Preparation And Application Of Biocontrol Formulation Of Nematode-trapping Fungus-Duddingtonia Flagrans

China is a large livestock breeding country,and there are many species and wide distribution of nematodes in the digestive tract of livestock and poultry,which causes serious economic losses to the breeding industry and hinders the sustainable development of the livestock industry.To prevent and control these diseases,deworming with chemical anthelmintics are usually used.But they also inevitably lead to anthelmintic resistance,which in turn affects the environment and human health.It is well-known that,biological control of parasites by nematode-trapping fungus,the natural enemy of parasitic nematodes,has great potential to replace or reduce chemical drugs,among which Duddingtonia flagrans is one of the most applicable biocontrol fungi.But what are the effects of biological control by nematode-trapping fungus on animals?In addition,combined with the actual production in China,the combination of nematode-trapping fungus and anthelmintic may be more effective,but what kind of dosage form is suitable?Due to the lack of relevant reports and affecting the clinical application of fungi,So the following tests were conducted:Firstly,on the basis of preparing a large amount of D.flagrans spore suspension,the experimental rabbits were fed with 5-fold and 10-fold doses of D.flagrans spore solution and then blood samples were collected at the same time on the 0th,5th and 10th day of the experiment to detect the changes of blood routine and blood biochemical indexes,and the physiological index data of the experimental rabbits were observed and recorded regularly every day.At the end of the experiment,the tissues of heart,liver,spleen,lung,kidney,lymph node,cerebrum,cerebellum and intestine were taken to observe the histological morphology and pathological changes,and finally made into sections and observed under microscope.The results showed that the behavior and physiological indexes of the experimental rabbits in each group were normal,and the data of blood routine and blood biochemical indexes were also in the normal range,and no obvious pathological changes were found in tissue sections.all these show that the fungus will not cause visible pathological changes in the animal body.Then,on the basis of previous experiments,tablets of D.flagrans spore lyophilized powder-ivermectin and capsules of D.flagrans spore lyophilized powder-albendazole were prepared respectively.Then an animal experiment was carried out in a Tibetan sheep farm in Qinghai Province in August 2019.The results showed that the fecal egg reduction rate and fecal larva reduction rate of D.flagrans combined with ivermectin preparation or albendazole preparation were up to 100%,which were better than those of single drug group,and the larval reduction rate of lyophilized powder of D.flagrans spores alone was 89.8%.Research shows that predation of lyophilized powder of nematode-trapping fungus-D.flagrans can effectively reduce the number of larvae in feces,and when combined with anthelmintic,it can not only effectively dewormed in animals,but also significantly reduced the number of larvae developed from eggs excreted in the environment,which greatly reduced the pollution of the grassland,and avoid reinfection.The above studies showed that the combination of the nematode-trapping fungus-D.flagrans and anthelmintics can achieve better control effect and is safe for animals,which provides basic data for further research and development of fungal-anthelmintic biocontrol agents in the future,and also helps to promote the clinical application of nematode-trapping fungus.