Articles de revues : « Predatory-prey systems »

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Mukherjee, Debasis, et A. B. Roy. « Global stability of prey-predator systems with predatory switching ». Biosystems 27, n^o 3 (janvier 1992) : 171–78. http://dx.doi.org/10.1016/0303-2647(92)90071-6.

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Nair, Ramith R., et Gregory J. Velicer. « Predatory Bacteria Select for Sustained Prey Diversity ». Microorganisms 9, n^o 10 (2 octobre 2021) : 2079. http://dx.doi.org/10.3390/microorganisms9102079.

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Predator impacts on prey diversity are often studied among higher organisms over short periods, but microbial predator-prey systems allow examination of prey-diversity dynamics over evolutionary timescales. We previously showed that Escherichia coli commonly evolved minority mucoid phenotypes in response to predation by the bacterial predator Myxococcus xanthus by one time point of a coevolution experiment now named MyxoEE-6. Here we examine mucoid frequencies across several MyxoEE-6 timepoints to discriminate between the hypotheses that mucoids were increasing to fixation, stabilizing around equilibrium frequencies, or heading to loss toward the end of MyxoEE-6. In four focal coevolved prey populations, mucoids rose rapidly early in the experiment and then fluctuated within detectable minority frequency ranges through the end of MyxoEE-6, generating frequency dynamics suggestive of negative frequency-dependent selection. However, a competition experiment between mucoid and non-mucoid clones found a predation-specific advantage of the mucoid clone that was insensitive to frequency over the examined range, leaving the mechanism that maintains minority mucoidy unresolved. The advantage of mucoidy under predation was found to be associated with reduced population size after growth (productivity) in the absence of predators, suggesting a tradeoff between productivity and resistance to predation that we hypothesize may reverse mucoid vs non-mucoid fitness ranks within each MyxoEE-6 cycle. We also found that mucoidy was associated with diverse colony phenotypes and diverse candidate mutations primarily localized in the exopolysaccharide operon yjbEFGH. Collectively, our results show that selection from predatory bacteria can generate apparently stable sympatric phenotypic polymorphisms within coevolving prey populations and also allopatric diversity across populations by selecting for diverse mutations and colony phenotypes associated with mucoidy. More broadly, our results suggest that myxobacterial predation increases long-term diversity within natural microbial communities.

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Pratt, P. D., et B. A. Croft. « Banker Plants : Evaluation of Release Strategies for Predatory Mites ». Journal of Environmental Horticulture 18, n^o 4 (1 décembre 2000) : 211–17. http://dx.doi.org/10.24266/0738-2898-18.4.211.

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Abstract Spider mites (Tetranychidae) are among the most injurious pests of commercial landscape plant nurseries. The introduction of predaceous mites (Phytoseiidae) into nursery crops for control of spider mites can be an effective alternative to pesticides. We sought to evaluate the use of banker plants as a method of rearing and dispersing predatory mites for the control of spider mites in landscape nursery systems. Banker plants include any plant addition that aids in development and dispersal of predators for control of herbivorous pests. Addition of the predatory mite Neoseiulus fallacis (Garman) into spider mite infested arborvitae and rhododendron banker plants held in replicated greenhouse cubicles resulted in more predatory mites dispersing to spider mite infested plants downwind than were originally inoculated. To improve persistence and subsequent dispersal of predatory mites in an arborvitae banker plant, we evaluated the use of adding supplemental prey (spider mites) and applying a portion of the plant foliage with a pyrethroid to provide a refuge for the prey. Reintroduction of prey increased the dispersal duration of N. fallacis but the pyrethroid-based refuge did not. Predatory mites dispersing from arborvitae banker plants of approximately 1.25 m (4.1 ft) tall were collected from receiver plants at 10, 20 and 30 m (10.9, 21.9 and 32.8 yd) down wind. Integration of a banker plant system into a landscape nursery operation is discussed.

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Wardill, Trevor J., Katie Knowles, Laura Barlow, Gervasio Tapia, Karin Nordström, Robert M. Olberg et Paloma T. Gonzalez-Bellido. « The Killer Fly Hunger Games : Target Size and Speed Predict Decision to Pursuit ». Brain, Behavior and Evolution 86, n^o 1 (2015) : 28–37. http://dx.doi.org/10.1159/000435944.

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Predatory animals have evolved to optimally detect their prey using exquisite sensory systems such as vision, olfaction and hearing. It may not be so surprising that vertebrates, with large central nervous systems, excel at predatory behaviors. More striking is the fact that many tiny insects, with their miniscule brains and scaled down nerve cords, are also ferocious, highly successful predators. For predation, it is important to determine whether a prey is suitable before initiating pursuit. This is paramount since pursuing a prey that is too large to capture, subdue or dispatch will generate a substantial metabolic cost (in the form of muscle output) without any chance of metabolic gain (in the form of food). In addition, during all pursuits, the predator breaks its potential camouflage and thus runs the risk of becoming prey itself. Many insects use their eyes to initially detect and subsequently pursue prey. Dragonflies, which are extremely efficient predators, therefore have huge eyes with relatively high spatial resolution that allow efficient prey size estimation before initiating pursuit. However, much smaller insects, such as killer flies, also visualize and successfully pursue prey. This is an impressive behavior since the small size of the killer fly naturally limits the neural capacity and also the spatial resolution provided by the compound eye. Despite this, we here show that killer flies efficiently pursue natural (Drosophila melanogaster) and artificial (beads) prey. The natural pursuits are initiated at a distance of 7.9 ± 2.9 cm, which we show is too far away to allow for distance estimation using binocular disparities. Moreover, we show that rather than estimating absolute prey size prior to launching the attack, as dragonflies do, killer flies attack with high probability when the ratio of the prey's subtended retinal velocity and retinal size is 0.37. We also show that killer flies will respond to a stimulus of an angular size that is smaller than that of the photoreceptor acceptance angle, and that the predatory response is strongly modulated by the metabolic state. Our data thus provide an exciting example of a loosely designed matched filter to Drosophila, but one which will still generate successful pursuits of other suitable prey.

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RUEDA-RAMÍREZ, DIANA, ERIC PALEVSKY et LILIANE RUESS. « Trophic links between soil predatory mites and nematodes as a key component of conservation biocontrol ». Zoosymposia 22 (30 novembre 2022) : 61. http://dx.doi.org/10.11646/zoosymposia.22.1.30.

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Biological control is an important ecosystem service for soil and plant health and has been successfully exploited, especially through augmentative biological control programs, for above-ground agricultural pest control often using predatory mites of Mesostigmata. Similar success has not been achieved for below-ground systems. Predatory mites are an important part of soil food webs, in which they have a regulatory impact. While this is mediated by the predator on the prey, recent studies suggest that biocontrol efficiency can be enhanced in the mid to long term for generalist predators by the presence of complementary prey. In below-ground systems, nematodes are an important food source and numerous species of predatory mites in soil may prefer them. Thus, nematodes are a viable and accessible alternative prey for these natural enemies. Our aim was to review the studies on mite-nematode trophic interactions and how these interactions affect the regulatory activity of predatory mites in soil. We found ca. 170 publications reporting a predator-prey interaction. The majority of the studies were conducted in the laboratory (149 studies), but important correlations between nematode and mite densities have been observed in greenhouses and in the open field. Most reports involved free-living nematodes (FLN), followed by plant-parasitic nematodes (PPN) and finally animal-parasitic nematodes (APN). These reports are for Astigmatina, Endeostigmata, Prostigmata, Oribatida (non-Astigmatina) and Mesostigmata, the latter group being the one in which most nematophagous species are known. The family with the most reports of nematophagy is Ascidae (46 species), followed by Macrochelidae and Laelapidae (both with 30 species). In many cases, a positive effect on reproductive parameters and developmental times of mite species has been observed with a nematode-based diet, especially FLN. Although still scarce, studies on species of Laelapidae, Macrochelidae, Parasitidae and Rhodacaridae have shown that supplementing FLN in the diet can favor reproduction and development, even though preference may change at different stages of development. Also, recent studies have shown that some organic amendments can increase the density and diversity of mites, FLN or both, enhancing top down forces by predatory mites in the soil food web. Although some steps have been taken, future studies should focus on transferring laboratory research to field and semi-field conditions. For this, a multidisciplinary approach is essential.

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Steyert, Susan R., et Silvia A. Pineiro. « Development of a Novel Genetic System To Create Markerless Deletion Mutants of Bdellovibrio bacteriovorus ». Applied and Environmental Microbiology 73, n^o 15 (8 juin 2007) : 4717–24. http://dx.doi.org/10.1128/aem.00640-07.

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ABSTRACT Bdellovibrio bacteriovorus is a species of unique obligate predatory bacteria that utilize gram-negative bacteria as prey. Their life cycle alternates between a motile extracellular phase and a growth phase within the prey cell periplasm. The mechanism of prey cell invasion and the genetic networks and regulation during the life cycle have not been elucidated. The obligate predatory nature of the B. bacteriovorus life cycle suggests the use of this bacterium in potential applications involving pathogen control but adds complexity to the development of practical genetic systems that can be used to determine gene function. This work reports the development of a genetic technique for allelic exchange or gene inactivation by construction of in-frame markerless deletion mutants including the use of a counterselectable marker in B. bacteriovorus. A suicide plasmid carrying the sacB gene for counterselection was used to inactivate the strB gene in B. bacteriovorus HD100 by an in-frame deletion. Despite the inactivation of the strB gene, B. bacteriovorus was found to retain resistance to high concentrations of streptomycin. The stability of a plasmid for use in complementation experiments was also investigated, and it was determined that pMMB206 replicates autonomously in B. bacteriovorus. Development of this practical genetic system now facilitates the study of B. bacteriovorus at the molecular level and will aid in understanding the regulatory networks and gene function in this fascinating predatory bacterium.

