IG Prey Research Articles

Dipteran Prey Vulnerability in Intraguild Predation (IGP) System Involving Heteropteran Predators: Density and Habitat Effects

(1) Background: The effects of density and the habitat conditions on the prey vulnerability in the Intraguild Predation (IGP) system were evaluated using the water bug D. rusticus as the top predator. (2) Methods: Using two different density levels (low or high) of the dipteran prey (mosquito and chironomid), the IGP system was set with A. bouvieri as the IG prey. (3) Results: The prey vulnerability was reduced in complex habitat conditions, irrespective of the prey and predator density levels and the prey identity. Correspondingly, the IG prey vulnerability was higher in the low shared prey density and complex habitat. The IG prey consumption by the top predator was higher with the mosquito as shared prey than chironomid as shared prey. Observations on the prey consumption indicated that the consumption of both the chironomid and the mosquito prey dwindled with the time for all combinations of the prey density and the habitat conditions. On a comparative scale, the prey clearance rates were higher for mosquitoes in contrast to the chironomid larvae as shared prey. (4) Conclusions: Apparently, a complex set of interactions involving the habitat conditions, top predator and the prey determines mosquito prey vulnerability against the water bug. Such interactions provide evidence for the coexistence of the mosquito larvae along with multiple predators in the wetland ecosystem.

Influence of habitat complexity on the prey mortality in IGP system involving insect predators (Heteroptera) and prey (Diptera): Implications in biological control.

Intraguild predation (IGP) is common in the freshwater insect communities, involving a top predator, intraguild prey (IG prey) and a shared prey. Influence of the habitat complexity on the prey-predator interactions is well established through several studies. In the present instance, the IGP involving the heteropteran predators and the dipteran prey were assessed in the background of the habitat complexity. The three predators Diplonychus rusticus, Ranatra filiformis, and Laccotrephes griseus, one intraguild prey Anisops bouvieri and two dipteran prey Culex quinquefasciatus and Chironomus sp. were used in different relative density against the complex habitat conditions to deduce the impact on the mortality on the prey. In comparison to the open conditions, the presence of the macrophytes and pebbles reduced the mortality of the shared prey under intraguild system as well as single predator system. The mortality of the shared prey was however dependent on the density of the predator and prey. Considering the shared prey mortality, predation on mosquito larvae was always higher in single predator system than chironomid larvae irrespective of identity and density of predators. However, for both the shared prey, complexity of habitat reduced the prey vulnerability in comparison to the simple habitat condition. Higher observed prey consumption depicts the higher risk to predation of shared prey, though the values varied with habitat conditions. Mortality of IG prey (A. bouvieri) in IGP system followed the opposite trend of the shared prey. The lower mortality in simple habitat and higher mortality in complex habitat conditions was observed for the IG prey, irrespective of shared prey and predator density. In IGP system, the shared prey mortality was influenced by the habitat conditions, with more complex habitat reducing the vulnerability of the shared prey and increased mortality of the IG prey. This implies that the regulation of the mosquitoes, in the IGP system will be impeded by the habitat conditions, with the heteropteran predators as the top predator.

Effects of enhanced productivity of resources shared by predators in a food-web module: Comparing results of a field experiment to predictions of mathematical models of intra-guild predation.

