Results
To investigate how evolved pesticide resistance and pesticide exposure impact host interactions with pathogens, we exposed control-regime and pesticide-selected populations to control and pesticide oral treatments, with and without Bt. We measured the main and interactive effects of pesticide selection regime (Reg), pesticide treatment (PTx), and Bt treatment (BtTx) on survival, development, and gene expression for OP and Pyr separately (see methods for full model description). In brief, we found that pesticide selection resulted in increased resistance to pesticide exposure. Exposure to Btt did not have an overall effect on survival but did delay development, and dual exposure to OP and Btt resulted in improved survival compared to larvae exposed to only OP. Moreover, dual exposure to either OP or Pyr and Bttresulted in faster development compared to individuals exposed to only pesticides. Last, we identified antagonistic gene expression interactions between Btt and OP exposure and Btt and Pyr selection that indicate changes in immune function in infected individuals either exposed to or selected for resistance to different pesticides.