Effects Of Intraguild Predation Research Articles

The Effects of Intraguild Predation on Phytoplankton Assemblage Composition and Diversity: A Mesocosm Experiment.

Intraguild predation (IGP) can have a significant impact on phytoplankton biomass, but its effects on their diversity and assemblage composition are not well understood. In this study, we constructed an IGP model based on the common three-trophic food chain of "fish (or shrimp)-large branchiopods (Daphnia)-phytoplankton", and investigated the effects of IGP on phytoplankton assemblage composition and diversity in outdoor mesocosms using environmental DNA high-throughput sequencing. Our results indicated that the alpha diversities (number of amplicon sequence variants and Faith's phylogenetic diversity) of phytoplankton and the relative abundance of Chlorophyceae increased with the addition of Pelteobagrus fulvidraco, while similar trends were found in alpha diversities but with a decrease in the relative abundance of Chlorophyceae in the Exopalaemon modestus treatment. When both predators were added to the community, the strength of collective cascading effects on phytoplankton alpha diversities and assemblage composition were weaker than the sum of the individual predator effects. Network analysis further showed that this IGP effect also decreased the strength of collective cascading effects in reducing the complexity and stability of the phytoplankton assemblages. These findings contribute to a better understanding of the mechanisms underlying the impacts of IGP on lake biodiversity, and provide further knowledge relevant to lake management and conservation.

Effects of intraguild predation and cannibalism in two generalist phytoseiid species on prey density of the pink citrus rust mite in the presence of high-quality food

Effects of intraguild predation and cannibalism in two generalist phytoseiid species on prey density of the pink citrus rust mite in the presence of high-quality food

Weak intra-guild predation facilitates consumer coexistence but does not guarantee higher consumer density

In plant communities, resource partitioning has been shown to facilitate species coexistence and, in turn, enhance community density. Such positive effects of resource partitioning in higher trophic levels are not as obvious possibly due to the occurrence of intra-guild predation (IGP). We thus built a model to explore the joint effects of IGP and resource partitioning on consumer coexistence and their collective density as rarely have studies investigated this joint effect. The model consists of two prey resources that do not directly compete with each other and two consumers that are engaged in IGP and can partition their use of the two prey resources. This model shows that the effects of IGP on consumer coexistence depend on which consumer requires the lower resource density to persist. When the IG predator is the inferior competitor, weak IGP enhances coexistence by lowering the minimum degree of partitioning that is required for coexistence; otherwise, IGP always constrains coexistence. In addition, the effects of IGP on total consumer density (Ztot) depends on which consumer has the lower maximum growth potential, defined as the difference between their maximum growth rate and mortality. Weak IGP increases Ztot when the IG predator has lower maximum growth potential; otherwise, IGP always decreases Ztot. Last, the criterion for IGP to have positive effects on consumer coexistence and Ztot are different. Our results show that weak to intermediate strengths of intra-guild predation can facilitate consumer coexistence and total community density, but consumer coexistence does not guarantee higher consumer density.

Gene expression correlates of facultative predation in the blow fly Chrysomya rufifacies (Diptera: Calliphoridae).

Effects of intraguild predation (IGP) on omnivores and detritivores are relatively understudied when compared to work on predator guilds. Functional genetic work in IGP is even more limited, but its application can help answer a range of questions related to ultimate and proximate causes of this behavior. Here, we integrate behavioral assays and transcriptomic analysis of facultative predation in a blow fly (Diptera: Calliphoridae) to evaluate the prevalence, effect, and correlated gene expression of facultative predation by the invasive species Chrysomya rufifacies. Field work observing donated human cadavers indicated facultative predation by C. rufifacies on the native blow fly Cochliomyia macellaria was rare under undisturbed conditions, owing in part to spatial segregation between species. Laboratory assays under conditions of starvation showed predation had a direct fitness benefit (i.e., survival) to the predator. As a genome is not available for C. rufifacies, a de novo transcriptome was developed and annotated using sequence similarity to Drosophila melanogaster. Under a variety of assembly parameters, several genes were identified as being differentially expressed between predators and nonpredators of this species, including genes involved in cell‐to‐cell signaling, osmotic regulation, starvation responses, and dopamine regulation. Results of this work were integrated to develop a model of the processes and genetic regulation controlling facultative predation.

Dragonflies community assembly in artificial habitats: Glimpses from field and manipulative experiments.

