0075006f0074002000410064006f0062006500200050004400460020002d0064006f006b0075006d0065006e007400740065006a00610020006c0061006100640075006b006100730074006100200074007900f6007000f60079007400e400740075006c006f0073007400750073007400610020006a00610020007600650064006f007300740075007300740061002000760061007200740065006e002e00200020004c0075006f0064007500740020005000440046002d0064006f006b0075006d0065006e00740069007400200076006f0069006400610061006e0020006100760061007400610020004100630072006f0062006100740069006c006c00610020006a0061002000410064006f00620065002000520065006100640065007200200035002e0030003a006c006c00610020006a006100200075007500640065006d006d0069006c006c0061002egt SVE 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 ENU (Use these settings to create Adobe PDF documents for quality printing on desktop printers and proofers Created PDF documents can be opened with Acrobat and Adobe Reader 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runners) did not consistently predict either prey composition or predation selectivityof arboreal hunting spider species From the economic standpoint Ph cespitumand Clubiona spp were found to be the most effective natural enemies of apple pestsespecially of aphids Finally the trophic niche width of C xanthogramma and Phcespitum increased during ontogeny resulting in a shift in their predation Theseresults demonstrate how specific generalist predators can differ from each other inaspects of their predation ecology even within a relatively narrow taxonomic group

Subjects Agricultural Science EcologyKeywords Araneae Beneficial arthropods Natural diet Intraguild predation Food webTrophic niche Biocontrol potential Ontogenetic shift Carrhotus xanthogrammaPhilodromus cespitum

INTRODUCTIONSpiders play an important role in ecosystems as predators of various invertebrate groupsIn certain habitats according to the highest realistic estimates spiders might kill up toapproximately 200 kg prey haminus1 yearminus1 (Nyffeler 2000) which by extrapolation suggeststhat the global spider community might consume up to 400ndash800 million tons of preyannually (Nyffeler amp Birkhofer 2017) Generally spiders are regarded as polyphagous(preying on a wide variety of prey) and opportunistic (taking their prey as a function ofeach prey speciesrsquo availability) although some degree of selectivity in foraging is oftenobserved (Nentwig 1980 Whitney et al 2018 Eitzinger et al 2019) Moreoverstenophagy has evolved in certain groups of spiders eg myrmecophagy in Zodariidae oraraneophagy in Salticidae (Pekaacuter Coddington amp Blackledge 2012 Pekaacuter amp Toft 2015)Spiders mainly prey on insects of which the preferred size is primarily ~50ndash80 of thespidersrsquo size (Nentwig amp Wissel 1986 Foelix 2011) but they can also feed on otherinvertebrates (Nyffeler amp Symondson 2001 Nyffeler et al 2017) or vertebrates (Nyffeler ampKnoumlrnschild 2013 Nyffeler amp Pusey 2014 Nyffeler Edwards amp Krysko 2017) eggs ofvarious arthropods (Nyffeler et al 1990 Ahmed et al 2018) or even on plant nectar andpollen (Nyffeler 2016 Nyffeler Olson amp Symondson 2016)

In agroecosystems spiders can contribute significantly to pest control by consuming alarge number of various insect pests (Nyffeler amp Benz 1988 Young amp Edwards 1990Marc Canard amp Ysnel 1999 Nyffeler amp Sunderland 2003 Birkhofer et al 2008 Liu et al2015 Suenaga amp Hamamura 2015 Lefebvre et al 2017) A recent meta-analysis(Michalko et al 2019) of 58 studies found that spiders suppressed agricultural insect pestsin 79 of the cases although their efficacy varied among crops From an economic point ofview hunting spiders have special importance as they collect their prey directly fromthe surface of the crop and thus they more frequently consume less mobile stages(eg eggs larvae nymphs) of various arthropods than web-building spiders (MarcCanard amp Ysnel 1999 Nyffeler 1999) Also hunting spiders have a wider trophic nichecompared to web-builders (Nyffeler 1999 Michalko amp Pekaacuter 2016) Furthermorebesides direct predation hunting spiders have several other non-consumptive effects onpestsherbivores (Mansour Rosen amp Shulov 1981 Sunderland 1999 Beleznai et al 2015



































