INSECTICIDAL ACTIVITY OF CHITIN SYNTHESIS INHIBITORSAGAINST DIAMONDBACK MOTH, PLUTELLA XYLOSTELLA

ests of the toxicity of several chitin synthesis inhibitors to the fourth instarlarvae of diamondback moth, Plutella xylostella, were carried out in the laboratory.The results indicated that toxicities of XRD-473, CME-134, Cascade and IKI-7899were markedly higher than those of Dimilin and Alsystin, and toxicities of all thesechitin synthesis inhibitors were significantly higher than those of the conventionalinsecticides DDVP, Cypermethrin and Dimehypo. Stomach poisoning was found to bethe main mode of action, and contact poisoning was also important for IKI-7899 tothe larvae. When adults were fed with the solutions of IKI-7899 or Cascade at 50ppm, life spans of the female and male moths were shortened by 1 and 4 days respectively, number of eggs laid was only about 1/3 that of the untreated moth and therates of egg hatching were reduced to 5.35% and 0, respectively. Temperature showed significant effect on the action of IKI--7899 in the speed of causing larval mortality, and the higher the temperature, the higher the mortality rate within the sameperiod.