causes and consequences of pollinator decline · • honey bee visitation has weaker effect, which...
TRANSCRIPT
Causes and consequences of pollinator declineEU Pollinator Initiative Workshop 15/03/2018
BELSPO (Belgian Science Policy Office), Avenue Louise 231, 1050 Brussels
Dr Adam VanbergenNERC Centre for Ecology & Hydrology (CEH)
China
USAex-USSR Germany
Argentina Spain
• Land use change
• Land management (intensity, GMO etc.)
• Pesticides (insecticides, herbicides)
• Pollinator diseases & bee husbandry
• Climate change
• Invasive alien species
Drivers of change in pollinators
• Reduction in food, nesting or other resources
Loss of habitatFragmentationDegradation
• Applies to agricultural, natural, urban and biocultural areas
• Loss of practices based on Indigenous and Local Knowledge, which can be beneficial to nature
Land use change
Land-use change, pollinator networks & plant mating
Birch Woods
Ungrazed GrazedFlo
we
rin
g p
lan
t s
pe
cie
s r
ich
ne
ss
20
22
24
26
28
30
32
34
N= 10
N= 10
Vanbergen et al. (2014) Functional Ecology 28 178-189
Floral Species Richness
4 6 8 10 12 14 16 18 20 22 24
Ne
two
rk C
on
nec
tan
ce
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8 AICc wi = 0.44
GRAZED n=5
UNGRAZED n=4
Standardised Connectance
0.2 0.4 0.6 0.8
Ou
tcro
ssin
g r
ate
(t m
)
0.4
0.5
0.6
0.7
0.8
0.9
1.0 AICc wi = 0.88= fully outcrossed
• Loss of non-cultivated habitat patches
• Large field sizes and monocultures
• High inputs of fertilizers, pesticides, herbicides etc.
• Intensive grazing
Intensive agriculture
• Broad range of lethal and sub-lethal effects
• Impacts vary with compound toxicity, exposure level, location and pollinator species
• Risks can be increased if:
Labelling is insufficient or not respected
Application equipment is faulty or not fit-for-purpose
Risk assessment or regulations are insufficient
Pesticides
Neonicotinoid use & pollinator decline: a 17 year correlation
Other pesticides (ns)
Oilseed rape cover (+ve)
Neonicotinoid use (-ve)
Volunteer surveys of
bees
BWARSBees, Wasps & AntsRecording Society
-18%
Red = Actual trend;
Blue = Estimated trend if NNI
were benign
Pro
bab
ility
Non-foragersOSR Foragers
Negative Positive
Bees feeding on rape
negatively affected
B.A. Woodcock et al. (2016) Impacts of neonicotinoid use on long-term
population changes in wild bees in England. Nature Communications 7,
12459. doi:10.1038/ncomms12459
Neonicotinoids (NNI) & bee health: a landscape experiment
Potential negative
interacting factors
Bee diet: Worse where
oilseed rape forms
much of diet
Bee health: Worse
where bees have high
disease load
• Negative & positive effects
on honeybee colony health
• Negative effects on
reproduction of wild bee
species (B. terrestris, O.
bicornis)
• More persistent in
soil than expected
Image cred
it: Bayer
B. A. Woodcock et.al. (2017) Country-specific effects of neonicotinoid
pesticides on honey bees and wild bees. Science. 356, 6345, 1393-1395
doi: 10.1126/science.aaa1190
0
100
200
300
400
500
600
700
0 1 2 3 4 5 6 7 8 9
GermanyHungaryUK
Neonicotinoid residues found in nests (ng g-1)
New
qu
een
s
Deformed Wing Viruselectron density image Source: Pavel Plevak
Asian hornet (Vespa velutina) eating a honeybee. Source Alain C.