Araneae65

Coleoptera44

Lepidoptera17

Formicidae79

Other Hymenoptera23

Brachycera193

Nematocera234

Auchenorrhyncha34

Heteroptera48

Sternorrhyncha238

Acari03

Ephemeroptera03

Neuroptera09

Psocoptera06

Thysanoptera03

Trichoptera01

Other26

0 10 20 30 40 50 60 70 80 90 100



Neutral54 (473)

Pest31 (277)



B









Pest

Neutral

Natural enemy

Other prey

Sternorrhyncha

Heteroptera


Brachycera


Lepidoptera

Coleoptera

Araneae

-05 00 05

axaT



+

+

+

+
















Othersalticids

Philodromuscespitum


Xysticusspp

Clubionaspp


Whole season 6512 5158 3275 5231 3842 4183


Whole season 0074 0045 0186 0065 0397 0066

Spring 0262 0075 0211 0048 0582 0186

Summer 0043 0157 0139 0094 0326 0060

Fall 0142 0161 0200 0212 0449 0097


Whole season 0142

Spring 0256

Summer 0130

Fall 0190



Club

Cxanth adults

Cxanth juvs

Etri

Osalt

Phcesp adults

Phcesp juvs

Xys

MDS-1

MD

S-2

DStress = 0089

Cxanth

Club

Etri

Osalt

PhcespXys

MDS-1

MD

S-2

CStress lt 0001


Club


Etri

Osalt

Phcesp adults

Phcesp juvs

Xyst

MDS-1

MD

S-2

BStress = 0071

Cxanth

Club

Etri

Osalt

Phcesp

Xyst

MDS-1

MD

S-2

AStress lt 0001







xat yerPa

Other prey

Sternorrhyncha

Heteroptera

Auchenorrhyncha

Nematocera

Brachycera

Other Hymenoptera

Formicidae

Lepidoptera

Coleoptera

Araneae

-03

-02

-01

00

01

02

03


















Othersalticids

Philodromuscespitum



Spring Summer Fall

N

275 46 105 44 46 55 571 161 293 117


186 (056) C 153 (036) B 159 (042) B 178 (035) C 186 (068) BC 120 (043) A 171 (055) 192 (059) b 153 (039) a 189 (066) b


118 (064) B 099 (049) AB 097 (061) A 128 (085) AB 139 (088) B 088 (039) A 112 (066) 130 (069) b 106 (066) a 103 (056) a


064 (028) A 066 (029) AB 062 (036) A 070 (041) AB 077 (050) AB 077 (030) B 066 (033) 068 (033) ab 069 (035) b 059 (027) a













































































































































































































