Effect of Fermentation Filtrate of Beauveria on Bio-activities of Different Nematodes

By means of dilute-separate technique and tissue-separate technique,105 isolates of Beauveria were seperated from insects and soil samples.20 isolates with strong bio-activity to Heterodera glycines were screened firstly,then their bio-activity were mensurated against to Meloidogyne incognita,Heterodera glycines,Aphelenchoides besseyi and Caenarhabditis sp..The results showed that 9 strains that were screened from 20 isolates had strong effects on different nematode species.Be treated with fermentation filtrate of strain B703147 for 24h,the corrected mortality rate of Meloidogyne incognita and Heterodera glycines were higher than 92.00%.After 48h,the lethal rate of strain B23 against to Meloidogyne incognita and Heterodera glycines reached to higher than 85%.The activity of strain B703148,which lethal rate reached to 66.15% after 48h,was the highest than other strains against to Aphelenchoides besseyi.Then lethal rates of most strains against to Caenarhabditis sp.reached to higher than 80%.There were significant differences among different Beauveria strains bio-activity against the same nematode species,and the selective toxicity of different nematode species differed from each other too.