| 論文英文摘要 |
The melon thrips, Thrips palmi, is a major pest of melons and eggplant in Taiwan. Spraying insecticide is main control practice. This study is to understand susceptibility of melon thrips to different MoA insecticides in Taiwan. Melon thrips T. palmi was collected from three populations on eggplant, and then the toxicity of recommended insecticides (deltamethrin, clothianidin, methiocarb, chlorfenapyr, spinetoram) were tested to these populations of melon thrips. Our result showed that LC90 values of these three melon thrips populations are much larger than the recommended concentration of deltamethrin and clothianidin. Therefore, melon thrips from these areas might be resistant to neonicotinoids and pyrethroids. Biochemical metabolic detoxification is one of resistance mechanisms for insect to pesticides. Synergists of piperonyl butoxide (PBO)、diethyl maleate (DEM)、triphenyl phosphate (TPP) was used with deltamethrin and clothianidin to measure the synergist ratio in order to identify which type of detoxification enzyme is involved in metabolic resistance of melon thrips. Our results showed that deltamethrin and clothianidin with PBO can result in significant synergism of more than six times in three tested populations of melon thrips, which implied the involvement of cytochrome P450 to the resistance against deltamethrin and clothianidin. In addition, when adding deltamethrin with TPP synergism was observed at least
four times of synergism, which implied esterases are involved, too. Besides, our study show melon thrips from three populations have also the point mutation (T929I) of sodium channel with frequency up to 100%. This phenomenon had confirmed that the high degree of resistance to pyrethroids also contributed with the target site point mutation of sodium channel. |