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.