A delayed epidemic model with stage-structure and pulses for pest management strategy

From a biological pest management standpoint, epidemic diseases models have become important tools in control of pest populations. This paper deals with an impulsive delay epidemic disease model with stage-structure and a general form of the incidence rate concerning pest control strategy, in which the pest population is subdivided into three subgroups: pest eggs, susceptible pests, infectious pests that do not attack crops. Using the discrete dynamical system determined by the stroboscopic map, we obtain the exact periodic susceptible pest-eradication solution of the system and observe that the susceptible pest-eradication periodic solution is globally attractive, provided that the amount of infective pests released periodically is larger than some critical value. When the amount of infective pests released is less than another critical value, the system is shown to be permanent, which implies that the trivial susceptible pest-eradication solution loses its attractivity. Our results indicate that besides the release amount of infective pests, the incidence rate, time delay and impulsive period can have great effects on the dynamics of our system.     

A impulsive infective transmission SI model for pest control

In this paper, we propose a model with impulsive control of epidemics for pest management. By using Floquet's theorem, small‐amplitude perturbation skills and comparison theorem, we show that there exists a globally asymptotically stable susceptible pest‐eradication periodic solution when the release amount of infective pests is larger than some critical value. However, when the amount of infective pests released is less than this critical value, the system is shown to be permanent, which implies that the trivial periodic susceptible pest‐eradication solution loses its stability. Further, the existence of a positive periodic endemic solution and other rich dynamics are also studied by numerical simulation. Therefore, we can use the amount of release of infective pests to control susceptible pests at desirable low levels. Copyright © 2007 John Wiley & Sons, Ltd.     

The onset of positive periodic solutions for a biochemical pest management model

In this paper, the bifurcation of nontrivial periodic solutions for an impulsively perturbed system of ordinary differential equations which models an integrated pest management strategy is studied by means of a fixed point approach. A biological control, consisting in the periodic release of infective pests, and a chemical control, consisting in pesticide spraying, are employed to maintain susceptible pests below an acceptable level. It is assumed that the biological and chemical control act with the same periodicity, but not in the same time. It is then shown that if the constant amount of infective pests released each time reaches a certain threshold value, then the trivial susceptible pest-eradication periodic solution loses its stability, which is transferred to a newly emerging nontrivial periodic solution.     

基于喷洒杀虫剂及释放病虫的脉冲控制害虫模型

基于喷洒杀虫剂及释放病虫的综合控制害虫策略,建立了具有脉冲控制的微分方程模型.利用脉冲微分方程的F loquet理论、比较定理,证明了害虫灭绝周期解的全局渐近稳定性与系统的持久性.     

MODELING INVASION OF PESTS RESISTANT TO Bt TOXINS PRODUCED BY GENETICALLY MODIFIED PLANTS: RECESSIVE VS. DOMINANT INVADERS

ABSTRACT. There is a growing public concern about the ecological and evolutionary consequence of the use of genetically modified organisms. We study the impact of Bt resistant pests on genetically modified Bt crops and compare exposure of Bt plants to recessive and dominant Bt resistant invaders. To simulate pest invasion we develop a conceptual reaction‐diffusion model of the Bt crop Bt susceptible insects Bt resistant insects for both the recessive and dominant pests. We show by means of computer simulations that there is a key parameter which we define as the growth number that characterizes the insects' fitness. We also show that the Bt resistant insects' invasion can lead to inhomogeneity in plant and insect spatial distributions. The plant and insect spatial patterns resulting from the Bt resistant insects' invasion are found to be dependent on the duration of the Bt resistant insect reproduction period. We compare averaged plant biomass resulting from the invasion of the dominant insects with the averaged plant biomass resulting from the invasion of the recessive insects. As a result, we show that in contrast to the recessive insects, the dominant ones initiate destruction of the plant population if the inflow of Bt susceptible insects is more than a critical value. In this case the plant biomass decays to zero. Otherwise, the plant biomass under the invasion of both the dominant and recessive insects depends on the duration of the insect reproduction period. We conclude that under invasion of dominant Bt resistant pests, the refuge strategy which has received wide acceptance in agricultural practice may not be scientifically sound practice.     

