Effects of Oxidative Stress on Xenobiotic Metabolizing Enzymes in Tuta Absoluta (Meyrick) (Lepidoptera: Gelechiidae)

Abstract

Objective: Tuta absoluta is one of the most important insects that destroy tomato plants. The larvae of T. absoluta infest tomato plants leading to significant reduction in tomato crop yield. It has been reported that several insecticides exert their effects by inducing oxidative stress with stimulation of reactive oxygen species formation. The aims of this study were to determine oxidative status of two different field populations and to analyse detoxification mechanisms in T. absoluta field populations under the oxidative stress conditions by using biochemical methods. Methods: Total thiol levels and enzymatic activities of esterases, cytochrome P450 monooxygenases and glutathione S-transferases were determined. Results: The thiol content was decreased in Adana (19% less) and Antalya (25% less) field populations compared to a susceptible population. While CYP450s did not show any significant activity increase, acetylcholinesterases did not show any significant activity decrease in both the field populations. However, a significant increase of 2.3-fold in EST-PNPA activity in Adana population was determined. Furthermore, GST-DCNB activity showed 2.7-fold and 1.8-fold increase compared to susceptible population in Adana and Antalya field populations, respectively. Conclusion: Consequently, GSTs seem to have an important role in overcoming oxidative stress in tested field populations. As acetylcholinesterases and CYP450s did not show significant changes, it was concluded that they are possibly not involved in causing oxidative stress in field populations of T. absoluta. In addition, a significant increase of 2.3-fold in EST-PNPA activity in Adana population indicating that ESTs could play a role in causing oxidative stress in Adana field population.