Intraspecific Predation Research Articles

Non-native amphipods reach higher maximum swimming velocities than natives

The invasion of non-native amphipods often leads to severe changes in the composition of aquatic communities and may also result in the local replacement of native species. Particularly, a lower risk of being preyed upon resulting from high swimming velocities can be an advantage in interspecific competition. Furthermore, as swimming velocities are ecologically important, they are often used in ecotoxicological studies to estimate effects of different stressors. However, knowledge on swimming velocities of native and non-native amphipods is still rather limited. We experimentally investigated the maximum swimming velocities of three native and three non-native amphipods via video analyses in the laboratory. Results showed that non-native species reach higher maximum swimming velocities compared to natives probably leading to a higher predation success and reduced risk of being preyed upon. Additionally, body length correlates positively with swimming velocities, except for the invader Dikerogammarus villosus. As D. villosus can be cannibalistic, the high swimming velocities of the small individuals may reduce the intraspecific predation and may increase the survival rates of smaller specimen. Hence, knowledge about the swimming velocities of species contribute to the understanding of interspecific competition among species and might support explanation approaches for the success of invasive species. Furthermore, it provides baselines for ecotoxicological studies of stressor impacts.

Meal or mate: Exploring the evidence of sexual cannibalism among amphibians.

Active forms of cannibalism that involve predation of live conspecifics occur widely among amphibians, most notably by tadpoles that feed on each other and adults that feed on juveniles. In contrast, cannibalism among amphibian adults (adult-adult cannibalism) is less often reported and there have been no investigations on the occurrence of sexual cannibalism in this group to date. In this study, we present an observation of potential sexual cannibalism involving an adult female green and golden bell frog, Litoria aurea, preying on a conspecific adult male during the species' breeding season. By comparing our observation to the available literature, we show that adult-adult cannibalism among amphibians is rare but tends to be committed by females against their male counterparts. We thus suggest that the occurrence of sexual cannibalism should be extended to include this group, where sexual size dimorphism occurs widely among adults that congregate spatially during breeding periods, both predictors of intra-specific predation. We hypothesise that amphibian females may be able to exploit male advertisement calls to differentiate suitable partners from potential prey and that male individuals are vulnerable to sexual cannibalism as they must risk attracting and physically exposing themselves to females in order to reproduce. Our findings reveal the complex dynamics that exist within adult amphibian populations, suggesting that females may have a choice when deciding how to interact with and utilise their male counterparts. As our findings are preliminary, based on a small sample size of records, including several from captive individuals, we encourage authors to publish their observations of cannibalism in the field, including unsuccessful attempts, to confirm the presence of sexual cannibalism in this group.

Canibalismo en Tityus metuendus Pocock, 1897 (Scorpiones: Buthidae) de la Amazonia brasileña

Scorpions are an important predator group in the habitats where they live, due to their voracity. However, their predatory habits are not well recorded, particularly in Amazonian species. Here we report four intraspecific predation events involving Tityus metuendus Pocock, 1987. In all cases, larger individuals acted as predators of smaller ones. These are the first reports of cannibalism involving scorpions in the Brazilian Amazon. Our findings are important to allow a better understanding of intraspecific interactions in tropical scorpion assemblages.

Dynamical of Prey Refuge in a Diased Predator-Prey Model with Intraspecific Competition for Predator

The predator-prey model described is a population growth model of an eco-epidemiological system with prey protection and predator intraspecific traits. Predation interactions in predator species use response functions. The aim of this research is to examine the local stable balance point and look at the characteristics of species resulting from mathematical modeling interventions. Review of balance point analysis, numerical simulation and analysis of given trajectories. The research results show the shape of the model which is arranged with a composition of 5 balance points. There is one rational balance point to be explained, using the Routh-Hurwitz criterion, . The characteristic equation and associated eigenvalues in the mathematical model are the local asymptotically stable balance points. In the trajectory analysis, local stability is also shown by the model formed. There are differences for each population to reach its point of stability. The role of prey protection behavior is very effective in suppressing the spread of disease. Meanwhile, intraspecific predator interactions are able to balance the decreasing growth of prey populations. If we increase the intraspecific interaction coefficient, we can be sure that the growth of the prey population will both increase significantly. When the number of prey populations increases significantly, of course disease transmission and prey protection become determining factors, the continuation of the model in exosite interactions. In prey populations and susceptible prey to infection, growth does not require a long time compared to the growth of predator populations. The time required to achieve stable growth is rapid for the prey species. Although prey species' growth is more fluctuating compared to predator populations. Predatory species are more likely to be stable from the start of their growth. The significance of predatory growth is only at the beginning of growth, while after that it increases slowly and reaches an ideal equilibrium point. Each species has its own characteristics, so extensive studies are needed on more complex forms of response functions in further research.