Modelling approach for biological control of insect pest by releasing infected pest

Models of biological control have a long history of theoretical development that have focused on the interactions between a predator and a prey. Here we have extended the classical epidemic model to include a continuous and impulsive pest control strategies by releasing the infected pests bred in laboratory. For the continuous model, the results imply that the susceptible pest goes to extinct if the threshold condition R₀ < 1. While R₀ > 1, the positive equilibrium of continuous model is globally asymptotically stable. Similarly, the threshold condition which guarantees the global stability of the susceptible pest-eradication periodic solution is obtained for the model with impulsive control strategy. Consequently, based on the results obtained in this paper, the control strategies which maintain the pests below an acceptably low level are discussed by controlling the release rate and impulsive period. Finally, the biological implications of the results and the efficiency of two control strategies are also discussed.     

An impulsively controlled predator–pest model with disease in the pest

In this paper, we consider an integrated pest management model with disease in the pest and a stage structure for its natural predator, which is subject to impulsive and periodic controls. A nonlinear incidence rate expressed in an abstract form, is used to describe the propagation of the disease, which is spread through the periodic release of infective pests, the functional response of the mature predator also being given in an abstract, unspecified form. Sufficient conditions for the local and global stability of the susceptible pest-eradication periodic solution are found by means of Floquet theory and comparison methods, the permanence of the system also being discussed. These stability conditions are shown to be biologically significant, being reformulated as balance conditions for the susceptible pest class.     

Eco-epidemiology model with age structure and prey-dependent consumption for pest management

In this paper, a prey-dependent consumption predator–prey (natural enemy-pest) model with age structure for the predators and infectious disease in the prey, is considered. Infectious pests, immature natural enemies and mature natural enemies are released impulsively. By using Floquet’s theorem, small-amplitude perturbation skills and comparison theorem, we obtain both the sufficient conditions for the global asymptotical stability of the susceptible pest-eradication periodic solution and the permanence of the system. The results provide a reliable theoretical tactics for pest management.     

Dynamics on a pest management SI model with control strategies of different frequencies

Based on spraying pesticide and introducing infected pest and natural enemy for pest control, an SI ecological epidemic model with different frequencies of pesticide applications and infected pests and natural enemy releases is proposed and studied. With spraying either more or less frequently than the releases, the threshold condition of existence and global attractiveness of susceptible pest extinction periodic solution is obtained. We investigate the effects of the pest control tactics on the threshold conditions. We also show that the system has rich dynamics including period-doubling bifurcations and chaos as the release period increases, which implies that the presence of impulsive intervention makes the dynamic behavior more complex. Finally, to see how the pesticide applications can be reduced, we develop a model involving periodic releases of natural enemies with chemical control applied only when the densities of the pest reaches the given Economic Threshold. It indicates that the hybrid method is the most effective method to control pest and the frequency of pesticide applications largely depends on the initial densities and the control tactics.     

空竭服务单重休假的MMPP(2)/G/1植物病虫害防治系统的效能

研究了空竭服务、单重休假的MMPP(2)/G/1植物病虫害防治系统模型的效能,并利用排队论及随机运筹学的有关知识,在模型的条件与假设下给出了模型的平稳条件、平均忙期长度,以及在忙期内防治完的害虫数等性能指标.     

森林病虫害模型的数值模拟

讨论森林病虫害的离散模型.根据森林病虫害传播的特征,针对各分块区域之间已感病树不互相转移的情况,建立差分方程模型;讨论系统的平衡点,并对无病平衡点和地方病平衡点进行稳定性分析,得到地方病平衡点稳定的充分条件;用Matlab进行多种情况的数值模拟,验证了理论结果.     

具非线性传染率与生物化学控制的害虫管理S-I模型

讨论了具有非线性传染率与脉冲控制的害虫管理S-I传染病模型,此模型考虑的是脉冲投放病虫和喷洒农药.不但得到了系统的所有解的一致完全有界,而且得到了害虫灭绝的边界周期解的全局渐进稳定和系统的一致持久的条件.为实际的害虫管理提供了可靠的理论依据.     

Impulsive control strategy of a pest management SI model with nonlinear incidence rate

In this work, we consider a pest management SI model with impulsive release of infective pests and spraying pesticides. We prove that all solutions of the investigated system are uniformly ultimately bounded and the pest-extinction periodic solution is globally asymptotically stable when some condition is satisfied. We also obtain the permanent condition of the system. It is concluded that the approach of combining impulsive release of infective pests with impulsive spraying pesticides provides reliable tactic basis for the practical pest management.     

