Study On The Preservation Materials Of Entomopathogenic Nematodes

Long-term unreasonable use of pesticides is a huge threat to human health and survival environment.Therefore,adaptation of new environmental protection method to control insect pest can reduce environment pollution and protect the human health.Entomopathogenic nematodes is a kind of biological control of parasitic factor,it can effectively prevent and control a variety of pests.However,its short shelf life and high technical requirements in the process of practical application limit its application in our daily life.Thus,the study to discover low cost and environmental friendly materials as preservatives for nematode to extend its shelf life is of great significance.In this dissertation,we used Galleria mellonella larva as an insect host for nematodes to culture Entomopathogenic nematodes,we determined some optimization based on the traditional white trap method,using a layer of transparent film sealed into the big petri dishes.Due to the applied optimized method,we collected higher quality and quantity of Entomopathogenic nematode.In this contribution,starch(soluble starch,sago starch,wheat starch,corn starch,potato starch),polysaccharide(tamarind,xanthan gum,trehalose)and inorganic(white carbon black,distilled water),modified fiber(HPMC,CMC)and sodium alginate were chosen to be used as preservative materials.The water content of 40%and 50%were prepared,respectively.And the water content of 70%and 80%of white carbon black preservation agent were also prepared.Additionally,10 ? and 18 ? were taken as preservation temperature,to study the types of material,water content and preservation temperature on nematode survival rate and the influence of shelf life.By comparing each material effect on the nematode survival rate,we can found that the preservation effect of nematodes to be in the following order:soluble starch>sago>wheat starch>corn starch>potato starch>silica tamarind>HPMC>trehalose>xanthan gum>CMC.Hence,starch was determined to be the most suitable material as the best preservative for nematodes.Specifically,the soluble starch exhibited the best effect especially when the preservative temperature was 10 ? and water content of 40%.In this fashion,nematode survival rate reached up to 81%after a period of 60 days,and the Entomopathogenic nematodes were still showing high energy and virulent.Entirely,the best preserved temperature for Entomopathogenic nematodes was found to be 10 ?,the optimum water content for soluble starch and sago was 40%,however,the optimum water content for wheat starch,corn starch,potato starch,tamarind,HPMC was 50%instead,and the best water content for white carbon black was 80%.This work studied the effects of preservative materials,such as starch,polysaccharide,mineral,modified cellulose and ionic salt,temperature and water content of the preservative materials toward the shelf life of Entomopathogenic nematodes.The cause and the effect of preservation conditions for nematode survival were discussed based on the aspects of theory to explore the influence of different conditions on the vitality of nematodes.