Studies On The Dynamics Of Arthropod Communities And The Relationships Of Pests With Their Natural Enemies In "Yuhualu" Juicy Peach Orchard

The arthropod community in "Yuhualu" juicy peach orchard was investigated inproving ground in Anhui Agriculture University. The dynamics of the arthropodcommunities and interaction of main insect pests with their predatory natural enemiesin2010, as well as2011spring-summer season were systematically studied by somemathematical analysis means such as community analysis, ecological niche, greysystem analysis and aggregation level index. These would provide theory foundationfor IPM for pests in juicy peach orchard.In2010, the number of arthropod in juicy peach orchard were51032, which wereshowed65species belonging to50families,37species of phytophages belonging to29families,19species of predators belonging to14families,9species ofparastitoids-neutralities belonging to7families. The relative dominance of thearthropod community and three sub-communities were phytophaga(0.3423)> totalcommunity(0.3219)> parasitic-neutralities(0.2552)> predators(0.3218). Thediversity index of the total community was highest in5.25. The evenness index ofthe phytophagous sub-communities and the total community were lowest in8.13.Individuals(species, dominance, dominant concentration, Pielou evenness,species richness and diversity index) of arthropod communities were analyzed byprincipal component analysis. In the second principal component, the contribution ofarthropod community, predacious sub-community and phytophagous sub-communitywas92.8119%,92.7294%,88.4006%respectively.The structural traits of total community, phytophagous and predacioussub-community in "Yuhualu" juicy peach orchard of2010year were analyzed byclustering. The results showed that the total community was divided into3clusterswhen D is1.72; the phytophagous community was divided into5clusters when D is1.71; the predacious was divided into4clusters when D is1.42.The clustering result of the optimization partitions in the arthropod totalcommunities in2010could be divided into five stages:4.4-6.8,6.22,7.10,7.26-10.16,10.31-11.15; phytophagous sub-community:4.4-4.24,5.10-6.8,6.22-10.16,10.31-11.15; predacious sub-community:4.4-4.24,5.10-9.15,9.28-10.31,11.15.The relation between diversity index and other ecological indexes in totalcommunities were analyzed by Path analysis in "Yuhualu" juicy peach orchard. Theresults indicated that, Dominance (-0.9088), dominant concentration index (-0.9382)and Pielou evenness (0.7079) were closely related with diversity index. Among them,the Pielou evenness was positively correlated with diversity index.The seasonal and annual variations of population quantities of six kinds of insectpests with their natural enemies were systematical investigated in “Yuhualu” juicypeach orchard. The findings of a paired t-testing demonstrated that the t values of sixmain pest numbers, i.e. Empoasca flavescens, Myzus persicae, Tetranychus viennensis,Cleoporus variabilis and Stephanitis nashi, were, respectively,1.43,0.38,0.86,1.30,2.14,0.44, all were lower than2.16(t0.05value), indicating that no significantdifferences existed. The t value of Harmonia axyridis was2.39>2.16(t0.05value), showing that the difference in numbers was significant between2010and2011, whilstthe t values of other natural enemies all were significantly lower than2.16(t0.05value),revealing that there were also no significant differences. The further analysis indicatedthat the t values of Empoasca flavescens, Stephanitis nashi, Misumenops tricuspidatus,Harmonia axyridis, were, respectively,5.63,76.38,3.28and4.82>3.01(t0.01),indicating that there were significant differences in their numbers in “Yuhualu” juicypeach orchard between the spring-summer season and the autumn season of2010.The t values of Altica sp was2.51>2.16(t0.05value), whereas no significantdifferences existed in the others.The quantity, time and space framework of Myzus persicae, Empoasca flavescens,Tetranychus viennens, Cleoporus variabilis, Stephanitis nash and their predatorynatural enemies in2010spring-summer season and autumn season, as well as2011spring-summer season were systematically studied using grey system analysis,ecological niche analysis and aggregated-intensity index analysis of spatial patterns.The synthetic ranking results indicated that, in2010spring-summer season, the ordersof main natural enemies of Empoasca flavescens were Misumenops tricuspidatus,Chrysopa Sinica and Theridion octomaculatum, whereas the ranks of main naturalenemies of Tetranychus viennensis were Clubiona japonicola, Theridionoctomaculatum and Erigonidium graminicola. In2011spring-summer season, theorders of main natural enemies of Myzus persicae, Empoasca flavescens, Cleoporusvariabilis, Stephanitis nashi and Tetranychus viennensis, were, respectively,Epistrophe balteata, Harmonia axyridis and Misumenops tricuspidatus; Erigonidiumgraminicola, Propylaea japonica and Misumenops tricuspidatus; Erigonidiumgraminicola, Misumenops tricuspidatus and Theridion octomaculatum; Misumenopstricuspidatus, Propylaea japonica and Erigonidium graminicola; Clubiona japonicola,Theridion octomaculatum and Erigonidium graminicola. In2010autumn-winterseason, the ranks of main natural enemies of the Empoasca flavescens and Stephanitisnashi, were, respectively, Chrysopa Sinica, Erigonidium graminicola andMisumenops tricuspidatus; Theridion octomaculatum, Erigonidium graminicola andMisumenops tricuspidatus. The further analyses showed that the average λ values ofEmpoasca flavescens, Stephanitis nashi and Tetranychus viennensis in2010, andMyzus persicae, Cleoporus variabilis, Stephanitis nashi and Tetranychus viennensis inthe spring-summer season of2011all are more than2, and in the four differentdirections of peach tree crown, the λ value of Tetranychus viennensis in the2010spring-summer season, and Empoasca flavescens in the2010autumn-winter season,as well as Cleoporus variabilis in the2011spring-summer season all are also morethan2, suggesting that the gathering cause of the insect pests resulted fromthemselves. However, the λ values of the other insect pests and natural enemies allwere less than2, indicating that their gathering was caused by certain environmentfactors.