ABSTRACT
Background: During the mid-1970s, larvicides have become available that are highly effective, yet selective in action, and therefore environmentally safe to non-target organisms, as well as for human exposure(1). Objectives: The small field trial was carried out from 12th of January to 16th of February 2008 in Khartoum State to evaluate the efficacy and persistence mosquito dunk® (Bti) against mosquito larvae and to measure the effect of physic-chemical properties on mosquito dunk. Material & Methods: The efficacy and persistence of Bacillus thuringiensis subspecies israelensis (mosquito dunk®) as a biological control agent against mosquito larvae was conducted in Khartoum State. Twelve ponds were used as natural breeding habitats of mosquitoes; six of them were treated with dunk at a rate of 1 dunk per 100 square feet and six ponds left untreated (control). Results: The study revealed that more than 80% reduction in immature stages density was observed up to 5, 3 and 2 weeks for the 3rd, 2nd and 4th instars of Anopheline spp., respectively. However, the study showed that the mosquito dunk was noteffective (under 80% mortality) against 1st, instar larvae and pupae of Anopheline species as well as Culex developmental stages. Conclusion & Interpretations: The dunk was very effective in controlling 3rd and 4th instars of Anopheles spp; for 2 weeks interval. Therefore we propose a surface application regime of once every 2 weeks for mosquito dunk