Abstract:

In order to study the insecticidal activity and mechanism of methoxyfenozide (RH-2485),this paper measured effects of the chemical on the activities of protective enzymes in the larvals of Lymantria dispar. The results showed that the activities of phenoloxidase (PO) and superoxide dismutase(SOD) in the larvae treated with methoxyfenozide were first induced, and then inhibited. The activities of peroxidase (POD) was different at different instar of larvals in response to treatment of methoxyfenozide. The activities of POD in the 4th and 6th instar larvals were first induced, and then inhibited too. The highest activities of POD in the 4th and 6th instar larvals occurred in 24 h,and were 1.603 and 1.805 times of CK in the same instar. The lowest activities of POD in the 4th and 6th instar larvals occurred in 48 h after being treated with methoxyfenozide, and they were 0.858 and 0.608 times of CK in the same instar, these differences were significant (P<0.01). POD activities of 2nd instar larvaes were remarkably inhibited by methoxyfenozide treatment,and the lowest activities of POD arose in 24 h,with 0. 541 times of CK in the same instar, the difference was significant (P<0.01). The activities of chitinase activities showed different with different instar after treatment with methoxyfenozide, and the chitinase activities in the 2nd instar larvaes were first induced, and then inhibited. But the chitinase activities in the 4th instar larvae and 6th instar larvae were inhibited obviously. Therefore, it was shown that methoxyfenozide disturbed the insect regular metabolism in the larvaes, by which the chemical could efficiently poison L. dispar.

Key words: methoxyfenozide, Lymantria dispar, protective enzymes