Biochemical Mechanisms of Phosphine Action and Resistance

摘要

Global grain shortages highlight the strategic requirement for dependable storage of food reserves. While phosphine fumigation has been the mainstay of grain protection for many years, resist-ance in pest insects threatens the continued effectiveness of phosphine. Effective management of phos-phine resistance requires an understanding of how phosphine acts as well as how organisms can over-come its action. Despite the importance of phosphine, its mode of action has not been determined. To resolve this problem, we have investigated the toxicology of phosphine in the model organism, C. ele-gans, which is ideal for laboratory studies. We see that mitochondrial activity is directly related to the effectiveness of phosphine, as mutation, chemical and physical treatments that reduced respiration cause resistance. In contrast, chemicals that activate mitochondrial electron transfer enhance phosphine toxici-ty, allowing resistance to be completely overcome. We have found that key metabolic regulatory path-ways that determine food abundance or deprivation are likewise capable of enhancing sensitivity toward phosphine,even in otherwise resistant organisms, apparently through regulation of metabolic rate. Our studies reflect and extend previous work with insects that demonstrated a requirement for oxygen and a role for mitochondria in phosphine toxicity. These results will assist us in the development of strategies to monitor resistance or enhance the efficacy of phosphine fumigation.