Overcoming insecticide resistance using diverse fungal pathogens and heterogeneous agricultural landscapes

Abstract

Pesticide-resistant insects remain among the most important obstacles to global food security; each newly developed control measure imposes intense selection on insect pests, which inevitably evolve resistance. Evolutionary genetic theory has established that balancing selection (which is needed to maintain genetic diversity for susceptible alleles) is more likely in heterogeneous environments that contrast sharply with industrial monocultures. However, practical considerations, such as difficulties in harvesting polycultures, have constrained previous efforts to incorporate this insight and overcome insecticide resistance. Our proposal exploits the fact that natural insect pathogens have substantially divergent modes of action that have been shaped over millions of years to elude resistance, and overlays this heterogeneity with practically feasible approaches to increasing the complexity of the agricultural landscape. In the pump-priming phase of our project, we will use a quantitative genetics experiment to demonstrate the theoretical principles with relevant insect pests and pathogens, alongside lab experiments to measure the effects of several fungal isolates on pest insects, and demonstrate that these isolates can operate in Brazil under relevant field conditions. (AU)