Intensity Of Intraguild Predation Research Articles

Effect of ant-attendance on the occurrence of intraguild predation

Parasitoids and predators exploiting similar food resource make aphidophagous guilds especially favourable systems for studying intraguild predation, but ants as third parties protect aphids against their natural enemies and in return obtain carbohydrate-rich honeydew as a nutritional resource. A field experiment on the interrelationship among aphids, ants and predators/parasitoids was conducted on two plants (hoary cress Cardaria draba L. [Brassicaceae) and Canada thistle Cirsium arvense L. [Asteraceae]). Cardaria was infested with the aphid Acyrthosiphon gossypii Mordvilko (Homoptera: Aphididae) tended by the ant Lasius turcicus Santschi (Hymenoptera: Formicidae). Cirsium was infested with the aphid Brachycaudus cardui L. (Homoptera: Aphididae) tended by the ant Crematogaster sordidula Nylander (Hymenoptera: Formicidae). The mean number of predators per aphid colony decreased significantly when the aphids were tended by ants on both host plants. In contrast, the parasitism rate of both aphids decreased significantly without the tending ant. Thus ant attendance can affect the occurrence and intensity of intraguild predation, and consequently provide enemy free space for parasitoids. If a foraging female aphid parasitoid succeeds in ovipositing into patches with guarding ants, then its offspring could be protected from the risk of intraguild predation.

Interaction between hunting strategy, habitat type and stratum drive intraguild predation and cannibalism

Intraguild predation (IGP) is a common interaction between generalist predators when they competitively exploit similar resources and prey on each other. Theoretical models predict limitations for intraguild predator coexistence unless some mechanisms, such as the utilization of alternative prey (i.e. trophic niche partitioning) and cannibalism, increase the relative intraspecific clustering and interspecific segregation. As hunting strategies determine trophic niches of predators and their own vulnerability to predation, the hunting strategies may also determine the relative importance of cannibalism, predation, and exploitative competition and consequently the intensity of IGP. The importance of hunting strategies on the potential outcome of IGP and how habitat properties modify the interaction between hunting strategies remain poorly understood. Using published data on spider prey of spider predators, we first investigated how predation of a top‐predator on a mesopredator is determined by the functional distance between both predators to understand how predation and exploitation are distributed in spider communities. Subsequently, we investigated the predation among spiders with particular hunting strategies to understand which strategies interact most frequently. We also investigated whether the interaction between hunting strategies was influenced by habitat type (forest, open (semi)natural habitat, agroecosystem) or by habitat stratum (ground versus vegetation). The hunting strategies of top‐predators and mesopredators interacted to determine the relative capture proportions of conspecifics and hetero‐specifics. This interaction was further modified by habitat type and stratum. Two mechanisms can reinforce coexistence in highly diverse spider communities. First, top‐predators preyed most frequently on functionally distinct mesopredators, which indicates the overall intensity of IGP may be relaxed by a balanced distribution between exploitative competition and predation. Second, cannibalism was common for top‐predators with a hunting strategy of frequently preying on functionally similar mesopredators. Cannibalism may lead to self‐limitation of top‐predator populations and may thereby facilitate coexistence between two predator species.

Alternative extraguild prey modifies focal extraguild prey consumption and parasitism but not intraguild predation intensity

Intraguild predation (IGP) refers to the predation of species that use similar resources and are, therefore, potential competitors. The consuming predator is known as the intraguild predator (IG-predator) and the predator or parasitoid being consumed as the intraguild prey (IG-prey). Prey belonging to another guild are known as extraguild prey (EG-prey). Within a single prey-predator framework, the presence of an alternative prey can reduce the predation rate of a focal prey. However, such an effect has not been studied in an IGP framework. In addition, most studies conducted to analyze IGP intensity (i.e., the level of consumption of the IG-prey) have focused on the influence of a single focal EG-prey but not on the effect of an alternative EG-prey. Therefore, in an IGP framework, we aimed to assess how the presence of an alternative EG-prey could affect the predation and parasitism rates of a focal EG-prey, as well as IGP intensity. On the basis of intrinsic characteristics of the IG-predator and current literature, we hypothesized that the presence of the alternative EG-prey would reduce predation and parasitism of the focal EG-prey as well as IGP intensity. Our results showed that, as expected, the presence of an alternative EG-prey reduces the predation rate of the focal EG-prey when both the IG-predator and the IG-prey are released concomitantly, but not when the IG-predator is released sequentially. In addition, contrary to our expectations, the presence of an alternative EG-prey did not reduce the intensity of IGP, indicating that besides intrinsic characteristics of the IG-predators, other factors may be important mediators of IGP intensity. Potential implications of these findings are discussed under a biological control perspective.

