Resistance of Blattella germanica to common used insecticides in some areas in Jiangsu Province

Objective To estimate the susceptibility or resistance of Blattella germanica,including normal strain and four field-collected strain to deltamethrin,beta-cypermethrin,dichlorvos,propoxur and acephate in some areas in Jiangsu Province.Methods Contacting with chemical cover.Results The average resistance ratios of field-collected strains to deltamethrin,beta-cypermethrin,dichlorvos,propoxur and acephate were 17.0,8.4,3.2,1.6 and 4.4 respectively.The resistance ratios of deltamethrin were high in Nanjing,Nantong and Huaian four field-collected strain(R=22.9,20.6,16.1).The resistance also reached the high level to beta-cypermethrin in Danyang strain(R=10.9).The average resistance ratios of field-collected strains to propoxur was low(R=1.6).Conclusion Field collected strains of Blattella germanica in Jiangsu Province have already developed different resistance to four kinds of insecticides.