| This paper was consisted of two parts: exploitation of Beauveria bassiana production and application of Beauveria bassiana against the 2 main pests. It included four chapters: studies on impacts of successive transfer culture on stability, spore-bearing yields and virulence of Beauveria bassiana; screening Beauveria bassiana strains with high virulence to the main pests; the technology of controlling the main pests with Beauveria bassiana and studied on Beauveria bassiana mixing with bio-chemical insecticide against the 2 main pests. Now compendium the research results as following:1. Studies on impacts of successive transfer culture on stability, spore-bearing yields and virulence of Beauveria bassianaThe past results showed that usually Beauveria bassiana strain would behaved degeneration after successive transfer culture, i.e. hypha grew vainly, growth rate increased, spore-bearing yields decreased, and the virulence to host descended. But after successive transfer culture for 10 generations,6 newly screened strains didn't show colonial saltation and growth rate, spore-bearing yields and virulence to host were stable. The results also showed that medium affected strains'stability, spore-bearing yields and virulence and medium of peptones+insect powder had positive effect.2. Screening Beauveria bassiana strains with high virulence to the main pests100 different strains isolated from different host pupae poisoned by Beauveria bassiana were obtained by tissue-separation and single-spore-separation. Their growth, spore-bearing yields, the beginning sporulation time, germination ratio and indoor virulence were tested and compared.10 new high virulence strains were screened, including 2 strains (i.e. Bpp and Bpp6) to Pantana phyllostachysae Chao,2 strains (i.e. Bxl and Bj1) to Dendrolimus punctatus Walker,3 strains (i.e. Bml-1, Bm3-3 and Bm2-7) to Lymantria xylina Swinhoe and 3 strains (i.e. Bal, Ba2 and Ba4) to Tessaratoma papillosa Drury. These strains were characterized by fast growth hypha, early sporulation time, high spore-bearing yields and high virulence to host.3. The primarily studies on the standardized techniques of Beauveria bassiana production technologyThe influence to Beauveria bassiana spore-bearing yields of different formulations of third-grade solid media, culture time of second-grade liquid media and third-grade solid media, temperature and humidity of third-grade solid media fermentation room were studied. It was summarized that spore-bearing yields was the highest if the proportion of bran and chaff of third-grade solid media was 9:1. The spore-bearing yields of strains reached the highest when it was cultured on third-grade solid media for 10 days after cultured on second-grade liquid media for 60 hours (22-26℃). Maximum of the spore-bearing yields was at 7-10 days on third-grade solid media (22-26℃). In order to prevent other fungus's pollution, the optimum temperature and relative humidity were 18-22℃and 95-100% for the first 3 days in the fermentation room of third-grade solid media. Standardized production technology not only produced the best powder, but also cut down cost.4. Studies on the technology of controlling the main pests with Beauveria bassianaIndoor virulence test and control experiment in field of 10 newly screened Beauveria bassiana strains to 2 main pests were done. The results showed that newly screened strains to Lymantria xylina Swinhoe had higher virulence to larvae of Lymantria xylina Swinhoe than strains to Dendrolimus punctatus Walker. Control effects of different strains in forest had distinct difference. Strains Bm1-1, Bm2-7 and Bm3-3 were advantage, characterized by early sporulation time, high spore-bearing yields, fast germinate-speed, high spore germination ratio, high virulence, high stability and resistance. Spraying or launching powder of 6 different strains had some effects to Tessaratoma papillosa Drury, but the best was strain Bal, which its average control effect reached 91.4%, and the poisoned pest ratio was the most. |
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