Several factors act on community structure, so determining species composition and abundance patterns. Core processes operating at local scales, such as species-environment matching and species interactions, shape observed assemblages. Artificial habitats (simplified structure) are useful systems for assessing the main factors affecting community composition and disentangling their assembly rules. Drinking troughs (brickwork tanks for free-ranging cattle watering) are widespread in Italy and represent a suitable aquatic habitat for colonization by various aquatic organisms. Dragonflies larvae are usually found in drinking troughs and often exhibit strong species interactions and striking community assembly patterns. Our primary aim was to search for Odonata communities exhibiting non-random co-occurrence/segregation patterns in drinking troughs. We performed null-model analyses by measuring a co-occurrence index (C-score) on larval Odonata assemblages (13 species from 28 distinct troughs). Overall, we found a non-random structure for the studied dragonfly assemblages, which, given their fast generation time, must have been generated by short-term ecological processes (i.e. interspecific interactions). We thus analyzed potential competition/predation among and within ecological guilds. From the field data, we speculated that interactions within the sprawlers’ guild is likely among the main drivers structuring the studied assemblages, especially the effect of intraguild predation between C. erythraea and Sympetrum spp larval stages. We then experimentally tested these interactions in laboratory and demonstrated that intraguild predation among larvae at different development stages may result in an effective exclusion/negative impact on density pattern, representing one of the processes to take into consideration when studying dragonfly assemblages.

Suitability of Schizaphis graminum Parasitized by Lysiphlebus testaceipes as Intraguild Prey for Chrysoperla rufilabris

Winter wheat (Triticum aestivum L.) often is the dominant crop in agricultural landscapes on the Southern Great Plains. The greenbug, Schizaphis graminum (Rondani), is a sporadic aphid pest on small grains in the region and capable of causing widespread destruction during outbreaks. Natural enemies such as parasitoid wasps (Braconidae), lady beetles (Coccinellidae), and green lacewings (Chrysopidae) are common in wheat fields and regularly prevent outbreaks of aphids. When natural enemies co-exist, and compete for common resources, intraguild predation can occur. Previous studies demonstrated that lady beetles readily feed on parasitized aphids but intraguild predation had negative consequences on survival, development, and adult body size of lady beetles. Green lacewings, especially Chrysoperla spp., significantly outnumber lady beetles in Oklahoma winter cropping systems, but effects of intraguild predation on parasitized aphids by green lacewings have not been studied. Feeding capabilities of first- and third-instar Chrysoperla rufilabris Burmeister and diet suitability were evaluated to determine if green lacewing larvae fed, survived, and developed on mummified greenbugs. C. rufilabris first and third instars readily fed on mummified greenbugs that were suitable for survival and development of the lacewings. Survival ratios, development times and adult weights of lacewings fed mummified greenbugs were similar to those fed aphid prey. The polyphagous green lacewing C. rufilabris seems well adapted for using nutritional resources of aphid prey and parasitoid competitors.

Effect of Intra-Guild Predation and Sub Lethal Concentrations of Insecticides on the Predation of Coccinellids

Effect of Intra-Guild Predation and Sub Lethal Concentrations of Insecticides on the Predation of Coccinellids

Seasonal Patterns of Intraguild Predation and Size Variation among Larval Salamanders in Ephemeral Ponds

Abstract Predation among potential competitors, or intraguild predation (IGP), is dependent on size disparities between competing predators and prey and strongly influences the ecology of larval amphibians in ephemeral ponds. Although intraguild prey are hypothesized to exhibit faster growth rates than intraguild predators and, therefore, outgrow predation risk through time, intraguild predation also is associated with significant increases in predator growth rates that are hypothesized to increase the potential for future predation. Given these conflicting hypotheses, how predation among amphibian larvae early in development should influence size disparities and ontogenetic shifts in predation risk is unclear. To clarify the effects of intraguild predation on predator and prey growth, we quantified size variation among larval salamanders (Ambystomatidae) in forested ephemeral ponds while concurrently monitoring seasonal patterns of intraguild predation through gut content analyses. Intraguild predation h...

Dynamics of asymmetric intraguild predation with time lags in reproduction and maturation

A three dimensional (3D) stage-structured predator–prey model is proposed and analyzed to study the effect of intraguild predation with harvesting of the adult species. Time lags in reproduction and maturation of the organism are introduced in the system and conditions for local asymptotic stability of steady states of delay differential forms of the ODE model are derived. The length of the delay preserving the stability is also estimated. Moreover, it is shown that the system undergoes a Hopf bifurcation when the time lags cross certain critical values. The stability and direction of the Hopf bifurcations are determined by applying the normal form method and the center manifold theory. Computer simulations have been carried out to illustrate various analytical results.

