Temperature Modulates Nutrient Metabolism and Antioxidative Fluctuations in Riptortus pedestris

Temperature plays a crucial role in influencing insect metabolism. In this study, we measured the body weight, CO2 emissions, nutrient substances, nutrient metabolic enzymes, and antioxidative enzymes in Riptortus pedestris within the range of 24–44 °C. The results show that CO2 emissions significantly varied between sexes and temperatures, peaking at 36 °C for females and 44 °C for males. The body weights were the lowest at 40 °C, with notable differences observed between genders. Total carbohydrate and protein contents were the highest at 44 °C, while glycogen and fat contents peaked at 36 °C and 40 °C for females and males, respectively. Enzyme activities varied, with glyceraldehyde-3-phosphate dehydrogenase and glycerol-3-phosphate dehydrogenase activities peaking at 28–32 °C, and citrate synthase activity fluctuated between 24 °C and 40 °C. Lactate dehydrogenase activity reached the highest level at 36 °C in females and at 32 °C in males and then decreased at 44 °C. 3-Hydroxyacyl-CoA dehydrogenase activity peaked at 44 °C in females and at 36 °C in males. Within the range of 24 °C to 44 °C, the ratio of HOAD to GAPDH indicated a shift from carbohydrate to lipid metabolism at higher temperatures, particularly at 44 °C. Superoxide dismutase peaked at 24 °C in females and at 44 °C in males. Catalase reached its maximum concentration between 32 °C and 40 °C. Malondialdehyde peaked between 32 °C and 36 °C. The total antioxidative capacity was the highest at temperatures between 24 °C and 36 °C. Peroxidase activity was the highest at temperatures ranging from 24 °C to 44 °C. Our observations suggest that temperature profoundly impacts the energy metabolism, enzyme activities, and physiological traits of R. pedestris.