Intraguild predation on Trichogramma chilonis Ishii (Hymenoptera: Trichogrammatidae) by the generalist predator Geocoris ochropterus Fieber (Hemiptera: Geocoridae)

Intraguild predation (IGP) is common in food web when two natural enemies share the same resources and prey. It may affect the success or failure of a biological control attempt. The role of intraguild predation by Geocoris ochropterus Fieber (Heteroptera: Geocoridae) on Trichogramma chilonis Ishii (Hymenoptera: Trichogrammatidae) developed on eggs of Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) and Corcyra cephalonica (Stainton) (Lepidoptera: Pyralidae) was evaluated under laboratory conditions. In choice experiments, both fifth instar nymph and adult of G. ochropterus preferred to predate on unparasitized eggs of H. armigera and C. cephalonica over parasitized eggs. In no-choice experiments, G. ochropterus nymph consumed 58 and 67% of unparasitized H. armigera and C. cephalonica eggs, compared to 3.33 and 7.38% of parasitized ones. A similar trend was observed in no-choice experiments with adult predator. Additional semi-field and field studies are required to explicate the consequences and intensity of intraguild predation in agro-ecosystem.

Abiotic factors and biotic interactions jointly drive spider assemblages in nest-boxes in mixed forests

Although spiders are common inhabitants of tree cavities, factors that drive their community structure in these microhabitats are little known. Here we investigated whether bark type, season, intraguild predation (IGP) among spiders, and presence of vertebrate predators can influence the spider community structure in tree cavities. We examined spider abundance and the taxonomic and functional composition of spiders in nest-boxes within two mixed forest stands in central Slovakia in 2012–2013. In total, 1211 spiders belonging to 31 species were sampled from 60 nest-boxes at two sites over three seasons. Spider abundance peaked in autumn as spiders sought wintering sites. Guilds and taxonomic composition changed seasonally with spring and autumn communities dominated by “Other hunters” (Anyphaenidae, Clubionidae, Philodromidae) while during summer the community was dominated by “Sheet web weavers” (Linyphiidae). The guild and taxonomic turnover may be partly explained by the interaction between spiders' phenology and IGP exerted by winter-active spiders on smaller spiders from autumn until spring. Bark type influenced the guild composition as dominance of “Space web weavers” was higher in trees with rough bark than in trees with smooth bark. The rough bark also reduced the intensity of IGP by Anyphaena accentuata (Sundevall, 1833) on philodromids. The presence of insectivorous birds reduced the abundance of spiders by 67%. The presence of bird predators altered the guild composition as they affected mostly the web spiders. The results show that the biotic interactions and abiotic factors interactively determined the spider community structure in the nest-boxes depending on spiders' functional traits.

Reciprocal intraguild predation between two mirid predators, Cyrtorhinus lividipennis and Tytthus chinensis (Hemiptera: Miridae)

