Studies On The Population Distribution And Dynamics Of Grasshopper In Sunan,CanSu Province

Systematically investigation for characteristic of grasshopper population and communitywas carried on the area of Huangcheng in SuNan,Gansu province.The composition ofcompound grasshopper population and it，s occurence dynamic were researched.The spatialdistribution of Oedaleus decorus asiaticus B.-Bienko. was surveyed and analyzed.Theresponse for the ecological effects of grasshopper community form vegetationcommunityandthe grasshopper competition in intraspecific and interspecific crossing were discussed.Theresults are as follows:1The diversity of grasshoppers,the occurence regular and population spatialdistribution of Oedaleus decorus asiaticus B.-BienkoAccording to the investigation,eighteen kinds of grasshopper which belong to twelvefamilies and seven subfamilies were found in experimental site form2010to2011.InTemperature Steppe, the Chorthippus fallax (Zub.) was dominant specie;In Steppe Desert,theGomphocerus licenti (Chang) and Pararcyptera microptera meridionalis (Ikonn.)weredominant species;In Mountain Meadow, the Euchorthippus yungningensis Cheng et Tu wasdominant specie.The grasshopper occurrence spike was in between middle of july and middleofaugust.The earlist occurrence appeared in Mountain Meadow,and the latest occurrenceappeared in Pasture-Agriculture Ecotone.The results showed that the Oedaleus decorusasiaticus B.-Bienko population spatial distribution could be divided into tow kinds oftypes.The initial stage of hatching and the last stage of adult are the particular stage,the spatialdistribution belonged to an aggregated distribution.In the mixed occurring stage of nymph ofthree to five instars and the stage of adule,it belonged to an uniform distribution.In the courseof hatching and spawning,it also pertained to aggregated distribution.2The response for the ecological effects of grasshopper community from vegetationcommunityThe complicated relationship was existed in between grasshopper community andvegetation community. The results of canonical correlation analysis (CCA) showed that infirst and second group of canonical variable,each group has significantly positive correlationbetween characteristic factors of grasshopper community and plant community(P＜0.01).Infirst canonical variable group:the vegetation community has intimate relationship with evenness degree、dominance indexs of cyperaceae plants and grass plants、vegetationcoverage.The grasshopper community has intimate relationship with populationcharacteristics of Angaracris rhodopa (F.-W.)、Pararcyptera microptera meridionalis (Ikonn.)、Oedaleus decorus asiaticus B.-Bienko; In second canonical variable group: the vegetationcommunity has intimate relationship with evenness degree and dominance of Cyperaceaeplants, and the grasshopper community has intimate relationship with populationcharacteristics of Chorthippus fallax (Zub.) and Myrmeleotettix palpalis (Zub.).Principal component analysis (PCA) revealed the contribution of the first (PC1)、thesecond(PC2)、the third (PC3)、the forth (PC4) principal components as43.01%、21.65%、13.5%、9.87%.PC1regards as comprehensive factors of relevance between dominance ofcyperaceae vegetation and grasshopper population characteristics of Chorthippus albonemusCheng et Tu;PC2regards as comprehensive factors of relevance between vegetation coverageand grasshopper population characteristics of Filchnerella beicki Ramme and Bryodemamiramae miramae B.-Bienko;sPC3regards as comprehensive factors of relevance betweenvertical structure of vegetation and grasshopper population characteristics of Euchorthippusyungningensis Cheng et Tu; PC1regards as comprehensive factors of relevance betweendominance of leguminosae and compositae plants and grasshopper population characteristicsof Filchnerella beicki Ramme and Bryodema miramae miramae B.-Bienko.Principal component analysis ordination arranged samples into five groups.Strengthenpreventive measures to control the risk of pest outbreaks,with occurrence and the number ofgrasshopper had rised in group one.Pontential conditions for grasshopper explosion existed ingroup four,prevention techniques should be strengthen.3The grasshopper competition in intraspecific and interspecific crossingThe grasshopper competition in intraspecific and interspecific crossing was strengthenedas density increased.The competition intense at initial density of12/0.25m2,the individualdeaths rised sharply.Competition effect of three kinds of grasshopper in differentcombinations made single species reduce it，s quantity to accommodate living environment.