Pest control by mites (Acari): present and future

This essay reviews advances in the systematics of mite families containing members that are acarine biocontrol agents (ABAs), including the Phytoseiidae which have several strains or races. Additions to the roster of mites that affect pests (including weeds and pathogens), and of pests that may be, or are, significantly affected by ABAs, were noted. The various pest-debilitating mechanisms used by ABAs, including predation, parasitism, parasitoidism, parasiticcastration, competition as well as reductions in weed and phytopathogenic fungal growth are listed. Theaffected targets include agricultural, veterinary and medical pests, as well as weeds, nematodes and fungi. The effect of intra-guild predation on the ABAs’ ability to affect pests is discussed, along with other organisms that increase the controlling impact of ABAs. The influence of host plants, including their architecture, leaf surfaces, domatia, pollen, genetically modified plants (GMOs) and volatiles are then reviewed. Then come mite feeding on soil-inhabiting pests and the newly-discovered effects of arbuscular mycorrhizal (AM) fungi. ABA feeding on weeds and on nematodes is briefly discussed next, along with the few known ABA diseases. The effect of plant-protection chemicals are then considered, followed by new techniques for the better implementation of ABAs. These include mass rearing, modes of distribution, long-term maintenance and the application of molecular methods to determine quantitative and qualitative feeding rates. This review ends with suggestions for further research, including more collecting and assaying of ABAs (especially indigenous species), determining the effects of secondary predators and of light regimes in greenhouses, and increasing studies on the role of volatiles of plant and nematode source, and of ABAs as vectors of pest diseases.

Dynamics of a stage-structured system with harvesting and discrete time delays

A two-dimensional single-species stage-structured model is proposed and analyzed to study the effect of intraguild predation with harvesting of the adult species. Time lags in reproduction and maturation of the organism are introduced in the system and conditions for local asymptotic stability of steady states are derived. The length of the delay preserving the stability is also estimated. It is found that there are stability switches for time delays, and Hopf bifurcations when time delays cross through some critical values. The stability and direction of the Hopf bifurcations are determined by applying the normal form method and the center manifold theory. Computer simulations have been carried out to illustrate various analytical results.

Trophic ontogenetic shifts of the dragonflyRhionaeschna variegata: the role of larvae as predators and prey in Andean wetland communities

Body size strongly influences the type and strength of species interactions. Animals with complex life cycles, such as dragonflies, usually go through different stages that include a variation in body size and may involve shifts in their trophic position in the food web. This investigation analyzes the position of the dragonfly Rhionaeschna variegata , in the food web according to its body size, in Andean wetland communities of Northwestern Patagonia (Argentina). The phenology of R. variegata larvae and their potential intraguild predators were studied in wetlands with different hydroperiods. Under controlled experimental conditions, feeding trials were performed to assess the effect of R. variegata on the survivorship of different types of prey. The effects of cannibalism and intraguild predation (IGP) on the survivorship of the small larvae of R. variegata were investigated with and without alternative prey as well as different sympatric predators. The phenology of R. variegata and intraguild predators differed among wetlands. The feeding trials showed that R. variegata has a significant effect on the survivorship of invertebrate and vertebrate prey. Cannibalism increased with body size in odonate larvae. The survivorship of small- and medium-sized larvae was mainly affected by the presence of larger predators such as belosmatids. The field and experimental data show that the effect of IGP and cannibalism is affected by the cohort dynamics of R. variegata . Body size in R. variegata determines the strength of its interaction with other components of the community.

Impact of Cheiracanthium pelasgicum (Araneae: Miturgidae) and Chrysoperla carnea (Neuroptera: Chrysopidae) intraguild predation on the potential control of cotton pest Helicoverpa armigera (Lepidoptera: Noctuidae)

Antagonist interactions such as intraguild predation (IGP) or cannibalism among predatory arthropods can reduce the impact of these invertebrates on pest limitation in agroecosystems. Here, the effects of IGP between two major natural enemies of cotton pests, the cursorial spider Cheiracanthium pelasgicum (C.L. Koch) and the common green lacewing Chrysoperla carnea (Stephens), were studied under laboratory conditions. First, a feeding preference test was carried out to determine the degree of C. pelasgicum preference for lacewing larvae, using second-instar Helicoverpa armigera larvae as alternative prey. In a second bioassay, the effects of predator interactions on potential predation of H. armigera larvae were analysed using three treatment combinations (plus a control with no predator): (1) spider alone, (2) lacewing larvae alone, (3) spider + lacewing larvae. Potential predation by C. pelasgicum on lacewing eggs was also studied. C. pelasgicum showed no significant preference for either of the two species, indicating that this spider may impact negatively on the green lacewing population. Findings revealed no additive effects and an antagonist interaction between C. pelasgicum and green lacewing larvae, which adversely affected H. armigera suppression; both predators displayed lower predation rates when kept together than either predator alone. However, presence of lacewing larvae and subsequent unidirectional IGP did not affect the predation capacity of C. pelasgicum. Finally, predation rates of C. pelasgicum on lacewing eggs were very low (mean 2.35 ± 0.71 eggs, 24 h after offering) indicating that the impact of C. pelasgicum on lacewing populations may be limited.

