Prey Feeding Research Articles

Prey capture kinematics of horned frogs (Anura: Ceratophryidae).

Horned frogs, members of the Ceratophryidae family, encompass a group of anurans varying in size and behavior, yet unified by morphological and behavioral traits enabling them to adopt a megalophagous diet (i.e., large prey feeding). Although the group has been the focus of numerous studies, our understanding of its feeding behavior remains limited. In this study, we characterize the feeding mechanism in five species representing the three extant genera of ceratophryid anurans, both in terrestrial and aquatic environments. We also explore the ability of Chacophrys pierottii to adjust feeding behavior based on prey type. Our findings show that all species are capable of widemouth opening, displaying an asymmetric feeding cycle. While tongue usage is the primary method for capturing prey on land, ceratophryids may use their forelimbs to manipulate prey into their mouths, exhibiting different behavioral patterns. C. pierottii shows modulation of its feeding kinematics and is also capable of some modulation of its feeding in response to prey properties.

Social information use in herbivore prey can influence the success of biological control

Predation-risk effects (PEs), i.e. costly consequences of antipredator trait responses in prey, have been the focus of many theoretical and applied studies on predator–prey systems, but we still have limited knowledge on how prey functional traits – such as the ability to acquire and use inadvertent social information (ISI) – influence the susceptibility to strong PEs. In this study, I used an individual-based model to explore how ISI use alters the relative importance of consumptive and predation-risk effects on herbivore prey abundance and total consumption, a proxy for plant damage. I found that ISI use contributed to higher prey abundance by lowering predation-related mortality, but it also decreased prey total consumption through PE irrespective of the relation between prey and predator detection ranges and the type of prey social organisation. Moreover, due to its stronger effect on the non-consumptive component of the total predation effect, ISI use contributed to an overall reduction in prey feeding performance. The estimated strengths of different predator effect components were also comparable to previous experimental findings. These findings provide strong support for the idea that the access to and use of risk-related social information not only result in more prey individuals exhibiting the antipredator response but also leads to strong behavioural PEs with substantial consequences on prey consumption.

Weathering the hunt: The role of barometric pressure in predator insects' foraging behaviour.

Abiotic factors strongly influence ecological interactions and the spatial distribution of organisms. Despite the essential role of barometric pressure, its influence on insect behaviour remains poorly understood, particularly in predators. The effect of barometric pressure variation can significantly impact biological control programs involving entomophagous insects, as they must efficiently allocate time and energy to search for prey in challenging environments. We investigated how predatory insects from different taxonomic groups (Coleoptera, Dermaptera and Neuroptera) adapt their foraging behaviour in response to variations in barometric pressure (low, medium and high). We also examined the response of different life stages to changes in pressure regimes during foraging activities. Our results showed that the searching time of Doru luteipes (Dermaptera: Forficulidae) was faster in a favourable high-pressure regime, whereas Chrysoperla externa (Neuroptera: Chrysopidae) and Eriopis connexa (Coleoptera: Coccinellidae) had similar searching times under varying pressure regimes. Although no differences in prey feeding time were observed among the studied species, the consumption rate was influenced by low barometric pressure leading to a decrease in the number of preyed eggs. Moreover, we provide novel insights into how hemimetabolous (D. luteipes) and holometabolous (E. connexa) species at different life stages respond to barometric pressure. Doru luteipes nymphs and adults had similar consumption rates across all pressure regimes tested, whereas E. connexa larvae consumed fewer eggs under low barometric pressure, but adults were unaffected. This highlights the importance of investigating how abiotic factors affect insects foraging efficiency and predator-prey interactions. Such studies are especially relevant in the current context of climate change, as even subtle changes in abiotic factors can have strong effects on insect behaviour. Barometric pressure is a key meteorological variable that serve as a warning signal for insects to seek shelter and avoid exposure to weather events that could potentially increase their mortality. Understanding the effects of barometric pressure on predatory insects' behaviour can help us develop more effective pest management strategies and promote the resilience of agroecosystems. We provide new insights into the complex relationship between barometric pressure and predator-prey interactions.

