Complexity

Volume 2017 (2017), Article ID 1950970, 15 pages

https://doi.org/10.1155/2017/1950970

## Extinction and Persistence in Mean of a Novel Delay Impulsive Stochastic Infected Predator-Prey System with Jumps

^{1}College of Mathematics and Systems Science, Shandong University of Science and Technology, Qingdao 266590, China^{2}State Key Laboratory of Mining Disaster Prevention and Control Co-founded by Shandong Province and the Ministry of Science and Technology, Shandong University of Science and Technology, Qingdao 266590, China^{3}Key Laboratory of Jiangxi Province for Numerical Simulation and Emulation Techniques, Gannan Normal University, Ganzhou 341000, China

Correspondence should be addressed to Xinzhu Meng

Received 25 March 2017; Revised 24 April 2017; Accepted 4 May 2017; Published 20 June 2017

Academic Editor: Fathalla A. Rihan

Copyright © 2017 Guodong Liu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

#### Abstract

In this paper, we explore an impulsive stochastic infected predator-prey system with Lévy jumps and delays. The main aim of this paper is to investigate the effects of time delays and impulse stochastic interference on dynamics of the predator-prey model. First, we prove some properties of the subsystem of the system. Second, in view of comparison theorem and limit superior theory, we obtain the sufficient conditions for the extinction of this system. Furthermore, persistence in mean of the system is also investigated by using the theory of impulsive stochastic differential equations (ISDE) and delay differential equations (DDE). Finally, we carry out some simulations to verify our main results and explain the biological implications.

#### 1. Introduction

With the development of the economy, environmental pollution is caused by various industries and other activities of human, which has been one of the most important social problems in the world today. Many species have gone extinct due to the toxicant in the environment. Therefore, controlling the environmental pollution has been the important topics around the world. There are many researchers which have investigated the pollution models in recent years [1–3]. In addition, a lot of animal populations suffer from infectious disease, so some scholars investigated the predator-prey systems with diseases [4–8]. For example, a deterministic predator-prey model with infected predator in an impulsive polluted environment is described by the following equation:where , , , , , is the density of the prey at time , and and represent the density of susceptible predator and infected predator at time , respectively. and stand for the concentrations of the toxicant in the organism and the environment at time , respectively. are dose-response parameter to the toxicant. stands for the intrinsic growth rate of the prey. denote the death rates of and , respectively. is the infection rate. are density-dependent coefficients, and and represent predation rate and ingestion rate, respectively. are environmental toxicant uptake rates, denote organismal net depuration rates, represent organismal net ingestion rates, is the loss rate of toxicant from environment, and denotes the amount of pulsed input concentration of the toxicant at every time. The above parameters are all positive constants. Next, we propose a new mathematical model by taking more factors into account based on model (1).

In the natural world, time delay often occurs in almost every situation. Thus it is significant to take time delay into consideration [9–14]. As we know, deterministic model is not enough to describe the species activities. Sometimes, the species activities may be disturbed by environmental noises. May [15] revealed that the birth rates, death rates, carrying capacities, competition coefficients, and other parameters involved in the system should exhibit random fluctuation to a greater or lesser extent. Hence some parameters should be stochastic [16–26]. First, we assume that the intrinsic growth rate and the death rates of species are disturbed by white noise, then and can be replaced bywhere are standard Brownian motions and are the intensities of . are mutually independent defined on a complete probability space .

Furthermore, populations may suffer from sudden environmental fluctuations, such as floods and earthquakes, which cannot be described by Brownian motions. To explain these phenomena, introducing a jump process into the underlying population dynamics is one of the important methods. Thus, there are many scholars introduce Lévy jumps into the population system [27–31]. Taking all above influences into consideration, we focus on the infected stochastic predator-prey system with Lévy jumps and delays in a polluted environmentwhere , , and stand for the left limits of , , and , respectively. denotes a Poisson counting measure with characteristic measure which defines a measurable bounded subset of with and , and is bounded and continuous with respect to and is -measurable, and (see [27–30]). Moreover, are independent of , are death rates of species, and represent the time delay. Other parameters are defined as system (1).