We compared the response to resource enhancement of a simple empirical model of intra‐guild predation (IGP) to the predictions of published, simple mathematical models of asymmetric IGP (a generalist IG Predator that feeds both on a specialist IG Prey and a Resource that it shares with the IG Prey). The empirical model was a food‐web module created by pooling species abundances across many families in a speciose community of soil micro‐arthropods into three categories: IG Predator (large predatory mites), IG Prey (small predatory mites), and a shared Resource (fungivorous mites and springtails). By pooling abundances of species belonging to broadly defined functional groups, we tested the hypothesis that IGP is a dominant organizing principle in this community. Simple mathematical models of asymmetric IGP predict that increased input of nutrients and energy to the shared Resource will increase the equilibrium density of Resource and IG Predator, but will decrease that of IG Prey. In a field experiment, we observed how the three categories of the empirical model responded to two rates of addition of artificial detritus, which enhanced the food of fungivores, the Resource of the IGP module. By the experiment's end, fungivore densities had increased ~1.5× (ratio of pooled fungivore densities in the higher‐input treatment to plots with no addition of detritus), and densities of IG Predators had increased ~4×. Contrary to the prediction of mathematical models, IG Prey had not decreased, but instead had increased ~1.5×. We discuss possible reasons for the failure of the empirical model to agree with IGP theory. We then explore analogies between the behavior of the empirical model and another mathematical model of trophic interactions as one way to gain insights into the trophic connections in this community. We also propose one way forward for reporting comparisons of simple empirical and mathematical models.

Impact of Additive Allee Effect on the Dynamics of an Intraguild Predation Model with Specialist Predator

Many important factors in ecological communities are related to the interplay between predation and competition. Intraguild predation or IGP is a mixture of predation and competition which is a very basic three-dimensional system in food webs where two species are related to predator–prey relationship and are also competing for a shared prey. On the other hand, Allee effect is also a very important ecological factor which causes significant changes to the system dynamics. In this work, we consider a intraguild predation model in which predator is specialist, the growth of shared prey population is subjected to additive Allee effect and there is Holling-Type III functional response between IG prey and IG predator. We analyze the impact of Allee effect on the global dynamics of the system with the prior knowledge of the dynamics of the model without Allee effect. Our theoretical and numerical analyses suggest that: (1) Trivial equilibrium point is always locally asymptotically stable and it may be globally stable also. Hence, all the populations may go to extinction depending upon initial conditions; (2) Bistability is observed between unique interior equilibrium point and trivial equilibrium point or between boundary equilibrium point and trivial equilibrium point; (3) Multiple interior equilibrium points exist under certain parameters range. We also provide here a comprehensive study of bifurcation analysis by considering Allee effect as one of the bifurcation parameters. We observed that Allee effect can generate all possible bifurcations such as transcritical bifurcation, saddle-node bifurcation, Hopf bifurcation, Bogdanov–Taken bifurcation and Bautin bifurcation. Finally, we compared our model with the IGP model without Allee effect for better understanding the impact of Allee effect on the system dynamics.

Dynamics of an intraguild predation food web model with strong Allee effect in the basal prey

Since intraguild predation (IGP) is a ubiquitous and important community module in nature and Allee effect has strong impact on population dynamics, in this paper we propose a three-species IGP food web model consisted of the IG predator, IG prey and basal prey, in which the basal prey follows a logistic growth with strong Allee effect. We investigate the local and global dynamics of the model with emphasis on the impact of strong Allee effect. First, positivity and boundedness of solutions are studied. Then existence and stability of the boundary and interior equilibria are presented and the Hopf bifurcation curve at an interior equilibrium is given. The existence of a Hopf bifurcation curve indicates that if competition between the IG prey and IG predator for the basal resource lies below the curve then the interior equilibrium remains stable, while if it lies above the curve then the interior equilibrium loses its stability. In order to explore the impact of Allee effect, the parameter space is classified into sixteen different regions and, in each region, the number of interior equilibria is determined and the corresponding bifurcation diagrams on the Allee threshold are given. The extinction parameter regions of at least one species and the necessary coexistence parameter regions of all three species are provided. In addition, we explore possible dynamical patterns, i.e., the existence of multiple attractors. By theoretical analysis and numerical simulations, we show that the model can have one (i.e. extinction of all species), two (i.e. bi-stability) or three (i.e. tri-stability) attractors. It is also found by simulations that when there exists a unique stable interior equilibrium, the model may generate multiple attracting periodic orbits and the coexistence of all three species is enhanced as the competition between the IG prey and IG predator for the basal resource is close to the Hopf bifurcation curve from below. Our results indicate that the intraguild predation food web model exhibits rich and complex dynamic behaviors and strong Allee effect in the basal prey increases the extinction risk of not only the basal prey but also the IG prey or/and IG predator.

