Studies On The Dynamics Of The Arthropod Communities In Maize Field In Guanzhong District

Based on the parameters (Shaannon-weiner diversity index H', specie (abandunce S, Pielou evenness index J, total individuals N and dominant concentration C), of the phytophagy arthropods, Predatism arthropods, Parasitism arthropods and Neutral arthropods sub-communities at the level of the total community and sub-community in the whole stages of maize in 4 different cultivated time were analysised and studied. Furthermore, the path analysis was used to study the diversity H' and constant between the whole community and sub-communities with the parameters above.Based on the experiments and investigations conducted both in the whole stage of maize fields and in the laboratory from April in 2001 to October in 2002,the total collection of arthropods produced 173 taxa, belonging to 86 families, of which, there were 71 taxa, 36 families of phytophagy arthropods; while predator arthropods were 58 taxa, 40 families; parasitoid arthropods as 27 taxa, 12 families; and all the neutral insects were 17 taxa, 11 families. Their proportion in the total individuals in the whole stages of the maize was 59.6518-75.4373%, 17.0013-28.2968%, 3.5458-5.5413%, and 5.2726-9.4698% respectively.At the early and late stages of the maize growth, the number of different insects was quite little, yet went up to its peak during the important period of maize (the big bell-mouthed period). The aphids were the dominant species during the total development stage of maize; while the most important insects as Ostrinia furnacalis (Guenee) and Proceras venosatum (Walker) belonged to the rare species and only appeared at the final-period. The quantity of neutral insects was quite low in all the seasons of the maize, and had a big fluctuation in the end period of maize.In all different maize fields in Guanzhong plain Shaanxi Province, the number of natural enemy sub-communities in maize was quite abundant, and the predators sub-communities was the main natural enemies, followed by the parasitism arthropods sub-community. Moreover, the diversity and constant of predators were higher than the parasitism. The dominant species of predators was Harmonia axyridis (Pallas) N Propyeajaponica (Thunberg). and Erigonidium graminicolum (Sundevall),while the dominant species of the Parasitism was Aphididae sp.The changes of the abundance of total individuals and natural enemies in maize cultivated in the first ten-day of June, were higher than other cultivated time which was in April, in May and in the second ten-day of June. Besides the higher diversity and stabilization.The analysis displayed that the parameters (Shaannon-weiner diversity index H', species S, Pielou evenness index J, total individuals N and dominant concentration C) of the whole community had little correlation with the cultivate time of maize, while to the adverse, these parameters of sub-community had closely relationship with the cultivate time.The Shaannon-weiner diversity index H' of the different arthropod community was mainly influenced by the dominant concentration(C) and Pielou evenness (J), by the analysis of path analysis. While to the subcommnities, the main factors were the dominant concentration (C) and speice abundance (S).The major effect factors to the Shaannon-weiner diversity index H'of different communities and subcommunities correspondent to the communities were the same, which was the H' of the phytophagy arthropod community.