| In China, Empoasca spp.（E. spp.） becomes the main tea pest today. It reduces the teayield and quality seriously. In order to control the pest, tea growers used a large amount ofchemical pesticide ever year, which will lead to the pesticide residues in tea exceed standardbadly. The pesticide residues will damage the environment, threaten the human health andhinder the tea export trade. The Beauveria bassianaYP9, which we used in this study, hasnoteworthy control efficiency against E. spp. So, Beauveria bassianaYP9, that has a gooddevelopment potential and application prospect.The main contents of this study were as follows:（1） The optimal results in solid state fermentation of Bb YP9are as follows: the initialmedium water content was65%, and it was regulated to68%after48h. The materials weremixed well at20h and40h, respectively. The temperature was25oC during048h（adaptive phase）,24oC during48108h （rapid growth phase） and28oC during108168h（stationary phase）. The aeration ratio was maintained at1:2during48108h, without anyaeration during048h and108168h. Under the optimum conditions, the sporulation of BbYP9in solid-state fermentation reached1.8×1010conidia/gdry weight, and the sporulation wasincreased by about360%, that reached the standard of industrial production．（2） The conidial thermotolerance of Bb YP9was enhanced by adding heat protectiveagents. We screened out six saccharides （glucose, sucrose, maltose, trehalose, lactose, andmannitol） from33additives first, and then optimized furthermore with response surfacemethodology （RSM） to obtain an ideal heat protective agent formula. The optimal additionconcentrations of the saccharides were as follows: glucose0.262g/mL, lactose0.276g/mL,and mannitol0.243g/mL. In the final validation experiments, the conidial germination rateafter adding the heat protective agents reached72.29%（the control was only4.57%）, whichwas very close to the predicting value72.28%. The results indicate that RSM was useful tooptimize the addition concentration of heat protective agents and the optimized results werereasonable.（3） After comparing the factors influencing on spore germination of BeauveriabassianaYP9, the optimal field application conditions were obtained as follows:2%wheatbran extract （natural pH） was used to promote spore germination; A trace amounts （0.5g/L） ofMg2+and Ca2+were added to the nutrient solution; The conidial suspensions were sprayed at5×107conidia mL-1; The suspensions were sprayed when the air temperature was about25oC（23oC28oC）, and the temperature lower than37oC, the sunlight less than3h during12hafter sprayed; The field trials in Wuxi, Kunming and Hangzhou have shown that, themaximal control efficacy of Beauveria bassianaYP9wad closed to that of pesticide. The trialsverified that the Bb YP9has a good development potentials and application prospect. |