Molecular analysis of the gut contents of Harmonia axyridis (Coleoptera: Coccinellidae) as a method for detecting intra-guild predation by this species on aphidophagous predators other than coccinellids

Several studies have demonstrated that the invasive ladybird Harmonia axyridis is a strong intra-guild predator of native species of ladybird. Laboratory studies have shown that H. axyridis can be an intra-guild predator of aphid predators other than coccinellids, including the hoverfly Episyrphus balteatus and lacewing Chrysoperla carnea. However, little is known about the effect of intra-guild predation (IGP) by H. axyridis on hoverfly and lacewing populations in the field. In the present study molecular analyses were used to detect the DNA of E. balteatus and C. carnea in the gut contents of H. axyridis. Primers for the syrphid and chrysopid prey were designed and feeding experiments performed to determine how long prey DNA remains detectable in the guts of this ladybird. DNA detection was influenced by the life stage of the predator and species of prey. Meal size did not affect detection time, except when fourth instar individuals of H. axyridis were fed 10 eggs or one second instar of C. carnea. Predator weight, sex and morpho-type (melanic/non-melanic) did not influence DNA detection. The half-life of the time for which the DNA of the prey remained detectable was calculated for each predator-prey combination, and ranged from 8.9 to 52.4 h. This method can be used to study the ecological importance of IGP by H. axyridis on aphidophagous predators other than coccinellids in the field.

Influence of intraguild predation between Episyrphus balteatus and Hippodamia variegata on their prey

Intraguild predation (IGP) is an interaction that frequently occurs in natural enemy communities, especially aphidophagous predators. This research investigated IGP intensity between Episyrphus balteatus De Geer (Diptera: Syrphidae), with Hippodamia variegata Goeze (Coleoptera: Coccinellidae). Five predator combinations including second and third larvae of H. variegata and third instar larvae of E. balteatus plus control treatment (totally six treatments) were tested. The effect of IGP on cotton aphid, Aphis gossypii Glover (Hemiptera: Aphididae) population density was investigated on sweet pepper seedlings under laboratory microcosms. In most combinations, the third instar larvae of E. balteatus alone reduced an A. gossypii population more efficiently than ladybird larvae and their combinations. Furthermore, IGP between third instar of E. balteatus and second larvae of H. variegata was asymmetrical; second instar H. variegata larvae were always the intraguild prey for third instar E. balteatus. The obtained result showed that outcome of IGP interaction on cotton aphid density was non-additive.

Effects of Intraguild Predation: Evaluating Resource Competition between Two Canid Species with Apparent Niche Separation

Many studies determine which habitat components are important to animals and the extent their use may overlap with competitive species. However, such studies are often undertaken after populations are in decline or under interspecific stress. Since habitat selection is not independent of interspecific stress, quantifying an animal's current landscape use could be misleading if the species distribution is suboptimal. We present an alternative approach by modeling the predicted distributions of two sympatric species on the landscape using dietary preferences and prey distribution. We compared the observed habitat use of kit foxes (Vulpes macrotis) and coyotes (Canis latrans) against their predicted distribution. Data included locations of kit foxes and coyotes, carnivore scat transects, and seasonal prey surveys. Although habitats demonstrated heterogeneity with respect to prey resources, only coyotes showed habitat use designed to maximize access to prey. In contrast, kit foxes used habitats which did not align closely with prey resources. Instead, habitat use by kit foxes represented spatial and behavioral strategies designed to minimize spatial overlap with coyotes while maximizing access to resources. Data on the distribution of prey, their dietary importance, and the species-specific disparities between predicted and observed habitat distributions supports a mechanism by which kit fox distribution is derived from intense competitive interactions with coyotes.

