Effects Of Ecological Stress On Oriental Army Worm, Mythimna Separata(Lepidoptera: Noctuidae)

Mythimna separata is a polyphagous pest and well known as oriental army worm. It has caused damage to wheat, corn and rice crops in China and its neighboring countries. Mostly chemicals are used to avoid the damage of this pest. As the excessive use of chemicals is not ecofriendly and it also produces resistance in pest. Alternative ecofriendly methods like Ecological stresses(UV radiation and thermal stress) can be used as a part of IPM strategy. So, in present study we tried to evaluate the physiology and antioxidant enzyme activity in response to Ecological stress in Mythimna separate. It will provide a foundation for scientific community to use these Ecological stresses in field as an IPM strategy to control this devastating agricultural pest.Effect of UV-A radiation as an Environmental stress on the development, longevity and reproduction of the oriental armyworm, Mythimna separata(Lepidoptera: Noctuidae)The effect of UV light-A radiation on development, adult longevity, reproduction and development of F1 generation of Mythimna separata was investigated. Our results revealed that the mortality of the 2nd instar larvae was higher than the 3rd and 4th instar larvae after UV-A radiation. As the time of UV-A irradiation for pupae prolonged, the rate of adult emergence reduced. Along with the extension of radiation time decreased the longevity of adult females and males. However, the radiation exposure of 1 and 4h/day increased fecundity of female adults and a significant difference was observed in a 1 h/day group. The oviposition rates of female adults in all the treatments were significantly higher than the control. In addition, UV-A radiation treatments resulted in declined cumulative survival of F1 immature stages(eggs, larvae and pupae). After exposure timeof 4 and 7 h/day, the developmental periods of F1 larvae increased significantly but no significant effects on F1 pupal period was recorded.Oxidative stress response and antioxidant enzyme activity in Mythimna separata(Lepidoptera: Noctuidae) after UV-A radiationIn the present study, we evaluated the effects of UV-A radiation on an important pest in China, the ear-cutting caterpillar Mythimna separata(Lepidoptera: Noctuidae). We exposed 3-day-old M. separata adults to UV-A radiation for different periods of time(0, 30, 60, 90, or 120 min) and evaluated the resulting total antioxidant capacity and the activity of the antioxidant enzymes superoxide dismutase, catalase, peroxidase, and glutathione-S-transferase. The total antioxidant capacity significantly increased after exposure to UV-A radiation for 60 min but decreased after 90 min and 120 min of exposure, compared with the control. The antioxidant activity of glutathione-Stransferase, superoxide dismutase, catalase, and peroxidase increased after exposure for 60 min and decreased after longer exposure periods. Our results demonstrated that UV-A radiation causes oxidative stress, affects the activity of antioxidant enzymes, and disturbs the physiology of M. separata adults. Therefore, it is a promising agent for use in the control of these insect pests.Response of Antioxidant Enzymes in Mythimna Separata(Lepidoptera: Noctuidae), Exposed to Thermal Stress.A number of physiological stress responses in insects due to variations in temperatures. The generation of reactive oxygen species in response to thermal stress is responsible for oxidative damage. The time-related effect(durations for 1, 4 and 7 h) of thermal stress conditions i.e., comparatively low(5, 10, 15 and 20oC) or high(30, 35, 40 and 45oC) temperatures on antioxidant enzymes activities along with superoxide dismutase(SOD), catalase(CAT), peroxidase(POX), glutathione S-transferases(GSTs), and totalantioxidant capacity(T-AOC) of the M.separata were observed in present study. A significant elevation in the activities of SOD, CAT and GSTs in results indicating, they were providing a defensive mechanism to counteract the oxidative damage in response to augmentation of ROS. However, at high temperature POX activity and T-AOC have additional role in scavenging of ROS as compare to lower temperatures. It also indicates extreme temperatures produce more ROS in M.separata. Present research confirmed, thermal stress was responsible for oxidative stress. To overcome that stress antioxidant enzymes possibly play a key role for diminishing oxidative damage in M. separata.