Effects of thermal stress on the antioxidant defenses in Paracoccus marginatus Williams and Granara de Willink parasitized by Acerophagus papayae Noyes & Schauff

Abstract

Acerophagus papayae (Encyrtidae: Hymenoptera) is a potential parasitoid successfully used to control papaya mealybug, Paracoccus marginatus (Homoptera: Pseudococcidae) on different horticultural crops such as papaya, mulberry, cotton, cassava, citrus, sweet potato, peas, beans, okra, eggplant, guava, Hibiscus Jatropha, Allamanda. However, the parasitic efficiency is mostly affected by prevailing weather parameter in the crop canopy. Understanding the effect of thermal stress on the parasitizing efficiency of natural enemy and the role of antioxidant mechanisms for temperature stress is important for improving efficiency under stressed condition. In this study, we investigated the effect of constant temperatures 25, 28, 30, 32 and 34oC on percent parasitism, developmental periods and adult emergence of A. papayae under laboratory condition. Increase in temperature negatively affected the performance of A. papayae in terms of developmental duration, parasitism efficiency and adult emergence. Exposure of A. papayae to different temperature led to overall increase in activities of superoxide dismutase, catalase, peroxidases and glutathione-S-transferases. Our results indicated that thermal tolerance in A. papayae could be mainly associated with changes in activity of antioxidant enzymes in scavenging of reactive oxygen species (ROS) under stress.