Blattella germanica to commonly used insecticides in Wuhu, Anhui Province, China, 2022
Objective To investigate the resistance levels of
Blattella germanica in Wuhu, Anhui Province, China, so as to provide a scientific basis for rational insecticide use.
Methods From March to June 2022, test
B. germanica cockroaches were collected from restaurants, bakeries, hotels, supermarkets, and farmers' markets in Yijiang, Jinghu, Sanshan, and Jiujiang districts of Wuhu. The resistance of
B. germanica to 12 commonly used insecticides was determined using the residual film method. SPSS 22.0 was used for data processing and analysis.
Results The 24 h mortality rates of
B. germanica treated with permethrin, tetramethrin, cypermethrin, deltamethrin, alpha-cypermethrin, beta-cypermethrin, lambda-cyhalothrin, propoxur, azamethiphos, acephate, dichlorvos, and chlorpyrifos were 91.20%, 18.40%, 91.33%, 89.47%, 77.85%, 92.62%, 99.19%, 100%, 96.85%, 100%, 76.06%, and 99.00%, respectively. The median knockdown time (KT
50) was 32.63, 900.61, 28.17, 30.47, 26.60, 11.06, 16.54, 17.93, 14.13, 59.66, 27.57, and 38.21 min, respectively. According to the resistance criteria by mortality,
B. germanica in Wuhu was sensitive to lambda-cyhalothrin, propoxur, azamethiphos, acephate, and chlorpyrifos; potentially resistant to permethrin, cypermethrin, deltamethrin, and beta-cypermethrin; and resistant to tetramethrin, alpha-cypermethrin, and dichlorvos. Based on the knockdown resistance criteria,
B. germanica in Wuhu was sensitive to azamethiphos; lowly resistant to beta-cypermethrin, lambda-cyhalothrin, propoxur, acephate, and chlorpyrifos, with the resistance ratios being 2.58, 3.21, 1.39, 2.01, and 1.41, respectively; moderately resistant to permethrin, cypermethrin, deltamethrin, alpha-cypermethrin, and dichlorvos, with the resistance ratios being 6.54, 6.39, 7.79, 5.58, and 7.14, respectively; and extremely high resistant to tetramethrin, with the resistance ratio being 259.54. KT
50 or 24 h mortality had no significant correlation with insecticide consumption (
24 h mortality-insecticide consumption=0.141, all
B. germanica in Wuhu has developed medium or high resistance to a variety of insecticides. In cockroach control, the use of insecticides should be regulated according to the results of resistance monitoring to delay the development of resistance.