Transcriptomic analysis of the honey bee (Apis mellifera) queen brain in response to pesticide exposure during development

Honey bees (Apis mellifera) are the most economically important insect, supplying an estimated $15 billion annually to our agricultural economy, primarily through crop pollination. Despite their importance, honey bee health has been challenged in recent years due to several factors including poor queen quality, parasites and pathogens, and exposure to pesticides. Our ongoing research projects are focused on understanding how queen health is affected by exposure to agricultural pesticides during development. Developing queens can be exposed to pesticides in the beeswax over time, including miticides used to treat the ectoparasitic mite, Varroa destructor and agrochemicals collected by foragers. Because behavior is dictated by neural responses, we want to understand how pesticide exposure during development might affect gene expression in the queen’s brain. Here, we sequenced the brain transcriptome of experimental queens that were reared by grafting one-day-old larvae into wax-coated cups that were either pesticide-free, or those containing field-relevant combinations of the miticides tau-fluvalinate and coumaphos (FC group), the miticide amitraz (A group), and the agrochemicals chlorothalonil and chlorpyrifos (CC group). We allowed the queens to develop and mate naturally. Once the queens were laying, we then dissected their brains (n = 3 per treatment), extracted RNA and sent the samples for sequencing. Preliminary analysis revealed 247 differentially expressed genes (DEGs) in the FC group, 668 DEGs in the A group and 244 DEGs in the CC group. Gene ontology analysis is ongoing to identify novel pathways associated with queen physiology for the focus of future studies.