Intraguild predation between two lady beetle predators is more sensitive to density than species of extraguild prey

Oenopia conglobata (Linnaeus) and Menochilus sexmaculatus Fabricius (Coleoptera: Coccinellidae) are important predators of the pistachio psyllid, Agonoscena pistaciae Burckhardt and Lauterer (Hemiptera: Psyllidae), a key pest of pistachio. The abundance of M. sexmaculatus has recently increased in pistachio orchards, while that of O. conglobata has declined. We designed laboratory experiments to (1) evaluate the potential for intraguild predation (IGP) between these two species, (2) detect any possible asymmetries in IGP interactions, and (3) characterize the sensitivity of IGP to varying densities of two extraguild (EG) prey, A. pistaciae and Aphis gossypii Glover (Hemiptera: Aphididae). We measured rates of IGP by fourth instar larvae and female adults (both starved for 12 h) on vulnerable immature life stages of the other species (eggs, first, and second instar larvae). IG and EG prey consumption were tallied after 12 h. All factors influenced rates of IGP, but species of IG predator, and life stage and density of EG prey, contributed the most variance. IGP decreased parabolically with increasing prey densities. IGP on eggs was higher than on first instars, which was higher than on second instars, suggesting palatability declined in later life stages. The larger M. sexmaculatus exhibited higher voracity than the smaller O. conglobata in both predation and IGP. Both species consumed more A. pistaciae than A. gossypii in all treatments, which may reflect either lower handling time or lower food value per prey.

Intra-guild predation (IGP) can increase or decrease prey density depending on the strength of IGP.

In consumer communities, intra-guild predation (IGP) is a commonly observed interaction that is widely believed to increase resource density. However, some recent theoretical work predicts that resource density should first decrease, and then increase as the strength of IGP increases. This occurs because weak to intermediate IGP increases the IG predator density more than it reduces the IG prey density, so that weak to intermediate IGP leads to the lowest resource density compared to weak or strong IGP. We test this prediction that basal resource density would first decrease and then increase as the strength of IGP increase. We used a well-studied system with two protozoa species engaged in IGP and three bacteria species as the basal resources. We experimentally manipulated the percentage of the IG prey population that was available to an IG predator as a proxy for IGP strength. We found that bacterial density first decreased (by ~25%) and then increased (by ~30%) as the strength of IGP increased. Using a modified version of a published IGP model, we were able to explain ~70% of the variation in protozoa and bacterial density. Agreement of the empirical results with model predictions suggests that IGP first increased the IG predator density by consuming a small proportion of the IG prey population, which in turn increased the summed consumer density and decreased the bacterial resource density. As IGP strength increased further, the IG predator became satiated by the IG prey, which then freed the bacterial resource from predation and thus increased bacterial density. Consequently, our work shows that IGP can indeed decrease or increase basal resource density depending on its strength. Consequently, the impacts of IGP on resource density is potentially more complex than previously thought.

Fear Induced Stabilization in an Intraguild Predation Model

In the present paper, we investigate the impact of fear in an intraguild predation model. We consider that the growth rate of intraguild prey (IG prey) is reduced due to the cost of fear of intraguild predator (IG predator), and the growth rate of basal prey is suppressed due to the cost of fear of both the IG prey and the IG predator. The basic mathematical results such as positively invariant space, boundedness of the solutions, persistence of the system have been investigated. We further analyze the existence and local stability of the biologically feasible equilibrium points, and also study the Hopf-bifurcation analysis of the system with respect to the fear parameter. The direction of Hopf-bifurcation and the stability properties of the periodic solutions have also been investigated. We observe that in the absence of fear, omnivory produces chaos in a three-species food chain system. However, fear can stabilize the chaos thus obtained. We also observe that the system shows bistability behavior between IG prey free equilibrium and IG predator free equilibrium, and bistability between IG prey free equilibrium and interior equilibrium. Furthermore, we observe that for a suitable set of parameter values, the system may exhibit multiple stable limit cycles. We perform extensive numerical simulations to explore the rich dynamics of a simple intraguild predation model with fear effect.

