Control of Mosquito Vectors of Tropical Infectious Diseases: (3) Susceptibility of Aedes Aegypti to Pyrethroid and Mosquito Coils (original) (raw)

2009, The Southeast Asian Journal of Tropical Medicine and Public Health

We collected 11 groups of Aedes aegypti mosquitoes from various locations of Thailand. After rearing in the laboratory, the colonies were tested for KT 50 values to dl,d-T80-allethrin 0.5% mosquito coils in a 25 m 3 room semi-field test and KD 50 and LD 50 values to dl,d-T80-allethrin by a topical application method. Two groups of mosquitoes were susceptible to allethrin similar to a SS (known allethrin sensitive) group, and other 9 groups showed various levels of lower susceptibility to allethrin; of these 6 had susceptibilities similar to a BS (known allethrin resistant) group with extremely low susceptibility, while the remaining 3 groups had susceptibilities to allethrin between the SS and BS groups. The KD 50 values with the topical application were found to correlate highly with the KT 50 values in the 25 m 3 room semi-field test, providing a useful test method for insect susceptibility evaluation. The allethrin mosquito coils, even at higher concentrations, had no activity against the 6 decreased susceptibility groups, similar to the BS group. With the 25 m 3 room semi-field test, mosquito coils with d,d-T-prallethrin at concentrations of 0.1 to 0.15% plus a synergist and those with methoxymethyl-tetrafluorobenzyl tetramethylcyclopropane carboxylate (K-3050) at a concentration of 0.1% plus a synergist were found to be highly effective against these mosquito groups. These two pyrethroids had smaller KD 50 and LD 50 values for topical application, and were more effective than dl,d-T80-allethrin, having the potential to control Ae. aegypti mosquitoes with low allethrin susceptibility. still in the future and treatment is not presently available, it is essential to protect humans from mosquito bites. There are two main methods for the control of vectors, namely larviciding and adulticides. After the Second World War, the WHO took a leading role in tackling mosquito vectors of tropical diseases, using residual spraying and larviciding with DDT, organophosphates and pyrethroids. Although vector-borne diseases were reduced or eliminated in many areas of the world, some vast regions still have a