RESUMO
Objective To investigate the insecticide resistance levels of adult Culex pipiens quinquefasciatus to four common insecticides in Guiyang City.Methods Larvae of Culex pipiens quinquefasciatus were collected from 8 areas of Guiyang City by larval scoop method from August to September 2015,and raised in the laboratory to adult Culex pipiens quinquefasciatus.Contact tube method was used to determine the insecticide resistance levels of adult Culex pipiens quinquefasciatus to four common insecticides,and knockdown rate of 1 h and mortality rate of 24 h recovery were calculated.The resistance level was judged according to the mortality rate:＜ 90％ was in the resistant group (R);90％-＜ 98％ was in the potential resistant group (M);and ≥98％ was in the sensitive group (S).Results The adult Culex pipiens quinquefasciatus were exposed to 7.70 g/L dichlorvos,3.30 g/L propoxur,0.25 g/L beta-cypermethrin and 0.20 g/L dehamethrin,knockdown rates of 1 h were 57.78％ (52/90)-91.11％ (82/90),86.67％ (78/90)-100.00％ (90/90),23.33％ (21/90)-77.78％ (70/90) and 27.78％ (25/90)-88.89％ (80/90),respectively;and mortality rates of 24 h recovery were 61.11％ (55/90)-94.44％ (85/90),90.00％ (81/90)-97.78％ (88/90),23.33％ (21/90)-73.33％ (66/90) and 21.11％ (19/90)-72.22％ (65/90),respectively.Conclusion Adult Culex pipiens quinquefasciatus in Guiyang City have developed some resistance to four common insecticides,in which the mosquito has a higher resistance to pyrethroid insecticides such as beta-cypermethrin and deltamethrin.