Filial cannibalism in rainbow boas (Epicrates cenchria and E. assisi)

Cannibalism, or intraspecific predation, refers to the practice in which an individual completely or partially consumes another conspecific. Filial cannibalism occurs when parents consume their own offspring, whether they are alive or stillborn. This study describes filial cannibalism behavior in just one female of each species, Amazon rainbow boa (Epicrates cenchria) and the Caatinga rainbow boa (E. assisi). We observed that female E. cenchria and E. assisi only consumed atretic eggs. A female E. cenchria consumed two out of the eight atretic eggs she delivered, while sparing the four neonates and the only stillborn fetus in her litter. A female E. assisi consumed two out of the four atretic eggs and attempted to ingest the amniotic sacs and liquid yolk throughout the entire observation, sparing two neonates. This is the first documented record of such behavior in E. assisi.

Feeding Spodoptera exigua larvae with gut-derived Escherichia sp. increases larval juvenile hormone levels inhibiting cannibalism

Feed quality influences insect cannibalistic behavior and gut microbial communities. In the present study, Spodoptera exigua larvae were fed six different artificial diets, and one of these diets (Diet 3) delayed larval cannibalistic behavior and reduced the cannibalism ratio after ingestion. Diet 3-fed larvae had the highest gut bacterial load (1.396 ± 0.556 × 1014 bacteria/mg gut), whereas Diet 2-fed larvae had the lowest gut bacterial load (3.076 ± 1.368 × 1012 bacteria/mg gut). The gut bacterial composition and diversity of different diet-fed S. exigua larvae varied according to the 16S rRNA gene sequence analysis. Enterobacteriaceae was specific to the Diet 3-fed larval gut. Fifteen culturable bacterial isolates were obtained from the midgut of Diet 3-fed larvae. Of these, ten belonged to Escherichia sp. After administration with Diet 1- or 2-fed S. exigua larvae, two bacterial isolates (SePC-12 and -37) delayed cannibalistic behavior in both tested larval groups. Diet 2-fed larvae had the lowest Juvenile hormone (JH) concentration and were more aggressive against intraspecific predation. However, SePC-12 loading increased the JH hormone levels in Diet 2-fed larvae and inhibited their cannibalism. Bacteria in the larval midgut are involved in the stabilization of JH levels, thereby regulating host larval cannibalistic behavior.

Larval feeding types shape the predation aggression of predatory mites in both intraspecific and interspecific encounters

Cannibalism (intraspecific predation) and intraguild (interspecific) predation are widely observed phenomena in the animal kingdom, including amongst predatory mites of the Phytoseiidae family. While the larval stage of phytoseiids is a vulnerable and important life stage, it has received less attention than the adult stage. The larvae of phytoseiid species can be categorised into three types based on their feeding behaviour: non-feeding, facultative feeding, and obligatory feeding. This study aimed to investigate the occurrence of cannibalism and intraguild predation among the larval stages of three generalist predatory phytoseiids: Amblydromalus limonicus (Garman & McGregor), Amblyseius herbicolus (Chant), and Neoseiulus cucumeris (Oudemans). We hypothesised that the larval feeding type could influence the aggressiveness of the predators in intraspecific and interspecific encounters, with obligatory-feeding larvae being the most aggressive and non-feeding larvae being the least aggressive. To test this hypothesis, we conducted a no-choice experiment under laboratory conditions using larvae to observe the prevalence of predation among conspecifics and heterospecifics in these three predatory mite species. In addition to observing predation outcomes, we measured larval body size, cheliceral size, and cheliceral morphology to investigate these parameters’ correlation with predation success. Our study revealed significant differences in the prevalence of cannibalism and intraguild predation among the three predatory species in agreement with our hypothesis: N. cucumeris larvae did not engage in predatory behaviours, while A. herbicolus displayed the highest predation success. Our findings suggest that cheliceral morphology may be a better indicator than body size of the aggressiveness of larval predation against conspecifics and heterospecifics. Our results provide valuable insights into the importance of larval behaviour in population dynamics and the development of effective pest management strategies. The study also highlights the need for further research on the larval stage of phytoseiids and emphasises the significance of considering larval behaviour when studying and managing these important predatory mites.

