CHANGES OF SENSITIVITY OF COTTON BOLLWORMS FEEDING ON DIFFERENT HOST PLANTS TO DECAMETHRIN
TAN WEI-JIA ZHAO HUAN-XIANGInstitute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing
The sensitivity to dccamethrin and relevant enzymic activities of the cotton bollworm He-liothis armigera (Hiibner) feeding on different host plants were tested with bioassay and biochemical methods. The results showed that there was significant difference in the sensitivity to this insecticide among the bollworms from different sources, suggesting the relationship between host plant and insecticide resistance. One of the major factors causing the diversity seems to be the difference in the activity of carboxylase which is widely distributed in different tissues and reaches predomination in the mid-gut. In the synergic experiments with specific enzymic inhibitors, the toxic effect of TPP mixed with decamethrin was nine times greater than that of decamethrin used alone. This may aptly serve as a confirmative evidence for the carboxylase in the biochemical pathway to detoxifying decamethrin.