Introduction


Results

Discussion

Conclusions

flink6

References

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PDFXCompliantPDFOnly false PDFXNoTrimBoxError true PDFXTrimBoxToMediaBoxOffset [ 000000 000000 000000 000000 ] PDFXSetBleedBoxToMediaBox true PDFXBleedBoxToTrimBoxOffset [ 000000 000000 000000 000000 ] PDFXOutputIntentProfile (None) PDFXOutputConditionIdentifier () PDFXOutputCondition () PDFXRegistryName () PDFXTrapped False CreateJDFFile false Description ltlt CHS ltFEFF4f7f75288fd94e9b8bbe5b9a521b5efa7684002000500044004600206587686353ef901a8fc7684c976262535370673a548c002000700072006f006f00660065007200208fdb884c9ad88d2891cf62535370300260a853ef4ee54f7f75280020004100630072006f0062006100740020548c002000410064006f00620065002000520065006100640065007200200035002e003000204ee553ca66f49ad87248672c676562535f00521b5efa768400200050004400460020658768633002gt CHT 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 ESP 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FRA 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 SUO 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 SVE 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 ENU (Use these settings to create Adobe PDF documents for quality printing on desktop printers and proofers Created PDF documents can be opened with Acrobat and Adobe Reader 50 and later) gtgt Namespace [ (Adobe) (Common) (10) ] OtherNamespaces [ ltlt AsReaderSpreads false CropImagesToFrames true ErrorControl WarnAndContinue FlattenerIgnoreSpreadOverrides false IncludeGuidesGrids false IncludeNonPrinting false IncludeSlug false Namespace [ (Adobe) (InDesign) (40) ] OmitPlacedBitmaps false OmitPlacedEPS false OmitPlacedPDF false SimulateOverprint Legacy gtgt ltlt AddBleedMarks false AddColorBars false AddCropMarks false AddPageInfo false AddRegMarks false ConvertColors NoConversion DestinationProfileName () DestinationProfileSelector NA Downsample16BitImages true FlattenerPreset ltlt PresetSelector MediumResolution gtgt FormElements false GenerateStructure true IncludeBookmarks false IncludeHyperlinks false IncludeInteractive false IncludeLayers false IncludeProfiles true MultimediaHandling UseObjectSettings Namespace [ (Adobe) (CreativeSuite) (20) ] PDFXOutputIntentProfileSelector NA PreserveEditing true UntaggedCMYKHandling LeaveUntagged UntaggedRGBHandling LeaveUntagged UseDocumentBleed false gtgt ]gtgt setdistillerparamsltlt HWResolution [2400 2400] PageSize [612000 792000]gtgt setpagedevice


































Araneae65

Coleoptera44

Lepidoptera17

Formicidae79

Other Hymenoptera23

Brachycera193

Nematocera234

Auchenorrhyncha34

Heteroptera48

Sternorrhyncha238

Acari03

Ephemeroptera03

Neuroptera09

Psocoptera06

Thysanoptera03

Trichoptera01

Other26

0 10 20 30 40 50 60 70 80 90 100



Neutral54 (473)

Pest31 (277)



B









Pest

Neutral

Natural enemy

Other prey

Sternorrhyncha

Heteroptera


Brachycera


Lepidoptera

Coleoptera

Araneae

-05 00 05

axaT



+

+

+

+
















Othersalticids

Philodromuscespitum


Xysticusspp

Clubionaspp


Whole season 6512 5158 3275 5231 3842 4183


Whole season 0074 0045 0186 0065 0397 0066

Spring 0262 0075 0211 0048 0582 0186

Summer 0043 0157 0139 0094 0326 0060

Fall 0142 0161 0200 0212 0449 0097


Whole season 0142

Spring 0256

Summer 0130

Fall 0190



Club

Cxanth adults

Cxanth juvs

Etri

Osalt

Phcesp adults

Phcesp juvs

Xys

MDS-1

MD

S-2

DStress = 0089

Cxanth

Club

Etri

Osalt

PhcespXys

MDS-1

MD

S-2

CStress lt 0001


Club


Etri

Osalt

Phcesp adults

Phcesp juvs

Xyst

MDS-1

MD

S-2

BStress = 0071

Cxanth

Club

Etri

Osalt

Phcesp

Xyst

MDS-1

MD

S-2

AStress lt 0001







xat yerPa

Other prey

Sternorrhyncha

Heteroptera

Auchenorrhyncha

Nematocera

Brachycera

Other Hymenoptera

Formicidae

Lepidoptera

Coleoptera

Araneae

-03

-02

-01

00

01

02

03


















Othersalticids

Philodromuscespitum



Spring Summer Fall

N

275 46 105 44 46 55 571 161 293 117


186 (056) C 153 (036) B 159 (042) B 178 (035) C 186 (068) BC 120 (043) A 171 (055) 192 (059) b 153 (039) a 189 (066) b


118 (064) B 099 (049) AB 097 (061) A 128 (085) AB 139 (088) B 088 (039) A 112 (066) 130 (069) b 106 (066) a 103 (056) a


