Abstract
The emergence of agricultural land use change creates a number of challenges that insect pollinators, such as eusocial bees, must overcome. Resultant fragmentation and loss of suitable foraging habitats, combined with pesticide exposure, may increase demands on foraging, specifically the ability to collect or reach sufficient resources under such stress. Understanding effects that pesticides have on flight performance is therefore vital if we are to assess colony success in these changing landscapes. Neonicotinoids are one of the most widely used classes of pesticide across the globe, and exposure to bees has been associated with reduced foraging efficiency and homing ability. One explanation for these effects could be that elements of flight are being affected, but apart from a couple of studies on the honeybee (Apis mellifera), this has scarcely been tested. Here, we used flight mills to investigate how exposure to a field realistic (10 ppb) acute dose of imidacloprid affected flight performance of a wild insect pollinator—the bumblebee, Bombus terrestris audax. Intriguingly, observations showed exposed workers flew at a significantly higher velocity over the first ¾ km of flight. This apparent hyperactivity, however, may have a cost because exposed workers showed reduced flight distance and duration to around a third of what control workers were capable of achieving. Given that bumblebees are central place foragers, impairment to flight endurance could translate to a decline in potential forage area, decreasing the abundance, diversity, and nutritional quality of available food, while potentially diminishing pollination service capabilities.
Highlights
The extent to which insects move across landscapes has significant implications for human welfare
We investigated the effects of acute oral neonicotinoid exposure on different aspects of bumblebee (Bombus terrestris audax) flight performance using a controlled tethered flight mill setup (Figure 1)
Workers could access the provisioned sucrose‐soaked cotton wool for 10 min, after which the cotton wool was removed and original bung replaced, followed by a 5‐min resting period inside the tube. While this protocol meant that we could not determine the precise dosage of imidacloprid consumed by each worker, which might have improved the predictive power of our models, it did allow workers to feed to satiation, which is a state likely to occur in the field during foraging bouts and allowed consumption volume to vary proportionately to individual worker size (Free & Butler, 1959; Goulson et al, 2002)
Summary
The extent to which insects move across landscapes has significant implications for human welfare. The majority of angiosperms, including around 3⁄4 of our crop species, are to some degree reliant upon the extensive movement of foraging insect pollinators (Gill et al, 2016; Kleijn et al, 2015; Klein et al, 2007; Ollerton, Winfree, & Tarrant, 2011) It is important we understand which, and to what extent, stressors affect insect pollinator flight performance if we are to mitigate threats to a global pollination service valued at >€150 bn annually (Benaets et al, 2017; Fischer et al, 2014; Gallai, Salles, Settele, & Vaissière, 2009; Gill & Raine, 2014; Stanley et al, 2015; Wolf et al, 2014). We tested the propensity of individual bees to fly, followed by the measures of their flight distance and duration, the dynamics of velocity over the course of the flight test, and investigated how neonicotinoid exposure interacted with worker body size on these performance measures
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