ABSTRACTInteractions between predator species shape ecological communities and are crucial in the relationship between biodiversity and ecosystem functioning. They contribute to improving the natural biological control. Cyrtorhinus lividipennis Reuter and Tytthus chinensis Stål (Hemiptera: Miridae) are important natural enemies of brown planthopper, Nilaparvata lugens Stål (Hemiptera: Delphacidae), the most destructive rice pest in Asia. Comparative functional responses of both sexes of the two mirids at different development stages were estimated and the direction, symmetry, as well as intensity of intraguild predation (IGP) were studied in the laboratory. Prey preferences of the two mirid species and the influence of alternative prey on functional responses were also evaluated. The mirids exhibited reciprocal IGP in addition to consuming eggs of BPH. All predator–prey combinations exhibited a type II functional response. Females and fourth instar nymphs of C. lividipennis showed greater voracity for eggs of BPH than of T. chinensis. The two mirids were more voracious to intraguild prey than to extraguild prey. Alternative prey released the functional responses of C. lividipennis to both intra- and extraguild prey. In contrast, alternative prey had no effect on the functional response of T. chinensis. RIGP was symmetrical in the absence of extraguild prey. And in the presence of extraguild prey that was common in the field, resulted in different responses by the mirids.

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 amongScolothrips longicornis(Thysanoptera: Thripidae),Neoseiulus californicusandTyphlodromus bagdasarjani(Acari: Phytoseiidae) under laboratory conditions

This study was carried out on the ability of predatory thrips Scolothrips longicornis Priesner to feed on 2 phytoseiid species and vice versa. Also the effect of predation of Neoseiulus californicus (McGregor) on Typhlodromus bagdasarjani Wainstein and Arutunjan and vice versa was evaluated. The larvae, prepupae, and pupae of thrips and the eggs, larvae, and protonymphs of phytoseiids were selected as intraguild prey. The intraguild predation (IGP) among S. longicornis and 2 phytoseiid species was unidirectional and in favor of phytoseiids, i.e., S. longicornis was not able to feed on larval stages of 2 phytoseiids. However, N. californicus and T. bagdasarjani fed on the 1st instar larvae (1.39 and 0.80 per day), 2nd instar larvae (0.87 and 0.55 per day), prepupae (0.51 and 0.48 per day), and pupae of thrips (0.51 and 0.49 per day, respectively). Both phytoseiids fed on eggs, larvae, and protonymphal stages of each other. Females of N. californicus consumed more phytoseiid larvae (2.49 per day) than T. bagdasarjani, which consumed 1.08 N. californicus larvae per day. When Tetranychus urticae was presented as an extraguild prey, intensity of IGP between 2 species of phytoseiids and on larval stages of S. longicornis reduced significantly. Therefore, it is concluded that (i) IGP existed among the 3 examined species and lack of feeding of S. longicornis on 2 phytoseiid species can be justified by its feeding type (monophagy), (ii) N. californicus was much more prone to IGP than was T. bagdasarjani.

How functional response and productivity modulate intraguild predation

Numerous models have been developed to predict the effect of environmental productivity on the coexistence of prey and predators within the three‐species module of intraguild predation. Theoretical models have mainly used Holling Type I and Type II functional response, the latter typically best describing the functional response of a predator. However, no empirical study has simultaneously examined the form of the functional response and the effect of prey density on intraguild interactions. This is surprising considering that the strength of the functional response is crucially important for the stability of simple predator‐prey systems and the persistence, sustainability and biodiversity of communities. In this study, we first developed a linear and a nonlinear functional response model for intraguild predators and next used a plant–aphid–predator mesocosm to parameterize the models and test their predictions at different prey densities. As expected, the assumptions of the linear model are not supported by empirical results which lead to systemic overestimation of the predation rate and the intensity of intraguild predation. On the other hand, the predictions of the nonlinear functional response model fit very well with experimental observations mainly because key behavioral characteristics such as handling time are integrated in this model. The nonlinear model is thus a good predictor of intraguild predation and allows a better understanding of how environmental productivity and predator behavior influence the occurrence and outcome of multiple predator interactions.