064 (028) A 066 (029) AB 062 (036) A 070 (041) AB 077 (050) AB 077 (030) B 066 (033) 068 (033) ab 069 (035) b 059 (027) a













































































































































































































Introduction


Results

Discussion

Conclusions

flink6

References








Pest

Neutral

Natural enemy

Other prey

Sternorrhyncha

Heteroptera


Brachycera


Lepidoptera

Coleoptera

Araneae

-05 00 05

axaT



+

+

+

+
















Othersalticids

Philodromuscespitum


Xysticusspp

Clubionaspp


Whole season 6512 5158 3275 5231 3842 4183


Whole season 0074 0045 0186 0065 0397 0066

Spring 0262 0075 0211 0048 0582 0186

Summer 0043 0157 0139 0094 0326 0060

Fall 0142 0161 0200 0212 0449 0097


Whole season 0142

Spring 0256

Summer 0130

Fall 0190



Club

Cxanth adults

Cxanth juvs

Etri

Osalt

Phcesp adults

Phcesp juvs

Xys

MDS-1

MD

S-2

DStress = 0089

Cxanth

Club

Etri

Osalt

PhcespXys

MDS-1

MD

S-2

CStress lt 0001


Club


Etri

Osalt

Phcesp adults

Phcesp juvs

Xyst

MDS-1

MD

S-2

BStress = 0071

Cxanth

Club

Etri

Osalt

Phcesp

Xyst

MDS-1

MD

S-2

AStress lt 0001







xat yerPa

Other prey

Sternorrhyncha

Heteroptera

Auchenorrhyncha

Nematocera

Brachycera

Other Hymenoptera

Formicidae

Lepidoptera

Coleoptera

Araneae

-03

-02

-01

00

01

02

03


















Othersalticids

Philodromuscespitum



Spring Summer Fall

N

275 46 105 44 46 55 571 161 293 117


186 (056) C 153 (036) B 159 (042) B 178 (035) C 186 (068) BC 120 (043) A 171 (055) 192 (059) b 153 (039) a 189 (066) b


118 (064) B 099 (049) AB 097 (061) A 128 (085) AB 139 (088) B 088 (039) A 112 (066) 130 (069) b 106 (066) a 103 (056) a


064 (028) A 066 (029) AB 062 (036) A 070 (041) AB 077 (050) AB 077 (030) B 066 (033) 068 (033) ab 069 (035) b 059 (027) a













































































































































































































Introduction


Results

Discussion

Conclusions

flink6

References















Othersalticids

Philodromuscespitum


Xysticusspp

Clubionaspp


Whole season 6512 5158 3275 5231 3842 4183


Whole season 0074 0045 0186 0065 0397 0066

Spring 0262 0075 0211 0048 0582 0186

Summer 0043 0157 0139 0094 0326 0060

Fall 0142 0161 0200 0212 0449 0097


Whole season 0142

Spring 0256

Summer 0130

Fall 0190



Club

Cxanth adults

Cxanth juvs

Etri

Osalt

Phcesp adults

Phcesp juvs

Xys

MDS-1

MD

S-2

DStress = 0089

Cxanth

Club

Etri

Osalt

PhcespXys

MDS-1

MD

S-2

CStress lt 0001


Club


Etri

Osalt

Phcesp adults

Phcesp juvs

Xyst

MDS-1

MD

S-2

BStress = 0071

Cxanth

Club

Etri

Osalt

Phcesp

Xyst

MDS-1

MD

S-2

AStress lt 0001







xat yerPa

Other prey

Sternorrhyncha

Heteroptera

Auchenorrhyncha

Nematocera

Brachycera

Other Hymenoptera

Formicidae

Lepidoptera

Coleoptera

Araneae

-03

-02

-01

00

01

02

03


















Othersalticids

Philodromuscespitum



Spring Summer Fall

N

275 46 105 44 46 55 571 161 293 117


186 (056) C 153 (036) B 159 (042) B 178 (035) C 186 (068) BC 120 (043) A 171 (055) 192 (059) b 153 (039) a 189 (066) b


