Predatory Behavior Research Articles

Stoichiometric theory in optimal foraging strategy.

Understanding how organisms make choices about what to eat is a fascinating puzzle explored in this study, which employs stoichiometric modeling and optimal foraging principles. The research delves into the intricate balance of nutrient intake with foraging strategies, investigating quality and quantity-based food selection through mathematical models. The stoichiometric models in this study, encompassing producers and a grazer, unveils the dynamics of decision-making processes, introducing fixed and variable energetic foraging costs. Analysis reveals cell quota-dependent predation behaviors, elucidating biological phenomena such as "compensatory foraging behaviors" and the "stoichiometric extinction effect". The Marginal Value Theorem quantifies food selection, highlighting the profitability of prey items and emphasizing its role in optimizing foraging strategies in predator-prey dynamics. The environmental factors like light and nutrient availability prove pivotal in shaping optimal foraging strategies, with numerical results from a multi-species model contributing to a comprehensive understanding of the intricate interplay between organisms and their environment.

Transfer and biological effects of cadmium along a tomato – thrip – predatory bug food chain

The heavy metal, cadmium (Cd) is an increasingly serious issue in agricultural ecosystems, mediating bottom-up effects on plants, herbivores and natural enemies. We measured how Cd modifies interactions between tomato Solanum lycopersicum, western flower thrips Frankliniella occidentalis, and the predatory bug Orius sauteri by examining Cd effects on the growth of tomato, the fitness of western flower thrips, and the survival and behavior of predators. The photosynthetic parameters of Pn (net photosynthetic rate), Gs (stomatal conductance), Ci (intercellular CO2 concentration), and Tr (transpiration rate) of tomato plants significantly decreased with the increase of Cd concentration. The total survival number of western flower thrips fed on tomato plants treated with different concentrations of Cd was significantly lower than that of the control, and sex ratios (female/male) gradually increased with the increase of Cd concentration. The numbers of thrips predated by O. sauteri on tomato plants treated with high concentrations of Cd (2.0 or 4.0mg/L) were significantly reduced by the second day. Cadmium was accumulated and bioconcentrated in the roots, stems, leaves of tomato plants, and transferred to F. occidentalis, and O. sauteri. Cadmium translocated in significant quantities from roots to the stems and leaves of tomato plants, and from the tomato leaf to F. occidentalis. However, there was minimal (non-significant) transfer of Cd from F. occidentalis to O. sauteri. The presence of Cd significantly reduced the growth of tomato plants, the fitness of F. occidentalis, and the predation efficiency of O. sauteri. Collectively, Cd can mediate bottom-up effects on tomato, thrip, and predatory bug along food chain, potentially interrupting pest biological control in tomato in heavy metal-contaminated ecosystems.

The impact of increasing turbidity on the predator–prey interactions of freshwater fishes

Abstract Human activities are exacerbating environmental change globally. Turbidity in freshwater systems is increasing due to extreme weather events and intensification of activities such as deforestation, urbanisation, agriculture and altering water flow with dams and other structures. Prey species may benefit from turbid habitats as turbidity creates a visual barrier to predators; such predators thus face reduced foraging success as water clarity decreases. However, the literature on the effects of water turbidity on predator–prey interactions in fish is often contrasting. Environmentally driven changes in predator and prey behaviour, foraging and survival ultimately have the potential to affect community structure and ecosystem functioning, thus understanding the impact of changes in turbidity on predator–prey interactions should be a priority. Given the contrasting results in the primary literature, the aim of this review is to provide a broad overview of the current knowledge on the impacts of increased turbidity on predator–prey interactions in freshwater fishes, summarise the published literature and identify knowledge gaps on this topic. We collated 281 studies from the peer‐reviewed literature that tested the impact of water turbidity on the foraging behaviour of predatory fish and anti‐predator behaviour of prey fish. We recorded changes in predator and prey behaviours in response to changes in turbidity levels. Furthermore, we reported whether these behavioural changes were considered to have a positive (e.g. enhanced foraging success) or negative (e.g. higher mortality) impact on the focal species, or whether the impact was unspecified (e.g. changes in anti‐predator behaviour without quantifying actual predation risk). The literature has some strong taxonomic, geographical and environmental biases, where most research focused on commercially important, temperate species. A large proportion of studies (47%) reported a negative (versus a positive or unspecified) impact of turbidity on the focal species (either predator or prey freshwater fish). Negative impacts were reported more often for predators (58%) compared to prey (19%) and while changes in behaviour were frequently reported in prey species, if these changes are adaptive or not is unclear, as actual predation risk was not assessed in the majority of relevant studies (55%). Increases in turbidity have complex effects on predator–prey interactions, with negative impacts more often reported for adult piscivore predators, while prey species may gain a relative advantage compared to visual predators. However, whether prey behavioural responses to increased turbidity are adaptive is generally unclear. We suggest that a more holistic and ecologically relevant experimental approach is needed to disentangle the underlying mechanisms and determine the adaptive nature of prey behavioural responses to increased turbidity. Our review serves as a broad and comprehensive summary of the empirical research conducted on impacts of increasing water turbidity on predator–prey interactions in freshwater fishes. It highlights knowledge gaps and provides a reference point to guide future experimentation and research synthesis in this crucial and growing area of research.

