Temperature Modulates Nutrient Metabolism and Antioxidative Fluctuations in <i>Riptortus pedestris</i>

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 <i>Riptortus pedestris</i> 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 <i>R. pedestris</i>.