Antioxidant responses of the pest natural enemy Hylyphantes graminicola (Araneae: Linyphiidae) exposed to short-term heat stress.

Abstract

Temperature is a critical abiotic factor that causes physiological changes in arthropods. However, little is known about the effect of heat stress on the antioxidant responses of Araneae species. Hylyphantes graminicola is a dominant predator in many cropping systems in China. In the present study, the effect of short-term heat stress (36, 38, 40 or 42°C) on the reactive oxygen species (ROS) levels, the activities of antioxidant enzymes (superoxide dismutase [SOD], catalase [CAT], peroxidases [POD] and glutathione-S-transferases GST]), total antioxidant capacity (TAC), malondialdehyde (MDA) concentrations and survival of H. graminicola spiderlings and adults were investigated. The results showed that H. graminicola adults had a significantly higher survival rate compared to spiderlings at 40°C. The heat stress increased ROS contents in H. graminicola. The SOD, CAT, POD and GST activities increased in spiderlings and adults under heat stress. These data suggest a defensive function for these enzymes in alleviating oxidative damage. Specifically, SOD plays a key role in reducing the high level of superoxide radicals in spiderlings and adults. Moreover, the POD and CAT capabilities for scavenging H2O2 in spiderlings were similar, and CAT may play a more important role than POD in scavenging H2O2 in adults at 42°C. The spiderling TAC increased significantly at 40 and 42°C, and the adult TAC was stable at 36-40°C but decreased at 42°C. These data suggest that TAC was insufficient in H. graminicola adults under more severe stress conditions. These results further our understanding of the physiological response of Araneae species exposed to heat stress.