Influence of conductivity on life history traits of exotic and native amphipods in the St. Lawrence River

We compared the survival, growth and fecundity of the Ponto-Caspian amphipod Echinogammarus ischnus and the North American amphipod Gammarus fasciatus across a range of conductivities in a fluvial lake at the confluence of the St. Lawrence and Ottawa rivers (Quebec, Canada). Previous work has found that water chemistry (conductivity) regulates the direction and intensity of intraguild predation between these two species. Because E. ischnus evolved in ion-rich waters, we hypothesized that low conductivity has a negative effect on its life history traits, whereas G. fasciatus would be more tolerant. Consistent with this hypothesis, E. ischnus is abundant along the south shore of the lake in water of high conductivity (300 μS/cm), but rare along the north shore where conductivity is subject to strong fluctuations (85-230 μS/cm). In laboratory experiments using water with low (108 μS/ cm), high (300 μS/cm) and intermediate (50:50 mix) conductivities, both species showed reduced growth at low conductivity, but E. ischnus also suffered higher mortality. E. ischnus collected from both shores did not differ in size-specific fecundity, size at reproduction, or size of adults. On the north shore, E. ischnus was present in low abundance at one site and absent from another site where it had been recorded in previous years. We conclude that low conductivity negatively affects the growth rate and mortality of E. ischnus, which is apparently eliminated from the north shore during periods of strong influx of ion-poor water from the Ottawa River, but re-establishes populations temporarily when higher conductivity is restored.

The Ecological Significance and Incidence of Intraguild Predation and Cannibalism among Anurans in Ephemeral Tropical Pools

Ephemeral pools are traditionally considered to be tadpole refuges, with few or no predators. While it is recognized that some tadpoles are predaceous, little attention has been given to understanding how tadpoles shape age and size structures of populations and the composition of tadpole assemblages. I examined the incidence of intraguild predation (IGP) among three species that co-occur in ephemeral pools in the Osa Peninsula, Costa Rica. I found a high incidence of IGP among the three species, with IG predators differing in their voracity for prey eggs and IG prey differing in their vulnerability to IGP. I also examined the factors that influence the intensity of cannibalism and tadpole performance in a model species, Smilisca phaeota. I manipulated predator and prey size and developmental stage, tadpole density, food quantity, and tadpole relatedness in microcosm experiments. Cannibalism in S. phaeota was dependent on tadpole predator and prey size and developmental stage, with medium and large tadpoles causing almost complete mortality of embryos, but little mortality of mobile hatchlings. In contrast, predation by small tadpoles was restricted primarily to the embryo developmental stage. Tadpole mortality was high in low plant food quantity treatments, suggesting a high incidence of cannibalism. Other measures of tadpole performance, including survival to metamorphosis, metamorph mass, and larval period, were influenced by tadpole density and plant food quantity. Additions of conspecific prey eggs and degree of tadpole relatedness did not affect tadpole performance. My results suggest that tadpoles are capable of playing a regulatory role, influencing the relative abundance and composition of species in pools through differential IGP and cannibalism on eggs and hatchlings. The intensity of IGP in ephemeral pools is likely influenced by the morphology of IG predators, reproductive mode and fecundity of IG prey, and priority effects. My study supports the view that we need to reconsider the position tadpoles occupy within the aquatic food webs, with greater appreciation for their role as predators.

Resource quality, resource availability, and intraguild predation among omnivorous mirids

Intraguild predation (IGP) among predatory species can influence many plant-arthropod associations. However, the relevance of IGP is poorly understood for truly omnivorous species such as those that can complete development on both animal and plant diets. Here we test the hypothesis that IGP among two omnivorous mirids is more common when extraguild food is either absent or not suitable. Laboratory experiments were performed in experimental cages in order to determine the effect of intraguild prey densities and diet availability on direction and intensity of IGP between Dicyphus tamaninii and Macrolophus caliginosus (Heteroptera: Miridae). Intraguild predation was symmetrical between the two mirid species in the absence of alternative food. Increasing densities of intraguild prey enhanced drastically the incidence of IGP. Intraguild predation was reduced when mirids were in the presence of green or red tomato fruits, but the presence of any other extraguild resources had no impact on IGP level. However, when given before the experiments, all resources with the exception of tomato leaves significantly reduced IGP. A second experiment was performed on live plants to compare the results of the previous trials with that obtained in a more natural setting. No IGP was observed when both mirid species were present on a plant. However, development of the intraguild prey (the more vulnerable stage) was hindered by the presence of the intraguild predator. The potential of such results is discussed from community ecology and biological control perspective.

