The impact of pesticides on the gut microbiome of honey bee queens

Previous research has shown that pesticide-exposure can negatively impact the gut microbiome of honey bee workers. However, there is very little research on what constitutes a healthy gut microbiome of a honey bee queen, let alone what impact pesticide exposure may have on microbial diversity and quantity. The goal of this research was to expose honey bee queens to a mixture of different agrochemicals and then determine how the microbial diversity and quantity within their guts differed from unexposed queens using 16s sequencing techniques. We chose to use field-relevant doses of three agrochemicals (azoxystrobin, chlorpyrifos, and pyraclostrobin) that are commonly used in large-scale corn and soybean agricultural operations in the Midwest. We reared honey bee queens within queen manipulation cages (QMCs) where we could easily expose a queen and her attending workers to the pesticide mixture through their pollen and sucrose feed. In addition to 16s sequencing to measure gut diversity and quantity, we also measured physiological parameters of queen reproductive health, such as egg laying rate and ovary size. We found that cages fed the pesticide mixture resulted in queens that laid a significantly lower number of mean total eggs when compared to control queens or queens that were only exposed to one of our pesticides of interest. However, we did not see a significant difference in ovary size between pesticide exposed and non-exposed queens. We are currently in the process of analyzing our 16s sequencing data, which will be ready to present at ESA.