A mathematical model of intraguild predation with prey switching

Intraguild predation (IGP) is widespread in nature. In this paper, a mathematical model of a tri-trophic food web with IGP and prey switching is considered, where the IG predator tends to consume disproportionately more of the relatively abundant prey. Bifurcation analysis shows that prey switching may (i) enhance the persistence of the IG prey when it is an inferior competitor for resources; (ii) enhance the persistence of the IG predator when one of the prey species is at least moderately abundant; (iii) facilitate coexistence of all species; and (iv) stabilize the population dynamics. It has been found that prey switching combined with predator interference may have a synergistic effect on enhancing coexistence and stabilizing population dynamics. Bistability and chaotic attractors are also observed in the mathematical model for a small range of parameter values.

A free boundary problem for the diffusive intraguild predation model with intraspecific competition

In this paper, we investigate a free boundary problem for the diffusive intraguild predation model with intraspecific competition in one dimensional space. The main objective is to portray the asymptotic behavior of spread of an invasive or new predator species via a free boundary. In this model, we assume both the IG prey and the IG (invasive/new) predator species with intraspecific competition, and the IG predator species can only expand further into the new environment from the right end of the initial region. In both cases, we prove a spreading–vanishing dichotomy for this model, specifically, the IG predator species either successfully spreads to infinity as t → ∞ at the front and survives in the new environment, or spreads within a bounded area and dies out in the long run. The long time behavior of ( R , N , P ) and criteria for spreading and vanishing are also obtained.

Warming drives higher rates of prey consumption and increases rates of intraguild predation

Warming due to climate change is expected to alter species interactions. These interactions are shaped by components of individual behavior, particularly foraging behaviors. However, few studies consider species' behavioral responses to warming to predict how species interactions will be affected by warming. We chose two complementary approaches to examine how climate warming may affect the behavior and interactions of aquatic intraguild predators. First, we measured behavioral responses to warming in six larval dragonfly species, expecting that feeding rate and activity would increase with temperature. Secondly, we conducted intraguild predation (IGP) trials with three species to understand how temperature affects IGP, and if species' behavioral responses to warming are indicative of the outcome of IGP interactions. Warming increased feeding rates by 42% on average across species but had no effect on activity rate. The magnitude of change in feeding rate was positively correlated with the maximum temperatures species experience across their ranges. Lastly, warming increased rates of IGP twofold, however, species' behavioral responses alone were not predictive of their susceptibility to become IG prey of other larvae at warmer temperatures. Our results provide evidence that IGP interactions may be greatly affected by future increases in temperature; however, activity responses to warming alone are weak predictors of the outcomes of these interactions. Future studies should consider other species' traits when forecasting the effects of climate change on species interactions.

Temperature dependency of intraguild predation between native and invasive crabs.

