Impacts of insecticide exposure on bumblebee behaviour in a warming world
File(s)
Author(s)
Kenna, Daniel
Type
Thesis
Abstract
With ongoing agricultural land-use intensification and climate change, important functional groups of organisms, including insect pollinators, are being simultaneously and ubiquitously exposed to both pesticides and changing temperatures. Given the notable ongoing declines in insect pollinators, understanding how these stressors affect aspects of key functional behaviours underpinning fitness and pollination service provision is of global ecological and economic importance. Importantly, a critical but understudied step in evaluating pesticide risk is to understand how environmental temperature modulates pesticide effects on these behaviours. Through empirical lab experiments on a key wild pollinator, the bumblebee Bombus terrestris, I quantified the temperature dependent effects of insecticide exposure on individual flight and general mobility. Neonicotinoid exposure dramatically impaired flight motivation and endurance, and these same performance traits were also found to be highly sensitive to environmental temperature. However, the effect of neonicotinoid exposure varied depending on post-exposure temperature, with impacts on flight being enhanced under warmer conditions and impacts on food consumption, walking, and general responsiveness being enhanced under cooler conditions. The hazard posed by insecticides to insect pollinators may therefore vary both temporally and spatially, with impairment to flight and mobility traits likely constraining colony foraging potential and diminishing pollination service capabilities. Interestingly, the same effects were not seen across a different class of insecticide, with the new to market sulfoximine insecticide, sulfoxaflor, showing no detectable effect on any measure of mobility regardless of temperature when applied at comparable concentrations. The findings of this thesis suggest both the choice of insecticide and timing of exposure need to be considered in farming practices. Additionally, my findings provide crucial information for advising insecticide risk assessment protocols, developing mitigative and conservation action, and above all understanding which possible climate regions in the world insect pollinators are most at risk from insecticide exposure.
Version
Open Access
Date Issued
2022-01
Date Awarded
2022-11
Copyright Statement
Creative Commons Attribution Licence
License URL
Advisor
Gill, Richard
Sponsor
Natural Environment Research Council (Great Britain)
Grant Number
NE/L002515/1
Publisher Department
Life Sciences
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)