A Survey of Insecticide Resistance in Aedes albopictus (Diptera: Culicidae) During a 2014 Dengue Fever Outbreak in Guangzhou, China

Abstract A dengue fever outbreak in Guangzhou, Guangdong Province, China, in 2014 resulted in ∼37,000 cases and five deaths. Insecticides were sprayed to control the vector of this outbreak, Aedes albopictus (Skuse), a species of mosquito. Aedes albopictus specimens collected from Huadu District (HD), Huangpu District (HP), Luogang District (LG), and Nansha District (NS) in Guangzhou were evaluated using WHO-recommended bioassays for both larvae and adult mosquitoes to determine population resistance to deltamethrin, beta-cypermethrin, cypermethrin, permethrin, dichlorvos, temephos, propoxur, and DDT. Compared with a susceptible laboratory strain of Ae. albopictus (S-lab), all populations showed decreased sensitivities to the eight insecticides, with resistance ratios (RRs) ranging from 2.2 to 275. The RRs were 6.8–275 for pyrethroids, 2.2–4.4 for organophosphates, 5.7–9.0 for carbamates, and 5.3–94.3 for organochlorines. For adult mosquitoes, all populations were sensitive to dichlorvos with 100% mortalities. Mosquitoes from HP, LG, and NS were also sensitive to propoxur. But for other tested insecticides, different degrees of resistance (mortality rate ranging from 11.7% to 94.7%) were observed. Among the four field populations, the resistance levels are presented as follows in descending order: HP > HD > NS > LG. The levels among insecticides classes were pyrethroids > organochlorines > carbamates > organophosphates.