Effect of pollen supplement on intraguild predatory interactions between two omnivores: The importance of spatial dynamics

Arthropods often engage in complex trophic interactions such as intraguild predation (IGP), true omnivory (i.e., feeding on plants and prey), and apparent competition. Theoretical treatments of the effects of such interactions on herbivore populations have been concerned almost entirely with equilibrium conditions. Yet these interactions are common in non-equilibrium settings such as agroecosystems, where they are likely to have a strong influence on pest populations. We therefore tested short-term effects of IGP and food supplementation on interactions between two predators (the phytoseiid mite Neoseiulus cucumeris and the anthocorid bug Orius laevigatus) and their shared prey, Frankliniella occidentalis, on strawberry plants. All three consumers feed on strawberry pollen, both mites and bugs prey on thrips, and the bug also feeds on the mites (IGP). Strong IGP on mites (IG prey) by the bugs (IG predator) was recorded in structurally-simple arenas. In a more complex setting (whole-plants), however, the intensity of IGP differed among plant structures. Likewise, pollen supplementation reduced both IGP and predation on thrips in a structurally simple setting. In the whole-plant experiment, IGP was more intense on pollen-bearing than pollen-free flowers. The study illustrated how spatial dynamics, generated when consumers track food sources differently in the habitat and possibly when herbivorous and IG prey alter their distribution to escape predation, led to site-specific configuration of interacting populations. The intensity of resulting trophic interactions was weakened by food supplementation and by increased complexity of the habitat.

Parasitized Aphids Are Inferior Prey for a Coccinellid Predator: Implications for Intraguild Predation

Discussions of intraguild predation (IGP) have assumed that the nutritional quality of intraguild (IG) prey is similar to that of any other prey available to the IG predator. It has been suggested therefore that generalist predators do not distinguish between healthy and parasitized aphids and thus function as facultative predators of parasitoids. More recent studies have shown that predators may selectively ingest prey of various nutritional qualities and that predators may have higher body nitrogen composition than herbivores. If so, predators may preferentially feed on other predators (i.e., IG prey) to increase their nitrogen intake. We used a system composed of larvae of the coccinellid Coccinella undecimpunctata (IG predator), the parasitoid Aphidius colemani (IG prey), and their shared food source, the green peach aphid Myzus persicae, to test whether (1) the predator preferentially feeds on parasitized over healthy prey, (2) predatory behavior on parasitized aphids changes with time elapsed after parasitism, and (3) parasitized and healthy aphids differ in their suitability for predator development. Results indicate that, given a choice, C. undecimpunctata larvae show no preference for either parasitized or healthy prey items, regardless of parasitoid age. Feeding time, however, increased with parasitoid age, leading to a reduction in the number of prey consumed per unit time. Mummified prey were protected from predation by C. undecimpunctata larvae but the larvae were able to feed and complete development on mummies with a broken cuticle. These predators, however, had an extended developmental time and lower pupal and adult weights in comparison to larvae fed healthy aphids. That parasitized aphids are inferior prey for C. undecimpunctata larvae should act to reduce intensity of IGP in the field and the negative impact IGP has on herbivore suppression.

A review of trophic interactions and their implications for biological control of arthropod pests in agroecosystems

