Glutathione S-Transferase Contributes to the Resistance of Megalurothrips usitatus Against Lambda-Cyhalothrin by Strengthening Its Antioxidant Defense Mechanisms

The damage caused by Megalurothrips usitatus, a common pest, has significantly affected the Chinese vegetable industry. The inappropriate application of chemical pesticides has caused M. usitatus to become highly resistant to conventional insecticides. Glutathione S-transferase (GST), known for its multifunctional properties, contributes to detoxification and antioxidation. It enhances insects' adaptability to pesticides by facilitating the elimination of lipid peroxidation products resulting from pyrethroid insecticides. This research employed RT-qPCR to identify GST genes that exhibited significant expression in response to lambda-cyhalothrin stress. It also quantified changes in antioxidant and apoptosis markers within the M. usitatus under lambda-cyhalothrin exposure. The functional significance of GST was validated by assessing alterations in the antioxidant defense system and resistance to lambda-cyhalothrin following the inhibition of GST activity. The study's outcomes indicated that MuGSTs1 was markedly upregulated in response to lambda-cyhalothrin stress (p < 0.0001). The GST activity was effectively suppressed by the specific inhibitor, diethyl maleate, achieving an inhibition rate of 64.05%. Following the inhibition of GST, the overall antioxidant capacity was reduced by 3.1-fold compared with the control, and the M. usitatus exhibited a 7.91-fold increase in sensitivity to lambda-cyhalothrin. These findings confirm the pivotal role of GST in the oxidative stress response of the M. usitatus and their contribution to the development of resistance to lambda-cyhalothrin through enhanced antioxidant defenses. This research offers valuable perspectives on the adaptive reactions of insects to chemical stressors, facilitating the management of resistance and the formulation of effective pest control strategies.