Laboratory efficacy of protection rate of torn nets treated with pyrethroids, cyfluthrin, deltamethrin and permethrin against Anopheles stephensi (Diptera: Culicidae)

Abstract

The effect of torn bednets treated with three dosages of cyfluthrin 5% EW, deltamethrin 10% SC and permethrin 10% EC were evaluated under laboratory condition in. The objective of the present study was to observe the effect of impregnated torn bednets on the number of bites by An. stephensi. A glass tunnel test was designed to induce hungry female mosquitoes to pass through holes cut in the pyrethroid treated nets. A guinea pig used as bait to attract mosquitoes through circular holes in the netting. With untreated netting, 81-95% of laboratory-reared females passed through the holes overnight, 75-93% blood-fed successfully and 0.36-4% died. When the netting was treated with cyfluthrin at doses of 25, 50 and 100 mg a.i. m-2, the entry Index (the proportions that passed through the holes overnight) were 43.37, 41.82 and 23.72%; mortality rates were 66.31, 81.45 and 95.99%; and the feeding rate were 16.13, 9.82 and 1.09%. Experiments with deltamethrin treated nets at dosages of 12.5, 25 and 50 mg a.i. m-2, the entry index was 78.10, 61.54 and 27.34%, respectively, mortality rates were 53.26, 58.85 and 82.35%; blood feeding rate was 46.72, 31.15 and 13.49%. When the netting was impregnated with permethrin at dosages of 200 and 500 mg a.i. m-2, the entry index was 33.58 and 14.95%; mortality rates were 93.80 and 100% and blood-feeding rate was 5.11 and 0.36%. In conclusion it should be stressed that efficacy of pyrethroid impregnated bednets using "Tunnel Tests" showing acceptable protection rate both in lower and higher dosages as well as cause dead in the blood-fed mosquitoes. In addition, the higher dosages of these three pyrethroids provided good levels of protection against An. stephensi. © 2006 Asian Network for Scientific Information.