Diversity Of Helicotylenchus Nematodes Of Plant Rhizosphere In Dashushan Hill

Biodiversity is critical for the stability of ecosystem.Soil biodiversity is an important aspect of biodiversity.Research on soil biodiversity have been focused for decades.Soil nematode plays an indispensable role in many soil biodiversity.A wide verities of soil nematodes exit in the soil with unique characters,so it is crucial to study soil nematodes.Soil nematodes are a good choice for being a biological indicator of soil.Helicotylenchus sp.cause damages to fruits and lawns.At present,in the suitable soil ecology,nematodes species are complex,normally predator-nematodes(main component of food chain)are small in quantity and difficult to identify.Previously,Helicotylenchus sp.have been identified in China and particularly in Anhui province.Soil nematodes distribution,large quantity and shape,and difficult to identify are factors that the soil nematodes effect the environment.Hence the study of the soil nematodes distribution and population dynamics is critical.We choose Dashushan hill because of its great soil ecology and social benefits,moreover,Dashushan hill is a very attractive place for people because of its natural forest.In this study,we measured and compared the population density,distribution and frequency of different parasitic-nematodes.The frequency of Helicotylenchus and other parasitic nematodes was analyzed.The morphological characteristics were observed according to de Man method under optical microscope.Different methods were used to identify the morphological features.The results are as follows:1.The diversity index of soil nematodes of Dashushan hill is higher as compared to farmland.Average Simpson index,Shannon index,Evenness,Brillouin index and McIntosh(Dmc)index of soil nematodes in Dashushan hill are 0.64,1.66,0.83,1.66 and 0.83 respectively,which are higher than diversity index of soil nematode in farmland.We found that the diversity of soil nematodes in Dashushan hill is superior as compared to diversity of soil nematodes in farmland.2.The frequency of Parasitic-nematodes is rising in Dashushan hill.We found the highest frequency rate of parasitic-nematodes during three years.Parasitic-nematodes frequencies were: 42.3%,35.1%,and 58.9% from 2014 to 2016.This indicates the increase in the frequency rate of parasitic-nematode.In the third year,the diversity index of parasitic-nematodes is decreasing,and it is getting worse.3.The parasitic-nematode has a wide range of species.During 2014-2016,we discovered three families of parasitic nematodes: Pratylenchidae,Criconematidae and Tylenchidae.Six genus of nematodes are also found in this study,include Helicotylenchus,Pararotylenchus,Tylenchorhynchus,Xiphinema,Hemicycliophora and Paratrichodorus.4.Four species of Helicotylenchus were identified: H.abunaamai,H.africanus,H.mucronatus and H.pseudorobustus.H.africanus and H.mucronatus were first time reported in China.The diversity index of Helicotylenchus changes a little,however,it has sustainable diversity.