فرمانتاسیون قارچ بیمارگر حشرات، Beauveria bassiana با استفاده از بسترهای آلی جامد و ارزیابی بیمارگری آن روی سفید‌بالک گلخانه

Entomopathogenic fungi have a special place among the microbial control agents of insects. Using these fungi as the commercial biological control agent requires mass production of them. Meanwhile, the cheap natural materials such as agricultural waste or byproduct have been used to commercializing the fungal products. This study aims to investigate the fermentation of an isolate of Beauveria bassiana ( Code: A1-1) on solid organic substrates including wheat bran, rice bran, corn bran, rice husk, rolled oat, and barley residues which had been consumed in the grain moth rearing insectarium. Before culturing the fungus, 100 ml of sterile distilled water was added to 100 g of each substrate inside the heat-resistant nylon bags and sterilized in an autoclave. In another experiment, the pathogenicity of conidia obtained from different substrates was evaluated on third instars of greenhouse whitefly, Trialeurodes vaporariorum in experimental condition. In the bioassay experiment, a fungal suspension having a concentration of 1×107 conidia/ml was used. The experiments were performed in a completely randomized design with four replications. The results of statistical analysis showed that there is a significant difference in the rate of fungal conidiation on different solid substrates (P˂0.05). Conidia production per gram of wheat bran, rice bran, corn bran, rice husk, rolled oat and barley were obtained 2.77×109, 2.52×109, 2.42×108, 3.52 ×108, 2.85×108 and 1.06×109 conidia/g respectively. The mean percent mortality of conidia obtained from wheat bran, rice bran, corn bran, rice husk, rolled oat and barley on whitefly nymphs were calculated as 68, 69, 86, 55, 64.2 and 64.8 percent, respectively. According to the results, corn bran, rice bran and wheat bran are recommended for mass production of fungus. The results showed that the type of organic substrate affects the production of conidia and rate of pathogenicity. Moreover, higher production of conidia in a given substrate does not necessarily correlate with more pathogenicity.