Population Genomic Insights into Insecticide Resistance in the Colorado Potato Beetle

Abstract

The ability of pests to develop resistance is still poorly understood, particularly regarding the process of adaptive change that leads to resistance. Understanding the mechanisms involved in pesticide adaptation is important because common methods of field-level resistance management assume that simple (single-gene) mutations cause resistance, but may not perform effectively when multiple loci and several molecular pathways confer resistance. Emerging experimental and genomic evidence suggests the single-gene model may be insufficient to explain many cases of rapid pest evolution. Here we review such evidence in the Colorado potato beetle, Leptinotarsa decemlineata, widely considered to be a super-pest due to its rapid evolution to most classes of insecticides. A combination of studies suggests that polygenic resistance drawn from standing variation best explains regional differences in patterns of insecticide resistance. However, these studies have lacked a temporal framework to demonstrate polygenic evolution unequivocally, as well as the ability to estimate key evolutionary parameters to model processes of rapid evolution. We suggest a temporal framework to empirically test for polygenic insecticide resistance evolution, as well as determine the proximate genetic and evolutionary mechanisms contributing to resistance. Emerging data from population genomics promise to increase our knowledge of insect pest molecular genetics by identifying gene networks involved in pesticide resistance, thereby providing a means to monitor the spread of resistance, develop management approaches that increase pesticide longevity, and identify new methods of gene-targeted pest control.