Font Size: a A A

The Influence Of Environment Factors On Community Diversity Of Wheat Aphid Parasitoid And Hyperparasitoid In Zhongning County, Ningxia

Posted on:2016-02-03Degree:MasterType:Thesis
Country:ChinaCandidate:Y J HuFull Text:PDF
GTID:2283330464464233Subject:Agricultural Entomology and Pest Control
Abstract/Summary:PDF Full Text Request
A systematic investigation on wheat aphid and it’s parasitoids in different wheat fields were made by five-point sampling method in Zhongning county of Ningxia,China.The species diversity and spatiotemporal dynamics of dominant species parasitoid communities were analyzed,the relationship between parasitoids and local landscape pattern was researched.The spatial pattern of wheat aphids and it’s parasitoids,as well as, the tracking effect of aphidiidae for wheat aphids was explored.The prediction was conducted with grey catastrophe model by collecting the occurrence of local wheat aphids,which could provide the theoretical foundation and method for the productive process of wheat and the pest population control. The results were showed as followed:1.The community compositions of parasitoid aphids were also analyzed to show the following indexes,namely diversity index(H’),evenness index(J),dominance index(C),richness index(D).The results were showed that as follows:919 parasitoid specimens were collected from wheat fields in Zhongning county,including 21 species in 12 genera 4 superfamilies,7 families.There are 11 parasitoid species and 10 hyperparasitoid species.The dominant species is Aphidius avenae among parasitoids,while the dominant species are Pachyneuron aphidis,Asaphes suspensus and Alloxysta sp. among hyperparasitoids.The diversity index of the parasitoids is higher than that of hyperparasitoids in early May,but the diversity index of the hyperparasitoids begin to increase after mid-May.The highest diversity index of the parasitoids and hyperparasitoids is observed in early June.The several indexes of community meet the functional equation and the fitting curve,and they could visually reflect the changes of indexes as time goes on.2.The population of wheat aphids and parasitoids in different agricultural landscapes were studied and the results showed that the species diversity index,richness index and evenness index of parasitoids in different sample spots were positive correlation,but the variation trend of dominance index was approximately contrary to evenness index. The variation of population changes of Sitobion avenae and Schizaphis graminum in different landscape structure were virtually identical, the population dynamics of parasitoid was virtually identical,but hyperparasitoid was different.The species and numbers of parasitoid and hyperparasitoid had no influence by landscape structure, but the species number of hyperparasitoid had significant influence by habitat area.The interaction of landscape and area had no effect on the species of parasitoids but had significant influence on the number of parasitoids.3.The distribution pallens and temporal dynamics of wheat aphids and it’s parasitoids were simulated with aggregation indices and grey relational degree in different landscape structures.There are 10 kinds of Aphidiidae and 1 kind of Aphelinidae in the local field.The population of cereal aphids(Sitobion avenae、Schizaphis graminum)and Aphidiidae mainly showed aggregation distribution fitted negative binomial distribution.The aggregation distribution index increased along with the increasing of density.The aggregate level of Sitobion avenae is affected remarkably by the complexity of field,but not Schizaphis graminum.the spatial pattern of Aphids changed periodically, from diffusion to assembly.The distribution of the aphid parasitoids illustrated that it can trace4.Sitobion avenae easier than Sitobion avenae.Such aggregation distribution was induced by environmental factors when tested by Blackith’s method,such as climate,growth period and so on.If the respective density of Sitobion avenae.Schizaphis graminum and Aphid parasitoids is more than 5.57,8.26,2.50 per wheat,aggregation depends on the interaction between creature themselves and environment.Aphidius avenae,A.gifuensis and A.sichuanensis for Wheat Aphid populations have significant trace relationships.At the same time Aphidius avenae,A.gifuensis and A.sichuanensis to Sitobion avenae tracking effect is stronger for Schizaphis graminum.5.The catastrophe prediction model of wheat aphid was established based on the observational data of wheat aphids from 1993 to 2003 in Zhongning county by using grey system theory.The double measured accuracy of this model was above 96.80% by residual examination.The model had successful predicted that the heavy year of catastrophe were taken in 2003 and 2015,but there were not the heavy year of catastrophe in 2013 and 2014.The model had provided a reliable control method for the forecast of wheat aphids.
Keywords/Search Tags:parasitoids, species diversity, landscape structure, spatial distribution pattern, temporal dynamics, grey system
PDF Full Text Request
Related items