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Brodin, Tomas, Susanna Piovano, Jerker Fick, Jonatan Klaminder, Martina Heynen et Micael Jonsson. « Ecological effects of pharmaceuticals in aquatic systems—impacts through behavioural alterations ». Philosophical Transactions of the Royal Society B : Biological Sciences 369, n^o 1656 (19 novembre 2014) : 20130580. http://dx.doi.org/10.1098/rstb.2013.0580.

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The study of animal behaviour is important for both ecology and ecotoxicology, yet research in these two fields is currently developing independently. Here, we synthesize the available knowledge on drug-induced behavioural alterations in fish, discuss potential ecological consequences and report results from an experiment in which we quantify both uptake and behavioural impact of a psychiatric drug on a predatory fish ( Perca fluviatilis ) and its invertebrate prey ( Coenagrion hastulatum ). We show that perch became more active while damselfly behaviour was unaffected, illustrating that behavioural effects of pharmaceuticals can differ between species. Furthermore, we demonstrate that prey consumption can be an important exposure route as on average 46% of the pharmaceutical in ingested prey accumulated in the predator. This suggests that investigations of exposure through bioconcentration, where trophic interactions and subsequent bioaccumulation of exposed individuals are ignored, underestimate exposure. Wildlife may therefore be exposed to higher levels of behaviourally altering pharmaceuticals than predictions based on commonly used exposure assays and pharmaceutical concentrations found in environmental monitoring programmes.

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Mathis, Ute, Sabine Eschbach et Samuel Rossel. « Functional binocular vision is not dependent on visual experience in the praying mantis ». Visual Neuroscience 9, n^o 2 (août 1992) : 199–203. http://dx.doi.org/10.1017/s0952523800009652.

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AbstractIn vertebrates, it has been shown that binocular visual experience is necessary to develop normal spatial vision. We have investigated whether this is also true for an invertebrate, the praying mantis. The praying mantis is a predatory insect in which prey localization involves the use of binocular disparities. We raised mantids which had one eye occluded throughout development and tested monocular visual fixation and binocular distance estimation in the adult animals. The results revealed that both fixation and prey catching behavior were normally functional in the monocularly reared animals. Thus we conclude that, in mantids, binocular vision is based on a fixed mode of development.

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Cairns, Johannes, Felix Moerman, Emanuel A. Fronhofer, Florian Altermatt et Teppo Hiltunen. « Evolution in interacting species alters predator life-history traits, behaviour and morphology in experimental microbial communities ». Proceedings of the Royal Society B : Biological Sciences 287, n^o 1928 (3 juin 2020) : 20200652. http://dx.doi.org/10.1098/rspb.2020.0652.

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Predator–prey interactions heavily influence the dynamics of many ecosystems. An increasing body of evidence suggests that rapid evolution and coevolution can alter these interactions, with important ecological implications, by acting on traits determining fitness, including reproduction, anti-predatory defence and foraging efficiency. However, most studies to date have focused only on evolution in the prey species, and the predator traits in (co)evolving systems remain poorly understood. Here, we investigated changes in predator traits after approximately 600 generations in a predator–prey (ciliate–bacteria) evolutionary experiment. Predators independently evolved on seven different prey species, allowing generalization of the predator's evolutionary response. We used highly resolved automated image analysis to quantify changes in predator life history, morphology and behaviour. Consistent with previous studies, we found that prey evolution impaired growth of the predator, although the effect depended on the prey species. By contrast, predator evolution did not cause a clear increase in predator growth when feeding on ancestral prey. However, predator evolution affected morphology and behaviour, increasing size, speed and directionality of movement, which have all been linked to higher prey search efficiency. These results show that in (co)evolving systems, predator adaptation can occur in traits relevant to foraging efficiency without translating into an increased ability of the predator to grow on the ancestral prey type.

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Soley, Fernando G. « Fine-scale analysis of an assassin bug's behaviour : predatory strategies to bypass the sensory systems of prey ». Royal Society Open Science 3, n^o 10 (octobre 2016) : 160573. http://dx.doi.org/10.1098/rsos.160573.

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Some predators sidestep environments that render them conspicuous to the sensory systems of prey. However, these challenging environments are unavoidable for certain predators. Stenolemus giraffa is an assassin bug that feeds on web-building spiders; the web is the environment in which this predator finds its prey, but it also forms part of its preys' sophisticated sensory apparatus, blurring the distinction between environment and sensory systems. Stenolemus giraffa needs to break threads in the web that obstruct its path to the spiders, and such vibrations can alert the spiders. Using laser vibrometry, this study demonstrates how S. giraffa avoids alerting the spiders during its approach. When breaking threads, S. giraffa attenuates the vibrations produced by holding on to the loose ends of the broken thread and causing them to sag prior to release. In addition, S. giraffa releases the loose ends of a broken thread one at a time (after several seconds or minutes) and in this way spaces out the production of vibrations in time. Furthermore, S. giraffa was found to maximally reduce the amplitude of vibrations when breaking threads that are prone to produce louder vibrations. Finally, S. giraffa preferred to break threads in the presence of wind, suggesting that this araneophagic insect exploits environmental noise that temporarily impairs the spiders' ability to detect vibrations. The predatory behaviour of S. giraffa seems to be adaptated in intricate manner for bypassing the sophisticated sensory systems of web-building spiders. These findings illustrate how the physical characteristics of the environment, along with the sensory systems of prey can shape the predatory strategies of animals.

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Duplisea, Daniel E. « Running the gauntlet : the predation environment of small fish in the northern Gulf of St Lawrence, Canada ». ICES Journal of Marine Science 62, n^o 3 (1 janvier 2005) : 412–16. http://dx.doi.org/10.1016/j.icesjms.2004.11.005.

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Abstract Predation size spectra were constructed for the northern Gulf of St Lawrence, covering prey size ranges that include pre-recruit cod. Predation by fish and harp seals was modelled with a log-normally distributed predator–prey size ratio along with a relationship between predator body size and the energy required. Fish concentrate predation on prey of weight 0.5–2 g, whereas harp seals prefer prey of 60–125 g. It is speculated that predation caused by harp seals on pre-recruits could be a major factor limiting cod recruitment in the system. The northern Gulf of St Lawrence is a cold boreal system with a large predatory seal population, and cod recruit older than elsewhere. Therefore, cod recruitment may be more strongly affected by predation in the northern Gulf of St Lawrence than in warmer systems such as the North Sea, where recruitment is strongly influenced by temperature.

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McKinley, Cheyenne N., et Sarah E. Lower. « Comparative Transcriptomics Reveals Gene Families Associated with Predatory Behavior in Photuris femme fatale Fireflies ». Genes 11, n^o 6 (7 juin 2020) : 627. http://dx.doi.org/10.3390/genes11060627.

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Identifying the basis of phenotypic variation is a key objective of genetics. This work has been mostly limited to model systems with a plethora of genetic manipulation and functional characterization tools. With the development of high-throughput sequencing and new computational tools, it is possible to identify candidate genes related to phenotypic variation in non-model organisms. Fireflies are excellent for studying phenotypic variation because of their diverse and well-characterized behaviors. Most adult fireflies emit a single mating flash pattern and do not eat. In contrast, adult females of many species in the genus Photuris employ multiple flash patterns and prey upon mate-seeking males of other firefly species. To investigate the genetic basis for this variation, we used comparative transcriptomics to identify positively selected genes between a predatory firefly, Photuris sp., and a non-predatory relative, Photuris frontalis, controlling for genes generally under selection in fireflies by comparing to a Photinus firefly. Nine gene families were identified under positive selection in the predatory versus non-predatory Photuris comparison, including genes involved in digestion, detoxification, vision, reproduction, and neural processes. These results generate intriguing hypotheses about the genetic basis for insect behavior and highlight the utility of comparative transcriptomic tools to investigate complex behaviors in non-model systems.

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Calvete, Juan J. « Snake venomics at the crossroads between ecological and clinical toxinology ». Biochemist 41, n^o 6 (2 décembre 2019) : 28–33. http://dx.doi.org/10.1042/bio04106028.

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Venoms are complex secretions used for predatory and defensive purposes by a wide range of organisms. Venoms and venom production represent fascinating systems to study fundamental evolutionary processes. Understanding the evolution of venom generation demands the integration of the selective interactions and mechanisms, which transformed ordinary genes into deadly toxins, in the context of the natural history of the producing organism. Humans are not prey for any extant venomous creature on Earth, and thus human envenomings result from unexpected encounters with venomous animals, e.g., snakes. Research on snake venoms conducted on mammalian prey from an ecologically informed perspective is conceptually transferable to the clinic, highlighting the mutually enlightening relationship between evolutionary and translational venomics.

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Matassa, Catherine M., et Geoffrey C. Trussell. « Prey state shapes the effects of temporal variation in predation risk ». Proceedings of the Royal Society B : Biological Sciences 281, n^o 1796 (7 décembre 2014) : 20141952. http://dx.doi.org/10.1098/rspb.2014.1952.

