Location: Carl Hayden Bee Research CenterTitle: Accelerated abdominal lipid depletion from pesticide treatment alters honey bee pollen foraging strategy, but not onset, in worker honey bees
Submitted to: Journal of Experimental Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/14/2023
Publication Date: N/A
Interpretive Summary: Food intake behavior helps maintain homeostasis. For honey bees, food intake for the entire colony is delegated to a demographic of workers that forage for pollen, nectar and water. Stressed bees may exhibit changes in foraging behavior, but the physiological mechanisms underlying these changes are unknown. We speculate that chronic stress depletes abdominal adipose tissue to disrupt appetitive patterns and increase food intake. To test this, we treated bees with pesticides and sampled them as foragers to assay both their abdominal and pollen lipid content. Stressed bees had less abdominal lipid and collected less, yet fattier pollen. Our results show that a stress-induced depletion of abdominal lipid signals a change in conscious feeding behavior to collect fattier foods.
Technical Abstract: Honey bee abdominal lipids decline with age, a change associated with the onset of foraging behavior. Whether or not bees with accelerated lipid loss vary from controls in both the onset and nutritional quality of pollen collected from foraging trips is not fully understood. We asked whether stress affects foraging behavior through the depletion of abdominal lipid, and whether stress-induced lipid depletion causes bees to forage earlier and for fattier pollen. We tested this by treating newly-emerged bees with one of two pesticides, pyriproxyfen (a JH analogue) and spirodiclofen (a fatty acid synthesis disruptor), that may affect energy homeostasis in non-target insects. Bees fed these pesticides were returned to hives to observe the onset of foraging behavior. We also sampled foraging bees to assay both abdominal lipid content and dietary lipid content of their corbicular pollen. Spirodiclofen-treated bees had significantly reduced abdominal lipid and collected less, but more lipid-rich, pollen. Pyriproxyfen treatment reduced the age at first forage, but did not affect abdominal or pollen dietary lipid levels. Our results suggest that bees with depleted lipid reserves compensate by collecting fattier pollen and that accelerated fat body depletion is not a prerequisite for precocious foraging.