Mechanism on susceptibility of striped flea beetle, Phyllotreta striolata to chlorpyrifos
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Key Words: striped flea beetle(SFB), chlorpyrifos, susceptibility, biochemical mechanism
Abstract:Bioassay was conducted to examine and compare LC50 values of a field natural population (FNP) and two laboratory population fed with Rorippa indica (RiP) and Brassica campestris (BcP) of striped flea beetle, Phyllotreta striolata(F.), exposed to hlorpyrifos. The results indicated that LC50 value of RIP to chlorpyrifos was lowest with 30.345 9 mg·L-1. while FNP the highest 77.844 8 mg·L-1The susceptibility index of FNP was 0.39.The enzymatic activities of acetylcholinesterase (AChE), carboxylesterase (CarE) and glutothinetransferase (GST) were measured to show difference of biochemical indexes of the SFB pulations. The lowest AChE activity was bserved in FNP, significantly different from those in RiP and BcP. The highest GST activity was found in FNP, while the lowest and highest CarE activities in RiP and FNP, respectively. Our study suggest that the susceptibility reduce of SFB to chlorpyrifos might be associated to some extent with lower AChE, as well as higher activities of CarE and GSTs.