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Chemical and biological approaches for citrusleafminer Phyllocnistis citrella stainton controlin a Clementine Orchard, in Moulouya region ofMorocco

Khalid Khfif , Mohammed Baala , Stuart Alan Walters , Rachid Bouharroud &Mohamed Sbaghi

To cite this article: Khalid Khfif , Mohammed Baala , Stuart Alan Walters , Rachid Bouharroud &Mohamed Sbaghi (2020): Chemical and biological approaches for citrus leafminer Phyllocnistiscitrella stainton control in a Clementine Orchard, in Moulouya region of Morocco, Archives ofPhytopathology and Plant Protection, DOI: 10.1080/03235408.2020.1795608

To link to this article: https://doi.org/10.1080/03235408.2020.1795608

Published online: 24 Jul 2020.

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Chemical and biological approaches for citrusleafminer Phyllocnistis citrella stainton control in aClementine Orchard, in Moulouya region of Morocco

Khalid Khfifa, Mohammed Baalab, Stuart Alan Waltersc, Rachid Bouharroudd

and Mohamed Sbaghie

aPlant Protection Laboratory, National Institute for Agricultural Research (Qualipole ofBerkane), Oujda, Morocco; bBiology Department, Faculty of Sciences, Mohammed PremierUniversity, Oujda, Morocco; cDepartment of Plant, Soil, and Agricultural Systems, SouthernIllinois University, Carbondale, Illinois, USA; dIntegrated Crop Production Unit, NationalInstitute for Agricultural Research, Inezgane, Morocco; ePlant Protection Department, ScientificDivision, National Institute for Agricultural Research, Rabat, Morocco

ABSTRACTThe citrus leafminer (CLM), Phyllocnistis citrella is consideredan important pest in young citrus nurseries and plantationsaround the world, as Morocco. Since management of CLMis based primarily on the use of insecticides, a study wasdeveloped to use biological approaches along with rationaland limited insecticide usage for an integrated manage-ment program based on degree-days (DD) required forinsect generations. This study was conducted over threeyears (2017, 2018 and 2019) in Clementine (Citrus reticutala‘Berkane’) fields located at Berkane area, Morocco. Citrusleafminer adults were monitored with two delta trapsbaited with pheromone capsules and checked weekly fromearly April to early September each year. Additionally, aweekly sampling of young leaves from new young shootsshowing CLM injury symptoms was conducted to identifythe status of larvae or pupae, and the influence of naturalenemies (parasitoids and predators). During 2017 and 2018,four peaks of adult flights were observed while five peakswere detected in 2019. However, several overlapping gen-erations occurred according to DD recorded during thestudy period (seven generations in 2017, six in 2018 andeight until early September 2019). The use of DD indicatedthat two insecticide applications in each 2018 and 2019 forcontrol of CLM were not needed. The maximum infestationlevel detected was 90% in early August 2017, and 100%near the beginning and end of July for 2018 and 2019,respectively, with CLM larvae and pupae most detected.The maximum rate of parasitism was observed in non-treated controls in late July 2017 at 37%, early July 2018 at48%, and late August 2019 at 32%. The parasitoids of CLMidentified were Citrostichus phyllocnistoides, Semielacherpetiolatus, Cirrospilus pictus (most abundant), Cirrospilus

ARTICLE HISTORYReceived 14 April 2020Revised 30 June 2020Accepted 6 July 2020

KEYWORDSdegree-days; insecticides;integrated managementprogram;parasitoids; predators

CONTACT Khalid Khfif khalild3@hotmail.com Plant Protection Laboratory, National Institute forAgricultural Research (Qualipole of Berkane), B.P 428, 60000 Oujda, Morocco� 2020 INRA-MOROCCO. Published by Informa UK Limited, trading as Taylor & Francis Group

ARCHIVES OF PHYTOPATHOLOGY AND PLANT PROTECTIONhttps://doi.org/10.1080/03235408.2020.1795608

vittatus, Pnigalio sp. and Chrysocharis sp., while the mainpredators were ants, ladybugs and spiders.

