STUDIES ON THE BIOLOGICAL ACTIVITIES OF SEVERAL CHITIN SYNTHESIS INHIBITORS AGAINST HELITHIS ARMIGERA (HUBNER)

A series of laboratory experiments was carried out to test the biological activities of several chitin synthesis inhibitors against the cotton bollworm (Heliotkis armigera (Hubner)). The adults which ingested IKI-7899 and IGR 1055 lived, mated and oviposited normally but the hatching rates of eggs laid were greatly reduced. Dipping treatments with various concentrations of IKI-7899 had no effects on egg hatching, but the larvae emerged from the treated eggs died before they entered the second or third instars. IKI-7899 and IGR 1055 had excellent activities against the bollworm larvae, while diflubenzuron and Su-Niao I had poor effects. The contact toxicides of IKI-7899 and KIR 1055 were both higher than their stomaeh toeiaitjes When the larvae were fed with these two chemicals for two days, the toxicicies of the insecticides were higher than those fed for one day with continual feeding and the larvae showed higher mortality.