In the last four decades there has been considerable interest in understanding the role of food web dynamics in the maintenance of plant productivity in ecosystems. This topic is particularly important in agroecosystems where the attack of erbivores can reduce plant productivity and cause severe economic damage to crops. The hypothesis that natural enemies indirectly regulate plant productivity through the suppression of herbivore populations (top-down control or trophic cascade hypothesis) has been the classical framework for biological control practitioners and ecologists interested in this topic. This hypothesis has proven to be controversial because empirical evidence shows that interspecific interactions among natural enemies in the third trophic level disrupt the top-down effects responsible for the suppression of herbivores and for the indirect benefits to plant productivity. Intraguild predation (IGP) is an important ecological process that can potentially dampen top-down control and contribute to reduce plant productivity due to the attack of unsuppressed herbivores. Thus, when aiming at the development of biological control programs with multiple species of natural enemies in the third or upper trophic levels, researchers must screen for some desirable traits of competing natural enemies. When both predators and parasitoids are present, predators are desirable in the system only if they do not eat parasitized hosts, which would disrupt parasitoid populations. When only predators are present, biological traits like mobility, body size, foraging strategy, level of diet specialization and species assemblage composition should be carefully investigated. These biological traits are related to the prevalence and intensity of IGP, to the choice and number of species to use in the program and to the choice of developmental stages to be introduced into crop fields. Observating these parameters and decision criteria may be crucial for the success of biological control programs.

Intraguild predation between syrphids and mirids: who is the prey? Who is the predator?

The mirid Macrolophus caliginosus Wagner (Hemiptera: Miridae), and the syrphids, Sphaerophoria rueppellii (Wiedemann), Sphaerophoria scripta (L.), and Epi- syrphus balteatus (DeGeer) (Diptera: Syrphidae), belong to the aphidophagous guild, feeding on aphids (Hemiptera: Aphididae) in Mediterranean vegetable crops. The direction, symmetry, and intensity of intraguild predation between different instar combinations of syrphids and mirid were studied in an arena without plants. Moreover, predatory interactions between syrphids and mirids on plants were also evaluated. The results obtained in the arena without plants demonstrated mutual intraguild predation, i.e., syrphid eggs were highly susceptible to predation, whereas mirid nymphs and adults were attacked by syrphid larvae. All syrphid species showed the same propensity to predation, which was unaffected by parasitism of syrphid larvae by Diplazon laetatorius (Fabricius) (Hymenoptera: Ichneumonidae). Sphaerophoria scripta eggs were less sus- ceptible to predation than those of the two other syrphid species. The experiment performed on plants showed different results. Predation by syrphid larvae on mirids never exceeded 10%, while 100% of syrphid eggs were preyed upon after 48 h. Intra- guild predation rates were not influenced by the presence or absence of aphids on the plants. This study demonstrated that results obtained from studying intraguild preda- tion in arenas that are highly artificial should be interpreted cautiously. Depending on the colonization history of a particular habitat in the field, syrphids should be more vulnerable to predation by mirids than vice versa.

Density of an intraguild predator mediates feeding group size, intraguild egg predation, and intra- and interspecific competition

Intraguild predation (IGP) is common in most communities, but many aspects of density-dependent interactions of IG predators with IG prey are poorly resolved. Here, we examine how the density of an IG predator can affect feeding group size, IG egg predation, and the growth responses of IG prey. We used laboratory feeding trials and outdoor mesocosm experiments to study interactions between a social intraguild predator (larvae of the wood frog; Rana sylvatica) and its prey (spotted salamander; Ambystoma maculatum). Larvae of R. sylvatica could potentially affect A. maculatum by consuming shared larval food resources or by consuming eggs and hatchlings. However, successful egg predation requires group feeding by schooling tadpoles. We established from five to 1,190 hatchlings of R. sylvatica in mesocosms, then added either 20 A. maculatum hatchlings to study interspecific competition, or a single egg mass to examine IGP. Crowding strongly suppressed the growth of R. sylvatica, and IGP was restricted to the egg stage. In the larval competition experiment, growth of A. maculatum was inversely proportional to R. sylvatica density. In the predation experiment, embryonic mortality of A. maculatum was directly proportional to the initial density of R. sylvatica and the mean number of tadpoles foraging on egg masses. IGP on eggs reduced A. maculatum hatchling density, which accelerated larval growth. Surprisingly, the density of R. sylvatica had no overall effect on A. maculatum growth because release from intraspecific competition via egg predation was balanced by increased interspecific competition. Our results demonstrate that the density of a social IG predator can strongly influence the nature and intensity of interactions with a second guild member by simultaneously altering the intensity of IGP and intra- and interspecific competition.