| Based on the thorough investigation, the dynamics of the arthropod communities in pomegranate fields and interaction of main insects with its natural enemies were studied by meas of community analysis, path analysis, greysystematic analysis, ecological niche analysis, and aggregation level index. These provided theory foudation for IPM.In 2008, the arthropod community in pomegranate fields was divided into several sub-communities, which were phytophages, predators, parastitoids and neutralities. The results were showed 82 species of arthropod belonging to 56 famlies, and relative abundance of the arthropod community were 0.5256. The relative abundance of phytophages sub-communities were 0.7313;predators were 0.2081;parastitoids and neutralities were 0.3531. The dominant concentration of the arthropod community were 0.2893, phytophages(0.5447)> parastitoids and neutralities(0.2433)> predators(0.1500), then the arthropod community were highest: the diversity index were in 7.17,evenness index were in 3.27. In 2009 spring-summer season, the arthropod community in pomegranate fields were 34 species belonging to 56 famlies. Then the arthropod community were highest: the diversity index were in 5.23,evenness index were in 4.1.The relationship between diversity indexes and other ecological indexes in every communities were analyzed by Path analysis, the most relative with evenness (0.9796), which showed the higher evenness, the higher diversity indexes .Total community and phytophage, predacious sub-community in 2008 were analyzed by clustering. The result: The total community was divided into 4 clusters when d is 1.68; the phytophage sub-community was divided into 5 clusters when d is 1.46; the predacious was divided into 5 clusters when d is 1.83. The clustering result of the optimization partitions in the arthropod total communities in 2008 was 3.27, 4.10-5.8, 5.22-9.11, 9.25-11.6 ; phytophage sub-community: 4.10-4.24, 5.8-5.22, 6.5-9.11, 9.25-11.6; predacious sub-community: 3.27, 4.10-5.8, 5.22-7.17, 7.31-11.6.Diversity indexes (individuls, species, dominant concentrtion, pielou evenness, dominance, speicies richness and hill divesity) of arthropod communities were analyzed by principal component analtsis , in the second principal component, the contribution of arthropod community, phytophagous sub-community and predacious sub-community was 93.2203%,94.7354%,89.0818% respectively.Studied on the relationships of the number, time and space of the major pests and their natural enemies using the correlation analysis, ecological niche analysis and spatial pattern of aggregation intensity index analysis, the result indicated that the order of the main natural enemies of Aphis gossypii was Harmonia axyridis, Chrysopa sinica and Theridion octomaculatum; Cnidocampa flavescens: Clubiona japonicola, Misumenops tricuspidatus, Erigonidium graminicolum; Empoasca flavescens : C. japonicola, Tetragnatha maxillosa and T. octomaculatum; Thosea sinensis: Tetragnatha maxillosa, T. octomaculatum, C. japonicola; Cryptothelea minuscula: M. tricuspidatus, C. japonicola, H. axyridis. Gathering averages of A. gossypii of major five pests were more than 2 due to the aggregation nature of the insect, while those of C. flavescens, E. flavescens, T. sinensis and C. minuscula was less than 2 due to the certain environmental factors.The synthetic ranking result indicated that the order of main enemies of A. gossypic in spring-summer season was H. axyridis, T. octomaculatum, E. fallaeids,P. japonica and M. tricuspidatus in 2008; The order of main natural enemies of A. gossypic in spring-summer season was H. axyridis, E. fallaeids,C. japonicola, P. japonica and C. sinica in 2009. The order of main natural enemies was H. axyridis, E. fallaeids and P. japonica in the two years. The order of main natural enemies of A. gossypic in autumn season was C. sinica, H. axyridis, C. japonicola, M. tricuspidatus and E. graminicola. The numbers of A. gossypic between the two years in pomegranate orchard was compared using T-test (t= 1.1369, tt0.05)between the two yesrs in pomegranate orchard, there were significant differences in the numbers of T. octomaculatum (t=3.0858, t>t0.05)between autumn season in 2008 and spring-summer season in 2009, the rest were no significant difference. The numbers of the rest natural enemies were no significant difference. The numbers of A. gossypic and its predatory natural enemies were no significant difference among spring-summer season in the two years and in autumn season in 2009. |
