Insecticide Susceptibility of Aedes aegypti in Different Parts of Thailand, 2006 - 2010

Larvae of Aedes aegypti, the main vector of dengue haemorrhagic fever, were collected from different parts of Thailand determined using average annual cases to be high risk areas. The larvae and adults were tested in the laboratory based on the standard WHO test, using diagnostic concentrations to determine their susceptibility to insecticides used for dengue control, ie temephos, permethrin, deltamethrin, cyfluthrin, malathion and fenitrothion. The results showed temephos resistance in 3 from 27 studied areas and permethrin resistance in all 25 studied areas. Susceptibility to the other insecticides varied in each studied area, from susceptible to tolerant, to resistance. The resistance to pyrethroids was higher than to organophosphate in all studied area. The results suggested that insecticides used for control of Ae. aegypti cannnot be used nationwide; but depends on mosquito susceptibility in the specific area. Insecticide susceptibility should be determined for each area, to inform appropriate insecticide selection. Key Words: susceptibility test, insecticide resistance, Aedes aegypti