Role of Phase III Metabolism in Insecticide Toxicity to Hyalella azteca

Abstract:

Agrochemicals are crucial for managing pest species and sustaining the agricultural industry of the Lake Erie grape belt; however, the overuse of pesticides contributes to the development of physiological resistance in insects. Although the catabolic mechanisms of resistance (e.g., Phase I and II metabolism) are well-studied, it is unclear how cellular export mechanisms (e.g., Phase III metabolism) contribute to insecticide resistance. Phase III metabolism involves the efflux of toxicants by ATP-binding cassette (ABC) transporters. This study aimed to determine the role of Phase III metabolism in dictating sensitivity to insecticides. A model arthropod, Hyalella azteca, was used to perform a series of 48-hour toxicity tests involving exposure to several common-use insecticides. The toxicity tests were then repeated with the addition of Phase III inhibitors (verapamil and cyclosporin A). Comparing the median lethal concentration (LC₅₀) in the presence and absence of inhibitors enabled us to evaluate the relative contribution of ABC transporters toward insecticide sensitivity. Understanding the physiological importance of Phase III mechanisms is beneficial for growers who are battling resistance pest populations in their fields.