Functional response and control potential of adult Arma chinensis on Colorado potato beetle in Xinjiang, China

AbstractPotato is an important food crop. The Colorado potato beetle (CPB) is its key pest. CPBs are now resistant to several chemical pesticides, making their control more difficult. The predatory insect, Arma chinensis, is a natural enemy of other plant pests. We studied the predation of adult A. chinensis on CPB eggs and young larvae under indoor controlled conditions and its control of CPB in cages under outdoor conditions. Adult A. chinensis effectively reduces CPB egg and larva populations, and its predatory functional response aligns with Holling’s Type II model. A. chinensis adults released within outdoor cages reduced CPB populations. Based on the predation behavior of the adults of A. chinensis to CPB eggs and young larvae, A. chinensis is an efficient and potential predator.

Crabs as snake predators? An observation from southern Italy leading to a comprehensive review

The recent elevation of the Western Grass Snake, Natrix helvetica, from subspecies status prompted an assessment of its natural history and ecological traits compared to closely related species. We report an unusual predation attempt by the freshwater crab Potamon fluviatile on N. helvetica sicula from Sicily, indicating an ecological interaction previously overlooked in this species. The observation suggests that this crab may utilise snakes’ muscle tissue as an additional nutrient source. This predator-prey interaction, although probably rare, adds to the understanding of the dynamics between crabs and snakes, shedding light on their interaction in freshwater habitats. To provide context for our observation and highlight its rarity, we searched through scientific literature and online sources to generate a comprehensive review of the phenomenon that examines the predatory behaviour of crabs on snakes.

Predator-prey space use and landscape features influence movement behaviors in a large-mammal community.

Predator hunting strategies, such as stalking versus coursing behaviors, are hypothesized to influence antipredator behaviors of prey and can describe the movement behaviors of predators themselves. Predators and prey may alter their movement in relation to predator hunting modes, yet few studies have evaluated how these strategies influence movement behaviors of free-ranging animals in a multiple-predator, multiple-prey system. We fit hidden Markov models (HMM) with movement data derived from >400 GPS-collared ungulates and large predators in eastern Washington, USA. We used these models to test our hypotheses that stalking (cougars [Puma concolor]) and coursing (gray wolves [Canis lupus]) predators would exhibit different broad-scale movement behaviors consistent with their respective hunting strategies in areas that increased the likelihood of encountering or capturing ungulate prey (e.g., habitats selected by deer [Odocoileus spp.]). Similarly, we expected that broadscale movement behaviors of prey would change in response to background levels of predation risk associated with each predator's hunting strategy. We found that predators and ungulate prey adjusted their broadscale movements in response to one another's long-term patterns of habitat selection but not based on differences in predator-hunting strategies. Predators changed their movement behaviors based on the type of prey, whereas ungulates generally reduced movement in areas associated with large predators, regardless of the predator's hunting strategy. Both predator and prey movements varied in response to landscape features but not necessarily based on habitat that would facilitate specific hunting behaviors. Our results suggest that predators and prey adjust their movements at broad temporal scales in relation to long-term patterns of risk and resource distributions, potentially influencing their encounter rates with one another at finer spatiotemporal scales. Habitat features further influenced changes in movement, resulting in a complex combination of movement behaviors in multiple-predator, multiple-prey systems.

