Observation on resistance of adult Aedes albopictus to commonly used insecticides in Xiamen City / 中华地方病学杂志

ABSTRACT

Objective:To investigate the resistance of adult Aedes albopictus to commonly used insecticides, in order to scientifically select and use insecticides. Methods:In Siming, Jimei and Haicang districts of Xiamen City in September 2018, and in Siming, Jimei and Xiang'an districts of Xiamen City in August 2019, larvae and egg blocks of Aedes albopictus in the field were collected by ladle method, and then raised to adult mosquitoes in the laboratory. The resistance of adult Aedes albopictus to 7 commonly used insecticides was determined by the contact tube method, and the knockdown rate of 1 h and mortality rate of 24 h recovery were calculated. The resistance level was determined according to the mortality rate ≥98% was the sensitive group (S); 80% - < 98% was potential resistant group (M); < 80% was resistant group (R). Results:In 2018 and 2019, adult Aedes albopictus were exposed to 0.1% deltamethrin, 0.4% beta-cypermethrin, 0.5% lambda-cyhalothrin, 1.4% alpha-cypermethrin, 3% permethrin, 0.5% malathion and 0.05% propoxur, the knockdown rates of 1 h were 95.1% (117/123), 98.3% (115/117), 100.0% (116/116), 99.2% (120/121), 98.4% (123/125), 97.5% (119/122), 100.0% (127/127) and 96.7% (118/122), 98.6% (143/145), 100.0% (139/139), 100.0% (149/149), 98.0% (146/149), 96.8% (121/125), and 100.0% (126/126), respectively. In 2018, the mortality rates of 24 h recovery were 91.1% (112/123), 78.6% (92/117), 75.0% (87/116), 88.4% (107/121), 96.0% (120/125), 99.2% (121/122), and 100.0% (127/127), respectively. In 2019, the adjusted mortality rates of 24 h recovery were 74.9%, 76.9%, 79.5%, 91.4%, 92.3%, 100.0%, and 100.0%, respectively. Conclusions:Adult Aedes albopictus in Xiamen City is sensitive to malathion and propoxur, and it has a high resistance to pyrethroids insecticides such as deltamethrin, beta-cypermethrin and lambda-cyhalothrin. Therefore, it is necessary to strengthen resistance monitoring and use different insecticides in turn to reduce and delay the development of resistance.