Fly ash based Bacillus thuringiensis var. israelensis formulation for use against Culex quinquefasciatus, the vector of filariasis in natural ecosystems.

BACKGROUND & OBJECTIVES Fly ash is produced in huge quantities by the various thermal power stations in India. This thermal waste has been employed as a carrier material in the preparation of a biopesticidal water dispersible powder (WDP) formulation for use against mosquitoes. In the present investigation, this newly developed fly ash based WDP formulation was evaluated in natural breeding habitats of mosquito. METHODS Fly ash based WDP formulation of Bacillus thuringiensis var. israelensis (VCRC B17) was evaluated for its efficacy and residual activity in aquatic habitats supporting breeding of Culex quinquefasciatus, the vector of lymphatic filariasis in Neyveli Township, Neyveli Lignite Corporation, India for a period of one month. RESULTS At an application rate of 10 kg/ha, the WDP was effective for five days regardless of the habitat, and provided 80-100% reduction in larval abundance of Cx. quinquefasciatus. INTERPRETATION & CONCLUSION The study indicates that for continued control of immature density and prevention of adult emergence, a weekly application of this formulation is necessary. This study also showed that fly ash based formulations can be used for immediate control of mosquitoes in different types of habitats and has also brought out a new avenue for the utilization of coal ash.