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The ecological impacts of predation risk are influenced by how prey allocate foraging effort across periods of safety and danger. Foraging decisions depend on current danger, but also on the larger temporal, spatial or energetic context in which prey manage their risks of predation and starvation. Using a rocky intertidal food chain, we examined the responses of starved and fed prey ( Nucella lapillus dogwhelks) to different temporal patterns of risk from predatory crabs ( Carcinus maenas ). Prey foraging activity declined during periods of danger, but as dangerous periods became longer, prey state altered the magnitude of risk effects on prey foraging and growth, with likely consequences for community structure (trait-mediated indirect effects on basal resources, Mytilus edulis mussels), prey fitness and trophic energy transfer. Because risk is inherently variable over time and space, our results suggest that non-consumptive predator effects may be most pronounced in productive systems where prey can build energy reserves during periods of safety and then burn these reserves as ‘trophic heat’ during extended periods of danger. Understanding the interaction between behavioural (energy gain) and physiological (energy use) responses to risk may illuminate the context dependency of trait-mediated trophic cascades and help explain variation in food chain length.

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New, J. G., L. Alborg Fewkes et A. N. Khan. « Strike feeding behavior in the muskellunge, Esox masquinongy : contributions of the lateral line and visual sensory systems ». Journal of Experimental Biology 204, n^o 6 (15 mars 2001) : 1207–21. http://dx.doi.org/10.1242/jeb.204.6.1207.

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The muskellunge, Esox masquinongy, is a predatory esocid fish with well-developed visual and lateral line systems. The purpose of this study was to determine the relative roles of these two sensory modalities in organizing the strike behavior of the animal. Subadult muskellunge were videotaped in a test arena while feeding on fathead minnows (Pimephales promelas). Animals were tested under five conditions: (i) control animals in which the visual and lateral line systems were intact; (ii) animals with lateral line afference suppressed by immersion for 12–24 h in 0.1 mmol l(−1) CoCl2; (iii) animals blinded by bilateral optic nerve transection; (iv) animals that had been unilaterally blinded; and (v) animals in which the lateral line system had been unilaterally denervated. The feeding behavior of the muskellunge consists of two phases: a slow stalk of the prey with minimal body movement followed by an explosive C- or S-start lunge at the prey. Quantitative comparisons of animals in the five test groups indicate that, although vision is used in the initial acquisition of the prey, both vision and the lateral line system play important roles in determining the initiation of the rapid strike. The lateral line system may play a critical role in the final capture of the prey at the end of the strike. In addition, lateral-line-suppressed muskellunge strongly alter their approaches to more distant prey. Bilaterally blinded muskellunge do not stalk their prey, but will lunge only at prey that are at close range. Unilaterally blinded or denervated muskellunge also alter their detection of and approach to prey, attending to a wider region of the intact sensory hemisphere. Our data suggest not only that the visual and lateral line systems play complementary roles in the feeding behavior sequence but also that each system plays a more or less dominant role during consecutive phases of the behavior.

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Ayala-Sulca, Yuri, Reynán Cóndor-Alarcón, Percy Colos-Galindo, Jorge Arenas-Terrel, Carlos Huayhua-Lobatón, Antonio Jeri-Chávez, Carlos Carrasco-Badajoz et José Iannacone. « PREDATORY EFFECT AND SELECTIVITY OF PREY OF NOTONECTA PERUVIANA (HEMIPTERA : NOTONECTIDAE) ON THE LARVAL CONTROL OF MOSQUITOES (DIPTERA : CULICIDAE) ». Oecologia Australis 26, n^o 01 (16 mars 2022) : 34–44. http://dx.doi.org/10.4257/oeco.2022.2601.04.

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The larval stage of culicid mosquitoes are the main food resource of notonectides in aquatic systems. Prey alternation and abundance can significantly affect predator-prey interaction and functional response (FR). We evaluated the effect of predation and prey selectivity of Notonecta peruviana in fourth-stage larvae (F1) of Aedes aegypti and Culex quinquefasciatus at different densities and two test systems: one prey and the combination of both (ratio 1: 1). We used the FR protocol to measure predation and the Manly preference index () to evaluate the selectivity of prey, in a CRD experimental design. N. peruviana generated type II RF (“concave model”) of greater impact in larvae of Ae. aegypti (p ≤ 0.01). Predation capacity was similar in both of the prey, 17 ± 4 larvae / day in Cx. quinquefasciatus and 21 ± 4 in Ae. aegypti. The attack coefficient (a), turned out to be similar for both prey species in both test systems and the handling time (Th) was lower for Ae. aegypti than for Culex. Notonecta peruviana demonstrated selectivity for larvae of Ae. aegypti especially at the highest densities (≥ 0.5), attributed to the inefficient anti depredation response, active mobility and smaller size compared to those of Cx. quinquefasciatus. The FR demonstrated the success of N. peruviana in the larval control of culicid mosquitoes, prioritizing the type of prey; thus, promoting the need for its applicability in the field.

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Buse, Alexanader J., Meghan A. Douglas, Thomas N. Giguere et Beren W. Robinson. « Adult Snapping Turtle (Chelydra serpentina) Feeding on Goldeneye Embryos of Pumpkinseed (Lepomis gibbosus) in Defended Nests ». Canadian Field-Naturalist 131, n^o 3 (28 février 2018) : 254–57. http://dx.doi.org/10.22621/cfn.v131i3.1859.

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Rarely observed predatory behaviour of adult Snapping Turtles (Chelydra serpentina) was recorded using remote video technology. We observed turtles inspecting and, in one case, apparently feeding on goldeneye stage embryos (< 3 mm) from defended nests of Pumpkinseed (Lepomis gibbosus). This novel behaviour was limited to nests in a secluded bay and was not observed at nests located along exposed shorelines or on shallow shoals in the deep open water habitat of an inland oligotrophic lake. The benefit of feeding on small prey is likely enhanced by embryos being clustered in nests and by an abundance of sunfish nests. Low-cost and low-intrusion video technology provides excellent opportunities, even in aquatic systems, to document novel predator and prey behaviours.

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Buchheister, Andre, et Robert J. Latour. « Dynamic trophic linkages in a large estuarine system — support for supply-driven dietary changes using delta generalized additive mixed models ». Canadian Journal of Fisheries and Aquatic Sciences 73, n^o 1 (janvier 2016) : 5–17. http://dx.doi.org/10.1139/cjfas-2014-0441.

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Trophic dynamics within aquatic systems are a predominant regulator of fish production and an important consideration for implementing ecosystem approaches to fisheries management. We analyzed 10 years of fish diet data from Chesapeake Bay, USA, to (1) evaluate the effects of environmental variables on trophic interactions of 12 common predatory fishes, (2) infer dynamics of four key prey groups (mysids, bay anchovy, bivalves, and polychaetes), and (3) evaluate whether interannual dietary trends were coherent among predators and regulated by prey availability. Based on delta generalized additive mixed models (delta-GAMMs), predator length was the most important covariate in modeling prey consumption. When latitude, temperature, and depth effects were statistically significant, the effects of each variable were largely similar across predators for a given prey. Annual patterns of mysid and bivalve consumption each showed a single, dramatic peak shared by multiple predators with varied feeding preferences and distributional characteristics, but annual trends were not correlated with available survey-based measures of prey availability, likely due to methodological differences. Overall, the coherence in consumption patterns across predators was consistent with supply-driven dynamics controlled by regional and annual changes in prey availability. Also, the novel application of delta-GAMMs to fish diet data was useful in characterizing the dynamics of poorly sampled prey groups and the trophic interactions for ubiquitous species from the Northwest Atlantic Ocean.

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Potier, Simon. « Visual Adaptations in Predatory and Scavenging Diurnal Raptors ». Diversity 12, n^o 10 (15 octobre 2020) : 400. http://dx.doi.org/10.3390/d12100400.

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Ecological diversity among diurnal birds of prey, or raptors, is highlighted regarding their sensory abilities. While raptors are believed to forage primarily using sight, the sensory demands of scavengers and predators differ, as reflected in their visual systems. Here, I have reviewed the visual specialisations of predatory and scavenging diurnal raptors, focusing on (1) the anatomy of the eye and (2) the use of vision in foraging. Predators have larger eyes than scavengers relative to their body mass, potentially highlighting the higher importance of vision in these species. Scavengers possess one centrally positioned fovea that allows for the detection of carrion at a distance. In addition to the central fovea, predators have a second, temporally positioned fovea that views the frontal visual field, possibly for prey capture. Spatial resolution does not differ between predators and scavengers. In contrast, the organisation of the visual fields reflects important divergences, with enhanced binocularity in predators opposed to an enlarged field of view in scavengers. Predators also have a larger blind spot above the head. The diversity of visual system specializations according to the foraging ecology displayed by these birds suggests a complex interplay between visual anatomy and ecology, often unrelatedly of phylogeny.

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Leighton, Lindsey R. « Inferring predation intensity in the marine fossil record ». Paleobiology 28, n^o 3 (2002) : 328–42. http://dx.doi.org/10.1666/0094-8373(2002)028<0328:ipiitm>2.0.co;2.

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Accurate estimates of predation intensity, the frequency of mortality from predation, are critical to studies of the evolution of species in response to predation, and to studies of predator-prey systems in general. Most commonly used indirect proxies for predation intensity in the fossil record have logistical or theoretical problems. Direct proxies, using actual traces of predatory activity, such as drilling and repair scars, may hold more promise. However, these direct proxies often have been used in conjunction with optimal foraging models, and in this context, the underlying assumptions and predictions of optimal foraging are examined.Results from theoretical models using optimal foraging suggest that (1) the ratio of internal shell volume to shell thickness of prey (benefit/cost ratio) may be a questionable measurement of prey “value” to the predator, as it fails to account adequately for energetic cost to the predator during pursuit and grappling; (2) drilling and repair frequency are invalid measures of prey preference, because optimal foraging predicts that specific prey types are either always taken or always ignored; (3) pooled drilling frequency will not be a useful metric of predation intensity in systems in which the predator need not always drill; and (4) an increase in repair frequency can be a consequence of either an increase or a decrease in predation intensity.Although drilling frequency may not indicate prey preference, it is a valid proxy for selection due to predation. An approach using size classes, in which the minimum size at which a predation refuge is achieved, is suggested for use with repair frequency.