1. Introduction

In Morocco, citrus trees suffer from several pest problems includingmedfly, mites, aphids, mealybugs, leaf miners, as well as other numerousfungal diseases (Abbassi 2010; Mazih 2015; Smaili 2017). However, inyoung citrus plantations and nurseries, the citrus leaf miner (CLM),Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) is consideredone of the important insect pests on a worldwide basis (Qureshi et al.2004; Browning et al. 2006), and is a devastating insect pest in Morocco(Beattie et al. 1995; Heppner 1995).The CLM is originally from South Asia (Clausen 1931; Hoy and

Nguyen 1997), with larval feeding resulting in characteristic serpentinemines under the leaf cuticle leading to eventual chlorosis and curledleaves, which may reduce or cause a total loss of a leaf’s photosyntheticcapacity (Chagas et al. 2001). Newly emerged leaflets (growth flush), par-ticularly along the midvein, are the preferred oviposition (egg laying)sites (Grafton-Cardwell et al. 2019). Furthermore, the feeding habits ofthese larvae facilitate the entrance of pathogenic microorganisms into theleaf, especially the bacterium, Xanthomonas axonopodis pv. citri, whichcauses citrus canker (Belasque et al. 2005).After the high CLM infestation on citrus shoots during 1996 in

Morocco, a biological control strategy was launched immediately tointroduce several natural enemies to suppress populations of this pest(Smaili et al. 1999; Rizqi et al. 2003; Smaili et al. 2013). Current pro-grams to manage CLM in citrus is mostly based on insecticide applica-tions (Mazih 2015), especially in the Basse Moulouya growing region ofMorocco. The extensive use of insecticides for control will most likelylead to the development of resistant strains of CLM, and other pests,such as scales (Tan and Huang 1996). The emergence of secondary pestsby elimination of their natural enemies, and growing public concernsover issues related to public health, environmental protection, and foodsafety are all reasons to try to minimize insecticide use (Tan and Huang1996; Sarada et al. 2014). Therefore, there is an urgent need to developan alternative to the sole use of insecticides to control CLM.The use of an integrated management program would be a sustainable

approach to managing CLM, via utilizing less insecticide applicationswith more reliance on natural enemies. Therefore, a study was conductedto monitor CLM and their natural enemies during the spring and

2 K. KHFIF ET AL.

summer of 2017, 2018, and 2019, and to develop a management programbased on using Degree Days (DD) for the development of CLMgenerations.

2. Materials and methods

2.1. Area and field trial

Field trials were conducted during 2017, 2018, and 2019 in Berkaneprovince, located in the northeast of the Kingdom of Morocco, this areais a collection of plains and mountains and an excellence region of citrusproduction (Figure 1). In 2017, a three-year old Citrus reticulata‘Berkane’ orchard was utilized in the Triffa Domains, which is eight km

Figure 1. Location of field experiments for 2017, 2018 and 2019 in Province ofBerkane, Morocco.

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from Laatamna, while in 2018 and 2019, a young two to three-year oldcitrus orchard using the same variety described previously was used thatwas located ten km from Madagh in the Zniber Domains (Riad de laCl�ementine). All orchards were drip irrigated and received recommendedfertilizer applications. The 2018 field experiments were divided into threefield blocks: control which did not receive any insecticide treatment; T1that received the standard insecticide for CLM control according toobserved field damage and calendar spray timings for the region, whichtypically coincided about a week before DD’s indicated that an applicationwas necessary; and, T2 which received the insecticide applications for CLMcontrol one-week after the recorded DD’s. In 2019, T1 and T2 blocks wereconsidered as a single block that received standard insecticide treatments,as described previously. The ingredient active of insecticides used are:Acetamiprid SL (30 cc/hl) and Abamectine EC (25 cc/hl). For 2017, noinsecticides were applied. This year was used as a preliminary evaluationfor field studies to be conducted in 2018 and 2019 (as replications).

2.2. Monitoring CLM for citrus infestation

In all years, five young shoots were randomly selected per tree, with fivetrees sampled in each plot for CLM population levels. Leafminer adultswere monitored with two Delta-type traps per block, each containing astuck plate (20 cm x 18 cm) and a pheromone capsule; these traps wereinstalled in Zniber Domain from mid-March to early-September eachyear, while those in Triffa Domain from late March to mid-August 2017.These traps were changed once a week as soon as CLM adults were cap-tured. Numbers of CLM adults captured were determined in the labora-tory using a binocular loupe.

