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Influence of honey bee seasonal phenotype and emerging conditions on diet behavior and susceptibility to imidacloprid

Mohamed Alburaki, Shayne Madella, Philene Vu, Miguel Corona
Apidologie 2022 v.53 no.1 pp. 12
Apis mellifera, climate, diet, imidacloprid, intestinal microorganisms, phenotype, summer, syrups, trophallaxis
Honey bee Apis mellifera L. colonies produce two distinct phenotypes of workers during summer and winter to cope with drastic seasonal variations in climate and food resources. Imidacloprid (IMP) is a neonicotinoid insecticide widely used in agriculture for pest management control. In this study, we investigate the influence of seasonal phenotype and emerging conditions on the diet behavior of bees fed ad libitum two concentrations of IMP. We performed three independent two-choice feeding experiments using summer bees either emerged in the laboratory or in-hive and winter bees. Diet behavior post-ingestive aversion responses to IMP were investigated as well as potential affinity to the physical location and contents of the diets. Caged bees were challenged with a physical rotation of the diet’s location and their susceptibility to 5 and 20 PPB of IMP was tested. From a behavioral standpoint, our results show that winter bees expressed no affinity to the physical location of the diet but rather to its content and strongly favored IMP-tainted syrup at both 5 and 20 PPB. The opposite was recorded for naïve summer bees that emerged in the laboratory, which avoided the tainted syrup at both concentrations, particularly at 20 PPB. Summer bees emerged in-hive, expected to have developed a mature intestinal microbiota through trophallaxis from older bee-mates, were mainly neutral, and showed no affinity to the diet location nor its contents. Our results indicate that the physiological changes associated with seasonal phenotype and initial exposure to older mates have important consequences on the bee diet behavior toward pesticides.