Environmental factors such as temperature can affect the geographical distribution of species directly by exceeding physiological tolerances, or indirectly by altering physiological rates that dictate the sign and strength of species interactions. Although the direct effects of environmental conditions are relatively well studied, the effects of environmentally mediated species interactions have garnered less attention. In this study, we examined the temperature dependency of size-structured intraguild predation (IGP) between native blue crabs (Callinectes sapidus, the IG predator) and invasive green crabs (Carcinus maenas, the IG prey) to evaluate how the effect of temperature on competitive and predatory rates may influence the latitudinal distribution of these species. In outdoor mesocosm experiments, we quantified interactions between blue crabs, green crabs, and shared prey (mussels) at three temperatures reflective of those across their range, using two size classes of blue crab. At low temperatures, green crabs had a competitive advantage and IGP by blue crabs on green crabs was low. At high temperatures, size-matched blue and green crabs were competitively similar, large blue crabs had a competitive advantage, and IGP on green crabs was high. We then used parameter values generated from these experiments (temperature- and size-dependent attack rates and handling times) in a size-structured IGP model in which we varied IGP attack rate, maturation rate of the blue crab from the non-predatory to predatory size class, and resource carrying capacity at each of the three temperatures. In the model, green crabs were likely to competitively exclude blue crabs at low temperature, whereas blue crabs were likely to competitively and consumptively exclude green crabs at higher temperatures, particularly when resource productivities and rates of IGP were high. While many factors may play a role in delimiting species ranges, our results suggest that temperature-dependent interactions can influence local coexistence and are worth considering when developing mechanistic species distribution models and evaluating responses to environmental change.

Reciprocal intraguild predation between Neoseiulus barkeri and Amblyseius swirskii (Mesostigmata: Phytoseiidae): Does experience affect anti-intraguild predation behaviors?

In order to increase their inclusive fitness, animals predominantly probe their changing environment for predation cues to adopt appropriate antipredator strategies and decrease the costs of defensive behavior. Intraguild predation (IGP) occurs when a predator kills and consumes individuals of another predator which is its competitor for a shared prey. IGP is prevalent among predatory mites of the family Phytoseiidae which are used as biological control agents of agricultural pests worldwide. Phytoseiid mite mothers usually display antipredator behaviors to avoid or reduce IGP risk of their juveniles. When facing a novel IGP risk, experience may enable the mothers to display more efficient antipredator responses. We studied the effect of experience on reciprocal antipredator behaviors of an indigenous predatory phytoseiid mite, i.e., Neoseiulus barkeri Hughes, and an exotic one, i.e., Amblyseius swirskii Athias-Henriot, as biological control candidates for integrated pest management strategies in Iran. First, we determined the occurrence of IGP and mutual risk of the predators within the guild; IGP occurred reciprocally and A. swirskii was the stronger IG predator. Second, in choice situations between a patch with only shared prey and a patch with shared prey plus IGP risk cues, we scrutinized patch choice, oviposition site selection and ability to counterattack by females of each species that had either experienced the IGP risk or not. The experience did not affect patch choice and oviposition behaviors of the species whereas it elicited an increase in their predation on IG predator juveniles. We suggest that the presence of IG predator juveniles and cues may not significantly modify the distribution of the IG prey species. The reinforced counterattack behavior in experienced females showed that both species were able to tune their antipredator behavior after exposure to IG predators. Consequences of the antipredator behaviors in experienced IG prey females on distribution and possibilities of the coexistence of the study species are discussed.

Theory does not meet experiment: transient dynamics changes patterns of exclusion in an intraguild predation system

AbstractAlthough empirical verifications of ecological theory are essential for the advance of our understanding of ecosystems functioning, they are often hard to obtain or even impractical. In this work we perform a detailed analysis of unexpected results found in a previous test of intraguild predation (IGP) theory. When the IG prey is the stronger competitor the IGP theory predicts a clear dynamical pattern along a resource gradient. In particular, the IG predator is expected to be excluded at low resources. In the experiment we analyze, IG prey was excluded at a resource level where the IG predator should be eliminated. We use a simple IGP model parametrized using mainly preliminary tests of the experiment. We suggest that experiment and theory agree if we look to the transient dynamics instead of asymptotic states, in which the usual theory is based. We show that extremely low IG prey populations during the transient may drive it to extinction and prevent the system from reaching long‐term states. Our results are shown to be robust with respect to changes in initial conditions and parameters.

