Studies On Arthropod Community Structures In Tobacco Field

To illustrate the community characters of arthropods in tobacco field of ShandongProvince, using the quantitative characteristic shown from the survey data, by the method ofcommunity ecology, pest and natural enemy communities in tobacco field were studied inTaian City, Shandong Province, China in2009and2012.1. The population dynamics of the main tobacco insect pests and their main enemieswere studied comparatively with the affected factors in2009and2012. The main pestscontained Nesidiocoris tenius, Myzus persicae, Bemisia tabaci and Helicoverpa armigera.Their natural enemies researched were Aphidius gifuensis, ladybirds, spiders and lace wings.By the combined influence of ecological factors, the peaks of population showed differencesin time series. The time of immigration of Myzus persicae was earlier than other pests,Nesidiocoris tenius later. The population of the natural enemies appeared a following relationwith the pests obviously, which meant that they took important combined control effect topests.2. The community of arthropod in tobacco field was made up of sap-sucking pests,leaf-feeding pests and their enemies. There were120species of arthropods, which contained65species of pests and56natural enemies, including4species of hyperparasitoids. Thesap-sucking pests which had the maximum proportion of individual number in the pestcommunity were Nesidiocoris tenius, Myzus persicae, Bemisia tabaci. The lace wings,ladybirds, predacious bugs and spiders in natural enemy community were in higher number.There were more species and individuals in2012compared with the species and individualsin2009.3. The dominant pest species of arthropod community in tobacco field included Bemisiatabaci, Myzus persicae, Nesidiocoris tenius, and the dominant natural species includedAphidius gifuensis, Chrysoperla nipponensis and spiders. The dominances shew differences invarious periods of the two years.4. By using the indexes for describing community characteristics such as abundance,evenness, diversity indexes to analyze the quantitative characteristics of arthropod communitystructure in tobacco field in two years, it was found that the negative correlation existedbetween the ecological dominance and the community diversity and evenness of arthropodcommunity in tobacco field; the fluctuations of diversity indexes in the two years weredifferent, which was caused by the populations with high degree of dominance and differentenvironmental conditions. 5. Through the research of the species abundance distribution of arthropod communitystructure in tobacco field in the two years, the results indicated that the relation between therelative abundance and number of species was in accordance with the log-series distributionmodel, rather than lognormal distribution model.6. The arthropod communities during the years in tobacco field were analyzedquantitatively by multivariate analysis. The temporal community structure was grouped into4continuous stages by using optimal sorting method, and the community characteristics weredescribed based on the climatic and phonological conditions at each stage. The subgroupswere determined at different growth stages of tobacco field through analyzing the communityby principal component analysis and factor analysis. The canonical correlation analysis wereused to analyze the significant correlation between dominant pests and natural enemies, theresult showed that there were significant correlations between the Myzus persicae andAphidius gifuensis, between Helicoverpa armigera and Campoletis chlorideae, and betweenNesidiocoris tenius and spiders.7. According to the inter specific relationships between the pests and natural enemies, thefood web of arthropods in tobacco field was explored and constructed tentatively, and thestructure of the food web was analyzed by the basic theories of food web.