Investigation Of Entomogenous Fungi Resource In Shanxi Province And Studies On Insecticidal Activity Of Pandora Neoaphidis Toxin

This paper consists of three parts as follow:1. Investigation and research of entomogenous fungi species in Shanxi province.2. Research of Pandora neoaphidis cultural characters and its pathogenicity against to Myzus persica.3. Research of the crude toxin constitutes seperated from the liquid cultural medium of Pandora neoaphidis and its biological activity.More than 200 insect host specimens were collected during 2001-2002 in Shanxi province. 89 strains of entomogenous fungi were obtained among 148 specimens which were cultivated with different culture medium. Identification adopt the Ainsworth taxonomic system. 12 genus and 15 species were identified in all.A strain of Pandora neoaphidis was cultivated and its pathogenicity test against the Myzus persica has been done. After cultivating on the modified culture medium for 4 days, the strain of Pandora neoaphidis has a 1.5 to 2.0 cm diameters hoariness colony which has inequalities and closed fuzz surface, slight cinnamon base medium. Conidia which size 18-32 × 12-16μm was from rotundity to ellipse shape and most of them have many fat globelet in center of the cell. The result of pathogenicity test against Myzus persica by means of spray conidia suspension reveals that the aphids began to die after 3 days, the number of death reach to top from 5th to 7th day and less death case appears after 9 days. The cumulate adjusted mortality in 12 days was 80.7% treated with conidia suspension at the concentration of 2.0 × 10⁸ conidia/ml. The test indicated that there was a certain extent of relationship between the concentration of conidia and the mortality.Culture the Pandora neoaphidis in liquid culture medium for 21 days. Crude toxin contains the metabolites of Pandora neoaphidis was obtained from the ferment liquid by means of a series of procedure. Thin layer chromatography(TLC) analysis was used toresearch the suitable constitutes and proportion of spread solvent which can separates the crude toxin. Put the silicon gel thin layer under the 254nm wavelength ultraviolet radiation and observe the bands pattern reflect by fluorescence. The results indicate that the suitable constitutes and the volume proportion of spread solvent is chloroform: methanol: acetic acid=16:l:3. A total of 9 bands which show different color respectively were seen under the 254nm wavelength ultraviolet radiation. Measure and record the Rf value. There is a possibility that the sample of crude toxin contains the alkaloid or lipid matter, but confirming the conclusion rely on the further research. The preparation TLC method was used to purify and obtain the matter which representative by 9 bands. The bioassay of the different matter against Myzus persica reveals that the 1st, 2nd and 5th components appear a certain extent biological activity and the toxins play an important role of lethiferous effect in Pandora neoaphidis against aphid.