Multiple predators induce risk reduction in coexisting vole species

Large predators may affect the hunting efficiency of smaller ones directly by decreasing their numbers, or indirectly by altering their behaviour. Either way this may have positive effects on the density of shared prey. Using large outdoor enclosures, we experimentally studied whether the presence of the Tengmalm's owl Aegolius funereus affects the hunting efficiency of the smallest member of the vole‐eating predator guild, the least weasel Mustela nivalis, as measured by population responses of coexisting prey species, the field vole Microtus agrestis and the sibling vole M. levis. We compared the density and survival probability of vole populations exposed to no predation, weasel predation or combined predation by a weasel and an owl. The combined predation of both owl and weasel did not result in obvious changes in the density of sibling and field vole populations compared to the control populations without predators, while predation by least weasel alone decreased the densities of sibling voles and induced a similar trend in field vole densities. Survival of field voles was not affected by predator treatment while sibling vole survival was lower in predator treated populations than in control populations. Our results suggest that weasels are intimidated by avian predators, but without changing the effects of predators on competitive situations between the two vole species. Non‐lethal effects of intraguild predation therefore will not necessarily change competitive interactions between shared prey species.

HABITAT STRUCTURE AFFECTS INTRAGUILD PREDATION

Intraguild predation is thought to be ubiquitous in natural food webs. Yet, theory on intraguild predation predicts the intraguild prey to persist only under limited conditions. This gap between theory and empirical observations needs scrutiny. One reason might be that theory has focused on equilibrium dynamics and a limited set of species (usually three) that interact in well-mixed populations in unstructured habitats, and these assumptions will often not hold in natural systems. In this review, we focus on the effects of habitat structure on intraguild predation. Habitat structure could reduce encounter rates between predators and prey and could create refuges for prey. In both cases, habitat structure could reduce the strength of intraguild interactions, thereby facilitating species coexistence. A meta-analysis of studies on manipulation of habitat structure shows that intraguild prey indeed suffer less from intraguild predation in structured habitats. This was further confirmed by a meta-analysis in which studies on intraguild predation were classified according to habitat structure. Intraguild predation reduced densities of the intraguild prey significantly more in habitats with little structure than in habitats rich in structure. The effect of intraguild predation on the shared prey was negative, and not significantly affected by habitat structure. We conclude that habitat structure may increase persistence of the intraguild prey by decreasing the strength of the interaction between intraguild predator and intraguild prey.

FOOD WEBS AND INTRAGUILD PREDATION: COMMUNITY INTERACTIONS OF A NATIVE MESOCARNIVORE

Trophic level interactions between predators create complex relationships such as intraguild predation. Theoretical research has predicted two possible paths to stability in intraguild systems: intermediate predators either outcompete higher-order predators for shared resources or select habitat based on security. The effects of intraguild predation on intermediate mammalian predators such as swift foxes (Vulpes velox) are not well understood. We examined the relationships between swift foxes and both their predators and prey, as well the effect of vegetation structure on swift fox-coyote (Canis latrans) interactions, between August 2001 and August 2004. In a natural experiment created by the Pinon Canyon Maneuver Site in southeastern Colorado, USA, we documented swift fox survival and density in a variety of landscapes and compared these parameters in relation to prey availability, coyote abundance, and vegetation structure. Swift fox density varied significantly between study sites, while survival did not. Coyote abundance was positively related to the basal prey species and vegetation structure, while swift fox density was negatively related to coyote abundance, basal prey species, and vegetation structure. Our results support the prediction that, under intraguild predation in terrestrial systems, top predator distribution matches resource availability (resource match), while intermediate predator distribution inversely matches predation risk (safety match). While predation by coyotes may be the specific cause of swift fox mortality in this system, the more general mechanism appears to be exposure to predation moderated by shrub density.

Interference competition among native and invader amphipods

Aquarium experiments were used to study indications of interference competition, such as substratum choice shifts, swimming activities and mortality of invasive and indigenous gammarids in each other's presence. The more recent invaders Gammarus tigrinus and Dikerogammarus villosus were more likely to prefer stone substratum, whereas the native Gammarus pulex and an earlier invader Gammarus roeseli were found more frequently in the water layer. Sand was the least likely substratum to be chosen by any of the species. G. pulex and G. roeseli did not alter their substratum preference in each other's presence. In the presence of D. villosus, G. pulex shifted towards smaller stones and increased its swimming activities, whereas D. villosus did not change its behaviour in the presence of G. pulex. These shifts may indicate interference competition, with D. villosus being the stronger competitor. The greatest shifts in substratum preference arose when one species had occupied a substratum before the other one was introduced, especially when D. villosus was already present before G. pulex was introduced, possibly indicating pre-emptive competition. Swimming activities of G. pulex increased in the presence of D. villosus, whereas D. villosus spent little time swimming. Mortality was comparable between the different experiments without any indication of predation. The effect of Intra Guild Predation (IGP) may not be reflected adequately by short-time experiments as moults occurred seldom during the experiments. Although no IGP was observed during our experiments, habitat shifts occurred, which may indicate that competitive interactions are apparent before IGP starts. Such shifts may serve to avoid intraguild competition.