Aphidophagous predators in commercial Capsicum cultivars and characterization of their trophic network using stomach content analysis

AbstractViruses and aphids, the most recent vectors of viruses (Hemiptera: Aphididae) of the genera Myzus and Aphis, are the main phytosanitary problems of Capsicum spp. (Solanales: Solanaceae) agricultural systems in Colombia. The incorporation of biological control in integrated pest management (IPM) programmes, which can be used to reduce aphid populations in solanaceous crops, is hampered by the lack of information on the natural enemy community, such as parasitoids, predators and generalist aphidophagous. For this reason, the objective of this research was to determine and characterize the community of generalist aphidophagous (Coccinellidae and Syrphidae) in the cultivation of chilli pepper in south‐western Colombia, and to characterize their diet through stomach content analysis using next‐generation sequencing (NGS) techniques. Two species of Coccinellidae and one species of Syrphidae were the most abundant predators in commercial crops of Capsicum spp. and fed preferentially on aphids that attacked the pepper plants. The characterization of the diet of these predators using molecular tools revealed intraspecific predation, secondary predation of aphid parasitoids and consumption of alternative prey to the aphids attacking the pepper plants. Differences in diet composition were observed between larval and adult coccinellids, and between coccinellids and the hoverfly species studied. The results suggest that dominant predators may be suitable for use in IPM programmes to control aphids in pepper crops, as their diet consists mainly of aphids that attack pepper plants. In addition, these predators can take advantage of the agricultural matrix by feeding on alternative prey in the absence of aphids.

Diverse strategies that animals use to deter intraspecific predation.

Intraspecific predation is a special case of prey-predator system that is taxonomically widespread. While a heterospecific predator's main goal is to achieve nutrition, intraspecific predation provides conspecifics with other benefits including elimination of competitors for resources and mates. Traditionally intraspecific predation is termed based on the context they occur within, for example egg cannibalism, infanticide and sexual cannibalism. These diverse forms of intraspecific predation and the strategies by which animals are known to deter them are summarized categorically in this review. The diversity of defence strategies animals deploy against conspecific predators is appreciable and raises interesting questions on their evolution for future research.

Larval pikeperch Sander lucioperca cannibals are more efficient predators on zebrafish Danio rerio than non-cannibals

Cannibalism is an intra-specific predation often resulting in massive mortality in intensive cultured fish species. In piscivorous species, the onset of predation is inevitable. This study explored the link between predation abilities and the onset of cannibalism in pikeperch larvae, a top predator species, with a potential for the European inland aquaculture. Cannibals and non-cannibals, aged between 17 and 34 days-post-hatching, were tested to compare their predatory behavior using zebrafish and pikeperch larvae as prey. Each tested fish was confronted with three other fish (pikeperch or zebrafish) (n = 204 tests) in an arena (20 × 7 × 4 cm with 2 cm of water height, 280 mL) and their behavior was recorded for 20 min. The normal predatory behavioral sequence (orientation, approach, attack and capture) was much more efficient in cannibals (calculated as the ratio of number of captures on the number of attacks) than in non-cannibals in both the predation (0.31 ± 0.28 vs. 0.05 ± 0.15; padjust < 0.0001) and the cannibalism (0.21 ± 0.29 vs. 0.02 ± 0.08; padjust = 0.0006) tests. The shift to a piscivorous diet involved a modification of the attack tactic, replacing a “S-shape” by an attack without “S-shape” but with a tail propulsion. This second tactic developed earlier in cannibals whereas non-cannibals are only able to perform the “S-shape” attack used during the first days of life. Cannibalism was linked to the onset of an efficient piscivory behavior.

A chemical defense deters cannibalism in migratory locusts.

Many animals engage in cannibalism to supplement their diets. Among dense populations of migratory locusts, cannibalism is prevalent. We show that under crowded conditions, locusts produce an anticannibalistic pheromone called phenylacetonitrile. Both the degree of cannibalism and the production of phenylacetonitrile are density dependent and covary. We identified the olfactory receptor that detects phenylacetonitrile and used genome editing to make this receptor nonfunctional, thereby abolishing the negative behavioral response. We also inactivated the gene underlying phenylacetonitrile production and show that locusts that lack this compound lose its protection and are more frequently exposed to intraspecific predation. Thus, we reveal an anticannibalistic feature built on a specifically produced odor. The system is very likely to be of major importance in locust population ecology, and our results might therefore provide opportunities in locust management.

