Effects of elevated CO2 concentration on enzyme activity of oriental armyworm, Mythimna separata (Walker)(Lepidoptera: Noctuidae) larvae
Author of the article:CHEN Xiao-Yan1** LI Yong-Chuan2 HAO Ruo-Shi3 KE Rui1 LI Ya-Hong2YANG Xue-Cun1 GUI Fu-Rong1, 3**
Author's Workplace：1. Key Laboratory for Agricultural Biodiversity and Pest Management of Ministry of Education, College of Plant Protection,YunnanAgricultural University, Kunming 650201, China; 2. Yunnan Plant Protection Station, Kunming 650034, China; 3. Yunnan Plateau Characteristic Agriculture Industry Research Institute, Kunming 650201, China
Key Words：Mythimna separata, different instar, CO2 concentration, detoxifying enzymes, protective enzymes, protease
Abstract： [Objectives] To determine the enzymatic response of different larval instars of the armyworm (Mythimna separata (Walker)) to elevated atmospheric CO2 concentration. [Methods] The activity of detoxifying, protective, and protease, enzymes in different larval instars were measured under different atmospheric CO2 concentrations (800 µL/L and 400 µL/L) in an artificial climate chamber. [Results] (1) The activity of four detoxifying enzymes increased significantly in different instars at higher CO2 concentrations (P<0.05). (2) Superoxide dismutase (SOD) activity tended to decline at a CO2 concentration of 800 µL/L, especially in fourth to sixth instar larvae (P<0.05). Peroxidase (POD) and catalase (CAT) activity tended to increase at 800 µL/L CO2 concentration, and CAT activity was significantly higher than that in the control at 400 µL/L CO2 concentration (P<0.05). (3) At 800 µL/L CO2 concentration, total protease activity increased with instar number and showed a rising, then falling, trend. Activity of the other three protease enzymes was lower than that at 400 µL/L concentration, and the activity of the chymotrypsin-like enzyme was significantly lower than in the control for all instars (P<0.05). [Conclusion] Most enzyme activity tended to decline at higher CO2 concentrations; detoxifying and protease enzymes were suppressed, and the balance between SOD, CAT and POD was disrupted, disturbing the normal physiological metabolism. The resultant damage increased in successive instars.