118 (064) B 099 (049) AB 097 (061) A 128 (085) AB 139 (088) B 088 (039) A 112 (066) 130 (069) b 106 (066) a 103 (056) a


064 (028) A 066 (029) AB 062 (036) A 070 (041) AB 077 (050) AB 077 (030) B 066 (033) 068 (033) ab 069 (035) b 059 (027) a













































































































































































































Introduction


Results

Discussion

Conclusions

flink6

References


Club

Cxanth adults

Cxanth juvs

Etri

Osalt

Phcesp adults

Phcesp juvs

Xys

MDS-1

MD

S-2

DStress = 0089

Cxanth

Club

Etri

Osalt

PhcespXys

MDS-1

MD

S-2

CStress lt 0001


Club


Etri

Osalt

Phcesp adults

Phcesp juvs

Xyst

MDS-1

MD

S-2

BStress = 0071

Cxanth

Club

Etri

Osalt

Phcesp

Xyst

MDS-1

MD

S-2

AStress lt 0001







xat yerPa

Other prey

Sternorrhyncha

Heteroptera

Auchenorrhyncha

Nematocera

Brachycera

Other Hymenoptera

Formicidae

Lepidoptera

Coleoptera

Araneae

-03

-02

-01

00

01

02

03


















Othersalticids

Philodromuscespitum



Spring Summer Fall

N

275 46 105 44 46 55 571 161 293 117


186 (056) C 153 (036) B 159 (042) B 178 (035) C 186 (068) BC 120 (043) A 171 (055) 192 (059) b 153 (039) a 189 (066) b


118 (064) B 099 (049) AB 097 (061) A 128 (085) AB 139 (088) B 088 (039) A 112 (066) 130 (069) b 106 (066) a 103 (056) a


064 (028) A 066 (029) AB 062 (036) A 070 (041) AB 077 (050) AB 077 (030) B 066 (033) 068 (033) ab 069 (035) b 059 (027) a













































































































































































































Introduction


Results

Discussion

Conclusions

flink6

References





xat yerPa

Other prey

Sternorrhyncha

Heteroptera

Auchenorrhyncha

Nematocera

Brachycera

Other Hymenoptera

Formicidae

Lepidoptera

Coleoptera

Araneae

-03

-02

-01

00

01

02

03


















Othersalticids

Philodromuscespitum



Spring Summer Fall

N

275 46 105 44 46 55 571 161 293 117


186 (056) C 153 (036) B 159 (042) B 178 (035) C 186 (068) BC 120 (043) A 171 (055) 192 (059) b 153 (039) a 189 (066) b


118 (064) B 099 (049) AB 097 (061) A 128 (085) AB 139 (088) B 088 (039) A 112 (066) 130 (069) b 106 (066) a 103 (056) a


064 (028) A 066 (029) AB 062 (036) A 070 (041) AB 077 (050) AB 077 (030) B 066 (033) 068 (033) ab 069 (035) b 059 (027) a













































































































































































































Introduction


Results

Discussion

Conclusions

flink6

References

















Othersalticids

Philodromuscespitum



Spring Summer Fall

N

275 46 105 44 46 55 571 161 293 117


186 (056) C 153 (036) B 159 (042) B 178 (035) C 186 (068) BC 120 (043) A 171 (055) 192 (059) b 153 (039) a 189 (066) b


118 (064) B 099 (049) AB 097 (061) A 128 (085) AB 139 (088) B 088 (039) A 112 (066) 130 (069) b 106 (066) a 103 (056) a


064 (028) A 066 (029) AB 062 (036) A 070 (041) AB 077 (050) AB 077 (030) B 066 (033) 068 (033) ab 069 (035) b 059 (027) a













































































































































































































Introduction


Results

Discussion

Conclusions

flink6

References












































































































































































































Introduction


Results

Discussion

Conclusions

flink6

References


beyond polyphagy and opportunism: natural prey of hunting ...beyond polyphagy and opportunism:...

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