| Dalbergia odorifera T.Chen is one of the most common precious mahogany in China,with high economic value and great market demand.With the continuous expansion of planting area,the diseases and insect pests of Dalbergia odorifera become increasingly prominent,which seriously restricts the healthy and sustainable development of Dalbergia odorifera industry.Biological insecticides have attracted more and more attention in the pest control of Dalbergia odorifera.Beauveria bassiana is a broad-spectrum entomopathogenic fungus,which has been widely used in the control of agricultural and forestry pests.In this study,a strain was isolated from Dalbergia odorifera forest HNCMBJ-P-01 as the object,the Beauveria bassiana was selected by UV microwave compound mutation,the high virulence Beauveria bassiana was screened,the fermentation conditions of the high virulence mutant were optimized,and the formula of Beauveria bassiana wettable powder was developed.The forest experiment was carried out to evaluate the control effect of the developed wettable powder on Plecoptera bilinealis,a leaf eating pest of Dalbergia odor ife ra.The main results are as follows:(1)Compound mutation breeding of Beauveria bassiana high virulence strain.The beauveria bassiana HNCMBJ-P-01 was mutagenized by ultraviolet mutagenesis,and the best mutagenic strain HBUV-22 was screened.Then microwave was used for compound mutagenesis,and finally the highly virulent mutagenic strain HB WB-44 was screened.The 10-day corrected mortality rate of the larvae of the larvae of the larvae of C.vulgaris reached 80.00%,and the mortality was 5.622 days,which was 1.23 times and 0.76 times that of the original strain HNCM-P-1.Moreover,the genetic performance of the strain is stable,and it has the value of further research.(2)Based on response surface analysis,the fermentation conditions of high virulence mutant were optimized.Through single factor test and response surface analysis,the effects of carbon and nitrogen sources,inorganic salts,culture time,inoculation amount,temperature and pH value on the fermentation culture of Beauveria bassiana HB WB-44 were systematically studied,and the target was determined.The optimal medium and culture conditions for the strain.The single factor test results showed that the best basic medium for strain HB WB-44 was SDY medium,the best carbon source was glucose,and the best nitrogen source was tryptone.Under the control of single fermentation culture conditions,it is determined that the optimal culture time of the strain is 3 days,the optimal inoculum amount is 3%,the optimal culture temperature is 28℃,and the optimal initial pH of the medium is 7.0.The response surface analysis is further conducted.The method optimizes its culture conditions and obtains the optimal combination of multiple parameters:culture time 3.458d,inoculum volume 3.285%,temperature 28.159℃,pH 6.702,and predicted mycelial growth to 13.073 g/L,which is to further improve the coccidia The yield of spore powder in the large-scale production of Beauveria bassiana provides a reliable theoretical basis.(3)Development of high toxic Beauveria bassiana wettable powder and its effect on forest control.The wettable powder of Beauveria bassiana HBWB-44 was developed,and the prepared wettable powder was tested for indoor toxicity and forest control,and the basic formula of Beauveria bassiana HB WB-44 wettable powder was determined as:30%Beauveria bassiana HBWB-44 spore powder,5%wetting agent polyvinyl alcohol,5%dispersant sodium polyphosphate,0.3%ultraviolet protectant,carrier diatomaceous earth to make up to 100%.The results showed that the insecticidal effects of 100 times Beauveria bassiana dilution,Beauveria bassiana spore suspension,1000 times green sea Beauveria bassiana dilution and 1000 times matrine dilution were similar after 10 days of treatment.In the Hainan Dalbergia odorifera plantation base,the fungus control effect was tested.The results showed that the control effect of 100 times liquid of Beauveria bassiana wettable powder can reach 60.89%,second only to the plant-derived fungicide matrine.Control,the wettable powder has a good control effect on Dalbergia odorifera leaf-eating pests. |
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