EFFICACY AND PERSISTENCY OF CERTAIN INSECTICIDES AGAINST HOUSE DUST MITE, Dermatophagoides pteronyssinus UNDER LABORATORY CONDITION

The acaricidal activity of certain insecticides viz., Lambda Cyhalothrin 5% w/w EC, Deltamethrin 2.8% w/w EC and Malathion 50% w/w EC was evaluated for their efficacy against dust mite, Dermatophagoides pteronyssinus under laboratory condition, using dry film method. Benzyl Benzoate 25% w/w was used as a positive standard. Efficacy was assessed at the dose recommended by WHOPES for indoor residual spray against Anopheles mosquito. Suitable concentrations according to the recommended dose of each insecticide were prepared in distilled water and applied on petridish of size, 44.16 cm2 at the rate of 0.75 mL/petridish. The dust mite at the rate of 25/petri dish was released and mortality was assessed at 24 hours after exposure. Persistency of the insecticides was assessed by releasing mite at 3 days after treatment and thereafter at weekly intervals. The results of the study revealed that all the insecticides are effective against the dust mite and were found to persist for 2 weeks. However, a decrease in efficacy was observed with weeks. Malathion 50% EC was observed to be better persistent followed by Deltamethrin 2.8% w/w EC and Lambda Cyhalothrin 5% w/w EC against the Dust Mite, Dermatophagoides pteronyssinus.