The Effect of Olfactory Exposure to Non-Insecticidal Agrochemicals on Bumblebee Foraging Behavior

Abstract

Declines in bumblebee populations have led to investigations into potential causes – including agrochemical effects on bumblebee physiology. The indirect effects of agrochemicals (i.e. behavior modulation) have been postulated, but rarely directly tested. Olfactory information is critical in mediating bumblebee-floral interactions. As agrochemicals emit volatiles, they may indirectly modify foraging behavior. We tested the effects of olfactory contamination of floral odor by agrochemical scent on foraging activity of Bombus impatiens using two behavioral paradigms: localization of food within a maze and forced-choice preference. The presence of a fungicide decreased bumblebees’ ability to locate food within a maze. Additionally, bumblebees preferred to forage in non-contaminated feeding chambers when offered a choice between control and either fertilizer- or fungicide-scented chambers.

Compounds without borders: A mechanism for quantifying complex odors and responses to scent-pollution in bumblebees

“…As of June 2019 Home Depot's website listed 333 products under plant care geared for disease control and fertilization. At least one prior study has shown that the scent of a consumer lawn product is capable of modifying bumblebee foraging behavior in the lab [10]-but piecewise testing of 333 products is an intractable amount of work for the academic community and agrochemical producers are unlikely to take up the cause. Agrochemical odor pollution is not confined to consumer products; commercial agrochemicals may also be problematic [10].…”

“…At least one prior study has shown that the scent of a consumer lawn product is capable of modifying bumblebee foraging behavior in the lab [10]-but piecewise testing of 333 products is an intractable amount of work for the academic community and agrochemical producers are unlikely to take up the cause. Agrochemical odor pollution is not confined to consumer products; commercial agrochemicals may also be problematic [10]. Using the CWB-method to calculate angular shifts due to agrochemical scent-pollution could identify products that shift odors into a 'zone of concern', namely outside the identified generalization zone.…”

“…Flowers provide multiple sensory advertisements to pollinators; such as shape, color, and scent [5][6][7]. Recent computational work indicates that odor is consistently available to searching bumblebees [8] and labbased experiments indicate that bumblebees are capable of using odor information alone to locate floral resources [9,10]. Floral-scent is likely an important sensory cue for bumblebee foragers; unfortunately anthropogenic activity has modified their olfactory landscape in urban, suburban and agricultural ecosystems [11][12][13][14][15].…”

“…Scents can also be contaminated by the addition of novel odors, resulting in a modified odor-blend. For example, the addition of some agrochemical odors to a learned scent have been shown to modify bumblebee foraging behavior [10]. Given the vast quantity of potential odor pollutants in human habitats, it is unrealistic to approach this problem through individual behavioral tests.…”

Non‐target effects of fungicides on nectar‐inhabiting fungi of almond flowers

“…These agrochemicals can contaminate both pollen and nectar, posing an ecological and economic risk for beneficial interactions (Chauzat et al, 2006;Gill et al, 2012;Krupke et al, 2012;Pettis et al, 2013). For instance, exposure to and consumption of fungicides can have detrimental effects on beneficial macroorganisms such as bees, affecting larval development (Mussen et al, 2004), foraging behavior (Sprayberry et al, 2013), and driving mortality through both direct and indirect pathways (Pettis et al, 2013;Bernauer et al, 2015). Although evidence is mounting on the detrimental effects of agrochemicals on macroorganisms, less attention has been paid to non-target microorganisms that may also benefit crop yield (but see Alvarez-P erez et al, 2016;Bartlewicz et al, 2016).…”