Study On The Influencing Factors Of Virulence Of Nematode-trapping Fungi

ObjectiveTo study the influence of passage times,predation organs and spatial distribution on the virulence of the nematode-trapping nematode,the results of the study will help to understand the virulence of microbes under natural conditions.Methods1.Preparation of strains: From the species center of the Germplasm Research Institute of the East Himalayan Research Institute,the traps were selected according to the spatial distribution of the strains,which were the same strains of adhesive nets,contracting rings,adhesive branches,and adhesive knobs.2.Strain resurrection and further identification: The strains obtained from the strain library were revived and purified on CMA and PDA medium,and further identified species were combined with morphology and molecules.3.Passage experiments: The defined strains were retransmitted to CMA medium,which was the first generation culture;when this plate grew well,it was transferred to the new CMA medium again,this is the second generation;Analogy until the passage to the fifth generation.4.Strain culture: The 1-5th generation strains were individually transferred to a CMA medium with an observation chamber and cultured in an incubator.The first-generation strains were used as test strains to study the changes in virulence under different soil quality,predation organs,watershed,latitude and longitude,and land and water.5.Determination of virulence: After the hyphae of the 1-5th generation strains were spread on the plate,the virulence of the predatory nematode fungus was measured with a self-preparation nematode fungal virulence tester and calculated.Results1.The virulence of the nematode-trapping fungi increased with the passage times,and the virulence weakened.The toxicity of the nematode-trapping fungi,which produced adhesive nets,decreased with the increase of the number of passages.2.The virulence of the nematode-trapping fungi producing different predatory organs was different.The overall result was that the predatory organs were contracting rings,and adhesive knobs,The virulence of the strains was the highest,followed by adhesive branches,and the adhesive nets strains had the lowest virulence.3.There is no difference in the composition of predation organs of nematode-trapping fungi in different soils,but the virulence of nematode-trapping fungi in different soils is different.4.There are some differences in the virulence of the nematode-trapping fungi in different latitude and longitude.5.On a large scale,there is a certain difference in the virulence of nematode-trapping fungi in the region where the three rivers flow in parallel;Dali is the dividing line.There are differences in the venom of the nematode-trapping fungi in the area south of Dali and in the area north of Dali,but east and west of Dali.There was no difference in the virulence of the nematode-trapping fungi in the two regions.At the small scale,the venom of nematode-trapping fungi in the upstream and downstream of the Lancang River basin was significantly different.6.The virulence of nematode-trapping fungi between land and water is significantly different,and the venom of nematode-trapping fungi on land is greater than that of water.7.The Arthrobotrys oligospora of different strains of the same species are different in a single basin and basin.ConclusionThe number of passages,predator organs,soil quality,watershed,latitude and longitude,and land and water will all affect the virulence of the nematode-trapping fungi.