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Gårdmark, Anna, Michele Casini, Magnus Huss, Anieke van Leeuwen, Joakim Hjelm, Lennart Persson et André M. de Roos. « Regime shifts in exploited marine food webs : detecting mechanisms underlying alternative stable states using size-structured community dynamics theory ». Philosophical Transactions of the Royal Society B : Biological Sciences 370, n^o 1659 (5 janvier 2015) : 20130262. http://dx.doi.org/10.1098/rstb.2013.0262.

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Many marine ecosystems have undergone ‘regime shifts’, i.e. abrupt reorganizations across trophic levels. Establishing whether these constitute shifts between alternative stable states is of key importance for the prospects of ecosystem recovery and for management. We show how mechanisms underlying alternative stable states caused by predator–prey interactions can be revealed in field data, using analyses guided by theory on size-structured community dynamics. This is done by combining data on individual performance (such as growth and fecundity) with information on population size and prey availability. We use Atlantic cod ( Gadus morhua ) and their prey in the Baltic Sea as an example to discuss and distinguish two types of mechanisms, ‘cultivation-depensation’ and ‘overcompensation’, that can cause alternative stable states preventing the recovery of overexploited piscivorous fish populations. Importantly, the type of mechanism can be inferred already from changes in the predators' body growth in different life stages. Our approach can thus be readily applied to monitored stocks of piscivorous fish species, for which this information often can be assembled. Using this tool can help resolve the causes of catastrophic collapses in marine predatory–prey systems and guide fisheries managers on how to successfully restore collapsed piscivorous fish stocks.

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DUSO, CARLO, ALBERTO POZZEBON, MARIO BALDESSARI, VINCENZO GIROLAMI, GINO ANGELI, PAOLA TIRELLO, MAURO LORENZON, VALERIA MALAGNINI et GIUSEPPINA PELLIZZARI. « Availability of alternative foods can influence the impact of pesticides on predatory mites (Acari) : a summary of the evidence* ». Zoosymposia 6, n^o 1 (20 décembre 2011) : 124–30. http://dx.doi.org/10.11646/zoosymposia.6.1.21.

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Generalist predatory mites belonging to the Phytoseiidae play a major role in keeping phytophagous mites below economic threshold levels in European apple orchards and vineyards. Apart from their primary prey, these phytoseiids can exploit a range of other foods, among which pollen and plant pathogenic fungi are very important. The ability of generalist predatory mites to feed on alternative foods is of importance for their persistence in perennial crops. Pesticides can exert dramatic effects on mite communities, and these effects can be more severe on predators than on phytophagous mites, with practical consequences for pest management. Several factors of intrinsic (e.g. resistance to stress) and extrinsic nature (e.g. immigration) can influence the response of predatory mite populations to pesticide applications. Environmental conditions, in particular availability of alternative foods, could affect the resilience of predatory mite populations after pesticide applications. Here we evaluate the role of availability of alternative foods on the response of predatory mite populations to pesticide applications in two crop systems: apple and grape. In the former, increasing the abundance of pollen through appropriate grass management resulted in less pronounced negative effects of some insecticides on the predatory mite Kampimodromus aberrans (Oudemans). In a controlled laboratory experiment, we demonstrated that availability of fresh pollen reduced the effect of pesticides on the fecundity of that predator. In the grape system, we found a positive effect of the plant pathogen grape downy mildew (GDM) on Amblyseius andersoni (Chant) populations, while some pesticides had a negative impact. GDM availability on plants favored the colonization by beneficial mites of pesticide treated plants with positive implications for mite persistence in vineyards.

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Hedgespeth, Melanie Lea, Tomasz Karasek, Johan Ahlgren, Olof Berglund et Christer Brönmark. « Behaviour of freshwater snails (Radix balthica) exposed to the pharmaceutical sertraline under simulated predation risk ». Ecotoxicology 27, n^o 2 (18 janvier 2018) : 144–53. http://dx.doi.org/10.1007/s10646-017-1880-6.

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AbstractDue to their potential for affecting the modulation of behaviour, effects of selective serotonin reuptake inhibitors (SSRIs) in the environment are particularly interesting regarding interspecies interactions and non-consumptive effects (NCEs) induced by predator cues in prey organisms. We evaluated the effects of sertraline (0.4, 40 ng/L, 40 µg/L) over 8 days on activity and habitat choice in the freshwater snail Radix balthica, on snails’ boldness in response to mechanical stimulation (simulating predator attack), and their activity/habitat choice in response to chemical cues from predatory fish. We hypothesised that sertraline exposure would detrimentally impact NCEs elicited by predator cues, increasing predation risk. Although there were no effects of sertraline on NCEs, there were observed effects of chemical cue from predatory fish on snail behaviour independent of sertraline exposure. Snails reduced their activity in which the percentage of active snails decreased by almost 50% after exposure to fish cue. Additionally, snails changed their habitat use by moving away from open (exposed) areas. The general lack of effects of sertraline on snails’ activity and other behaviours in this study is interesting considering that other SSRIs have been shown to induce changes in gastropod behaviour. This raises questions on the modes of action of various SSRIs in gastropods, as well as the potential for a trophic “mismatch” of effects between fish predators and snail prey in aquatic systems.

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Lam, Weng Ngai, Ying Yi Chou, Felicia Wei Shan Leong et Hugh Tiang Wah Tan. « Inquiline predator increases nutrient-cycling efficiency of Nepenthes rafflesiana pitchers ». Biology Letters 15, n^o 12 (décembre 2019) : 20190691. http://dx.doi.org/10.1098/rsbl.2019.0691.

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The modified-leaf pitchers of Nepenthes rafflesiana pitcher plants are aquatic, allochthonous ecosystems that are inhabited by specialist inquilines and sustained by the input of invertebrate prey. Detritivorous inquilines are known to increase the nutrient-cycling efficiency (NCE) of pitchers but it is unclear whether predatory inquilines that prey on these detritivores decrease the NCE of pitchers by reducing detritivore populations or increase the NCE of pitchers by processing nutrients that may otherwise be locked up in detritivore biomass. Nepenthosyrphus is a small and poorly studied genus of hoverflies and the larvae of one such species is a facultatively detritivorous predator that inhabits the pitchers of N. rafflesiana . We fitted a consumer–resource model to experimental data collected from this system. Simulations showed that systems containing the predator at equilibrium almost always had higher NCEs than those containing only prey (detritivore) species. We showed using a combination of simulated predator/prey exclusions that the processing of the resource through multiple pathways and trophic levels in this system is more efficient than that accomplished through fewer pathways and trophic levels. Our results thus support the vertical diversity hypothesis, which predicts that greater diversity across trophic levels results in greater ecosystem functioning.

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Free, Brian A., Matthew J. McHenry et Derek A. Paley. « Probabilistic analytical modelling of predator–prey interactions in fishes ». Journal of The Royal Society Interface 16, n^o 150 (janvier 2019) : 20180873. http://dx.doi.org/10.1098/rsif.2018.0873.

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Predation is a fundamental interaction between species, yet it is largely unclear what tactics are successful for the survival or capture of prey. One challenge in this area comes with how to test theoretical ideas about strategy with experimental measurements of features such as speed, flush distance and escape angles. Tactics may be articulated with an analytical model that predicts the motion of predator or prey as they interact. However, it may be difficult to recognize how the predictions of such models relate to behavioural measurements that are inherently variable. Here, we present an alternative approach for modelling predator–prey interactions that uses deterministic dynamics, yet incorporates experimental kinematic measurements of natural variation to predict the outcome of biological events. This technique, called probabilistic analytical modelling (PAM), is illustrated by the interactions between predator and prey fish in two case studies that draw on recent experiments. In the first case, we use PAM to model the tactics of predatory bluefish ( Pomatomus saltatrix ) as they prey upon smaller fish ( Fundulus heteroclitus ). We find that bluefish perform deviated pure pursuit with a variable pursuit angle that is suboptimal for the time to capture. In the second case, we model the escape tactics of zebrafish larvae ( Danio rerio ) when approached by adult predators of the same species. Our model successfully predicts the measured patterns of survivorship using measured probability density functions as parameters. As these results demonstrate, PAM is a data-driven modelling approach that can be predictive, offers analytical transparency, and does not require numerical simulations of system dynamics. Though predator–prey interactions demonstrate the use of this technique, PAM is not limited to studying biological systems and has broad utility that may be applied towards understanding a wide variety of natural and engineered dynamical systems where data-driven modelling is beneficial.

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Yang, Yajie, Jie Wang, Yingying Mi, Junjie Gu, Giovanni Benelli, Nicolas Desneux, Su Wang, Shu Li et Yanli Yue. « Ladybird-Mediated Indirect Interactions between Two Aphid Species When Using a Banker Plant System ». Agronomy 12, n^o 12 (9 décembre 2022) : 3134. http://dx.doi.org/10.3390/agronomy12123134.

