Modeling And Analysis Of Wheat Aphid Ecosystems

Wheat aphid populations is the main insect in the wheat growth.The wheat production is reduced by 10% in norm years and 30% in disaster years.Because the aphid populations have the following characteristics,such as stronger reproductive and shorter life cycle,the outbreak happens frequently,which leads to the difficulty of the pest management.It is necessary to control the aphid populations.On the ground of wheat aphid ecosystems,the catastrophe models are established to reveal the ecological mechanism of the outbreak of the aphid populations using the existing data.The main contents are as follows:Part I,on the basis of existing data,firstly,the scatter plots of the state variables and control variables are drawn using the SPSS software to make sure whether the catastrophe of the aphid ecosystem exists and to propose the cusp catastrophe model.Secondly,the model is tested by using regression analysis.Finally,the different regions of the model are determined,that is the stable safe area,the potential hazard area and the stable hazard area,which provides the basis for predicting the outbreak of aphid population.Part II,on the basis of existing data,firstly,the number of rules in the T-S fuzzy model is determined using the cluster analysis method.Secondly,some initial T-S fuzzy models with Gauss Triangle and trapezoid memberships are proposed by ANFIS,in which intrinsic growth rate of aphid population is as the state variable.Thirdly,the model which fits the data better is chosen by error analysis.Finally,the exact T-S models are built using the training processes of ANFIS,and the model simulations are carried out to prove the catastrophe of the model,which reveals the outbreaks of the aphid ecosystems from a new perspective.The study of the paper realizes the combination of the theory and practice.