Study On Dynamic Analysis Of Huanglongbing Models Based On Vector Resistance And Preference

Citrus Huanglongbing is known as "citrus cancer",which has caused devastating damage to citrus industry.It is a great concern for many citrus growers and the agricultural departments to control the citrus greening scientifically and effectively.In this paper,several dynamic models are proposed,which the grafting infection,resistance,preference and diffusion are taken into consideration in the spread and control of citrus Huanglongbing.The dynamic properties of the model are analyzed,and the effects of resistance and preference on the transmission of the disease are discussed.The details are as follows:In Chapter 1,the research background and significance of citrus greening disease are introduced.The pest control under the development of resistance and preference of vector at home and abroad based on the topic of this paper.Finally,the main structure arrangement and innovation points of the paper are briefly listed.In Chapter 2,a control dynamical model of citrus Huanglongbing with grafting infection and resistance is established,the disease-free equilibrium and the basic reproduction number R0 is calculated,the local stability of disease-free equilibrium and the global stability without considering grafting infection are analyzed,and the persistence of the disease is proved.To assess the risk of transmission of Huanglongbing,the global sensitivity analysis of the basic reproduction number R0 with respect to the model parameters is analyzed.Then the optimal strategy to control the spread of citrus Huanglongbing is obtained and the uniqueness of the optimal control solution is demonstrated by introducing two time-varying control measures including insecticides spraying and infected trees removal determined from sensitivity analysis into the HLB system.Finally,analytical and numerical findings show that the comprehensive control strategy is the optimal control strategy,and illustrate that both resistance and grafting infection are not conducive to disease control.In Chapter 3,two dynamic models of citrus Huanglongbing are proposed based on the preference and diffusion of citrus psyllid.The first model is a single-patch model of citrus Huanglongbing with preference,the basic reproduction number of the model is calculated,dynamic properties of the single-patch model including existence and local stability of the disease-free equilibrium are analyzed,and through sensitivity analysis,the parameters which have great influence on the basic reproduction number are obtained.The numerical simulation are carried out to illustrate that the preference of psyllid is not conducive to the prevention of disease.Considering the diffusion of citrus psyllid between two patches,a two-patch dispersal model of citrus Huanglongbing with preference is formulated in this chapter.The global basic reproduction number of the dispersal model is given,and the global stability of disease-free equilibrium is proved under certain conditions.Finally,the numerical simulation results show that the influence of preference and diffusion of psyllid on disease transmission between two patches.In Chapter 4,the main research results of this paper are summarized,and the future research work is proposed.