2.3. Monitoring of CLM natural enemies

Additionally, a weekly sampling was conducted on twenty-five youngleaves mined from young shoots per treatment block. Each leaf was thensubjected to binocular observation to identify the status of CLM larvaeor pupae that were parasitized or non-parasitized, which included alive,dead or empty body castings. A determination and enumeration of nat-ural mortality of this pest was conducted in 2018 and 2019.The identification of some parasitoids was determined in Plant

Protection Laboratory in INRA-Qualipole of Berkane, according to mor-phological adult after larval rearing found near CLM larvae or pupae.Each mined leaf with a CLM parasitoid was placed individually in a petridish enclosed by parafilm and humidified paper. In 2019, enumeration

4 K. KHFIF ET AL.

and identification of predators present were determined from five youngshoots per tree, with five trees sampled randomly per block.

2.4. Data and statistical analysis

The CLM infestation rate (A) was calculated as the total number ofshoot infested (B) divided by the total number of shoot sampled(twenty-five per plot) during 2017, 2018 and 2019; [A¼B/25]. A shootwas considered infested when one or more CLM was found alive on ashoot leaf. The density of male adult CLM and their natural enemieswere recorded. The percentage of CLM (R) larvae (L) or pupae (P) thatwere alive (a), dead (d), parasitized (p) or empty mine (m)/pupae cham-ber (c) was calculated by the number of each found divided by the totalCLM numbers (T) on twenty-five leaves sampled per plot during 2018and 2019; [RIi¼ Ii/T; where (i¼ a,d,p, m or c) and (I¼ L or P)]. Therate of parasitism (M) was calculated as the number of parasitizedCLM’s out of the total number of detected per 25 mined leaves sampledper plot during 2017, 2018 and 2019; [M¼RLpþRPp]. The predationrate (N) calculated from the number of empty mines per plot out oftwenty-five mined leaves sampled per plot during 2019; [N¼RLm].Degrees-Days (DD) were calculated, starting from 1st Jan. each year,

by cumulating the subtraction of the mean daily temperature [(tempera-ture minimalþ temperature maximal)/2] and the minimum developmen-tal zero for CLM, which is 12.1 �C (Ujiye 2000). The daily DD wascorrected to zero if the mean daily temperature was under developmentalzero. The minimal theoretical DD from the egg to adult emergence is206 DD, which is used to predict the emergence of the new generation(Ujiye 2000). The weather data were recorded daily at INRA ofQualipole of Berkanefar, which is 10 km from both of field sites, using aGP2 Data Logger (Delta-T Devices Ltd.).The analysis of variance (ANOVA), correlation, and mean comparisons

using student’s t-tests were performed using IBM SPSS Statistics (V.20).

3. Results and discussion

3.1. CLM Monitoring

Monitoring CLM during 2017, 2018, and 2019 indicated different periodsof peak population levels based on the recorded DDs (Figure 2). Fromsix to thirteen generations developed per year depending on foliagegrowth cycles and weather conditions, with highest populations detectedin early summer and early autumn (Kheder et al. 2002; Amiri-Besheli 2011).

ARCHIVES OF PHYTOPATHOLOGY AND PLANT PROTECTION 5

During 2017 and 2018, four peaks of adults were observed, while fivepeaks were detected in 2019. In comparison, several overlapping genera-tions occurred during these three years based on DD, and included sevengenerations in 2017, six in 2018 and eight until the beginning ofSeptember for 2019.The highest CLM flight peaks were observed in July each year (Figure 2).

The highest flight peaks were detected in mid-July for 2017 and 2018, andlate-July for 2019, with 679, 1,443 and 1,130 CLM adults caught per trapeach week, for 2017, 2018, and 2019, respectively. Numbers of CLM adultsmales caught were highly correlated with temperature in all years, withr¼ 0.563, P¼ 0.012 for 2017; r¼ 0.518, P¼ 0.014 for 2018; and r¼ 0.627,P¼ 0.001 for 2019. This indicates that generation development timing wasdefinitely influenced by higher temperatures. This variation in flight peakswas due to temperature differences, which was higher in 2017, and allowedthe insect to complete its generation cycle faster than in 2018. This alsoexplains the delay in the first generation in 2019 due to low temperaturesrecorded during the spring of this year compared to previous years.The total generation period of CLM fluctuates between 13 to 52 days