Revealing the Diversity of Sequences, Structures, and Targets of Peptides from South China Sea Macrodactyla doreensis Based on Transcriptomics.

The South China Sea is rich in sea anemone resources, and the protein and peptide components from sea anemone toxins comprise an important treasure trove for researchers to search for leading compounds. This study conducted a comprehensive transcriptomic analysis of the tentacles and column of Macrodactyla doreensis and explored the distribution and diversity of proteins and peptides in depth using bioinformatics, initially constructing a putative protein and peptide database. In this database, typical peptide families are identified through amino acid sequence analysis, and their 3D structures and potential biological activities are revealed through AlphaFold2 modeling and molecular docking. A total of 4239 transcripts were identified, of which the putative protein accounted for 81.53%. The highest content comprised immunoglobulin and a variety of proteases, mainly distributed in the column and related to biological functions. Importantly, the putative peptide accounted for 18.47%, containing ShK domain and Kunitz-type peptides, mainly distributed in the tentacles and related to offensive predatory behavior. Interestingly, 40 putative peptides belonging to eight typical peptide families were identified, and their structures and targets were predicted. This study reveals the diversity and complexity of Macrodactyla doreensis toxins and predicts their structure and targets based on amino acid sequences, providing a feasible approach for research regarding the discovery of peptides with potentially high activity.

Updating the prey menu of the ophiophagous snake Erythrolamprus aesculapii (Linnaeus, 1758) with two heterospecific snakes from the Amazon and Atlantic Forest

The Aesculapian false coral snake, Erythrolamprus aesculapii, is reported here preying on two heterospecific snake species. An individual of E. aesculapii was observed preying an adult Atractus cf. major in the municipality of Presidente Figueiredo, state of Amazonas, Brazil, and another on an adult Tropidodryas striaceps in the municipality of Divino de São Lourenço, state of Espírito Santo, also in Brazil. Both observations detail the predatory behavior of E. aesculapii, from chasing to immobilizing and ingesting the prey snakes. These findings expand knowledge of the predatory interactions of E. aesculapii, including the addition of two new prey species, reinforcing the ophiophagous nature of its feeding behavior.

Behaviour of protected predators and man

Behaviour of protected predators and man

Linguistic rights, translation, and State-sponsored violence in Mexican prisons

This article examines linguistic violence experienced by incarcerated indigenous-language speaking women in Mexico. Drawing from a survey of incarcerated individuals, we demonstrate that, despite constitutional guarantees for language access, non-Spanish speakers often lack access to translation services. This deprivation is a form of linguistic violence. Furthermore, we find that such linguistic violence correlates with predatory behavior from authorities—specifically physical and sexual violence. This predatory behavior is reported more frequently by female indigenous-language speakers than any other group. We propose two reasons why this might be the case: limited Spanish proficiency traps these women in prolonged legal limbo, increasing their interactions with potentially abusive authorities, and the language barrier fosters isolation, hindering their ability to report abuses. This phenomenon illustrates how linguistic violence can lead to physical violence.

An Improved Whale Optimization Algorithm with Adaptive Fitness‐Distance Balance

AbstractWhale optimization algorithm (WOA) is a new bio‐meta‐heuristic algorithm presented to simulate the predatory humpback whales' behavior in the ocean. In previous studies, WOA has been observed to exhibit lower accuracy and slower convergence rates. In this paper, we propose an improved the WOA by innovatively incorporating an adaptive fitness‐distance balance strategy, namely AFWOA. AFWOA can continuously and efficiently identify the maximum potential candidate solutions from the population within the search process, thus improving the accuracy rate and convergence speed of the algorithm. Through various experiments in IEEE CEC2017 and an ill‐conditional problem, AFWOA is proven to be more competitive than the original WOA, several other state‐of‐the‐art WOA variants and other four classic meta‐heuristic algorithms. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Mobilized Resilience and Development under Sanctions in Iran

