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The chemical insecticides are still contributing to human life enormously, but they have been distributed in ecological system of organisms including human beings because of their low specific toxicity to any organism and their low specific toxicity to any organism and their slight decomposition in nature. Therefore, many biological control of insects have been investigated. Currently, researches on the use pathogenic microorganisms to control insect pests are increasing. Microbial pest control is practiced in different parts of the world though utilization of pathogen like fungi, bacteria, viruses and nematodes. Bacterial research causing disease in insects began in the late nineteenth century. It was a study of flacherie of the silkworm, bombx mori in this report on the discovery of sotto bacillus, reffered briefly to occurrence of sotto bacillus-like organism, which causes the disease to silkworm larvae. Ten-fold serial dilutions of the heated suspension in sterile distilled water were placed on nutrient agar (NA-pH 7.5). After two days of incubation at 28oC, Bacillus colonies were recorded. After 2 to 3 days incubation, crystalliferous sporeforming bacteria were determined in phase contrast microscop. Isolation from five soil samples yielded about 35 isolates, only one was identified as B. thuringiensis.
Key Word: B. thuringiensis. Biological Agent |
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