(Pandey and Pandey 1964). The shortest recorded period between twopeaks of adult flights was 15 days in 2017 and 2019, and 16 days in 2018.The longest generation cycle each year was at 31, 41, and 40 days for2017, 2018 and 2019, respectively. The optimal temperature for CLMdevelopment is 30 �C (Elekcio�glu and Uygun 2004), which coincides withaverage summer temperatures in Morocco. However, high summer tem-peratures at 40 �C or above, can cause CLM mortality, and 95% and 60%mortality rates were observed for larvae and nymphs, respectively, inTunisia during 1998 (Kheder et al. 2002).

3.2. CLM Infestation assessment

The infestation of young citrus shoots infested by CLM was determinedeach year (Figure 3). During 2017, CLM populations were first detected

Figure 2. The development of CLM adult males over time on citrus trees and correlationwith the degree-days (DD) required for generation cycling during 2017, 2018 and 2019.

6 K. KHFIF ET AL.

on citrus in mid-April and reached a peak shoot infestation of 90% bylate July. For 2018, CLM were first observed in early May, with 52% ofcitrus shoots infested with CLM incidence in late May and then 100%infestation occurring late-June and again in mid-July. During 2019, CLMinfestation of citrus shoots was 68% at late June and reached 100% dur-ing late July. Our results, somewhat agree with Attrassi and Badoc(2013) who reported that CLM infestation of citrus ranged from 25% inJune to 85% in Sept. in Kentira region of Morocco.The differences observed between years for CLM infestation of young

citrus shoots can be related to several factors. Temperature definitelyhad an influence on CLM infestations detected among the 2017, 2018,and 2019 growing seasons, and certainly affected the numbers of CLMadults detected each year. The percentage of citrus shoots infested andCLM population levels were correlated each year, with r¼ 0.618,P¼ 0.006; r¼ 0.621, P¼ 0.0001; and r¼ 0.726, P¼ 0.0001 for 2017,2018, and 2019, respectively. Chhetry et al. (2012) confirmed the sameresults as this study over multiple seasons in Jammu region of India.The amounts of CLM infestation could also be influenced by the differ-ence in tree age between the two Domains evaluated. Additionally, irri-gation and fertilization management methods can affect and modify thetiming of new citrus growth. Younger trees are more likely to beinfested by CLM than others, due to the high amounts of newly devel-oped leaves, as well as the time of their appearance during the springand summer.

3.3. CLM Control using DDs

The use of DDs is an effective way to manage CLM with properly timedinsecticides (Figure 2). The temperature difference between years influen-ces both the length and numbers of CLM generations each year, whichhas a direct influence on insecticide application timing and frequencythat is required. During both 2018 and 2019, some insecticide applica-tions for CLM control were not correctly timed. In 2018, the first insecti-cide application was applied once the first visual damage appeared on

Figure 3. Rate of citrus shoot infestation by CLM during 2017, 2018 and 2019.

ARCHIVES OF PHYTOPATHOLOGY AND PLANT PROTECTION 7

leaves, which was more than two weeks after the emergence of the firstCLM generation as predicted by DD. The second and third applicationswere applied once the residual activity of the previous insecticide appli-cation had dissipated and was no longer effective, as these applicationswere made in the absence of new generations. However, in comparison,these two applications were justifiable for 2017 in which two predictedgenerations were present when insecticide sprays were made. The otherapplications made for CLM control in 2018 were more or less a weekfrom recorded DDs for emergence of new generations which would bejustified. For 2019, two insecticide applications were made in the absenceof new generations, although one of these applications could be justifiedfor 2017, since the emergence of one generation was predicted at thistime. Avoid using insecticides at wrong time will led to reduce insecti-cide applications and cost also engender a monetary savings with healthand environmental protection.The use of insecticides a week before or after recorded DD did not differ

(P� 0.05) for male adult CLM control (Figure 4), as the two applicationsprovided similar results for numbers of adult males caught in traps.However, numbers of male adult CLMs caught were influenced by date(P¼ 0.0001), which increased at mid-May from 365 to 1000 by mid-July.The development of CLM infestation of young citrus shoots between

the two insecticide applications (a week before and after recorded DD)was similar, as no differences were detected (P¼ 0.8373) (Figure 5).However, CLM infestation levels of young citrus shoots significantlyincreased (P¼ 0.0001) from 32% in mid-May to 96% by mid-July, whichwas a 300% increase in shoot infestation over this time period.

