Examining the role of Phase III metabolism in insecticide susceptibility of Chironomus dilutus

Abstract:

The economy of northwestern Pennsylvania relies heavily on the viticulture industry. To ensure adequate harvests, viticulturists utilize synthetic insecticides to control pest numbers and prevent the destruction of crops. Due to the frequent use of these chemicals, there is concern that local populations of a grape pest, the grape berry moth (GBM; Endopiza viteana), have developed resistance to commonly used insecticides. Although pesticide resistance in E. viteana is well-documented, the exact mechanisms of resistance are unknown. Due to limited availability of E. viteana larvae outside of the growing season, Chironomus dilutus was selected as a model organism to explore the role of ATP-Binding Cassette (ABC) transporters in the development of resistance in invertebrates. ABC transporters are a mechanism of Phase III metabolism that utilizes active transport to translocate potentially harmful metabolites out of a cell. To address the objective, acute toxicity tests were conducted using multiple common-use insecticides and second-instar larvae (collected from lab populations) to determine to the median lethal concentration (LC₅₀). Once baseline toxicity was calculated, the tests were repeated with the addition of sublethal concentrations of ABC transport inhibitors: verapamil and cyclosporin A. Preliminary results suggest that Phase III inhibition increases the toxicity of insecticides, although the relative effect of each ABC transport inhibitor varies by insecticide. Further investigation into this phenomenon will provide information that may aid pest control efforts in Pennsylvania and abroad.