1985 Volume 36 Issue 1 Pages 25-30
The use of insecticide-treated curtain made of wide mesh net has been developed for the vector mosquito control, as an alternative to the indoor residual spray. The nets, which had an opening large enough to allow mosquitoes to pass through, were impregnated with the candidate insecticides, fenitrothion and phenothrin, at diffent doses. Contact toxicity tests were conducted with 3-5 day old unfed female Anopheles stephensi. The mortality was observed periodically. As a result, three types of nylon net treated with 1.0g/m^2 of both chemicals retained their insecticidal effectiveness for more than 34 weeks. In order to assess behaviour of the mosquitoes under influence of insecticides, a series of cage tests were carried out in laboratory using an apparatus which is composed of a plastic bag served as a release chamber and of a wire cage (30×30×30cm) served as a baited chamber. The netting, impregnated with the insecticides, was interposed between a cage of avid mosquitoes and a baited chamber. Mosquitoes were released at 3p.m. and recovered at 10a.m. of the following day. The number of dead and live, fed and unfed mosquitoes which were found in each chamber were counted and recorded separately. In the control apparatus, fed mosquitoes rested in the baited chamber. However, the engorged females were driven out from the baited chamber into the released chamber in the apparatus treated with either chemical, at the dose of 0.04g/m^2,at one month post impregnation. There was a reduced entry of mosquitoes into the phenothrin-treated chamber. It appears that phenothrin has a deterrent effect, preventing the mosquitoes from entering through the treated net.
