Evaluating the interaction between oxidative stress management and insecticide susceptibility in Chironomus dilutus

Abstract:

The Great Lakes support a thriving viticulture industry in the northeastern United States, which drives the local economies of this region. Agricultural productivity in the Lake Erie wine belt is threatened seasonally by the grape berry moth (GBM; Endopiza viteana), a native species whose larvae infest grape clusters. To prevent crop damage, grape growers have employed the use of insecticides for decades; however, the rising prevalence of insecticide resistance threatens the efficacy of these treatments. The physiological basis of insecticide resistance is often complex and can be influenced by other seemingly unrelated biochemical processes (e.g., oxidative stress management). While oxidative stress is known to induce the activity of enzymes that are involved in xenobiotic metabolism (e.g., glutathione-S-transferases; GST), the direct influence of this process on insecticide susceptibility is unknown. This study explores the relationship between oxidative stress and susceptibility to a common-use pyrethroid insecticide (bifenthrin) in the model organism Chironomus dilutus. Using second-instar larvae harvested from lab cultures, the activity of GST was quantified in vitro before and after the induction of oxidative stress via cadmium chloride. Following these enzyme assays, acute toxicity tests were performed on second-instar larvae to determine the relationship between GST specific activity and bifenthrin sensitivity. The information gathered from this study will improve our understanding of the interplay between exogenous and endogenous stressors in the context of insecticide resistance.