Spatiotemporal dynamics and spatial pattern in a diffusive intraguild predation model with delay effect

Based on biological meaning, a kind of diffusive intraguild predation (IGP: resource, IG prey and IG predator) model with delay effect is investigated in this paper. The model has Holling-Type I functional response between resource-IG prey and resource-IG predator; Holling-Type II functional response between IG prey and IG predator. We first give sufficient conditions on the stability of possible nonnegative constant steady-state solutions for the proposed model, which give us a complete picture of the global dynamics. Then we investigate Hopf bifurcation near the unique positive constant steady-state solution by taking delay as bifurcation parameter and derive the Hopf bifurcation threshold. It is shown that the delay can induce three types of bistability (node-node bistability, node-cycle bistability and cycle-cycle bistability), periodic oscillations and irregular oscillations triggering spatiotemporal chaos in the diffusive IGP model. Numerical simulations are performed to illustrate our theoretical results and suggest that delay can even trigger the emergence of self-organised spatiotemporal patterns, which evolve from spiral patterns to irregular spatial patterns via spatiotemporal Hopf bifurcation. In addition, the impact of diffusion on the model’s dynamics under certain time delay are also explored.

Intraguild Predation And Cannibalism Among Mite Predators: Stethorus gilvifrons (Mulsant) (Coleoptera: Coccinellidae), Orius albidipennis (Reuter) (Hemiptera: Anthocoridae) And Scolothrips longicornis Priesner (Thysanoptera: Thripidae)

Stethorus gilvifrons (Mulsant), Orius albidipennis (Reuter) and Scolothrips longicornis Priesner are the key predators of Tetranychus urticae in Egypt. In this study, the intraguild predation (IGP) and cannibalism of adult females of these predators were studied under laboratory conditions. Data revealed that in the absence of extra guild prey (T. urticae), the adult females of IG predator S. gilvifrons consumed more larvae or nymphs of IG prey species than IG predators of O. albidipennis or S. longicornis. Females of S. gilvifrons showed significantly a higher predation rate on heterospecific young and old nymph instars of O. albidipennis than on S. longicornis. Interactions of adults S. gilvifrons and larvae or nymphs of O. albidipennis or S. longicornis were highly asymmetric or unidirectional predation always being the IG predator. S. gilvifrons had stronger intraguild predator than O. albidipennis or S. longicornis. Intraguild predation could be considered mutual between O. albidipennis and S. longicornis but there is neither predation nor egg deposition occurred on young or old larvae of S. gilvifrons. The IG predator O. albidipennis showed higher predation rate on S. longicornis than on conspecific nymphs. Whereas, S. longicornis showed high predation rate on conspecific larvae. Females of S. gilvifrons provided with conspecific or heterospecific young and old larvae or nymphs were able to lay eggs when fed on S. gilvifrons, O. albidipennis and S. longicornis. Also, O. albidipennis and S. longicornis laid eggs when fed on conspecific or heterospecific young and old larvae or nymphs except when fed on larvae of S. gilvifrons as IG prey. Obviously, the presence of T. urticae led to significant decrease in IGP.

Prey abundance and intraguild predation between Adalia bipunctata (Coleoptera: Coccinellidae) and Macrolophus pygmaeus (Hemiptera: Miridae)

Macrolophus pygmaeus Rambur (Hemiptera: Miridae) and Adalia bipunctata (L.) (Coleoptera: Coccinellidae) are two pred- atory insects commonly used as biological control agents. In order to determine the incidence with which both species attack and eat each other (Intraguild predation (IGP)), the direction and symmetry of the interaction between A. bipunctata and M. pygmaeus were characterized. In addition, whether the intensity of IGP between these two predators increased when the number of extraguild prey Acyrthosiphon pisum (Harris) (Hemiptera: Aphididae) decreased, was also determined. Unidirectional sensu stricto IGP between A. bipunctata and M. pygmaeus was recorded: when IGP occurred, A. bipunctata was always the IG predator that killed and ate M. pyg- maeus, the IG prey. However, the intensity of IGP was a function of the abundance of the extraguild prey, A. pisum, since IGP increased when the number of extraguild prey decreased. These results are discussed in terms of theoretical models that predict stability and the outcome of using natural enemies to control pests.

