Determination Of Comparative Prevalence Of Insecticide Resistance In Anopheles Funestus (giles) In Ahero And Rota, Kenya.

Abstract

Resistance, according to World Health Organization (WHO), refers to the development of an ability in a strain of some organisms to tolerate doses of a toxicant that would prove lethal to a majority of individuals in a normal population of the same species. Over 125 mosquito species are documented as resistant to one or more insecticides. Resistance of mosquitoes to some insecticides has been documented within just a few years of insecticides introduction. The development of resistance to insecticide used in residual spraying was a major impediment during the Global Malaria Eradication Campaign (GMEC). Prudent use of insecticides in control of insects and in agriculture should therefore be practiced to limit the development and spread of resistance. Control programs that integrate and conduct regular surveillance can detect developing resistance in mosquitoes. The status of resistance in Anopheles funestus (Diptera: Culicidae) mosquitoes sampled from Ahero and Rota in Western Kenya to bendiocarb, DDT, permethrin, fenitrothion and lambdacyhalothrin was lirvestigated. Standard WHO insecticide resistance bioassay kits were used. Mosquito specimens were sampled as gravid or half gravid females resting indoor on house walls and allowed to oviposit in the insectary. The resulting FI progeny were reared to adulthood. All field-collected mosquitoes were initially identified using morphological characteristics and thereafter by the Polymerase Chain Reaction (PCR) molecular technique. Mortality rates 24hrs post -exposure were 100%, (>98%) for all the samples tested in all the five insecticides. Bendiocarb and fenitrothion always achieved ]00% knockdown while Pennethrin, DDT and lambdacyhalothrin had their least knockdown of83.82%, 77.35% to 83.33% within respective standard durations. The insecticides achieved mortality 24 hrs post -exposure. Seasonal and study area variation was insignificant. However, Ahero appeared less sensitive than Rota by knockdown comparison, (t-test: P>O.5562 and teal.< terit.).Kdt95 values from LdP line'" analysis suggested lower sensitivity in Ahero, (92.91, 79.52 and 162.25) compared to Rota (55.98, 52.73 and 139.15) respectively for DDT, pennethrin and lambdacyhalothrin, table 3.3. Overall results based on mortality 24hrs postexposure indicated all the five insecticides in study could be used for control purposes against An. funestus in Rota and Ahero. Since there was no resistance, there was no difference in prevalence of insecticide resistance.