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Banker plant systems have the advantages of introducing natural enemies preventively and maintaining by providing alternative prey, thus controlling the pests sustainably. Banker plant systems are usually composed of three factors: a banker (secondary) plant, an alternative prey, and a shared predator (attacking an alternative prey on the secondary plant, and the targeted pest on the crop). However, for most banker plant systems, there is a lack of understanding regarding the dynamic relationship among these elements, with detrimental effects on practical applications. Therefore, in this study, the control of Myzus persicae on Capsicum annum by the Coccinella septempunctata–Megoura japonica–Vicia faba banker plant system was used as the research system. The effects of different release time of predators, different initial numbers of alternative prey (Me. japonica) and different initial ratios of target pests/alternative prey on the indirect interaction of two aphids and the biological control effect of shared predators were tested. The occurrence of indirect interactions between the two aphid preys, the impact on population dynamics, and biological control effectiveness of the shared predator C. septempunctata were investigated. When the initial numbers of both species of aphids were equal (200 each), the delay between aphid and C. septempunctata introduction in the cage had no effect on My. persicae, but Me. japonica showed lower numbers when testing the least time between predatory introductions. When the numbers of the two aphids were manipulated, the My. persicae population was significantly reduced by the predator only at a ratio of My. persicae to Me. japonica < 1, while initial ratios ≥ 1 enabled My. persicae population growth. In 1–6 days, the control effect of C. septempunctata was the best. Principal component analysis showed that the experimental time, initial numbers of Me. japonica, and relative numbers of Me. japonica affected the predation of My. persicae by C. septempunctata. In addition, when the initial aphid ratio was greater than 1/4, C. septempunctata was able to effectively control My. persicae. Overall, our study confirmed the number-mediated indirect interaction (apparent competition) relationship and its impact on prey population dynamics. We provide useful information for optimizing banker plant systems, to boost biocontrol of aphid pests.

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Atherton, Jennifer A., et Mark I. McCormick. « Parents know best : transgenerational predator recognition through parental effects ». PeerJ 8 (18 juin 2020) : e9340. http://dx.doi.org/10.7717/peerj.9340.

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In highly biodiverse systems, such as coral reefs, prey species are faced with predatory threats from numerous species. Recognition of predators can be innate, or learned, and can help increase the chance of survival. Research suggests that parental exposure to increased predatory threats can affect the development, behaviour, and ultimately, success of their offspring. Breeding pairs of damselfish (Acanthochromis polyacanthus) were subjected to one of three olfactory and visual treatments (predator, herbivore, or control), and their developing embryos were subsequently exposed to five different chemosensory cues. Offspring of parents assigned to the predator treatment exhibited a mean increase in heart rate two times greater than that of offspring from parents in herbivore or control treatments. This increased reaction to a parentally known predator odour suggests that predator-treated parents passed down relevant threat information to their offspring, via parental effects. This is the first time transgenerational recognition of a specific predator has been confirmed in any species. This phenomenon could influence predator-induced mortality rates and enable populations to adaptively respond to fluctuations in predator composition and environmental changes.

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Diakité, Nana R., Konan G. N'Zi, Mamadou Ouattara, Jean T. Coulibaly, Jasmina Saric, Patrick K. Yao, Jan Hattendorf, Jürg Utzinger et Eliézer K. N'Goran. « Association of riverine prawns and intermediate host snails and correlation with human schistosomiasis in two river systems in south-eastern Côte d'Ivoire ». Parasitology 145, n^o 13 (24 septembre 2018) : 1792–800. http://dx.doi.org/10.1017/s003118201800135x.

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AbstractThe current emphasis of schistosomiasis control is placed on preventive chemotherapy using praziquantel. However, reinfection may occur rapidly in the absence of complementary interventions. Recent studies from Senegal suggest that predatory prawns might feed on intermediate host snails and thus impact on schistosomiasis transmission. We designed a study with four repeated cross-sectional surveys pertaining to prawns and snails, coupled with a single cross-sectional parasitological survey among humans. We assessed for potential associations between the presence/density of prawns and snails and correlation withSchistosomainfection in a composite sample of school-aged children and adults. The study was carried out between October 2015 and December 2016 in 24 villages located near the Agnéby and Mé coastal river systems in south-eastern Côte d'Ivoire. At each site, snails and prawns were collected, and in each village, 150 individuals were subjected to stool and urine examination for the diagnosis ofSchistosoma mansoniandS. haematobium. We found peaks of relative abundance of intermediate host snails in the villages of the Agnéby River system, while predatory prawns were predominantly recorded in the Mé River system. A negative association was observed between intermediate host snail densities and riverine prawns; however, no pattern was found between this trend in the predator–prey relationship and the prevalence of human schistosomiasis.

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Midway, Stephen R., Caleb T. Hasler, Tyler Wagner et Cory D. Suski. « Predation of freshwater fish in environments with elevated carbon dioxide ». Marine and Freshwater Research 68, n^o 9 (2017) : 1585. http://dx.doi.org/10.1071/mf16156.

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Carbon dioxide (CO2) in fresh-water environments is poorly understood, yet in marine environments CO2 can affect fish behaviour, including predator–prey relationships. To examine changes in predator success in elevated CO2, we experimented with predatory Micropterus salmoides and Pimephales promelas prey. We used a two-factor fully crossed experimental design; one factor was 4-day (acclimation) CO2 concentration and the second factor CO2 concentration during 20-min predation experiments. Both factors had three treatment levels, including ambient partial pressure of CO2 (pCO2; 0–1000 μatm), low pCO2 (4000–5000 μatm) and high pCO2 (8000–10000 μatm). Micropterus salmoides was exposed to both factors, whereas P. promelas was not exposed to the acclimation factor. In total, 83 of the 96P. promelas were consumed (n=96 trials) and we saw no discernible effect of CO2 on predator success or time to predation. Failed strikes and time between failed strikes were too infrequent to model. Compared with marine systems, our findings are unique in that we not only saw no changes in prey capture success with increasing CO2, but we also used CO2 treatments that were substantially higher than those in past experiments. Our work demonstrated a pronounced resiliency of freshwater predators to elevated CO2 exposure, and a starting point for future work in this area.

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Diel, Patricia, Marvin Kiene, Dominik Martin-Creuzburg et Christian Laforsch. « Knowing the Enemy : Inducible Defences in Freshwater Zooplankton ». Diversity 12, n^o 4 (7 avril 2020) : 147. http://dx.doi.org/10.3390/d12040147.

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Phenotypic plasticity in defensive traits is an appropriate mechanism to cope with the variable hazard of a frequently changing predator spectrum. In the animal kingdom these so-called inducible defences cover the entire taxonomic range from protozoans to vertebrates. The inducible defensive traits range from behaviour, morphology, and life-history adaptations to the activation of specific immune systems in vertebrates. Inducible defences in prey species play important roles in the dynamics and functioning of food webs. Freshwater zooplankton show the most prominent examples of inducible defences triggered by chemical cues, so-called kairomones, released by predatory invertebrates and fish. The objective of this review is to highlight recent progress in research on inducible defences in freshwater zooplankton concerning behaviour, morphology, and life-history, as well as difficulties of studies conducted in a multipredator set up. Furthermore, we outline costs associated with the defences and discuss difficulties as well as the progress made in characterizing defence-inducing cues. Finally, we aim to indicate further possible routes in this field of research and provide a comprehensive table of inducible defences with respect to both prey and predator species.

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Friedman, Robert. « A Hierarchy of Interactions between Pathogenic Virus and Vertebrate Host ». Symmetry 14, n^o 11 (30 octobre 2022) : 2274. http://dx.doi.org/10.3390/sym14112274.

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This review is of basic models of the interactions between a pathogenic virus and vertebrate animal host. The interactions at the population level are described by a predatory-prey model, a common approach in the ecological sciences, and depend on births and deaths within each population. This ecological perspective is complemented by models at the genetical level, which includes the dynamics of gene frequencies and the mechanisms of evolution. These perspectives are symmetrical in their relatedness and reflect the idealized forms of processes in natural systems. In the latter sections, the general use of deep learning methods is discussed within the above context, and proposed for effective modeling of the response of a pathogenic virus in a pathogen–host system, which can lead to predictions about mutation and recombination in the virus population.

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Munyai, Linton F., Tatenda Dalu, Ryan J. Wasserman, Lutendo Mugwedi, Farai Dondofema, Gordon O’Brien et Ross N. Cuthbert. « Functional Responses and Additive Multiple Predator Effects of Two Common Wetland Fish ». Water 14, n^o 5 (23 février 2022) : 699. http://dx.doi.org/10.3390/w14050699.

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Understanding trophic interactions is essential for the prediction and measurement of structure and function in aquatic environments. Communities in these ecosystems may be shaped by variables such as predator diversity, prey density and emergent multiple predator effects (MPEs), which are likely to influence trophic dynamics. In this study, we examined the effect of key predatory fish in floodplain wetlands, namely Oreochromis mossambicus and Enteromius paludinosus, towards Chironomidae prey, using a comparative functional response (FR) approach. We used single predator species as well as intra- and interspecific paired species to contrast FRs under multiple predator scenarios. Attack rate and handling time estimates from single predator FRs were used to predict multiple predators’ feeding rates, which were compared to observe multiple predators’ feeding rates to quantify potential MPEs. From single fish trials, each species displayed a significant Type II FR, characterized by high feeding rates at low prey densities. Oreochromis mossambicus had a steeper (initial slope, i.e., higher attack rate) and higher (asymptote of curve, i.e., shorter handling time and higher maximum feeding rate) FR, whereas E. paludinosus exhibited lower-magnitude FRs (i.e., lower attack rate, longer handling time and lower feeding rate). In multiple predator scenarios, feeding rates were well-predicted by those of single predators, both in conspecific and interspecific pairs, and thus we did not find evidence for antagonistic or synergistic MPEs. Predator–prey interactions in wetland systems can have significant consequences on the structure and dynamics of ecological communities. In turn, this could have destabilizing effects on resources in tropical wetlands. These results, although experimental, help us understand how trophic interaction among conspecific or interspecific fish species in Austral tropical wetlands might influence their aquatic prey species. This will help us to understand food web dynamics better.

