Studies On The Dynamics Of Arthropod Communities And The Relationships Of Pests With Their Natural Enemies In "518" Nectarine Orchard

The dynamics of the arthropod communities and interaction of main insect pests withtheir predatory natural enemies in2009spring-summer season and autumn season, as wellas2010spring-summer season of “518” nectarine orchard were systematically studied bysome mathematical analysis means such as community analysis, grey system analysis andecological niche analysis. These provided theory foudation for integrated pestmanagement.In2009, the results were showed73species of arthropod belonging to51families,and relative dominance of the arthropod community was0.4679. The relative dominanceof three sub-communities were phytophaga（0.4905）> parasitic-neutralities（0.3473）>predators（0.2843）. The dominant concentration of the arthropod community was0.3763,phytophaga（0.4131）> parasitic-neutralities（0.2743）> predators（0.2150）,then thearthropod community were highest: the diversity index and evenness index were all in8.5.Species (individuls, dominant concentrtion, dominance, diversity index, pielouevenness and species richness) of arthropod communities were analyzed by principalcomponent analysis. In the second principal component, the contribution of arthropodcommunity, phytophagous sub-community and predacious sub-community was95.2924%,93.6361%,82.3200%respectively.Total community and phytophagous, predacious sub-community in “518” nectarineorchard of2009year were analyzed by clustering. The total community was divided into4clusters when d was1.64; the phytophagous sub-community was divided into5clusterswhen d is1.59; the predacious sub-community was divided into5clusters when d is1.68.The clustering result of the optimization partitions in the arthropod total communitiesin2009was4.1-4.10,4.25-6.4,6.18-7.17,8.5-10.30; phytophagous sub-community:4.1-4.10,4.25-6.4,6.18-7.17,8.5-10.30; predacious sub-community:4.1-4.25,5.5-8.5,8.23-9.25,10.15-10.30.The relations between diversity indexes and other ecological indexes were studiedusing Path analysis in every communities, The synthetic ranking results indicated that, intotal community pielou evenness was positively correlated with diversity index and otherecological indexes had indirect effects on diversity index through it;in phytophagoussub-community dominant concentrtion had positively correlated with diversity indexmostly; the predacious sub-community was similar to the total community. The quantity, time and space framework of Myzus persicae, Empoasca flavescens,Tetranychus viennens, Cleoporus variabilis and their predatory natural enemies in2009spring-summer season and autumn season, as well as2010spring-summer season weresystematically studied using grey system analysis, ecological niche analysis andaggregated-intensity index analysis of spatial patterns. The synthetic ranking resultsindicated that, in2009spring-summer season, the orders of main natural enemies ofEmpoasca flavescens, Myzus persicae, Tetranychus viennensis, and Cleoporus variabiliswere, respectively, Harmonia axyridis, Theridion octomaculatum and Propylaea japonica;Chrysopa Sinica, Clubiona japonicola and Harmonia axyridis; Erigonidium graminicola,Misumenops tricuspidatus and Propylaea japonica; and Erigonidium graminicola,Theridion octomaculatum and Propylaea japonica. In2010spring-summer season, theorders of main natural enemies of the four pests were, respectively, Propylaea japonica,Theridion octomaculatum and Erigonidium graminicola; Chrysopa Sinica, Epistrophebalteata and Clubiona japonicola; Theridion octomaculatum, Erigonidium graminicolaand Propylaea japonica; and Erigonidium graminicola, Theridion octomaculatum andHarmonia axyridis. In2009autumn season, the orders of main natural enemies of the fourpests were, respectively, Propylaea japonica, Erigonidium graminicola and Harmoniaaxyridis; Theridion octomaculatum, Harmonia axyridis and Clubiona japonicola;Misumenops tricuspidatus, Propylaea japonica and Theridion octomaculatum; andErigonidium graminicola, Theridion octomaculatum and Misumenops tricuspidatus. Inaddition, our results also showed that the λ values of gathering average of all four insectpests, i.e. Empoasca flavescens, Myzus persicae, Tetranychus viennensis, and Cleoporusvariabilis, were greater than two, indicating that the aggregation of insect pest was causedby itself. The λ values of gathering average of some natural enemies, i.e. Harmoniaaxyridis and Chrysopa Sinica in May5,2009as well as Erigonidium graminicola in June18,2009, were also greater than two. However, the λ values of gathering average of mostnatural enemies were less than two, implying that the aggregation of most natural enemieswas caused by different environmental factors. These above results might provide animportant foundation for further protecting natural enemies and optimizing controlstrategies of the four major insect pests in peach orchard.