Varroa mite (Varroa destructor) on a honeybee. Source: Rob Paxton
Nosemaceranaea fungal parasite of honeybees Source: IngemarFries
Pests & pathogens
Bee trade, pests and pathogens
Ryabov et al. 2014. PLoS Pathog 10Wilfert et al 2016. Science 351Martin et al 2012. Science 336Szabo et al 2012.Conservation Letters 5Furst et al 2014. Nature 506McMahon et al . 2015. JAE 84Moritz et al 2005. Ecoscience 12Vanbergen et al. 2018, Nature Ecology & Evolution 2
• For some pollinators (e.g. bumblebees and butterflies):
Range changes
Altered abundance
Shifts in seasonal activities
Risk of disruption of future crop pollination
• Climate shifts across landscapes may exceed species dispersal abilities
Climate Change
Jeremy T. Kerr et al. Science 2015;349:177-180
Invasive alien species
• Identity and evolutionary history of the
invader & recipient ecosystem matters…
Bartomeus, et al. 2010.. Journal of Ecology 98.Vila, et al. 2009. PRSB 276.Lopezaraiza-Mikelet al 2007. Ecology Letters 10Vanbergen et al. 2018, Nature Ecology & Evolution 2
Asian hornet (Vespa velutina) and honeybee
Multiple impacts across biological scales
Vanbergen A.J. and the Insect Pollinators Initiative (2013). Threats to an ecosystem service: pressures on pollinators. Frontiers in Ecology and the Environment
Other potential drivers
• Pollution - Heavy metals- Nutrients (e.g. Nitrogen)- Particulates (e.g. diesel)- EMR: visible light; other wavelengths (e.g. 3/4/5G)
• Fungicides & their interactions
• More than 75% of leading food crops
• Almost 90% of the world’s flowering plants
Rely, at least in part, on animal pollination
Risks of pollinator decline
Status of insect-pollinated wild plants
• Insect pollinator
dependence correlated
with plant decline
• Threatened plants
dependent on pollinators
declined >4x rate of
species not dependent
t = 5.23, d.f.= 465.72, P<0.001
t = 3.53, d.f= 48.63 P<0.001
Non-conservation status plant species
Conservation status plant species
Vanbergen A.J., Heard, M.S., Breeze, T., Potts, S.G. & Hanley, N. (2014) Status and value of pollinators and pollination services - A report for the Department for Environment, Food and Rural Affairs (Defra UK) Contract number: PH0514.
Status of insect-pollinated wild plants
• Insect pollinator
dependence correlated
with plant decline
• Threatened plants
dependent on pollinators
declined >4x rate of
species not dependent
t = 5.23, d.f.= 465.72, P<0.001
t = 3.53, d.f= 48.63 P<0.001
Non-conservation status plant species
Conservation status plant species
Vanbergen A.J., Heard, M.S., Breeze, T., Potts, S.G. & Hanley, N. (2014) Status and value of pollinators and pollination services - A report for the Department for Environment, Food and Rural Affairs (Defra UK) Contract number: PH0514.
What are the consequences for the organisms, above and belowground,
linked to declining pollinator-dependent plants?
Is pollination a keystone interaction?
Crop pollination services• Wild insect visitation enhances crop production & stability• Honey bee visitation has weaker effect, which supplements, but does
not replace, the pollination service by wild insects
Garibaldi et al. Science 2013 339:1608-1611
Rader et al. (2015) PNAS.
Pollinators increase crop yields
Crop pollination: by few species
• ~80% of crop pollination delivered by 2% of bee species
• These are common & perhaps robust to agricultural intensification
But pollinator diversity may provide resilient pollination services
Kleijn, et al (2015) Nature Communincations, 6.
Crop pollination services
Rader et al. PNAS 2015 doi/10.1073/pnas.1517092112
• Diversity and identity of pollinators varies between crops • Species pool varies for a given crop across geographic
regions
Crop pollination: diversity matters
Potential crop pollination deficits?
-0.25 - -0.125
-0.125 - 0
0 - 0.125
0.125 - 0.25
High FD
Low FD
National distribution of functional diversity of native crop pollinators. Note potential deficits in areas of important crop production
Woodcock, et al (2014) Journal of Applied Ecology, 51, 142-151.Source: Polce et al. (2013) PLoS ONE, 8, e76308
• Bee species richness or functional diversity • Modelled from species occurrence records• Related to agricultural statistics (e.g. crop cover)
‘Causes’ – key messages
• Multiple anthropogenic drivers affect pollinators and pollination, and some of which may interact
• Drivers can have negative, but sometimes positive, effects on pollinators & pollination
• Often difficult to link drivers to declines over time; but can be inferred from short-term impact studies
• Considerable knowledge gaps remain about the effects of different drivers, their interplay, and relative importance
Threats to pollinators risks:
• Disrupting wild plant pollination
• Altering wider ecological interactions & functions?
• Reducing delivery of sustained crop pollination services
• Impacts on crop production and stability of yield
• Economic, social and health costs to humans
‘Consequences’ – key messages
• The Chairs, authors, TSU & secretariat of the IPBES assessment
• The authors of all the studies highlighted here
• European Commission for this nascent pollinator initiative and hosting this workshop
Acknowledgements