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Fang, Yan, Shu Li, Qingxuan Xu, Jie Wang, Yajie Yang, Yingying Mi, Zhenyu Jin, Nicolas Desneux et Su Wang. « Optimizing the Use of Basil as a Functional Plant for the Biological Control of Aphids by Chrysopa pallens (Neuroptera : Chrysopidae) in Greenhouses ». Insects 13, n^o 6 (16 juin 2022) : 552. http://dx.doi.org/10.3390/insects13060552.

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Effective biological control agents that can provide sustainable pest control need to be researched in further detail; functional plants (or non-crop insectary plants), in particular, are garnering increased research interest. Much remains to be learned as to how non-crop plants can augment biological control in greenhouse systems. In this study, we combined laboratory and greenhouse assays to assess the extent to which basil (Ocimum basilicum L.) (Lamiales: Lamiaceae) affected the biological control of aphids by the predatory lacewing Chrysopa pallens (Rambur) (Neuroptera: Chrysopidae). In the presence of the target prey (peach aphid; Myzus persicae (Sulzer)), both the vegetative and flowering stages of basil enhanced C. pallens longevity and (early-age) fecundity as compared to a control treatment. When basil plants were established near aphid infested eggplants (Solanum melongena L.), the C. pallens colonization rate improved by 72–92% in the short-term. Lacewing colonization patterns were modulated by the basil planting density and spatial arrangement (i.e., perimeter planting vs. intercropping). Under high density intercrop arrangements, C. pallens colonization rates were highest, its populations persisted longer in the crop, and the aphid numbers declined more rapidly. Our work shows how basil enhanced the key fitness attributes of a generalist predatory lacewing and benefitted aphid biological control in a greenhouse setting.

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Ouyang, Fang, Bing Yang, Jing Cao, Yuqian Feng et Feng Ge. « Tracing prey origins, proportions and feeding periods for predatory beetles from agricultural systems using carbon and nitrogen stable isotope analyses ». Biological Control 71 (avril 2014) : 23–29. http://dx.doi.org/10.1016/j.biocontrol.2014.01.001.

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Stockwell, Jason D., Thomas R. Hrabik, Olaf P. Jensen, Daniel L. Yule et Matthew Balge. « Empirical evaluation of predator-driven diel vertical migration in Lake Superior ». Canadian Journal of Fisheries and Aquatic Sciences 67, n^o 3 (mars 2010) : 473–85. http://dx.doi.org/10.1139/f09-198.

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Recent studies on Lake Superior suggest that diel vertical migration (DVM) of prey (generalized Coregonus spp.) may be influenced by the density of predatory siscowet ( Salvelinus namaycush ). We empirically evaluated this hypothesis using data from acoustic, midwater trawl, and bottom trawl sampling at eight Lake Superior sites during three seasons in 2005 and a subset of sites in 2006. We expected the larger-bodied cisco ( Coregonus artedi ) to exhibit a shallower DVM compared with the smaller-bodied kiyi ( Coregonus kiyi ). Although DVM of kiyi and cisco were consistent with expectations of DVM as a size-dependent, predator-mediated process, we found no relationship between siscowet density and the magnitude of DVM of either coregonid. Cisco appear to have a size refuge from siscowet predation. Kiyi and siscowet co-occur in demersal habitat > 150 m during the day, where visual predation is unlikely, suggesting predator avoidance is not a factor in the daytime distribution of kiyi. Seasonal patterns of kiyi DVM were consistent with reported DVM of their primary prey Mysis relicta . Our results suggest that consideration of nonvisual foraging, rather than light-based foraging theory (i.e., the antipredation window), is necessary to understand the processes driving DVM in deepwater systems.

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Brooker, Rohan M., Philip L. Munday, Douglas P. Chivers et Geoffrey P. Jones. « You are what you eat : diet-induced chemical crypsis in a coral-feeding reef fish ». Proceedings of the Royal Society B : Biological Sciences 282, n^o 1799 (22 janvier 2015) : 20141887. http://dx.doi.org/10.1098/rspb.2014.1887.

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The vast majority of research into the mechanisms of camouflage has focused on forms that confound visual perception. However, many organisms primarily interact with their surroundings using chemosensory systems and may have evolved mechanisms to ‘blend in’ with chemical components of their habitat. One potential mechanism is ‘chemical crypsis' via the sequestration of dietary elements, causing a consumer's odour to chemically match that of its prey. Here, we test the potential for chemical crypsis in the coral-feeding filefish, Oxymonacanthus longirostris , by examining olfactory discrimination in obligate coral-dwelling crabs and a predatory cod. The crabs, which inhabit the corals consumed by O. longirostris , were used as a bioassay to determine the effect of coral diet on fish odour. Crabs preferred the odour of filefish fed their preferred coral over the odour of filefish fed a non-preferred coral, suggesting coral-specific dietary elements that influence odour are sequestered. Crabs also exhibited a similar preference for the odour of filefish fed their preferred coral and odour directly from that coral, suggesting a close chemical match. In behavioural trials, predatory cod were less attracted to filefish odour when presented alongside the coral it had been fed on, suggesting diet can reduce detectability. This is, we believe, the first evidence of diet-induced chemical crypsis in a vertebrate.

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Dukas, Reuven. « Bumblebee Preadators Reduce Pollinator Density and Plant Fitness ». UW National Parks Service Research Station Annual Reports 28 (1 janvier 2004) : 94–97. http://dx.doi.org/10.13001/uwnpsrc.2004.3583.

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Research in pollination biology has focused on the interactions between animals and the flowers they visit for food reward. However, other selective agents, including predators, seed feeders and herbivores, may affect pollination systems. Because flowers are predictable food sources for a variety of species, flowers are also reliable sites at which predators can locate flower-visiting animals. Prominent among pollinators' predators are beewolves (Philanthus spp), common sphecid wasps (Sphecidae) that prey almost exclusively on bees. My field work over three years indicates, first, that an area of approximately 50 square km surrounding a single bumblebee wolf (Philanthus bicinctus) aggregation had a low bumblebee (Bombus spp) density caused by intense predation by the wasps, and, second, that fruit set of the bumblebee pollinated western monkshood (Aconitum columbianum) was significantly lower at locations and times of bumblebee wolf activity than at control locations and times with no such predatory activity. These results indicate that predation can sometimes alter plantÂpollinator interactions.

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Haghani, Somayeh, Azadeh Zahedi-golpayegani, Alireza Saboori et Hossein Allahyari. « The effect of con/heterospecific diet on predation, oviposition and longevity of Amblyseius swirskii, Neoseiulus californicus and Phytoseiulus persimilis (Acari : Phytoseiidae) ». Systematic and Applied Acarology 24, n^o 11 (23 novembre 2019) : 2240–52. http://dx.doi.org/10.11158/saa.24.11.14.

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Intraguild predation (IGP) consists of interacting individuals with context dependent roles that compete for food. Information about the predator trophic interactions i.e. cannibalism or feeding on heterospecific juveniles, is a key to understand the real impact of their combinations when introduced in biological control systems. The hypothesis here, assumed that the pairwise introduction of the female predatory mites, N. californicus (predator) + P. persimilis (heterospecific prey) and vice versa, A. swirskii (predator) + P. persimilis (heterospecific prey) and vice versa could exist in the Tetranychus urticae (main prey) scarcity. Three diets consisted of either conspecific or heterospecific six eggs, four eggs + four larvae and four protonymphs were introduced to the guilds. The predation and oviposition rates and the longevity of each female intraguild predator on detached bean leaf disc was recorded every three hours for 12 consecutive days. Neoseiulus californicus predation rate was estimated to be highest on conspecific eggs + larvae (11.35 ± 1.12) and so was on those of P. persimilis (55.7 ± 3.42). No significant difference was observed in N. californicus oviposition rate on three conspecific diets (P > 0.05), while its oviposition rate was highest on P. persimilis eggs + larvae (7.15 ± 0.80). Phytoseiulus persimilis predation rate was estimated to be highest on eggs + larvae both on N. californicus and P. persimilis as prey. Its oviposition rate was estimated to be highest when feeding on conspecific eggs (2.25 ± 0.19) and N. californicus eggs + larvae. Amblyseius swirskii fed on 45 ± 2.79 P. persimilis and 12.90 ± 1.51 A. swirskii eggs + larvae, which was significantly higher than predation rates on other stages (P < 0.01). Amblyseius swirskii oviposition rate was not significantly different on each of the three diets or on A. swirskii or P. persimilis as prey (P > 0.05). The oviposition rate of P. persimilis was the highest on A. swirskii eggs + larvae (1.45 ± 0.19). When N. californicus fed on each of the three diet types, no significant difference was observed in its longevity. The greatest longevity of P. persimilis was recorded when feeding on N. californicus/P. persimilis eggs. Longevity of A. swirskii was the greatest on P. persimilis eggs and protonymphs. Similarly, P. persimilis had the greatest longevity feeding on A. swirskii eggs. We concluded that the predator species were capable of surviving under conditions of scarce prey when heterospecific species are present.