3.4. Monitoring of natural enemies of leafminer

a. CLM natural mortality

Figure 4. The influence of insecticide applications one week before and after recorded DDon CLM adult male population levels on young citrus shoots over the 2018 growing season.

8 K. KHFIF ET AL.

During 2018 and 2019, more CLM larvae were found than pupae (Figures6 and 7). Parasitized larva were higher in control than those treated withinsecticide during both years, indicating that insecticide applications werealso killing natural enemies of CLM. Larvae (whether dead or alive) werethe most observed stage of CLM on young citrus shoots. The percentage ofalive and dead larvae were similar between insecticide treated and non-treated controls for each 2018 and 2019. Although dead larvae can be easyexplained in the treatment with insecticide, high temperatures or possibleeffect of entomopathogens in the non-treated control are the probablecause of larval death. The investigation of entomopathogens revealed thepresence of fungi isolated from dead CLMs, which could be part of a futurebiological control program for CLM.The empty mines were higher in insecticide treatments than in non-

treated controls by 60% and 17% for 2018 and 2019, respectively

Figure 5. The infestation rate (%) of young citrus shoots by CLM in 2018 after insecticideapplications.

Figure 6. Influence of treatments on CLM larvae status (± SE) in 2018 and 2019 (differentletters indicate difference by Student’s t-test).

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(Figure 6). This result could result from insecticide use or possible effectof predation, especially in controls. In Florida (USA), during the growingseason, a high proportion of the CLM mines were empty due to preda-tion (Hoy et al. 2007), and in Turkey, up to 14% mines were found withno pest predation (Elekcio�glu 2013).For pupae, alive and empty chambers were the most observed during

2018 and 2019 (Figure 7). There were few dead or parasitized pupaefound each year. The empty pupae chamber could be the result of adultemergence, while those that were alive could be explained by insecticideineffectiveness when the pupae is covered in its chamber. The absence ofAgeniaspis citricola in Morocco explains the lack of parasitoids that canattack the pupal stage of CLM, especially when CLM larvae escape frompredation. Athough parasitoids, such as Cirrospilus pictus, is an effectiveparasitoid CLM larvae, the introduction of A. citricola in Algeria didcontrol the CLM (Saharaoui et al. 2001).Correlations indicated relationships among alive, parasitized, and

empty mine chamber CLM larvae/pupae. Considering both larvae andpupae, a correlation was observed in 2018 between the rates of dead andparasitized (r¼ 0.444, P< 0.01) and also between rates of empty mines/chambers and dead (r¼ 0.526, P< 0.01). For 2019, a correlation wasagain observed between the rates of dead and parasitized larvae/pupae(r¼ 0.523, P¼ 0.007) and between the rates of alive and empty mines/chambers of larvae/pupae (r¼ 0.753, P¼ 0.0001).

Figure 7. Influence of treatments on CLM pupae status (± SE) in 2018 and 2019 (differentletters indicate difference by Student’s t-test).

10 K. KHFIF ET AL.

b. Parasitoids

Parasitoids had decreased CLM populations during each growing seasonon citrus. Parasitoid monitoring in control treatments indicated that themaximum rate of CLM larvae parasitism was 37% during late July for2017, 48% in early July for 2018, and 32% during late August for 2019(Figure 8). The maximum rates of parasitism each year coincided with theappearance of young shoots, which also occurred during times of highCLM larvae population levels. When insecticides were applied, the max-imum rate of parasitism was 22% in early July for 2018 and 20% in earlyAugust for 2019, which was about 50% of that parasitism rate detected incontrol treatments. The use of selective insecticides is justifiable, especiallyduring maximum activity of parasitoids to provide control of CLM larvaewithout injury natural enemies. In comparison, the lowest levels of para-sitism were observed in late winter and early spring under tropical condi-tions in Florida (USA) (Hoy and Nguyen 1997). Our results confirmearlier results found by Saharaoui et al. (2001) who reported parasitismrates of about 46% at the end of July during 1998 in Orangers, Algeria.There are numerous parasitoids of CLM found in Morocco. Recently,

