Study On Screening And Application Of Beauveria Brongriartii Petch From Plateaus

In order to screen out the best strain and plating medium, explore the biological character of the five strains obtained from the field. Beauveria brongniartii Bbr05 strain was used to survey and evaluate the host range.Flowing this, the fermentation conditions and fermentation medium were screened out. The main results are as follows:1.Different biological and ecological characteristics, strains growth rate, spore production, spore germination at different temperatures and humidity, ultraviolet resistant ability were measured respectively.The Beauveria brongniartii Bbr05 strain was determined as the best strain and the PPDA1 medium which contains potato 200g, glucose 20g, peptone lOg and agar 20g. Five isolates were collected from high altitude showed different characteristics from the low-altitude ones, as strong drought resistance and UV capabilities.2.The selected strain was used to infect the original host grub and other four insect pests. The result indicated that Beauveria brongniartii is effective to Coleoptera, Lepidoptera and Homoptera,Because of the host specificity characteristic, the Beauveria brongniartii Bbr05 strain had higher infectivity against the Larva of Melolontha hippocastan mongolica Menetries.The death rate reached 94.4%.For the other insects, the effect to the Homoptera was the best and the effect to the Lepidoptera was the second.The death rate of Brevicorvyne brassicae Linnaeus was the highest and the death rate of the Larva of Tenbrio motitor Linnaeus was the lowest.3. Beauveria brongniartii grew on different liquid culture medium were studied with the general sporulation as an estimate .The result showed that: in the trial three medium formulations,the treatment 2 in formul 2 was economical and the treatment 5 in formul 3 culture medium on which Beauveria brongniartii grow well and produce highest spores ,which was regarded as a ideal liquid carrier culture medium. The treatment 5 culture medium contains:5% wheat bran leachate,2% sucrose,0.4% the larvae of Tenbrio motitor Linnaeus tissue fluid,0.05% KH2PO4 and 0.02%MgSO4, the maximum sporulation capacity:25.17×108/ml.In the same liquid culture medium ,through comparing the sporulation at different times, showed that 72H was the best seed inoculation time.Beauveria brongniartii grow well on culture medium which contains complex nutritions and add proper animal protein can enhance the spores of liquid fermentation and culture effectively. The larvae of Tenbrio motitor Linnaeus tissue fluid was first used as nitrogen source and obtained higher spore production. This presents a valuable reference for the animal protein in the culture medium as nitrogen source.4. Screen out the relative optimum Beauveria brongniartii solid state fermentation medium from 4 solid medium.The formulation composition is:70% of the cottonseed shell, 25% wheat bran,5% corn flour. Maximum sporulation was:40×108/ml. The best combination of culture conditions:20.2-21.8℃, the medium thickness of culture culture medium 2.9-3.47cm with 14.5-15.5% inoculum. Wheat bran and corn meal provide adequate nutrient substance for the solid fermentation,and good water retention properties of cotton seed shell meet Beauveria brongniartii mycelial growth during the fermentation of water needed, while the fermentation process to ensure ventilation requirements.