Effects Of Metabolic And Protective Enzymes Of Cantharidin On Mythimna Separata

Cantharidin is an important natural defenses product and widely exsists in the meloid insect(Lepidoptera: Meloidae). Traditionally,it has been widely used as medicine,Because of its good therapeutic effect upon antitumor. It was also reported that it has toxicity activities against some pests、plant pathogens and weeds.It would play an important role in agriculture. Previous studies have reported that cantharidin has good toxic activities on Mythimna separate and Plutella xylostella, and the metabolism pathway of cantharidin in the pests is not clear.Esterase(including CarE and AKP),GST,P450 are all important detoxification enzymes,it involved in various metabolic processes of exogenous toxic. The effect of Exogenous substance on the enzyme system will result in affecting insect metabolic of the normal life processes disordered.So this study tests with the armyworm to determinate the toxic effects on its larvae and impact on haemolymph, especially the metabolic and protective enzymes.It helps to clarify the toxicological mechanism and pharmaceutical targets of cantharidin and provide scientific basis for developing new animal insecticide with cantharidin and a theoretical basis for resistance to pests .1. Cantharidin has a strong antifeedant and insecticidal action on Armyworm. The results showed that it has good antifeedant activity on 5th instar lavae of armyworm and its 48h selectivity test of AFC50 is 707.57mg / L,48 h non-selective test of AFC50 is 354.90mg / L, and also has strong cytotoxic activity,and 48h of LC50 is 500 mg / L.2. The effect of cantharidn on the activities of metabolic enzymes of armyworm is very complex.The activity of esterases and carboxyl esterases (CarE) in the tested larvae was activated obviously by cantharidin, ACP showed no distinct change at 6h and 12h after treatment and then was activated at 24h after treatment and different from the control; The activity of alkaline phosphatase (ALP) was inhibited obviously, the inhibition became more intensive as the exposure timeprolonged; The activity of cytochrome P450 was first inhibited, and then activated;GSTs was first activated and then inhibited; PPO activities were strongly inhibited by cantharidin, both in vitro and in vivo.3. It also has a significant impact on the protective enzymes. SOD was first inhibition and then activatied; CAT activity showed inhibition after 24h and the rate of inhibition is 45.5%; POD was first activated and then inhibited afer 48h, and POD activity reached a maximum of 1.63 times for the same period in the control.4. It had certain impact on hemolymph in physical and chemical characteristics. Insect haemolymph content was gradually increased, then decreased; accounted for by the rise; and osmotic pressure changed little during the treatment period; hemolymph protein content was gradually activated after the inhibitory.To summer up the result, catharidin can notably affect the metabolic and protective enzymes and has certain impact on hemolymph in physical and chemical characteristics. The inhibition on ALP and PPO may be related to its toxic effect as the insecticide resistance of insect and metabolic enzyme are closely related to the activities. It has potential application value on integrated pest management and can also be developed for new pesticides or synergist.