five exotic parasitoids were introduced into Morocco from 1995 to 2000(Rizqi et al. 2003): Ageniaspis citricola Logvinovskaya (Hymenoptera:Encyrtidae), Cirrospilus ingenuus Gahan (Hymenoptera: Eulophidae),Quadrastichus sp. (Hymenoptera: Eulophidae), Semielacher petiolatusGirault (Hymenoptera: Eulophidae), and Citrostichus phyllocnistoidesNarayanan (Hymenoptera: Eulophidae). In addition to the four speciesof parasitoids identified in this study during 2017 (C. phyllocnistoides, S.petiolatus, Cirrospilus pictus Nees (Hymenoptera: Eulophidae) andCirrospilus vittatus Walker (Hymenoptera: Eulophidae)), two new specieswere found in 2018: Pnigalio sp. (Hymenoptera: Eulophidae) andChrysocharis sp. (Hymenoptera: Eulophidae), although the most abun-dant parasitoid found under our conditions was C. pictus (Figure 9).Other regions of the world have reported other dominant parasitoids

of CLM. Elekcio�glu (2013) found that C. phyllocnistoides was the most

Figure 8. The parasitism rate of CLM in insecticide and control treatments during 2017,2018 and 2019.

ARCHIVES OF PHYTOPATHOLOGY AND PLANT PROTECTION 11

abundant species in Turkey during 2007 to 2008 with parasitism rates upto slight over 48%, with preference towards the third instar of CLM.However, in Florida, Ageniaspis citricola and Pnigalio sp. were reportedto be the most abundant parasitoids resulting in high natural rates ofCLM mortality (Khfif and Qureshi, unpublished). Furthermore, inFlorida (USA), the appearance of A. citricola occurred when CLM popu-lations increased during the second citrus growth flush (June to July),with pupae parasitism rates up to 39% in the untreated controls; and,these rates increased through the season, peaking at 56% (Hoy et al.2007). In Alabama (USA), the parasitism rate was just 10% compared tothe high percentage of predation, since up to 96% of dead CLM were

Figure 9. The development cycle of citrus leafminer’s most important parasitoid in Morocco(Cirrospilus pictus): (A arrow) first larval stage, (B arrow) last larval stage, (C) nymph, and(D) adult.

12 K. KHFIF ET AL.

found (Xiao and Fadamiro 2010). This low rate of parasitism was alsorecorded in Mexico at 20%, with the dominant parasitoid,Zagrammosoma multilineatum (Ashmead) (Hymenoptera: Eulophidae)causing most CLM death (Legaspi et al. 2001).

c. Predators

Many predators of CLM were also detected during the course thisstudy. During 2018 and 2019, monitoring of predators attacking CLMindicated the presence of several predatory insects, with most being ants,spiders, ladybugs, lacewings and stink-bugs. The main predators detectedin 2019 were ladybugs and spiders in mid-April peaking at 3% and 1%,respectively, although ants were also detected with several peaks coincid-ing with higher CLM population levels and peaked at 10% in late June(Figure 10). In Turkey, Elekcio�glu (2013) confirmed that spiders, greenlacewing (Chrysoperla carnea), and ants were the most abundant preda-tors of CLM with predation rates up to 16.61%, 8.57% and 3.78%,respectively. These predators also caused the greatest amounts of naturalmortality of P. citrella in Alabama (USA), especially spiders (Xiao andFadamiro 2010). Another study in Spain indicated that the most import-ant mortality of CLM by natural enemies was predation, which occurredat higher rates during citrus growth flushes (Urbaneja et al. 2004).Additionally, in Algeria, the hoverfly (Episyrphus balteatus De Geer) wasalso observed as predators of CLM larvae (Saharaoui et al. 2001).

4. Conclusion

This study indicated the presence of many species of parasitoids attack-ing the larvae stage of CLM, although predators, such as ants, are alsoconsidered important to provide natural mortality of P. citrella in

Figure 10. Development of CLM predation rate in insecticide and control treatments dur-ing 2019.