ABSTRACTHow do states maintain economic development in the face of sanctions? Recent studies have examined economic resilience as a property of a system preceding a shock, leaving unanswered questions about how sanctioned states discipline employers and limit predatory behaviour. Using the case of Iran, this article aims to fill this gap by presenting a model of mobilized resilience, describing how bottom‐up and top‐down mobilizations can create demand for institutional capacity. Integrating unique qualitative and quantitative material, the author argues that Iran's political elites responded to sanctions by launching top‐down campaigns that appealed to workers, promoted capital–labour unity, and demanded state commitment to development. These campaigns facilitated widespread labour protests that further empowered the state to block capital flight and steer firms onto more profitable, growth‐oriented routes. Labour ‘resistance’ thus unexpectedly helped to realize the Supreme Leader's calls for a ‘resistance economy’. These findings suggest that political support for worker mobilization in the context of sanctions can result in economic benefits, with significant consequences for our understanding of economic statecraft, development and labour movements.

Daily Activity Rhythms of Animals in the Southwest Mountains, China: Influences of Interspecific Relationships and Seasons

Temporal and spatial factors regulate the interactions between apex predators, mesocarnivores, and herbivores. Prey adjust their activity patterns and spatial utilization based on predator activities; in turn, predators also adapt to the activities of their prey. To elucidate the factors influencing the daily activity rhythms of animals, 115 camera traps were established from September 2019 to June 2023 to assess the influences of interspecific relationships and seasons on the daily activity rhythms of animals in the southwest mountains of China. The species captured by the cameras included six Carnivora (such as Panthera pardus and Lynx lynx), six Artiodactyla (such as Moschus spp. and Rusa unicolor), one Primate (Macaca mulatta), and two Galliformes (Crossoptilon crossoptilon, Ithaginis cruentus). The results demonstrated that the 15 species exhibited different activity rhythms and peak activities to reduce intense resource competition. There were differences in the species’ activity rhythms in different seasons, with competition among different species being more intense in the cold season than in the warm season. In predation relationships, the overlap coefficient in the cold season exceeded that of the warm season, possibly due to the abundant resources in summer and food scarcity in winter. In competitive relationships, 15 pairs of species exhibited significantly higher overlap coefficients in the cold season compared to the warm season, possibly due to increased demands for energy during the cold period or seasonal changes in predatory behavior. By analyzing the daily and seasonal activity patterns of dominant species in the study area, temporal niche overlaps were established to compare the competition levels between species. These findings indicate that the activity rhythms of the animals in this area not only result from evolutionary adaptation but are also influenced by season, food resources, and interspecific relationships (predation and competition). Thus, efforts should be made to reduce human interference, protect food resources in the winter, and monitor animals’ interspecific relationships to protect animal diversity and maintain the stability of the ecosystem in this biodiversity hotspot in China.

Recording potential predators of herpetofauna in southern Mexico using camera traps and realistic models

ABSTRACT Knowledge of biotic predator–prey interactions is essential for understanding the role of species in the food web; however, information on these interactions is scarce for most species. Our aim in this study was to gather information on the potential predators of two species of herpetofauna abundant in the rainforest they inhabit, the frog Craugastor loki and the snake Ninia sebae. For this, realistic models of the two species were placed, and monitored using camera traps, in 13 sites located in a forest fragment belonging to a private protected natural area in southern Veracruz in three seasons (dry, rainy and windy) in 2019. In addition, the temporality and seasonality of the events and some behaviours of the potential predators are described. The recorded events were classified into four categories: presence, interest, contact and aggression. For C. loki, 159 events of appearances of potential predators were identified (32 with interaction: 18 events of interest, 2 contact and 12 aggressions). The aggressions were carried out by the mammals Didelphis marsupialis and Peromyscus sp. In the case of N. sebae, 201 appearances of potential predators were identified (75 with interaction: 36 events of interest, 7 contact and 32 aggressions). The aggressions were carried out by 10 species (seven birds and three mammals). Bird predation events towards models of both species occurred during daytime while the attacks by mammals occurred at night. Agonistic behaviours included pecking, biting and urine marking, previously unknown. Events of each category were recorded every season. Our results indicate that C. loki and N. sebae may have more predators than were previously known, and suggest that these species can be an important food resource for different species of birds and mammals in the environments where they live.

