Natural Variation in Pesticide Susceptibility

Individuals within a species can differ substantially in their susceptibility to environmental toxicants. Understanding the genetic basis of these differences is important for identifying mechanisms of pesticide resistance, accurately assessing toxicant risk, and understanding how populations adapt to chemical exposures. Our research uses genetically diverse C. elegans strains and high-throughput phenotyping to identify the genetic variants and biological pathways that influence pesticide susceptibility.

Chlorfenapyr resistance. We identified substantial natural variation in susceptibility to chlorfenapyr, a widely used pesticide, and mapped a major resistance locus to chromosome V. Using recombinant inbred lines, near-isogenic strains, whole-genome sequencing, and molecular genetic approaches, we are refining this locus and investigating candidate genes, including members of the cytochrome P450 family. This work aims to identify the genetic and molecular mechanisms responsible for differences in chlorfenapyr resistance.

Pyrethroid susceptibility. We are investigating natural variation in responses to pyrethroid insecticides, including permethrin, deltamethrin, and lambda-cyhalothrin. We have developed quantitative behavioral assays that can be used to identify differences in susceptibility among wild strains and will soon apply these tools to determine how genetic variation influences the behavioral and physiological effects of these neurotoxic compounds.

Neurotoxicant interactions and behavioral effects. A longer-term goal is to examine the effects of combined chemical exposures, determining whether pesticide interactions are additive, synergistic, or antagonistic. By integrating quantitative dose-response models with genetic mapping, we aim to identify loci that modify responses to individual chemicals and their combinations, including genetic variants that influence non-additive interactions.