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Morocco. Additionally, the use of DDs for this insect pest predicted thetiming of adult emergence in real time, which also allowed determinationof peak infestation periods. The proper timing and use of insecticides iscritical to reduce CLM population levels, as the use of pesticides at thewrong time is only resulting in increased input costs without providingany additional CLM control. The use of DDs for CLM management pro-vides a promising technique for sustainable CLM management that canhelp preserve natural enemies through the judicious use of pesticides,especially at the active period of parasitoids and/or predators that typic-ally occur during citrus growth flushes as indicated in this study.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Funding

This study was supported by the National Institute for Agricultural Research ofMorocco (Regional Center of Agricultural Research of Oujda). We thank the Triffa andZniber Domains (heads and technicians) for their technical support, availability andvaluable advice.

References

Abbassi M. 2010. New pests in Morocco and their natural enemies (1970-2010). In:Garcia-Mari F, editor. Proceeding of Working Group “Integrated Control in CitrusFruit Crops. IOBC/wprs Bull, 1–3; p. 237.

Amiri-Besheli B. 2011. The Effect of Some Botanical Pesticides Against Citrus Leafminer(CLM) and Two Spotted Mite (TSM), Pesticides in the Modern World - PesticidesUse and Management, Dr. Margarita Stoytcheva (Ed.), ISBN: 978-953-307-459-7,InTech, Available from: http://www.intechopen.com/books/pesticides-in-the-modern-world-pesticides-use-andmanagement.

Attrassi K, Badoc A. 2013. Infestation de Phyllocnistis citrella de vergers d’agrumes duGharb. Bull Soc Pharm Bordeaux. 152(1–4):65–74.

Beattie GAC, Somsook V, Watson DM, Clift AD, Jiang L. 1995. Field evaluation ofSteinernema carpocapsae (Weiser) (Rhabdtida: Steinernematidae) and selected pesti-cides and enhancers for control of Phyllocnistis citrellaStainton (Lepidoptera:Gracillariidae). Aust J Entomol. 34(4):335–342.

Belasque J Jr, Parra-Pedrazzoli AL, Rodrigues Neto J, Yamamoto PT, Chagas MCM,Parra JRP, Vinyard BT, Hartung JS. 2005. Adult citrus leafminers (Phyllocnistis cit-rella) are not efficient vectors for Xanthomonas axonopodis pv. citri. Plant Dis. 89(6):590–594.

Browning HW, Childers CC, Stansly PA, Pe~na J, Rogers ME. 2006. Florida citrus pestmanagement guide: Soft-bodied insects attackingfoliage and fruit. University ofFlorida/IFAS, Gainesville FL. http://edis.ifas.uX.edu/CG004.

14 K. KHFIF ET AL.

Chagas MCM, Parra JRP, Namekata T, Hartung JS, Yamamoto PT. 2001. Phyllocnistiscitrella Stainton (Lepidoptera: Gracillariidae) and its relationship with the citrus can-ker bacterium Xanthomonas axonopodispv. citri in Brazil. Neotrop Entomol. 30(1):55–59.

Chhetry M, Gupta R, Tara JS, Pathania PC. 2012. Seasonal abundance of citrus leafminer Phyllocnistis citrellastainton (Lepidoptera: Gracillariidae), from Jammu andKashmir. J Insect Sci. 25(2):144–149.

Clausen SP. 1931. Two citrus leaf miners of the Far East. USDA, Washington, DC. TechBull. 252:1–13.

Elekcio�glu Z. 2013. Determination of the natural mortality factors of Citrus leafminer[Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae)] in Adana Province,Turkey. T€urk Entomol Derg. 37(1):21–30.

Elekcio�glu Z, Uygun N. 2004. The effect of temperature on development and fecundityof Phyllocnistis citrella Stainton (Lepidoptera: Gracillaridae). Turk Entomol Derg.28(2):83–93.

Grafton-Cardwell EE, Morse JG, Haviland DR, Faber BA. 2019. Citrus - Pest manage-ment guidelines for agriculture. UC IPM Pest Management Guidelines - CITRUS:80–85.

Heppner JB. 1995. Citrus leafminer (Lepidoptera: Gracillariidae) on fruit in Florida. FloEntomol. 78(1):183–186.

