| As one of the pillar industries in Xinjiang,animal husbandry plays a crucial role in the development of the whole society.Nematode,a kind of worm,occupy a large proportion in the whole parasite population.There are diarrhea,vomiting and malnutrition in livestock infected with nematode disease,which will make the utilization rate of livestock feed low and cause serious economic losses.Once acute cases occur,they can lead to the death of livestock.Drug treatment is usually used for the treatment of livestock with nematode disease.The use of anthelmintic can achieve good results at the initial stage,but long-term use will result in drug resistance and drug residues.In order to effectively control the effects of nematodes on livestock,human body,environment and economy,nematode-trapping fungi,which exist naturally in soil,have been studied and applied for parasite control at home and abroad.In the application process of nematode-trapping fungi to control nematodes,each region has its own unique dominant strains affected by the geographical environment differences in different regions.Therefore,when using nematode-trapping fungi,it is necessary to isolate candidate strains suitable for local survival,so as to improve the predation efficiency of nematodes.This study collected soil from Nanshan pasture farm in Urumqi,Xinjiang and the campus of Xinjiang Agricultural University,and soil dispersion method was adopted.With Caenorhabditis elegans as bait nematode,3 fungi strains with nematode trapping activity were isolated.After the species were identified by morphology and molecular biology,the predation process of 3 fungus strains was observed in detail by optical microscope,and finally the predation efficiency of 3 strains of nematode-trapping fungi was measured by CMA medium.The results provide theoretical basis for biological control of animal nematode diseases in Xinjiang.The main results are as follows:(Ⅰ)3 strains of nematode-trapping fungi were isolated from 30 soil samples in this experiment.According to the morphological study,the conidia of strain 1 was conical,and the length of conidia was 29.8μm ～ 36.2μm,which was separated at 2/3 of the conidia.The conidia of strain 2 were plump pear-shaped,and the length of conidia was 16.2 μm ～ 24.5 μm,which was separated at the base of the conidia.The conidia of strain 3 were elliptical,and the length of conidia was 15.1 μm ～ 20.5 μm.Some of the conidia had no septum,and the septum was located at 1/2 of the conidia.Through preliminary morphological identification,3 nematode-trapping fungi belonged to Arthrobotrys.PCR amplification,sequence alignment and phylogenetic analysis of ITS2 gene for the isolated nematode-trapping fungi showed that 3 nematodetrapping fungi were Arthrobotrys conoides,Arthrobotrys oligospora and Arthrobotrys superba,respectively.(Ⅱ)By observing the predation process of 3 nematode-trapping fungi,it was found that all three nematode-trapping fungi carried out predation by adhesive nets,and all of them produced thick-walled spores in the later stage of predation.However,in the process of predation on nematodes,there were significant differences in the growth speed,the predation time of nematodes,and the time and growth mode of thickwalled spores.Finally,three nematode-trapping fungi strains were used to test their predation activity in laboratory,and the results showed that the predation rates of 3 nematode-trapping fungi strains on the third stage larvae of donkey digestive tract nematodes in CMA medium were 97.47%,92.17% and 96.52%,respectively.This study identifies 3 nematode-trapping fungi by morphological and molecular biological methods,which are Arthrobotrys conoides,Arthrobotrys oligospora and Arthrobotrys superba respectively.all of them carry out predation by adhesive nets.The predation process of 3 fungus strains is described in detail,and the similarities and differences of 3 nematode-trapping fungi in the predation process are summarized.Finally,the predation rates of 3 nematode-trapping fungi,Arthrobotrys conoides,Arthrobotrys oligospora and Arthrobotrys superba,on the third stage larvae of donkey digestive tract nematodes are 97.47%,92.17% and96.52%,respectively.All of them show good predation effect,which can lay a foundation for the clinical application of nematode-trapping fungi in the future in Xinjiang. |
