Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 1/3/2006
Publication Date: 1/3/2006
Citation: Zhu, Y., Snodgrass, G.L., Chen, M. 2006. Comparative study on glutathione s-transferase activity, cdna, and gene expression between malathion susceptible and resistant strains of the tarnished plant bug, lygus lineolaris. National Cotton Council Beltwide Cotton Conference. Interpretive Summary: This study provides information on resistance gene regulation in malathion-resistant strains of the tarnished plant bug. GST inhibitors effectively abolished the resistance and significantly increased susceptibility in resistant strains. In addition, we found that the GST activity increased over the season. This phenomenon was well synchronized with the movement of the bugs into cotton where they were exposed to organophosphate insecticides. The consistency of reduced sensitivity to malathion and increased GST activity, may have resulted from elevated gene expression, demonstrated that the GSTs were involved in malathion detoxification and resistance development.
Technical Abstract: The tarnished plant bug, Lygus lineolaris, has become a serious pest because of the widespread adoption of Bt cotton and resistance development to synthetic insecticides. Previous reports indicated that the tarnished plant bug developed a metabolic resistance to permethrin and malathion through increased gene expression of a cytochrome P450 and an esterase. Glutathione S-transferase (GST) is another important metabolic enzyme for detoxification and resistance development to malathion. To understand resistance mechanisms and to develop resistance management strategies, we compared GST enzyme activity between susceptible and resistant strains, and examined if the GST inhibitors synergized malathion toxicity through suppression of the GST activity. Results showed that the resistant strain had significantly higher GST enzyme activity than a susceptible strain. GST inhibitors significantly suppressed GST activity and substantially increase susceptibility to malathion in the resistant bugs.