Behavioural responses to mammalian grazing expose insect herbivores to elevated risk of avian predation.

Large mammalian herbivores (LMH) are important functional components and drivers of biodiversity and ecosystem functioning in grasslands. Yet their role in regulating food-web dynamics and trophic cascades remains poorly understood. In the temperate grasslands of northern China, we explored whether and how grazing domestic cattle (Bos taurus) alter the predator-prey interactions between a dominant grasshopper (Euchorthippus unicolor) and its avian predator the barn swallow (Hirundo rustica). Using two large manipulative field experiments, we found that in the presence of cattle, grasshoppers increased their jumping frequency threefold, swallows increased foraging visits to these fields sixfold, and grasshopper density was reduced by about 50%. By manipulatively controlling the grasshoppers' ability to jump, we showed that jumping enables grasshoppers to avoid being incidentally consumed or trampled by cattle. However, jumping behaviour increased their consumption rates by swallows 37-fold compared with grasshoppers that were unable to jump. Our findings illustrate how LMH can indirectly alter predator-prey interactions by affecting behaviour of avian predators and herbivorous insects. These non-plant-mediated effects of LMH may influence trophic interactions in other grazing ecosystems and shape community structure and dynamics. We highlight that convoluted multispecies interactions may better explain how LMH control food-web dynamics in grasslands.

Oxygen loss compromises growth and cognition of cuttlefish newborns.

Ocean deoxygenation and standing levels of hypoxia are shrinking fundamental niches, particularly in coastal areas, yet documented repercussions on species development and behaviour are limited. Here, we tackled the impacts of deoxygenation (7 mg O2 l-1), mild hypoxia (nocturnal 5 mg O2 l-1) and severe hypoxia (nocturnal 2 mg O2 l-1) on cuttlefish (Sepia officinalis) development (hatching success, development time, mantle length), cognition (ability to learn individually and socially) and behaviour (ability to camouflage and to explore its surroundings spatially). We found that hypoxia yielded lower survival rates, smaller body sizes and inhibited predatory (increased latency to attack the prey) and anti-predator (camouflage) behaviours. Acute and chronic exposure to low oxygen produced similar effects on cognition (inability to socially learn, increased open-field activity levels, no changes in thigmotaxis). It is thus expected that, although cuttlefish can withstand oxygen limitation to a certain degree, expanding hypoxic zones will diminish current habitat suitability.

Refurbishing the marine parasitoid order Pirsoniales with newly (re)described marine and freshwater free-living predators.

Pirsoniales is a stramenopile order composed of marine parasitoids of diatoms with unique life cycle. Until recently, a single genus, Pirsonia, uniting six species, was known. The recent identification of new free-living eukaryotrophic Pirsoniales Pirsonia chemainus, Feodosia pseudopoda, and Koktebelia satura changed our understanding of this group as exclusively parasitic. However, their cell ultrastructure and feeding preferences were not fully studied due to the death of the cultures. In this study, we re-isolated some of these Pirsoniales and established six new strains exhibiting predatory behavior, including a first freshwater representative. This allowed us to describe five new genera and species, as well as to emend the diagnosis of the order Pirsoniales. The 18S rRNA gene phylogenetic analysis revealed the position of new strains within Pirsoniales and their relationships with parasitoid relatives and environmental sequence lineages. Feeding experiments on novel Pirsoniales strains using diverse algal prey showed that they were not able to form trophosomes and auxosomes. The ability of cell aggregation in Pirsoniales was observed for the first time. One of the studied strains contained intracellular gammaproteobacteria distantly related to Coxiella. Ultrastructural analyses revealed a more complex cytoskeleton structure in Pirsoniales than previously thought and supported the monophyly of Bigyromonadea and Pseudofungi.

