Identification And Description Of A New Entomopathogenic Nematode Heterorhabditis Beicherriana, And Its Mechanism In Biological Control Application

As an obligate parasitic natural enemies, entomopathogenic nematodes (EPN) with different species or strains, can achieve the best effect in different pests control. Thus the accurate identification and description of the entomopathogenic nematodes is particularly important. Using morphological identification and ITS rDNA gene and28s rDNA sequence analysis method, together with the morphology structure of new EPN isolation (Cherry nematode), Cherry nematodes was finally determined as a new species of the genus(Heterorhabditis) and named as (Heterorhabditis beicherriana). The name "beicherriana" is derived from the Beijing region where the nematode was isolated (-bei-), the cherry orchard habitat where the nematode was found (-cherr-) and the suffix (-iana). In this paper, the biological, ecological characteristics and infective death mechanism was studied, so as to make full use of the Cherry nematode in bio-control application.(1) Since Cherry nematode has good infection against the insect host, it can be developed and utilizated as bio-control agent, especially can be used in a relatively high temperature dry areas for underground pest bio-control. Besides, Cherry nematodes can be stored by inducing dormancy, but in order to ensure the infection, induction period should not be too long, problem because the inactivation of nematodes symbiotic bacteria caused by long-time dormancy.(2) The contents of carbohydrate and protein of Tenebrio molitor decreased to varying degrees within0-40h after infected with Cherry nematode in compared with the control. There are dose effects between the nematode quantity and the contents of the three energy substances, in other words, the more of nematodes infecting T molitor, the more the three energy substances consumed by nematode. The activities of antioxidative and detoxifying enzymes, tyrosinase (TYR), acetylcholinesterase(AChE), carboxylesterase(CarE), glutathione s-transferase(GSTs), superoxide dismutase (SOD),peroxidase (POD), catalase (CAT) and the contents of MDA significantly changed in dose-dependent and time-dependent manners.(3) SA could inhibit the in the hatch processing of root knot nematode, and also could partly dissolved root knot nematodes eggs. Cherry nematode also has inhibition effect of root knot nematodes, and the combination of SA and Cherry nematode has gain effect during the use in suppressing the root knot nematode.(4) SA had poison effects on Cherry nematode, but gave nutritional support for Cherry nematode and their symbiotic bacteria. Thus it makes Cherry nematode lives longer in SA solution than in the water. Due to root knot nematode and Cherry nematodes have competition for oxygen in solution, Cherry nematode died from short of oxygen when the root-knot nematode existed.(5) In early experiment, Cherry nematodes has some interference to root knot nematode during invasion of cucumber seedling root. Thus under the synergy of the two, into the cucumber root root knot nematodes is relatively small, Cherry nematodes plays a main role; Late experiment, soil restoration agent SA to consolidate the role of root system structure, can be appropriate to forestall the deeper part of the root knot nematodes, slow or stop the growth of root knot nematodes.(6) Only into the root knot nematodes M treatment group, the number of root knot nematodes and other plant nematodes, and applied into the SA treatment group increase in the number of nematodes food bacteria, nematode higher total abundance, soil restoration agent and can improve the diversity of soil nematodes of entomopathogenic nematodes. SA and Cherry synergy, can significantly improve the basis of soil food web components, enhance the ability to resist outside pressure.Change over time, as primary metabolic pathway from the metabolism of bacteria to fungal metabolic changes, but the SA and Cherry nematodes can effectively alleviate the trend of the application.Soil nematodes indicate no significant difference of soil food web structure, but then be deepening.(7) Into the soil restoration agent SA and Cherry significant increase in the treatment group of cucumber leaf area of c. elegans, cucumber seedling fresh weight increases, shows that soil restoration agent have the effect of the growth of cucumber above ground, significantly better Yu Qingshui and nematodes, and both nematodes (soil restoration agent SA and Cherry) compound fertilizer effect is gain.