Differential Susceptibilities of Brontispa longissima (Coleoptera: Hispidae) to Insecticides in Southeast Asia

To present the susceptibility of Brontispa longissima (Gestro) (Coleoptera: Hispidae) to insecticides, 22 populations were collected in Southeast Asia from 2007 to 2010. Moreover, the laboratory susceptible strain was maintained. The results demonstrated that the lethal concentration50 value of the susceptible strain to avermectin, β-cypermethrin, and acetamiprid was 0.034, 0.024, and 1.843 mg liter-1, respectively. Compared with the susceptible strain, 10 populations developed a medium level of resistance to avermectin (10.8-fold < resistance ratio [RR] < 34.7-fold) and 11 populations had low or minor resistance (3.6-fold