| In order to explore the susceptibility of different host populations of the fruit fly to insecticides, in this sduty, the susceptibilities of the 4-day-old Zeugodacus cucurbitae adults from four host (Benincasa Hispida, Cucumis sativus, Luffa cylindrica, Momordica charantia) populations, to four insecticides were determined by the drug-film method in the laboratory. Then, the lethal concentration LC50 of different host populations of Z.cucurbitae was compared to calculate theresistance ratio. The results showed that the susceptibilities of the four host populations to emamectin benzoate were as in order of B. hispida, C. sativus, L. cylindrica and M. charantia, and with the LC50 values of 0.250, 0.391, 0.809 and 1.035 mg/L, respecyively. The sensitivities of the four host populations to methomyl were as follow: B. hispida, C. sativus, M. charantia, L. cylindrica, and their LC50 values were 0.302, 0.318, 0.652 and 0.804 mg/L, respectively. The sensitivities to spinosad were C. sativus, B. hispida, L. cylindrica and M. charantia, and with the LC50 values of 1.157, 1.198, 1.232 and 2.029 mg/L, respectively. The sensitivities to acetamiprid were in the order of M. charantia, B. hispida, C. sativus and L. cylindrica, and their LC50 value were 17.946, 20.166, 20.190 and 21.986 mg/L, respectively. The largest difference between different host populations was abserved in the sensitivities when they were treated by emamectin benzoate with 4.140 fold, and following treated by methomyl, which was 2.654 fold, the smallest sensitivity difference was abserved in acetamiprid, with 1.225 fold. This implies host plants can cause changes in the susceptibility of Z. cucurbitae to insecticides. |