Breeding Biology of the Yellow-legged Gull (Larus michahellis, Naumann, 1840): a Small Island Population in Southwestern Türkiye

Urbanization and fisheries affected a rapid increase in seagull populations in western Mediterranean populations of the yellow-legged gull. The main reason is the increased food resources such as fisheries, big ports, and dumps. In this study, we aimed to understand and to compare the breeding biology of the yellow-legged gull in eastern Mediterranean. We studied on the small island in southwestern Türkiye between 2013 and 2015. All nesting sites were determined, marked, and monitored once a week. The breeding season has started in late February, nesting and laying eggs have started at the beginning of March, and they left the island in the second half of June after fledging. The incubation period is 29.17±2.85 days, only one clutch in a season and 2 or 3 eggs were laid in the nests. There was a slight increase in the number of pairs and nests between years but there is no significant difference in all parameters such as laying date, clutch size, hatching and fledging success in Pırasalı Island population and the rate of both hatching and fledging success are lower than western Mediterranean populations. While predation is the weakest factor for lower breeding success, intraspecific predation may be the factor but the main effect is the lower food abundance for the hatchlings.

Cannibalism in bears

Bears are the largest terrestrial carnivores, and most bear species can be characterized as opportunistic omnivores. An infrequent foraging tactic for bears is cannibalism, where a bear consumes a conspecific individual, either through scavenging or following intraspecific predation. Although several reports of cannibalism events are known, no attempt has been made so far to gather the available information to analyze for general patterns. We therefore performed a systematic literature review to understand patterns of cannibalism in bears. We documented 39 studies detailing 198 cannibalism events. We only found evidence of cannibalism in 4 of the 8 bear species, with more events reported for polar bears (Ursus maritimus; n = 107, 54.0%) than for all other species combined. Cannibalism was most frequently associated with infanticide (n = 66, 33.3%) and conspecific strife (n = 30, 15.2%), both of which were more frequent among males than females. The most common apparent reason for cannibalism among predators is to increase fitness (i.e., eating a conspecific increases nutrition, whereas killing reduces competition for resources), but is also often linked to sexually selected infanticide in bears. Cannibalism most often appears to be an opportunistic consumption of an available carcass and not directly connected with the primary cause of death. As such, cannibalism in bears may be more casual and opportunistic than a behavior that evolved as a life history strategy.

Dynamical analysis of a juvenile-adult model

Because of the competition among populations in the world, cannibalism is practiced by a wide variety of populations. In most populations where cannibals part resources with their immolation, dependent of a size trait is observed. Using this perspective, a juvenile-adult model is developed under the assumption that adults prey juveniles and adults are bigger in size than juveniles. The model incorporates a Holling type I function that proper the intra-specific predation mount of the crowd at that the juvenile is used up, each adult, as a subordinate of the juvenile density making the model applicable to most population structures as compared to those in literature. Furthermore, the presented sufficient conditions in which the system reaches an equilibrium show the exibility of the model. In particular, we discussed the stability conditions of equilibriums.

The (De)Stabilizing effect of juvenile prey cannibalism in a stage-structured model.

Cannibalism, or intraspecific predation, is the act of an organism consuming another organism of the same species. In predator-prey relationships, there is experimental evidence to support the existence of cannibalism among juvenile prey. In this work, we propose a stage-structured predator-prey system where cannibalism occurs only in the juvenile prey population. We show that cannibalism has both a stabilizing and destabilizing effect depending on the choice of parameters. We perform stability analysis of the system and also show that the system experiences a supercritical Hopf, saddle-node, Bogdanov-Takens and cusp bifurcation. We perform numerical experiments to further support our theoretical findings. We discuss the ecological implications of our results.

Dietary shifts and niche partitioning throughout ontogeny reduce intraspecific competition in a pelagic generalist predator

Patterns of feeding strategy change throughout ontogeny according to size-specific abilities and requirements. Characterizing the extent and potential repeated occurrence of dietary differences within the population can improve understanding of the intraspecific predation regime and population dynamics. Here, we investigated size-related feeding habits and trophic niche partitioning of an iconic pelagic generalist predator, the jumbo squid Dosidicus gigas, by a combined analysis of morphologic indicators of feeding capability (fin and feeding apparatuses), trophic biochemical tracers (stable isotopes and fatty acids), and stomach contents. Results showed significant variation in prey composition, isotopic values, and fatty acid profiles with size. D. gigas exhibited a shift in diet at approximately 250 mm mantle length (ML). The trophic niche of small (ML ≤ 250 mm) and large (ML &gt; 250 mm) squid revealed low potential for resource overlap, suggesting segregation in terms of spatial and food resources of different size groups. Large individuals tend to feed deeper and on smaller prey to optimize food capture costs and energy benefits. This feeding strategy is likely related to variability in the development of feeding capacity, increasing swimming ability, and metabolic demand as squid grow and may reduce intraspecific competition to improve survival. These results highlight the dietary flexibility of D. gigas and demonstrate that niche differentiation acts as a major factor in a cohort, which may have important implications for their population dynamics and management. In addition, this study demonstrates that using multiple diet tracers can highlight subtle differentiations in diet correlated to growth in a pelagic generalist predator.

