| Gypsy moth, (Lymantria dispar L.) is one of the most important Lepidopteran defoliator pests all over the world. It has many characteristics, such as wide distribution, mixed food and having caused very economic loss in agriculture and forestry production. Meanwhile the gypsy moth is an important international quarantine pests whice may seriously affect China's exports. Furan tebufenozide is a newly developed insect growth regulator and has been applied as a pesticide in agriculture in China, which can simulate the function of ecdysone of Lepidoptera larvae, and act on ecdysone receptor leading to the lethality during insect molting.lt had high toxic effect against the pharmaceutical Lepidoptera pests on crops and high security against the environment and non-target organisms. With a low dosage, persistence of long, stable, efficient, safe to humans and animals, so it is an important tool for integrated pest management. To better study the biological activity and mechanism of furan tebufenozide, its bioactivity against the different instar larvae of L. dispar and its effect on the development, the activities of protective enzymes and detoxifying enzymes were assayed by leaf membrane method, which provided theoretical basises for the applications of furan tebufenozide and other non-steroidal ecdysone analogs in forestry and new insecticides research.The toxic effect on the different instar larvae of Lymantria dispar were assayed by leaf membrane. The results showed furan tebufenozide on the moth, LC50 of its against 2-6 instar larvae are 0.219,0.369,0.450,0.842,1.372 mg/L (24 h). Furan tebufenozide was showing high activity on instars of gypsy moth larvae and the smaller age of insects, the more sensitive of pharmacy. With the growth of larval age, increasing the required dose. The developement time was prolonged and the survival rate of larvaes were significantly reduced after the 3rd-instar larvaes were continuously treated, using the LC10 (0.108 mg/L)and LC30 (0.224 mg/L) concentrations of furan tebufenozide.Relative growth rate (RGR), relative consumption rate (RCR) efficiency of the conversion of ingested food (ECI) efficiency of the conversion of ingested food (ECI) cof 3rd-instar larvae fed on poplar leaves treated by sublethal concentration of furan tebufenozide were significantly lower than those of fed on normal polar leaves (P< 0.05).In order to study the insecticide activity and mechanism of furan tebufenozide, its effect on the activities of protective enzymes and detoxifying enzymes against the 3rd and 5th instar larvals of L. dispar were assayed. The results showed the larvae of protective enzymes and detoxification enzyme activity could be interfered after treatment of furan tebufenozide. The activities of phenoloxidase, catalase and chitinase in the treated 3rd larvae were first activated, then inhibited and further activated and superoxide dismutase, carboxylesterase, glutathione S- transferase were first activated and then inhibited by using furan tebufenozide treatment. The activities of peroxidase and acid phosphatase were significantly inhibited. The activities of alkaline phosphatase was showed inhibition-induction-inhibition and the MFO-O-demethylase at first inhibited, then activated. In addition, the activities of phenoloxidase, catalase, chitinase and peroxide were showed induction-inhibition-induction in the treated 5th larvae by using furan tebufenozide treatment.Of superoxide dismutase was first activated and then inhibited. The activities of carboxylesterase was showed inhibition-induction-inhibition. Furthermore, glutathione S-transferase and acid phosphatase were showed sustained inhibition, alkaline phosphatase and the MFO-O-demethylase for the first performance of the role of inhibition of activation.These results indicated that furan tebufenozide as a non-steroidal ecdysone agonist had a higher biological activity against the L. dispar, and its major protective enzymes and detoxifying enzymes in the body were significantly interfered, and it also showed a high cytotoxicity on larvae of L. dispar. Therefore, furan tebufenozide as a safe and effective pharmaceutical can achieve ecological security of the purpose to controling the damage of gypsy moth.
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