Hoy M, Singh R, Rogers M. 2007. Citrus Leafminer, PhyllocnistisCitrella (Lepidoptera:Gracillariidae), and natural enemy dynamics in central Florida during 2005. FloEntomol. 90(2):358–369.

Hoy MA, Nguyen R. 1997. Classical biological control of the citrus leafminerPhyllocnistis citrella Stainton (Lepidoptera: Gracillariidae): theory, practice, art animalscience. Trop Lep. 8(suppl):1–19.

Kheder SB, Jerraya A, Jrad F, Fezzani M. 2002. �Etude de la mineuse des agrumesPhyllocnistis citrella Stainton (Lep. Gracillariidae) dans la r�egion du Cap Bon(Tunisie). Fruits. 57(1):29–42.

Legaspi JC, French JV, Zu~niga AG, Legaspi BC. 2001. Population dynamics of the citrusleafminer, Phyllocnistis citrella (Lepidoptera: Gracillariidae), and its natural enemies inTexas and Mexico. Biol Control. 21(1):84–90.

Mazih A. 2015. Status of citrus IPM in the Southern Mediterranean basin Morocco.North Africa. Actahorticulturae. 1065:1097–1103.

Pandey ND, Pandey YD. 1964. Bionomics of Phyllocnistis citrella Stt. (Lepidoptera:Gracillariidae). Indian J Entomol. 26:417–423.

Qureshi JA, Stelinski LL, Stansly PA. 2004. Management of Asian citrus psyllid and cit-rus leafminer. Citrus industry. 4.

Rizqi A, Nia M, Abbassi M, Roch A. 2003. Establishment of exotic parasites of Citrus leaf-miner, Phyllocnistis citrella, in citrus groves in Morocco. IOBC/wprs Bull. 26(6):1–6.

Saharaoui L, Benzara A, Doumandji-Mitiche B. 2001. Dynamique des populations dePhyllocnistis citrella Stainton (1856) et impact de son complexe parasitaire en Alg�erie.Fruits. 56(6):403–413.

Sarada G, Gopal K, Gouri-Sankar T, Mukunda-Lakshmi L, Gopi V, Nagalakshmi T,Ramana KTV. 2014. Citrus leaf miner (Phyllocnistis citrella Stainton. Lepidptera:Gracillariidae): Biolology and management: A review. RRJAAS. 3(3):39–48.

Smaili CM, Afellah MA, Arab A, Zrida L. 1999. Biology and ecology of leafminer andevaluation of parasitoids in Clementine in the Gharb area (Morocco). MedFacLandbouww. 64/3a:121–131.

ARCHIVES OF PHYTOPATHOLOGY AND PLANT PROTECTION 15

Smaili MC. 2017. Current pest status and the integrated pest management strategy inthe citrus groves in Morocco. In IOBC/Wprs Citrus Working Group Meeting onCitrus Pests, Diseases and Weeds. p. 25–27.

Smaili MC, Abbassi M, Boutaleb JA, Blenzar A. 2013. Richesse sp�ecifique des ennemisnaturels associ�es aux vergers d’agrumes au Maroc: Int�eret et implication pour la luttebiologique. EPPO Bull. 43(1):155–166.

Tan B, Huang M. 1996. Managing the citrus leafminer in China. In: Hoy MA, editor.Managing the Citrus Leafminer, Proc. Intern. Conf., Orlando, Florida; April 23–25,1996, 4. 11952. Gainesville: Univ. Florida. p. 119.

Ujiye T. 2000. Biology and control of the Citrus Leafminer. PhyllocnistiscitrellaStainton(Lepidoptera: Gracillariidae) in Japan. JARQ. 34(3):167–173.

Urbaneja A, Mu~noz A, Garrido A, Jacas JA. 2004. Which role do lacewings and antsplay as predators of the citrus leafminer in Spain? SJAR. Span J Agric Res. 2(3):377–384.

Xiao Y, Fadamiro HY. 2010. Exclusion experiments reveal relative contributions of nat-ural enemies to mortality of citrus leafminer, Phyllocnistiscitrella (Lepidoptera:Gracillariidae) in Alabama satsuma orchards. Biol Control. 54(3):189–196.

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