Comparative effects of heat and cold stress on physiological enzymes in Sitophilus oryzae and Lasioderma serricorne

Insects are poikilotherms, and temperature is a critical abiotic factor that causes physiological changes. In this study, the effects of short-term heat (28, 31, 34, 37, 40 °C) and cold (−3, 0, 3, 6 °C) stress on the activities of protective enzymes (superoxide dismutase [SOD] and peroxidase [POD]) and detoxification enzymes (acetylcholinesterase [AChE] and glutathione-S-transferase [GST]) were assessed in the stored-product pests Sitophilus oryzae (L.) (Coleoptera: Curculionidae) and Lasioderma serricorne (F.) (Coleoptera: Anobiidae). The results showed that there were significant differences in the metabolic enzyme activities of these two pests under different temperature treatments. Under high temperature stress, the metabolic enzyme activities were significantly higher than in the control, except for AChE in L. serricorne. Under low temperature stress, the protective and detoxification enzyme activities of these two pests significantly increased or decreased, except for SOD. Therefore, we speculate that, in response to high temperature stress, the main activated enzymes are POD, SOD, AChE, and GST in S. oryzae and POD, SOD, and GST in L. serricorne; in response to low temperature stress, the main activated enzymes are POD, AChE, and GST in both insect species. This study reveals that short-term exposure to extreme temperatures significantly affects the detoxification and protective enzymes in S. oryzae and L. serricorne. These findings provide foundational data that can help elucidate the adaptive mechanisms of these two stored-product pests to fluctuating temperatures and temperature-related strategies to sustainably control stored-product pests.