Detection of insecticide resistance in Aedes aegypti to organophosphate and synthetic pyrethroid compounds in the north-east of Thailand.
AbstractAedes aegypti is a vector of dengue fever, which is a public health problem in the north-east of Thailand. During epidemics, emphasis is laid on the use of insecticides for the control of the disease. A survey of insecticides used was carried out in eight provinces, namely Amnat Charoen, Kalasin, Mukdahan, Nakhon Phanom, Sakon Nakhon, Si Sa Ket, Ubon Ratchathani and Yasothon. The study indicated that temephos was the only chemical used for the control of mosquito larvae while cypermethrin was used as space spray for the control of adult mosquitoes. Based on the results of resistance ratio of Ae. aegypti in comparison to the susceptible Bora Bora strain, Ae. aegypti showed greater resistance to deltamethrin and permethrin at a high level, with a 10-fold resistance ratio. Regarding the resistance in all study areas of Ae. aegypti to malathion and fenitrothion, it varied from low to medium levels. With biochemical assay, the results demonstrated that monooxygenase and esterase activity of Ae. aegypti had increased in all strains. Nevertheless, the glutathione-S-transferase activity had increased in seven strains. Therefore, monooxygenase, esterase and glutathione-S-transferase activity seems to be associated with mechanisms for creating pyrethroid-resistance in Ae. aegypti. These chemicals were used for the control of adult mosquitoes, which showed a high resistance ratio in these areas. Consequently, the continued use of these insecticides would lead to operational failure.
Pimsamarn, S., Sornpeng, W., Akksilp, S., Paeporn, P & Limpawitthayakul, M. (2009). Detection of insecticide resistance in Aedes aegypti to organophosphate and synthetic pyrethroid compounds in the north-east of Thailand.. WHO Regional Office for South-East Asia.. http://www.who.int/iris/handle/10665/170964