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Yong, Xi, Man-Hong Yung, Xue-Ke Song, Xun Gao et Angsheng Li. « Emergence of Network Bifurcation Triggered by Entanglement ». Quantum 3 (3 juin 2019) : 147. http://dx.doi.org/10.22331/q-2019-06-03-147.

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In many non-linear systems, such as plasma oscillation, boson condensation, chemical reaction, and even predatory-prey oscillation, the coarse-grained dynamics are governed by an equation containing anti-symmetric transitions, known as the anti-symmetric Lotka-Volterra (ALV) equations. In this work, we prove the existence of a novel bifurcation mechanism for the ALV equations, where the equilibrium state can be drastically changed by flipping the stability of a pair of fixed points. As an application, we focus on the implications of the bifurcation mechanism for evolutionary networks; we found that the bifurcation point can be determined quantitatively by the microscopic quantum entanglement. The equilibrium state can be critically changed from one type of global demographic condensation to another state that supports global cooperation for homogeneous networks. In other words, our results indicate that there exist a class of many-body systems where the macroscopic properties are invariant with a certain amount of microscopic entanglement, but they can be changed abruptly once the entanglement exceeds a critical value. Furthermore, we provide numerical evidence showing that the emergence of bifurcation is robust against the change of the network topologies, and the critical values are in good agreement with our theoretical prediction. These results show that the bifurcation mechanism could be ubiquitous in many physical systems, in addition to evolutionary networks.

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Barua, Agneesh, et Alexander S. Mikheyev. « An ancient, conserved gene regulatory network led to the rise of oral venom systems ». Proceedings of the National Academy of Sciences 118, n^o 14 (29 mars 2021) : e2021311118. http://dx.doi.org/10.1073/pnas.2021311118.

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Oral venom systems evolved multiple times in numerous vertebrates, enabling the exploitation of unique predatory niches. Yet how and when they evolved remains poorly understood. Up to now, most research on venom evolution has focused strictly on toxins. However, using toxins present in modern-day animals to trace the origin of the venom system is difficult, since they tend to evolve rapidly, show complex patterns of expression, and were incorporated into the venom arsenal relatively recently. Here we focus on gene regulatory networks associated with the production of toxins in snakes, rather than the toxins themselves. We found that overall venom gland gene expression was surprisingly well conserved when compared to salivary glands of other amniotes. We characterized the “metavenom network,” a network of ∼3,000 nonsecreted housekeeping genes that are strongly coexpressed with toxins and are primarily involved in protein folding and modification. Conserved across amniotes, this network was coopted for venom evolution by exaptation of existing members and the recruitment of new toxin genes. For instance, starting from this common molecular foundation, Heloderma lizards, shrews, and solenodon evolved venoms in parallel by overexpression of kallikreins, which were common in ancestral saliva and induce vasodilation when injected, causing circulatory shock. Derived venoms, such as those of snakes, incorporated novel toxins, though they still rely on hypotension for prey immobilization. These similarities suggest repeated cooption of shared molecular machinery for the evolution of oral venom in mammals and reptiles, blurring the line between truly venomous animals and their ancestors.

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Backhouse, Amy, Steven M. Sait et Tom C. Cameron. « Multiple mating in the traumatically inseminating Warehouse pirate bug, Xylocoris flavipes : effects on fecundity and longevity ». Biology Letters 8, n^o 5 (9 mai 2012) : 706–9. http://dx.doi.org/10.1098/rsbl.2012.0091.

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Optimal mating frequencies differ between sexes as a consequence of the sexual differentiation of reproductive costs per mating, where mating is normally more costly to females than males. In mating systems where sexual reproduction is costly to females, sexual conflict may cause both direct (i.e. by reducing female fecundity or causing mortality) and indirect (i.e. increased risk of mortality, reduced offspring viability) reductions in lifetime reproductive success of females, which have individual and population consequences. We investigated the direct and indirect costs of multiple mating in a traumatically inseminating (TI) predatory Warehouse pirate bug, Xylocoris flavipes (Reuter) (Hemiptera: Anthocoridae), where the male penetrates the female's abdomen during copulation. This study aimed to quantify the effects of TI on female fecundity, egg viability, the lifetime fecundity schedule, longevity and prey consumption in this cosmopolitan biocontrol agent. We found no difference in the total reproductive output between mating treatments in terms of total eggs laid or offspring viability, but there were significant differences found in daily fecundity schedules and adult longevity. In terms of lifetime reproduction, female Warehouse pirate bugs appear to be adapted to compensate for the costs of TI mating to their longevity.

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Weissburg, M. J., et R. K. Zimmer-Faust. « Odor plumes and how blue crabs use them in finding prey. » Journal of Experimental Biology 197, n^o 1 (1 décembre 1994) : 349–75. http://dx.doi.org/10.1242/jeb.197.1.349.

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Orientation of animals using chemical cues often takes place in flows, where the stimulus properties of odorants are affected by the characteristics of fluid motion. Kinematic analysis of movement patterns by animals responding to odor plumes has been used to provide insight into the behavioral and physiological aspects of olfactory-mediated orientation, particularly in terrestrial insects. We have used this approach in analyzing predatory searching by blue crabs in response to plumes of attractant metabolites released from the siphons of live clams in controlled hydrodynamic environments. Crabs proceed directly upstream towards clams in smooth-turbulent flows and show high locomotory velocities and few periods of motionlessness. Crabs assume more indirect trajectories and display slower locomotion and more stopping in rough-turbulent flows. This degradation of foraging performance is most pronounced as flow shifts from a smooth- to a rough-turbulent regime, where the change in hydraulic properties is associated with contraction of the viscous sublayer region of the boundary layer. Because flow in this region is quasilaminar, the viscous sublayer may be a particularly effective vehicle for chemical stimulus transmission, such that orientation is severely compromised when it is reduced or removed. Our results also suggest that rheotactic and chemical information are both necessary for successful orientation. Perception of chemical cues acts to bias locomotion upcurrent, and feedback from odorant stimulus distributions appears directly to regulate subsequent stopping and turning en route to prey. Although the mechanisms of orientation to odorant plumes displayed by insects and blue crabs are largely similar, blue crabs appear to rely more heavily on spatial and/or temporal aspects of chemical stimulus distributions than has been suggested for insect systems.

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Young, Bruce A., Molly Phelan, Malinda Morain, Melissa Ommundsen et Robert Kurt. « Venom injection by rattlesnakes (Crotalus atrox) : peripheral resistance and the pressure-balance hypothesis ». Canadian Journal of Zoology 81, n^o 2 (1 février 2003) : 313–20. http://dx.doi.org/10.1139/z03-007.

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Differential venom injection by snakes, between two size classes of prey for example, has typically been explained within the rubric of the venom-metering hypothesis, which claims that snakes decide how much venom to inject in a given strike. Recently, an alternative, the pressure-balance hypothesis, was advanced, which attributes differential venom flow to the balance of internal forces acting at the venom gland and venom chambers and external forces acting at the exit orifice of the fang. This study tests these competing hypotheses. High-speed digital videos of predatory and defensive strikes by western diamondback rattlesnakes, Crotalus atrox, revealed considerable variation in the trajectory of the fang relative to the target, which would yield wounds with potentially different levels of peripheral resistance. The importance of peripheral resistance was also suggested by the expulsion of venom from the fang after withdrawal from the target (in 7% of strikes) and by the forceful ejection of fluid from the target around the embedded fang (in 2.8% of strikes). Experimental milking chambers were constructed that exposed the right and left venom-delivery systems to different levels of peripheral resistance; with increased peripheral resistance significantly less venom was injected into the chamber and significantly more venom was released on the chamber's surface.

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Bunn, Stuart E., Peter M. Davies et Dominica M. Kellaway. « Contributions of sugar cane and invasive pasture grass to the aquatic food web of a tropical lowland stream ». Marine and Freshwater Research 48, n^o 2 (1997) : 173. http://dx.doi.org/10.1071/mf96055.

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In-stream ecosystem processes in a tropical lowland stream in far north Queensland were studied by measuring open-system community metabolism and analysing stable isotopes. The stream catchment, like many others in this region, has been extensively cleared for the cultivation of sugar cane, and in the absence of riparian shading, aquatic and semi-aquatic plants choke the stream channel. Stream community metabolism switched between autotrophy and heterotrophy, depending on the degree of cloud cover. Successive cloudy days may be sufficient to result in anoxia in the stream, particularly in the benthos, where limited oxygen penetration into the sediments was recorded. Stable-isotope data indicated that little of the primary production from sugar cane or other C4 plants was transferred into the aquatic food web. The only significant contribution of C4 carbon was to the diets of some larger predatory fish, which must be directly dependent on terrestrial prey. In the absence of significant riparian inputs of C3 carbon, it appears that in-stream primary production supported the aquatic invertebrate community. Restoration of disturbed stream systems such as this one must include the establishment of appropriate riparian species for the reduction of excessive in-stream primary production and the supply of detritus for the maintenance of aquatic food webs.

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Schausberger, Peter. « Population growth and persistence when prey is diminishing in single-species and two-species systems of the predatory mites Euseius finlandicus, Typhlodromus pyri and Kampimodromus aberrans ». Entomologia Experimentalis et Applicata 88, n^o 3 (septembre 1998) : 275–86. http://dx.doi.org/10.1046/j.1570-7458.1998.00372.x.

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Abalde, Samuel, Sébastien Dutertre et Rafael Zardoya. « A Combined Transcriptomics and Proteomics Approach Reveals the Differences in the Predatory and Defensive Venoms of the Molluscivorous Cone Snail Cylinder ammiralis (Caenogastropoda : Conidae) ». Toxins 13, n^o 9 (10 septembre 2021) : 642. http://dx.doi.org/10.3390/toxins13090642.