Learning behavior of Neoseiulus californicus from astigmatid to spider mites

Oulenziella bakeri is often used as an alternative prey for the mass rearing of Neoseiulus californicus in China. Long-term alternative prey feeding experience may cause a decline in the predatory capacity of phytoseiid mites toward their target prey. Learning behavior of predatory mites can help them adapt to the changes from preying on thrips to preying on spider mites (Rahmani et al., 2010), but there are few studies on the learning behavior of predatory mites from astigmatid mites to spider mites. Here, we compared the attack latency, prey preference, and functional response of N. californicus toward Tetranychus urticae among the “natural prey strains” (feeding only on T. urticae), “alternative prey strains” (feeding only on O. bakeri), and “learning behavior treatment” (alternative prey strains experienced in attacking but not feeding on T. urticae). The results showed that the attack latency of “alternative prey strain” of N. californicus on T. urticae was significantly longer than that of “natural prey strain” and “learning behavior treatment”. The “alternative prey strain” showed no obvious predatory preference between the protonymphs of T. urticae and O. baker. There were no significant differences in the capture rate and handling time among the three treatments. Our results indicated that the long-term rearing on alternative prey mainly prolonged the attack latency of N. californicus to the target prey and changed its prey preference, while learning behavior could help alternative prey strain of N. californicus to shorten the attack latency and restore its prey preference toward target prey (Zhu et al., 2022).

Comparative transmission of bacteria from Artemia salina and Brachionus plicatilis to the cnidarian Nematostella vectensis.

The microbial community associated with animals (microbiome) is essential for development, physiology, and health of host organisms. A critical step to understand the assembly of microbiomes is to determine how effectively bacteria colonize and establish within the host. Bacteria commonly colonize hosts through vertical transmission, passively from the environment, or through food consumption. Using the prey feeding method (PFM), we test transmittance of Bacillus velezensis, Pseudoalteromonas spiralis, and Vibrio alginolyticus to Nematostella vectensis using two prey, Artemia salina and Brachionus plicatilis. We compare PFM to a solution uptake method (SUM) to quantify the concentration of bacteria in these host organisms, with plate counts. Larvae had a similar uptake with SUM at 6h but had greater concentrations at 48h versus PFM. Juveniles acquired similar concentrations at 6h for SUM and PFM using B. plicatilis and A. salina. At 2 days, the quantity of bacteria vectored from PFM increased. After 7 days the CFUs decreased 2-fold with B. plicatilis and A. salina relative to the 2-day concentrations, and further decreased after 14 days. Therefore, prey-mediated methods provide greater microbe transplantation than SUM after 24h, supporting this approach as a more successful inoculation method of individual bacterial species.

Effect of Fasting and Refeeding on Juvenile Leopard Mandarin Fish Siniperca scherzeri.

Simple SummaryThe development of live prey feed domestication techniques for the carnivorous leopard mandarin fish (Siniperca scherzeri) requires establishing nutritionally complete diets and research into optimal feeding regimes. Accordingly, the purpose of this experiment was to investigate the effects of varied feeding regimes for S. schezeri on compensatory growth. Individuals were divided into a daily feeding control group (C), a 5-day fasting group (F5), a 10-day fasting group (F10), and a 14-day fasting group (F14). The results demonstrated that after four weeks of treatment, all experimental groups experienced full compensatory growth and reached the control group weight. Therefore, this information will be valuable for effective management when fasting is necessary in S. schezeri aquaculture.To verify the effect of fasting on juvenile leopard mandarin fish (Siniperca scherzeri mean weight, 14.7 g), compensatory growth, body composition, and blood content of juveniles were investigated for six weeks following two-week feeding treatments: fed continuously (control), and fasted for 5 (F5), 10 (F10) and 14 days (F14). Full compensatory growth was evident after four weeks of food resupply in all fasting groups. Specific growth rate, feeding rate, and feed efficiency in all fasting groups were significantly higher than those of the control after the first 2 weeks of food resupply. At the end of fasting, the lipid content, ratio of lipid to lean body mass, hepatosomatic and viscerosomatic indices in all fasting groups, or total cholesterol content in F14 significantly decreased compared to the control. These results indicated that juvenile leopard mandarin fish subjected to 5–14 days of food deprivation could achieve full compensatory growth after feeding resumption for 4 weeks and that the morphological and biochemical indices, as well as body and blood composition, remained comparable to the control group after the completion of the study under our experimental conditions.

Reliance of young sharks on threatened estuarine habitats for nutrition implies susceptibility to climate change

Climate change and urbanization of coastal areas are impacting estuarine habitats globally. While these regions are important for the early-life development of many aquatic species, links between habitat use and foraging ecology are not well known. Thus, it is essential to understand the importance of threatened habitats for animals inhabiting estuaries to promote their conservation and improve ecosystem management. This study examined the importance of estuarine habitats as feeding grounds for juvenile bull sharks (Carcharhinus leucas) in the Clarence River, a nursery area where the species is targeted by commercial fisheries in New South Wales, Australia. Juvenile sharks (n = 54) ranging from one to ∼6.5 years-old, together with particulate matter and several primary producer species of mangrove and saltmarsh, were sampled for δ13C, δ15N and δ34S stable isotopes. Bayesian mixing models and a Generalized Additive Mixed Model were used to investigate the contribution of estuarine habitats to the diet of bull sharks and changes with growth. The importance of resources consumed from within mangrove habitats for juvenile bull shark resource use was minimal but slightly increased with age, with younger sharks (<2.5 years) relying on prey feeding on sources derived from particulate organic matter, while older juveniles (4–6.5 years) preyed on species that relied mostly on threatened saltmarsh habitats. Our findings highlight the important linkages between habitats of conservation concern and species redistribution in response to climate change, particularly as the animals could be moving towards new areas lacking suitable estuarine habitats.

