Susceptibility test of Aedes aegypti to Pyrethroid insecticide in 8 Northern provinces of Thailand, 2015-2016

Abstract

This study determined resistance levels of pyrethroids used in Upper Northern Provinces between 2015 – 2016. The aedes mosquito larvae were collected in 11 villages in 8 provinces, Mae Hong Son, Chiang Rai, Lampang, Phayao, Chiang Mai, Lamphun, Phrae and Nan. All young larvae were transferred and reared in the laboratory to increase the numbers of adult mosquito. Pyrethroid group, deltamethrin lambda-cyhalothrin, alpha-cypermethrin and bifenthrin were selected for susceptibility test following WHO standard procedure. The results showed that Aedes aegypti from Chiang Rai, Phayao, Nan and Phrae were resistant to bifenthrin, deltamethrin and lambda-cyhalothrin.  Ae. aegypti from Mae Hong Son, Lampang and Chiang Mai demonstrated incipient resistance to alpha-cypermethrin, bifenthrin, and deltamethrin. Whereas Ae. aegypti from Lampang and Lamphun were susceptible to deltamethrin and alpha-cypermethrin. This study indicated that the susceptibility levels of   Ae. aegypti varied in different localities and by Pyrethroid chemical, from susceptible to resistant. Therefore the susceptibility test to determine the susceptible level of mosquitoes to various chemicals should be performed on a regular basis for effective control of mosquito vectors.