Missing Nurse Bees—Early Transcriptomic Switch From Nurse Bee to Forager Induced by Sublethal Imidacloprid

Abstract

The environmental residue/sublethal doses of neonicotinoid insecticides are believed to generate a negative impact on pollinators, including honey bees. Here we report our recent investigation on how imidacloprid, one of the major neonicotinoids, affects worker bees by profiling the transcriptomes of various ages of bees exposed to different doses of imidacloprid during the larval stage. The results show that imidacloprid treatments during the larval stage severely altered the gene expression profiles and may induce precocious foraging. Differential expression of foraging regulators was found in 14-day-old treated adults. A high transcriptome similarity between larvae-treated 14-day-old adults and 20-day-old controls was also observed, and the similarity was positively correlated with the dose of imidacloprid. One parts per billion (ppb) of imidacloprid was sufficient to generate a long-term impact on the bee’s gene expression as severe as with 50 ppb imidacloprid. The disappearance of nurse bees may be driven not only by the hive member constitution but also by the neonicotinoid-induced precocious foraging behavior.

Chronic Effects of Imidacloprid on Honey Bee Worker Development—Molecular Pathway Perspectives

“…To comprehensively evaluate the molecular effects of imidacloprid on worker development, transcriptomes of 9-day-old larvae and 0-, 7-, 14-, and 20-day-old adults were sequenced after exposure to 1 μL of 1 ppb, 10 ppb, or 50 ppb imidacloprid during the larval stage for 4 consecutive d (2-day-old to 5-day-old larvae) [ 79 ]. The numbers of DEGs and the developmental queue showed no significant correlation, and a dosage-dependent effect was observed only on 9-day-old larvae and 0-day-old adults.…”

“…The transcriptomic profiles suggested the development of precocious foragers in 14-day-old adults after imidacloprid treatment during the larval stage. The switch from nurse bees to foragers may involve many physiological changes in tissues/organs, and foragers are more positively phototactic [ 79 , 85 ]. Thus, at least three pathways were correlated with the development of honey bees.…”

“…From the perspective of the developmental queue, the affected genes and functional pathways were diverse among workers of different ages. Nevertheless, they seemed to be coordinated with bee development and task performance and may consequently result in precocious foragers [ 79 ].…”

Acute oral toxicity, apoptosis, and immune response in nurse bees (Apis mellifera) induced by flupyradifurone

“…In the wild, honey bee foragers may carry pesticide-contaminated nectar or pollen back to the colony. These pesticide-laden foods can harm not only the foragers themselves, but also the larvae through the nurse feeding behavior ( Medrzycki et al, 2003 ; Forfert and Moritz, 2017 ; Abou-Shaara et al, 2021 ; Chen et al, 2021 ; Wueppenhorst et al, 2022 ). Young bees (hive bees) between 3 and 13 days old were termed as nurse bees, whose tasks were mainly processing food and provisioning bee larvae.…”

European Honey Bee (Apis mellifera L.) Foraging Activities, Impacts and Potential Factors of Decline- A Review

“…Colony parameters influenced labor division and the nurse bee's ability to execute foraging activities (Chen et al, 2021). Differences in messenger RNA quantity in the worker bee's brain are also significant (Ustaoglu et al, 2021).…”