Intraguild Predation in Heteroptera: Effects of Density and Predator Identity on Dipteran Prey.

In tropical freshwaters, different species of water bugs (Heteroptera) constitute a guild sharing similar prey resources including chironomid and mosquito larvae. Assuming possibilities of intraguild predation (IGP) among the constituent members, an attempt was made to evaluate the effects of prey and predator density on the mortality of mosquito and chironomid larvae (shared prey), using Laccotrephes griseus Guérin-Méneville (Hemiptera: Nepidae) and Ranatra filiformis Fabricius (Hemiptera: Nepidae) as IG predators and Anisops bouvieri Kirkaldy (Hemiptera: Notonectidae) as IG prey. The predation on mosquito and chironomid larvae varied with the density and combinations of the predators. When present as conspecific IG predators, L. griseus exhibited greater effect on the prey mortality than R. filiformis. The effects on shared prey suggest that the two predators are not substitutable in terms of the effect on the shared prey mortality. The mortality of A. bouvieri (IG prey) at low shared prey density was significantly different (p < 0.05) from high shared prey density. In view of predatory effect of the heteropteran predators on the dipteran larvae, the results suggest possible interference by the presence of A. bouvieri as an intermediate predator. It seems that the presence of heteropteran predators including A. bouvieri as IG prey may benefit the dipteran prey under situations when the density is low in tropical waters. The intensity of the predatory effect may differ based on the species composition at IG predator level. For mosquito biological control, the interactions between the predators may not be substitutable and are independent in their effects.

Foraging behaviour of the parasitoid Eretmocerus eremicus under intraguild predation risk by Macrolophus pygmaeus.

Intraguild predation (IGP), predation between species that use a common resource, can affect the populations of a pest, of the pest's natural enemy (IG prey) and of the predator of the pest's natural enemy (IG predator). In this study, we determined whether the parasitoid Eretmocerus eremicus (Hymenoptera: Aphelinidae) (IG prey), modifies its foraging behaviour under the risk of IGP by Macrolophus pygmaeus (Hemiptera: Miridae) (IG predator). Parasitoid behaviour was analysed using two bioassays (choice and no-choice) with the following treatments: (i) control, tomato leaf infested with whitefly nymphs; and (ii) PEP, tomato leaf infested with whitefly nymphs and previously exposed to the IG predator; and (iii) PP, tomato leaf infested with whitefly nymphs, with both, the IG predator and the IG prey present. In both bioassays, we found that E. eremicus did not significantly modify the number of ovipositions, time of residence, duration of oviposition or behavioural sequence. However, in the no-choice bioassay, the number of attacks was higher and their duration shorter in the PEP treatment than in the control. Our results indicate that the parasitoid may detect IGP risk to a certain extent, but it did not significantly modify its foraging behaviour, suggesting that simultaneous release of the two natural enemies can be successfully employed.

Population dynamics of intraguild predation in a lattice gas system

In the system of intraguild predation (IGP) we are concerned with, species that are in a predator–prey relationship, also compete for shared resources (space or food). While several models have been established to characterize IGP, mechanisms by which IG prey and IG predator can coexist in IGP systems with spatial competition, have not been shown. This paper considers an IGP model, which is derived from reactions on lattice and has a form similar to that of Lotka–Volterra equations. Dynamics of the model demonstrate properties of IGP and mechanisms by which the IGP leads to coexistence of species and occurrence of alternative states. Intermediate predation is shown to lead to persistence of the predator, while extremely big predation can lead to extinction of one/both species and extremely small predation can lead to extinction of the predator. Numerical computations confirm and extend our results. While empirical observations typically exhibit coexistence of IG predator and IG prey, theoretical analysis in this work demonstrates exact conditions under which this coexistence can occur.