Screening And Identification Of Biocontrol Strains Of Cereal Cyst Nematode

Wheat cyst nematode(Heterodera avenae) is a kind of dangerous pathogens on wheat production in the world, has brought serious threat to wheat production. At present, in our country is lack of effective measures to prevent and control the disease.Use biocontrol microorganisms to contrlo wheat cereal cyst nematode is considered have great potential development. Therefore, this study screening of wheat cereal cyst nematode biocontrol strains, and the prevention mechanism of biocontrol strain is studied, the main results were as follows:1 The Wheat cereal cyst nematode field soil was collected from yongdeng county and tianzhu county of gansu province.499 fungi strains wered isolated using martin substratum and PDA medium. 104 bacterial strains wered isolated using NA medium.2 The parasitic test of cereal cyst nematode eggs was carried on 501 strains of fungi, 27 strains of fungi was screened by parasitism rate of over 40%,the preliminary morphological identification and molecular biology identification were also carried on this fungi.The results showed that 27 strains of fungi belong to 5 genera and 9 species. Among them the egg parasitism rate of over 70% of the 8 strains, 6 strains of Trichoderma longibrachiatum, respectively, the strain were TL13、TL6、TL14 、TL17、TL12 and TL8,1 strain of Aspergillus terreus was AT9,1 strain of Aspergillus parasiticus was AP2.Lethal force was determined by J2, 17 strains of bacteria was screened, the preliminary morphological identification and molecular biology identification were also carried on this strains. The results showed that 17 strains belong to 15 species of the genus Bacillus.The strains of lethality rate of J2 more than 90% after 72 h were B10, B20, B24, B26 and B30. The strain of B10 was identified as B. cereus, B20 was B.muralis, B24 was B thuringiensis, B26 was B. methylotrophicus, B30 was B. amyloliquefaciens.3 The study of mode of action on part of fungi strains was carried on, the results showed that the strain of T. longibrachiatum of the J2 fatality rate was 92.97%, egg parasitic rate was 77.67%,the eggs hatching inhibition rate was 70%.The strain of A. terreus of the J2 fatality rate was 90.40%, egg parasitic rate was 74.33%,the eggs hatching inhibition rate was 66.20%. the strain of A. parasiticus of the J2 fatality rate was 68.13%, egg parasitic rate was 70.00%,the eggs hatching inhibition rate was 66.20%.At the same time, the test results show that the same strain of different sources, the role of parasitic eggs, hatching inhibition and lethal effect on J2 also showed great differences.The results mode of action of bacterial biocontrol showed that, the J2 lethality rate more than 90% and the eggs hatching inhibition rate more than 50% of the 5 kinds of bacteria.The strain of B. muralis of the J2 fatality rate was 100%, and the eggs hatching inhibition rate was 63.07%. The strain of B. methylotrophicus of the J2 fatality rate was 100%, and the eggs hatching inhibition rate was 57.20%. The strain of B. thuringiensis of the J2 fatality rate was 98.80%, and the eggs hatching inhibition rate was 67.57%. The strain of B. cereus of the J2 fatality rate was 96.73%, and the eggs hatching inhibition rate was 70.27%. The strain of B. amyloliquefaciens of the J2 fatality rate was 93.63%, and the eggs hatching inhibition rate was 66.67%.4 Based on different seasons cysts parasitic fungi separation test, the 7 genera 10 species of fungi were isolated.The Fusarium spp. isolation frequency of 59.3%;The Alternaria spp. isolation frequency of 17.8%; The Aspergillus spp. isolation frequency of 2.6%;The Trichoderma spp. isolation frequency of 3.2%;The Penicillium spp. isolation frequency of 12%;The Phoma medicaginis isolation frequency of 4.2%;The Talaromyces spp. isolation frequency of 0.8%;The advantage of parasite cysts in four seasons were P. chrysogenum、F. solani、F. oxysporum and A. alternate,these four fungi can be isolated from spring, summer, autumn and winter.Secondly, P. medicaginis and T. longibrachiatum had a higher frequency separation.A. parasiticus was a winter incidental species,A. fumigates was a spring incidental species,T. variabilis was a fall incidental species, A. carneus was a summer incidental species, not separation in other seasons.