Effect of pymetrozine interferes with feeding behaviour ofBemisia tabaci (Homoptera, Aleyrodidae)

Key Words： pymetrozine，Bemisia tabaci，feeding interference, honeydew

Abstract：        We tested the mortality and LC₅₀ of pymetrozine against whiteflies using the cabbage leaf-disc dipping method.The concentration of pymetrozine ranged between 9.38mg/L and 300mg/L and mortality was significantly dosage-dependent.There were significant differences in the honeydew quantities (0.37-0.42、0.59-0.72 and 1.48 mm2,respectively) of adults feeding on leaves dipped in 75-150、9.38-37.5 and 0 mg/L pymetrozine (P<0.05).The effect of pymetrozine on different phases of stylet penetration and feeding activity of individual whiteflies was studied using the Electrical Penetration Graph technique (EPG). When low-concertration pymetrozine (75 mg/L) was applied to leaves,whiteflies started feeding normally.However,after some time they withdrew their stylets from the phloem. Higher concertrations of pymetrozine (300 mg/L) inhibited stylet insertion into the plant.Therefore，pymetrozine may be one of the most effective chemicals for the control of sweet-potato whiteflies, which are vectors of tomato yellow-leaf curl viruses.