Predation Efficiency and Biological Control Potential of Micromus angulatus Against Aphis craccivora

Micromus angulatus (Neuroptera: Hemerobiidae) is a widely distributed and highly effective predator that shows promise as a biological control agent against agricultural pests, particularly Aphis craccivora, the cowpea aphid, which threatens leguminous crops globally. This study aimed to evaluate the predation behaviour, search efficiency, and intraspecific interference of M. angulatus at different developmental stages, including first- to third-instar larvae and adults, in controlling adult A. craccivora populations. The results demonstrated that all developmental stages of M. angulatus exhibited predatory behaviour towards adult aphids, with the functional response fitting the Holling Type II model. The instantaneous attack rates for first-, second-, and third-instar larvae and adults were 1.0017, 1.0448, 0.9581, and 0.9508, respectively; the handling times were 0.0158, 0.0051, 0.0016, and 0.0011 days, respectively; and the theoretical maximum daily predation rates were 63.2911, 196.0784, 625, and 909.0909 aphids, respectively. The pest control efficacies were 63.3989, 204.8672, 598.8311, and 864.3192, respectively. The search efficiency at each developmental stage was negatively correlated with aphid density, which decreased as the prey density increased, with second-instar larvae showing the greatest decrease and adults the least. When the aphid density was fixed, the daily predation rate of individual M. angulatus decreased with increasing conspecific density, indicating that predation was affected by its own density, with the interference effect equation being E = 0.6194P−0.87. These findings indicate that M. angulatus, especially in the third-instar larval and adult stages, has considerable potential as a biological control agent for managing A. craccivora populations in agricultural settings. This study contributes valuable insights for developing sustainable agricultural practices by decreasing reliance on chemical pesticides.

Evolution of novel sensory organs in fish with legs

How do animals evolve new traits? Sea robins are fish that possess specialized leg-like appendages used to "walk" along the sea floor. Here, we show that legs are bona fide sense organs that localize buried prey. Legs are covered in sensory papillae that receive dense innervation from touch-sensitive neurons, express non-canonical epithelial taste receptors, and mediate chemical sensitivity that drives predatory digging behavior. A combination of developmental analyses, crosses between species with and without papillae, and interspecies comparisons of sea robins from around the world demonstrate that papillae represent a key evolutionary innovation associated with behavioral niche expansion on the sea floor. These discoveries provide unique insight into how molecular-, cellular-, and tissue-scale adaptations integrate to produce novel organismic traits and behavior.

Predation of salamander egg sacs by the water strider Gerris (Macrogerris) insularisMotschulsky (Hemiptera: Gerridae)

AbstractWater striders (Hemiptera: Gerridae) are sucking predators that inhabit freshwater and marine environments. They prey mainly on insects that fall on the water surface, but they are also known to feed on amphibian eggs. Here, we report on the predation of egg sacs of Hynobius nigrescens (Caudata: Hynobiidae) by Gerris (Macrogerris) insularis. We observed predation on egg sacs of H. nigrescens by G. insularis at a pond in a mountainous area of Nagano City, Nagano Prefecture, Japan. We also found egg sacs with predation marks probably made by water striders at a pond in the mountainous area of Nishimeya Village, Aomori Prefecture, Japan. Five water striders collected around the preyed egg sacs were identified as G. insularis. We filled three tanks with water and an egg sac, and three water striders that were collected at the site in Nishimeya Village were placed together in each tank. In two tanks, the jelly layer of the egg sac was partially cut in a horizontal manner, while in another tank, the jelly layer was removed on the part of the egg sac exposed on the water surface. Notably, the water striders exhibited predatory behavior only when the jelly layers were removed. Considering the results of the rearing experiment and the predation marks observed in the field, G. insularis is also likely to prey on egg sacs at the site in Nishimeya Village. Our study suggested that predation by G. insularis occurs when eggs are accidentally exposed due to disturbance of the jelly layer.