Oviposition attractancy of an infusion from a wood inhabiting fungus for vector mosquitoes

Background & objectives: Review of literature indicates that none of the ch emicals so far studied for oviposition attractancy was found to be promisin g for operational use. Efforts are being made to find an effective substanc e to corner a large number of ovipositing females to selective breeding sit es for ease of control operation. This will reduce insecticidal consumption and will be cost-effective. This study is aimed to evaluate the ovipositio n attractancy of aqueous infusion from a wood inhabiting fungus (Polyporus spp.) for vector mosquitoes both in the laboratory and under field conditio ns. Methods: An aqueous infusion (10%) was prepared by soaking 10 g of fungal p owder in 100 ml of chlorine-free tap water. The mixture was shaken thorough ly and filtered through Whatman No.1 filter paper. The filtered infusion te as tested for oviposition attractancy against vector mosquitoes both in the laboratory and under field conditions. Results: The laboratory study on the dose-effect relationship indicated tha t at an optimum concentration of 4 ppm, maximum attractancy was observed. W ater treated with aqueous fungal infusion (AFI) at 4 ppm received significa ntly more egg rafts/eggs of vector mosquitoes than other substrates like re aring water, natural breeding water and tap water. Trials conducted in the field showed that mud pots treated with AFI placed in both indoor and outdo or locations received significantly more Aedes aegypti eggs than the contro l. Similarly, treated pots placed in paddy fields attracted significantly m ore gravid Anopheles subpictus for oviposition than untreated pots. In cont rast, the number of egg rafts of Culex quinduefasciatus laid in AR treated pots was significantly less than in the control ones owing to strong natura l olfactory factors associated with the breeding habitat. Interpretation & conclusion: The results indicated that there is scope for developing a trap incorporating this oviposition attractant along with inse ct growth regulator(s) (IGR) for surveillance and/or control of Ae. aegypti and other vector mosquitoes breeding in paddy fields.