Abstract

In India, the most important diseases transmitting mosquitoes belong to the genera Anopheles, Culex, Aedes and Mansonia. The indiscriminate use of synthetic insecticides creates multifarious problems like environmental pollution, global warming, insecticide resistance and is hazardous to humans. In the present study, bacterial pesticide, Bacillus sphaericus a soil dwelling bacteria, isolated from the sludge samples collected from Bharathiar University, Coimbatore, India cultured with required substrates and used to control the malaria vector, Anopheles stephensi. Bioassay was conducted to test the larval toxicity, fecundity and mosquito longevity. LC₅₀ and LC₉₀ values were calculated for the larval instars of the malaria vector, A. stephensi. The fecundity and adult longevity were highly reduced after the treatment with B. sphaericus. Field trials were also conducted in different breeding sites of A. stephensi with different range of temperature and altitude. Percentage reduction of larval population was maximum (100%) at 96 h of treatment. Toxicity efficacy of B. sphaericus was varied according to the temperature and altitude of the study area. The bacterial pesticide B. sphaericusproved that it is an effective mosquito control agent and can be used for further integrated pest management programmes.

Key words: Bacillus sphaericus, larval toxicity, lethal concentration, Anopheles stephensi, field studies.