Virulence Of Beauveria Bassiana Against The Ostrinia Furnacalis (Guenee)

In this study, we used 5-d-age larva of cultured Ostrinia furnicalis(Guenee) as test insect,established a standard method and formula for the virulence bioassay of Beauveria bassiana .We also try to estalish new methods by test the correlations of the mortality of B. b against the larva of Ostria furnicalis(guenee) and the activities of the extracellular protease and chitinase.First,we study the characters's (10 era)hereditary stability of the cultured Ostrinia furnicalis(Guenee).The RSD(%) of the severial characters were 3.2, 4.7, 3.1, 2.2.The range of the cumulative mortalities of the 17 isolates'(1.0×10~7 conidiophore /ml)against the 5-d-age larva of Ostrinia furnicalis(Guenee) was76.67 - 96.67 % .The results indicates the larva have high hereditary stabilities and high sensitivities to B.b and it can be used as test insect.Second ,we study the characters such as conidiophore output,abilities against UV and high temperature and others of the 17 isolates and select SC-2 as the standard isolates .We use varing culture medium and conditions;varing treatment of dryness and conservation and select the standard combination of standard sample.We study the virenlence of B.b against the larva of Ostrinia furnicalis(Guenee). As difference was little in physiological characters individuals 5-day-age larva of Ostrinia furnicalis(Guenee) used as test insect. The bioassays were accuracy. The correlation coefficient between sample concentration and insect death rate was more than 0.9.The test period was only 5 days when the insect were cultured at 27±1□ and and humidity was 80- 100 % for 120 h. The reproducibility was good when 10×6 larva were used in the bioassay. The producer and method of the assay have been used for testing the potency of B. b productions and the results were stable and reliable .The extracellular protease and chitinase of 17 isolates of B.b. Virulence bioassay of each isolate include about 10x3 5-day-age larva of Ostrinia furnicalis(Guenee) receiving topical inoculation with the suspension of 10~7 conidia/ml.In the assay of the enzymes N-Acetyl-D-glucos-amine and L-tyrosine were used as a substrate to measure the abilities of ptotease and...