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Venoms are complex mixtures of proteins that have evolved repeatedly in the animal kingdom. Cone snail venoms represent one of the best studied venom systems. In nature, this venom can be dynamically adjusted depending on its final purpose, whether to deter predators or hunt prey. Here, the transcriptome of the venom gland and the proteomes of the predation-evoked and defensive venoms of the molluscivorous cone snail Cylinder ammiralis were catalogued. A total of 242 venom-related transcripts were annotated. The conotoxin superfamilies presenting more different peptides were O1, O2, T, and M, which also showed high expression levels (except T). The three precursors of the J superfamily were also highly expressed. The predation-evoked and defensive venoms showed a markedly distinct profile. A total of 217 different peptides were identified, with half of them being unique to one venom. A total of 59 peptides ascribed to 23 different protein families were found to be exclusive to the predatory venom, including the cono-insulin, which was, for the first time, identified in an injected venom. A total of 43 peptides from 20 protein families were exclusive to the defensive venom. Finally, comparisons of the relative abundance (in terms of number of peptides) of the different conotoxin precursor superfamilies showed that most of them present similar abundance regardless of the diet.

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GRUTTER, A. S. « Cleaning symbioses from the parasites' perspective ». Parasitology 124, n^o 7 (24 septembre 2002) : 65–81. http://dx.doi.org/10.1017/s0031182002001488.

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Cleaning behaviour has generally been viewed from the cleaner or client's point of view. Few studies, however, have examined cleaning behaviour from the parasites' perspective, yet they are the equally-important third players in such associations. All three players are likely to have had their evolution affected by the association. As cleaner organisms are important predators of parasites, cleaners are likely to have an important effect on their prey. Little, however, is known of how parasites are affected by cleaning associations and the strategies that parasites use in response to cleaners. I examine here what parasites are involved in cleaning interactions, the effect cleaners have on parasites, the potential counter-adaptations that parasites have evolved against the predatory activities of cleaner organisms, the potential influence of cleaners on the life history traits of parasites, and other factors affected by cleaners. I have found that a wide range of ectoparasites from diverse habitats have been reported to interact with a wide range of cleaner organisms. Some of the life history traits of parasites are consistent with the idea that they are in response to cleaner predation. It is clear, however, that although many cleaning systems exist their ecological role is largely unexplored. This has likely been hindered by our lack of information on the parasites involved in cleaning interactions.

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Emmert, Elizabeth A. B., Zachary M. Haupt, Katherine M. Pflaum, Jennifer L. Lasbury, Justin P. McGrath, Allison E. Collins et Christopher H. Briand. « Bdellovibrio bacteriovorus protects Caenorhabditis elegans from bacterial pathogens ». Fine Focus 1, n^o 1 (1 décembre 2014) : 51–61. http://dx.doi.org/10.33043/ff.1.1.51-61.

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Bdellovibrio bacteriovorus is a naturally predatory bacterium that multiplies inside Gram negative prey bacteria. There is much interest in using Bdellovibrio as a living antibiotic to control infections by Gram negative pathogens. In recent years Caenorhabditis elegans has proven to be an attractive animal model of bacterial pathogenesis for a range of pathogens. We have used the C. elegans animal pathogenesis model to examine the ability of B. bacteriovorus to protect nematodes from four bacterial pathogens. In all cases, nematodes treated with B. bacteriovorus and the pathogen survived at a significantly higher level than nematodes treated with the pathogen alone. Treatment with B. bacteriovorus alone was nontoxic to the worms. We monitored the persistence of E. coli K-12 and E. coli OP50 in both B. bacteriovorus treated nematodes and control nematodes. E. coli K-12 levels were significantly lower in B. bacteriovorus treated nematodes than in control nematodes one day after Bdellovibrio exposure and E. coli K-12 was eliminated from the worm gut two days faster in B. bacteriovorus treated nematodes. E. coli OP50 also demonstrated significantly lower levels in B. bacteriovorus treated nematodes and faster elimination from the worm gut. The successful use of B. bacteriovorus as a therapeutic agent in C. elegans indicates that it may be useful as a living antibiotic in other animal systems.

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Behrens, Jane W., Marie P. Ryberg, Heli Einberg, Redik Eschbaum, Ann-Britt Florin, Wlodzimierz Grygiel, Jens Peter Herrmann et al. « Seasonal depth distribution and thermal experience of the non-indigenous round goby Neogobius melanostomus in the Baltic Sea : implications to key trophic relations ». Biological Invasions 24, n^o 2 (5 novembre 2021) : 527–41. http://dx.doi.org/10.1007/s10530-021-02662-w.

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AbstractNative to the Ponto-Caspian region, the benthic round goby (Neogobius melanostomus) has invaded several European inland waterbodies as well as the North American Great Lakes and the Baltic Sea. The species is capable of reaching very high densities in the invaded ecosystems, with not only evidence for significant food-web effects on the native biota and habitats, but also negative implications to coastal fishers. Although generally considered a coastal species, it has been shown that round goby migrate to deeper areas of the Great Lakes and other inland lakes during the cold season. Such seasonal movements may create new spatio-temporal ecosystem consequences in invaded systems. To seek evidence for seasonal depth distribution in coastal marine habitats, we compiled all available catch data for round goby in the Baltic Sea since its invasion and until 2017. We furthermore related the depths at capture for each season with the ambient thermal environment. The round goby spend autumn and winter at significantly deeper and offshore areas compared to spring and summer months; few fish were captured at depths < 25 m in these colder months. Similarly, in spring and summer, round goby were not captured at depths > 25 m. The thermal conditions at which round goby were caught varied significantly between seasons, being on average 18.3 °C during summer, and dropping to a low 3.8 °C during winter months. Overall, the fish sought the depths within each season with the highest possible temperatures. The spatial distribution of the round goby substantially overlaps with that of its main and preferred prey (mussels) and with that of its competitor for food (flatfish), but only moderately with the coastal predatory fish (perch), indicating thereby very complex trophic interactions associated with this invasion. Further investigations should aim at quantifying the food web consequences and coupling effects between different habitats related to seasonal migrations of the round goby, both in terms of the species as a competitor, predator and prey.

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Steneck, Robert S., Michael H. Graham, Bruce J. Bourque, Debbie Corbett, Jon M. Erlandson, James A. Estes et Mia J. Tegner. « Kelp forest ecosystems : biodiversity, stability, resilience and future ». Environmental Conservation 29, n^o 4 (décembre 2002) : 436–59. http://dx.doi.org/10.1017/s0376892902000322.

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Kelp forests are phyletically diverse, structurally complex and highly productive components of coldwater rocky marine coastlines. This paper reviews the conditions in which kelp forests develop globally and where, why and at what rate they become deforested. The ecology and long archaeological history of kelp forests are examined through case studies from southern California, the Aleutian Islands and the western North Atlantic, well-studied locations that represent the widest possible range in kelp forest biodiversity. Global distribution of kelp forests is physiologically constrained by light at high latitudes and by nutrients, warm temperatures and other macrophytes at low latitudes. Within mid-latitude belts (roughly 40–60° latitude in both hemispheres) well-developed kelp forests are most threatened by herbivory, usually from sea urchins. Overfishing and extirpation of highly valued vertebrate apex predators often triggered herbivore population increases, leading to widespread kelp deforestation. Such deforestations have the most profound and lasting impacts on species-depauperate systems, such as those in Alaska and the western North Atlantic. Globally urchin-induced deforestation has been increasing over the past 2–3 decades. Continued fishing down of coastal food webs has resulted in shifting harvesting targets from apex predators to their invertebrate prey, including kelp-grazing herbivores. The recent global expansion of sea urchin harvesting has led to the widespread extirpation of this herbivore, and kelp forests have returned in some locations but, for the first time, these forests are devoid of vertebrate apex predators. In the western North Atlantic, large predatory crabs have recently filled this void and they have become the new apex predator in this system. Similar shifts from fish- to crab-dominance may have occurred in coastal zones of the United Kingdom and Japan, where large predatory finfish were extirpated long ago. Three North American case studies of kelp forests were examined to determine their long history with humans and project the status of future kelp forests to the year 2025. Fishing impacts on kelp forest systems have been both profound and much longer in duration than previously thought. Archaeological data suggest that coastal peoples exploited kelp forest organisms for thousands of years, occasionally resulting in localized losses of apex predators, outbreaks of sea urchin populations and probably small-scale deforestation. Over the past two centuries, commercial exploitation for export led to the extirpation of sea urchin predators, such as the sea otter in the North Pacific and predatory fishes like the cod in the North Atlantic. The large-scale removal of predators for export markets increased sea urchin abundances and promoted the decline of kelp forests over vast areas. Despite southern California having one of the longest known associations with coastal kelp forests, widespread deforestation is rare. It is possible that functional redundancies among predators and herbivores make this most diverse system most stable. Such biodiverse kelp forests may also resist invasion from non-native species. In the species-depauperate western North Atlantic, introduced algal competitors carpet the benthos and threaten future kelp dominance. There, other non-native herbivores and predators have become established and dominant components of this system. Climate changes have had measurable impacts on kelp forest ecosystems and efforts to control the emission of greenhouse gasses should be a global priority. However, overfishing appears to be the greatest manageable threat to kelp forest ecosystems over the 2025 time horizon. Management should focus on minimizing fishing impacts and restoring populations of functionally important species in these systems.

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