The Study On Application Of Beauveria Bassiana And Metarrhizium Anisopliae Against Laphygma Exigua Hubner

The method that the research use is isolating the entomopathogenic funigi from soil with Tenebrio molitor.Soil samples were collected in different soil in the surroundings of baoding and some places of Hebei.There are 3 species of 3 genera were encountered from the infected Tenebrio molitor of soil samples .The genera are Beauveria, Metarhizium and Paecilomyces. For species of entomopathogenic fungi, Beauveria bassiana, Metarhizium anisopliae and Paecilomyces fumoso-roseus,isolated from Tenebrio molitor. Approximately,There are totally 50 strains.The eight strains Beauveria bassiana and Metarhizium anisopliae parasitized on Tenebrio molitor and became the thick spore layer.We cultivate these strains and have a test on Laphygma exigua Hubner and Leucania separate Walker. We also researched the biology characteristics of these strains.The result showed these strains were highly virulent and had quick lethal action to Laphygma exigua Hubner but low virulent action to Leucania separate Walker. Beauveria bassiana BD-B015 and BD-B038 have quick lethal action than others, and virulent of Metarhizium anisopliae 060 is higher than 038.Biological research contain Conidia bourgeon, Growth, Conidia production, Protea-Bse activity leve and Infestivity.The result showed the BD-B015 and BD038 strains are better than others of Beauveria bassiana,theBD-M060 strains have good Conidia bourgeon, Growth , Conidia production, Protease activity leve and Infestivity.At the same time, In different mediums Cazpek, PPDA, SDAY , PDA ,The result is that the BD-B015 strains grow better on all medium except PDA and there is no effect for Conidia production on different medium.The research of the BD-B015 strain infection process and histopathological changes of infected Laphygma exigua Hubner by Beauveria bassiana and Metarhizium anisopliae, as well as the defense response of the host to the pathogen. The purposes of this study were to establish the pathogenesis of Metarhizium anisopliae to the diamondback moth and interaction between pathogen and Laphygma exigua Hubner, to evaluate the potential of the fungus as a biocontrol agent for Laphygma exigua Hubner, which provide the basis for the application of the pathogen in the integrated control of diamondback moth and provide new exemplum for the research of interaction between host and pathogens.Laphygma exigua Hubner was infected by two isolates of Metarhizium anisopliaeand two isolates of Beauveria bassiana. There were some changes in color and morphology on the Laphygma exigua Hubner .The result of Paraffin sections showed that the invasion process by Beauveria bassiana were similar by Metarhizium anisopliae.B\xt the invasion speed was different. The invasion speed of Metarhizium ansopliae was faster than Beauveria bassiana. The BD-M060 faster than the BD-M086.The BD-B015was faster than the BD-B038.The spore in the intestine was not bourgeon and the organization of Laphygma exigua Hubner was not change at 24h. After 48h, the spore was bourgeon on the cuticular. By 72h,the hypha could be observed in the blood and began to reproduced in hemocoele. And then,the fattiness ,muscle tissue and alimentary tract carryeg on a series of pathological changes.The hypha emerged through the cuticle and formed hyphal layer on the surface of the dead insect 120h postinoculation. The hypha emerged through the cuticle when Laphygma exigua Hubner was infected by Metarhizium anisopliae BD-M060 at 72h By 96h,the organization of Laphygma exigua Hubner by Metarhizium anisopliae 086 was destroyed entirely.The analytic result of esterase of infected Laphygma exigua Hubner and the healthy Laphygma exigua Hubner were analyzed with PAGE analysis show that the enzyme band numher of the infected nymphs decreased and the band got more blurred, especially in the later infection stage.The esterase areas corlor ofBD-B038 isolate become shallow and the number reduced immediately.Different from the 038 isolate ,most esterase areas of BD-B015 isolate disappear in the fourth day, leaving only the easte area of part A, which has low activity.There are also some differences in Esterase isoenzymes of the Laphygma exigua Hubner that infected by two Metarhizium anisopliae isolates: There are a great contrast in the fourth day,for example, esterase band of 060 isolate take the number increase but the BD-M086 isolate reduced to only one.And part A part B part D have some imperfection.The common place expressing that,part C of both strains imperfected seriously.There are also some imperfection in part C of Beauveria bassiana.but the degree of imperfection is lower than Metarhizium anisopliae.