Cannibalistic necrophagy in red foxes: do the nutritional benefits offset the potential costs of disease transmission?

Cannibalism, or intraspecific predation, occurs when an individual consumes another individual of its own species; c.f. ‘cannibalistic/conspecific/intraspecific necrophagy’ when the individual consumes all or part of a dead conspecific. These behaviors are widespread across animal taxa but are considered rare among mammalian carnivores. The consumption of conspecifics could involve ecological and nutritional benefits in providing high-quality resources. However, it can carry potential risks such as those related to pathogen transmission. Despite this, the overall role of conspecific consumption in disease transmission among animals has received little attention. Here, we report the first direct observations of cannibalistic necrophagy in red foxes Vulpes vulpes. Our photographs of this behavior prompt speculation on the role of cannibalism in fox population dynamics and intraspecific disease transmission. We placed six fox and seven lamb carcasses of similar size to determine possible differences in the scavenging behavior of red foxes between dead conspecifics and heterospecifics. Conspecific necrophagy was recorded at all fox carcasses, involving foxes scavenging fox carcasses at different stages of decay. Carcass detection time by foxes was similar at both fox and lamb carcasses, but lambs were completely consumed in a shorter period, evidencing a preference for heterospecific consumption. Our findings contrast with other studies which argue that cannibalism avoidance in mammalian carnivores is due to an evolutionary strategy to reduce the probability of disease transmission. In fact, our observations of conspecific necrophagy provide direct evidence against the parasite-avoidance hypothesis, suggesting that carnivore and conspecific carcasses can represent an alternative trophic resource for foxes in certain areas and circumstances.

Dynamics and patterns of species abundance in ocean: A mathematical modeling study

In the complex and competitive world of oceans, different size of plants and animals exist. All of them compete for the limited resources; e.g., nutrients, sunlight, minerals etc. Size-specific and intraspecific predation is common among zooplankton. We design a model food chain and explore dynamics, and patterns of species abundance in ocean. The proposed mathematical model is based on a parameter; exponent of closure, m. A value of m less than 1 represents both size-specific and intraspecific predation among zooplankton. The mathematical model has been extended to include random movements of all the constituent populations by adding Fickian diffusion. Eigenvalues and amplitude equations are used to figure out relevant parameter spaces for numerical exploration. An analysis of the spatial system in the neighborhood of a critical parameter is performed using amplitude equation. Choosing appropriate control parameter from the Turing space, existence conditions for stable patterns are derived. Equal density contours were plotted for all the constituents of the model food chain. Epidemiological significance of these spatial patterns is provided.

Review of inter and intraspecific predation by shorebirds

Predation is often the most important driver of breeding productivity and population dynamics in birds, with an increasing impact in the currently rapidly changing world. Despite decades of intensive research, our understanding of trophic interactions and food webs is still limited. Although there is good knowledge of regular predators within particular groups of animals, focused overviews of such predator-prey interactions are often lacking. Here, I review predation behaviour by shorebirds: plovers, sandpipers and allies, over the globe – presenting 16 cases of interspecific predation relationships and two cases of intraspecific predation of eggs or chicks, altogether involving 11 species of predators and 13 species of prey.

Unbalanced population structure and reliance on intraspecific predation by largemouth bass in an agricultural pond with no available prey fish

The carnivorous largemouth bass Micropterus salmoides has been introduced to many regions and poses a threat to native aquatic organisms due to predation, resulting in a significant decrease in biodiversity. Under conditions of prey scarcity, the largemouth bass is thought to consume smaller conspecifics. However, little is known about this species’ dietary reliance on intraspecific predation and its impact on the population structure. We investigated the length–frequency distribution of largemouth bass and estimated their reliance on intraspecific predation using stable carbon and nitrogen isotopes in an agricultural pond with no available prey fish. Almost all individual largemouth bass were collected via the pond drainage system. Within the largemouth bass population, the dominant length class was composed of fish measuring 100–160 mm standard length (SL), whereas few individuals measuring < 100 mm SL (first-year juveniles) were collected. The results from a Stable Isotope Analysis in R mixing model indicated that all four length classes (105–146, 165–180, 216–246, and 300–337 mm SL) of largemouth bass fed mainly on juvenile conspecifics and on red swamp crayfish (Procambarus clarkii). First-year juveniles could have been predated by other individuals of various sizes. The dominant 100–160 mm SL length class may have experienced a weak predation pressure when they were in the first-year juvenile class. Consequently, the largemouth bass population was unbalanced, with few first-year juveniles (< 100 mm SL) and dominance of a 100–160 mm SL length class.