The rest of this paper is arranged as follows. Section 2 introduces some lemmas which will be used in our main results. In Section 3, we show the main results. We examine the extinction of system (3) in Section 3.1; in Section 3.2 we also prove the permanence in mean of this system. Finally, we present some simulations and conclusions in Section 4.

#### 2. Preliminary Results

Throughout the paper, we assume that , , , and are continuous at and is left continuous at and . Moreover, let be a complete probability space with a filtration satisfying the common conditions (i.e., it is increasing and right continuous while contains all -null sets).

For the sake of convenience, we introduce some notions and some lemmas which will be used for the main results. We definewhere is a bounded continuous function on .

Then we show some basic properties of the subsystem of system (3)

Lemma 1 (see [3]). *System (5) has a unique positive -periodic solution which is globally asymptotical stable. Furthermore, if and , then and for all , where for , , and .*

It can be obtained from a simple calculation that Since is a periodic function, then we getThus we have

From Lemma 1, we know that the long time dynamical behaviors of system (3) can be replaced by the dynamical behaviors of the following limiting system:

Now we give an assumption which will be used in the following proof.

*Assumption 2. *There exist constants such that

Lemma 3. *For any given initial value , there is a unique solution of (10) on and the solution will remain in with probability 1.*

*Proof. *This proof is the same as Theorem in [11] by defining where Thus, we omit it here.

The stochastic comparison theorem and limit superior and limit inferior theory are given as follows.

Lemma 4 (see [27]). *Suppose that .**(i) If there exist three positive constants , , and such thatfor all , where and are constants, then**(ii) If there exist three positive constants , , and such thatfor all , then *

First, we explore the following auxiliary system:

Lemma 5. *For system (17), let be the solution of this system with initial value .**(i) If , then **(ii) If , when , then**(iii) If , , when , then**(iv) If , when , then*

*Proof. *Applying Itô’s formula to system (17) leads toIntegrating both sides of (22), we haveThen we can obtain*Case (i)*. From Lemma 4 and (24), if , then we have Obviously, we find*Case (ii)*. By Lemma 4, it is derived from (24) and conditions thatSince then we obtainUsing Assumption 2 and the strong law of large numbers for local martingales, one hasThen, substituting (31) into (24) yieldsSincethen we have that, for any , there exists such thatCombining (25) with (36) yieldsFrom Lemma 4 and conditions, we have Obviously, we have *Case (iii)*. By (25), we obtainIt can infer from (37), (40), and Lemma 4 that Since is an arbitrary number, then we get Combining this equality with (25) leads toSimilar to (34) and (35), we have that, for any , there exists such thatNote that , so we have *Case (iv)*. By (26), we getWhen , from (44) and (46), using Lemma 4 results inSince is an arbitrary number, then we can obtain Combining this equality with (26) leads toThis completes the proof of Lemma 1.

#### 3. Main Results

##### 3.1. Extinction

Now we are going to show our main results. By Lemma 5, we can get the extinction of system (10).

Theorem 6. *For system (10), let be the solution of this system with initial value .**(i) If , then **(ii) If , when , then**(iii) If , , when , then *

*Proof. *By stochastic comparison theorem, we haveBy (34), we deriveIn the same way, we can verify thatIt follows from (33), (43), and (49) thatApplying Itô’s formula to system (10) leads toThen we can obtainComputing (60) × + (61) × leads towhere is given in Appendix.*Case (i)*. By Lemma 5, we know that , if . From (53), we have Obviously, we get *Case (ii)*. By Lemma 5, we know that , if and . From (53), we have Then we obtain By using (60) and Lemma 4, we can prove *Case (iii)*. Similarly, by Lemma 5, we get that , if , , and . By (53), we obtain Combining Lemma 4 with (56) and (63), we get From (60), we haveThen we infer from Lemma 4 that By (61), we get From Lemma 4, we obtain By (60), we have