Geometrical analysis of a pest management model in food-limited environments with nonlinear impulsive state feedback control

In this paper, a nonlinear impulsive state feedback control system is proposed to model an integrated pest management in food-limited environments. In the system, impulsive feedback control measures are implemented to control pests on the basis of the quantitative state of pests. Mathematically, an intuitive geometric analysis is used to indicate the existence of periodic solutions. The stability of periodic solutions is investigated by using Analogue of Poincar\''{e} Criterion. At last, numerical simulations are given to verify the theoretical analysis.     

阻滞增长模型支持下对益虫和害虫数量关系及农药影响的分析

研究了在自然状态和喷洒农药情况下益虫和害虫数量的发展趋势.基于logistic模型并加以改进建模,通过分析微分方程平衡点的稳定性,分别得出了自然状态下益虫和害虫的数量发展规律.在此基础上,进而建立了农药影响的模型并进行了计算机仿真,仿真结果证明了新模型的合理性和适用性,解决了Lotka—Volterra模型存在的问题.另外,该仿真程序本身可以作为应用程序用于实际的农田管理.     

MATHEMATICAL STUDY OF A PEST CONTROL MODEL INCORPORATING STERILE INSECT TECHNIQUE

The menace of insect pests is a topic of major concern throughout the world. Chemical pesticides are conventionally used to control these insect pests. However, the adverse effects of these synthetic pesticides, such as high toxicity from residues in food, contamination of water and the environment resulting in human health hazard and resistance of the pest to the pesticides have necessitated development of some nonconventional approaches of biological pest control. In this research, we have focused on a mathematical model of biological pest control using the sterile insect release technique. Unlike most of the existing modeling studies in this field that mainly deal with the pest population only, we have incorporated the crop population as a distinct dynamical equation together with the fertile and sterile insect pests. Local stability analysis is performed around the crop and fertile insect free axial equilibrium, the fertile‐insect‐free boundary equilibrium, the crop‐free boundary equilibrium and the equilibrium point of coexistence. From the study we have derived a number of thresholds for the SIRR (the main parameter for our study) that cause existence and or extinction of the crop population as well as the fertile insect pests. A global study of the model system using comparison arguments revealed existence of a global attractor for the system. Numerical simulations are done to support and augment analytical results.     

基于元胞自动机的植物病虫害传播的计算机仿真

利用元胞自动机方法建立植物病虫害传播的数学模型。在此基础上,分别对两种不同病虫害来源的情况进行仿真。仿真结果表明,在参数给定的情况下,无论病虫来源于自身还是外界,植物病虫害的传播均在一定时间后达到稳定状态,不同状态元胞占有率相近;相同参数下,同病虫来源于自身相比,植物病虫从外界入侵时,植物被感染的变化率较低,病虫害传播路径较有规律,有利于病虫害源的确定和病虫害的治理。     

Nonlinear incidence rate of a pest management SI model with impulsive control strategy

In this work, we consider a pest management SI model with concerns about releasing of infective pests and spraying pesticides at different fixed moments. We prove that all solutions the investigated system are uniformly ultimately bounded, and there exists globally asymptotic stable pest‐extinction boundary periodic solution when certain condition is satisfied. Furthermore, the permanent condition of the system is also obtained. It is concluded that the approach, which combines releasing infective pests with spraying pesticides in different fixed moments, provides reliable tactic basis for the practical pest management. Copyright © 2009 John Wiley & Sons, Ltd.     

Mathematical modelling to control a pest population by infected pests

In this paper, we formulate and investigate the pest control models in accordance with the mathematical theory of epidemiology. We assume that the release of infected pests is continuous and impulsive, respectively. Therefore, our models are the ordinary differential equations and the impulsive differential equations. We study the global stability of the equilibria of the ordinary differential equations. The permanence of the impulsive differential equations is proved. By means of numerical simulation, we obtain the critical values of the control variable under different methods of release of infected pests. Thus, we provide a mathematical evidence in the management of an epidemic controlling a pest.     

Pest management of two non-interacting pests in presence of common predator

The paper considers two mutually independent pests in presence of their common predator and discusses their control biologically by release of additional predators and chemically by using non-selective non-residual pesticide. It also verifies the results by special choice of parameters.