Blood Taurine Dynamics in Captive Lions: Relationship with Feed and Bile Acid Composition.

Taurine is an essential nutrient for felines including lions. Various severe symptoms induced by taurine deficiency have been reported for domestic and captive felines. Particularly for captive lions in zoos, little information related to taurine requirements is available. Therefore, this study evaluated the relationship between blood taurine concentration and taurine content in prey feed given at zoos, as well as the composition, types, and conjugation properties of bile acids (BAs) in blood collected repeatedly from four lions housed at three zoos. Blood taurine concentrations in four lions were within the normal range, although individual differences and variations were found. Taurine was abundant in feed supplied at the zoos. A positive correlation between blood taurine concentration and feed amount was observed in lions housed at the same zoo. Approximately 70-80% of the total BA pool was cholic acid, with 50-70% being taurine-conjugated. Individual differences and variations were found. No correlation was found between blood taurine concentration and the compositions of BAs in the blood. Results showed that supply of taurine was sufficient for all lions fed the prey feed. Future studies must be conducted to clarify influences on individual differences, as well as individual variations in blood taurine concentration and blood BA composition.

Prey capture kinematics of wild and hatchery juvenile common snook Centropomus undecimalis

Common snook Centropomus undecimalis is an important estuarine-dependent predatory fish species. In Florida, the decline of wild stocks, due mainly to fishing pressure and loss of habitat, has led to increasingly restrictive management actions in the last 50 years. This has also promoted its culture for stock enhancement as one of many management actions. Stocking efforts indicate that survival of snook fingerlings can be poor and improvements could be achieved through prerelease conditioning. In this study we compared prey capture kinematics between naïve hatchery juvenile snook and wild conspecifics. Capture behavior, quantified with high-speed cameras, identified specific differences in prey capture of hatchery and wild snook. Naïve juvenile hatchery snook exposed to live prey made fewer attempts to feed, had longer delays in the time to strike, exhibited higher strike velocities and engulfed prey earlier in the gape cycle, and had less overall feeding success compared to wild fish. However, experience with repeated live prey feeding events quickly improved hatchery snook feeding success, similar to wild fish. Therefore, prerelease training via exposure to live prey could improve feeding performance and overall fate of snook released into the wild.

Genome of the pincer wasp Gonatopus flavifemur reveals unique venom evolution and a dual adaptation to parasitism and predation

BackgroundHymenoptera comprise extremely diverse insect species with extensive variation in their life histories. The Dryinidae, a family of solitary wasps of Hymenoptera, have evolved innovations that allow them to hunt using venom and a pair of chelae developed from the fore legs that can grasp prey. Dryinidae larvae are also parasitoids of Auchenorrhyncha, a group including common pests such as planthoppers and leafhoppers. Both of these traits make them effective and valuable for pest control, but little is yet known about the genetic basis of its dual adaptation to parasitism and predation.ResultsWe sequenced and assembled a high-quality genome of the dryinid wasp Gonatopus flavifemur, which at 636.5 Mb is larger than most hymenopterans. The expansion of transposable elements, especially DNA transposons, is a major contributor to the genome size enlargement. Our genome-wide screens reveal a number of positively selected genes and rapidly evolving proteins involved in energy production and motor activity, which may contribute to the predatory adaptation of dryinid wasp. We further show that three female-biased, reproductive-associated yellow genes, in response to the prey feeding behavior, are significantly elevated in adult females, which may facilitate the egg production. Venom is a powerful weapon for dryinid wasp during parasitism and predation. We therefore analyze the transcriptomes of venom glands and describe specific expansions in venom Idgf-like genes and neprilysin-like genes. Furthermore, we find the LWS2-opsin gene is exclusively expressed in male G. flavifemur, which may contribute to partner searching and mating.ConclusionsOur results provide new insights into the genome evolution, predatory adaptation, venom evolution, and sex-biased genes in G. flavifemur, and present genomic resources for future in-depth comparative analyses of hymenopterans that may benefit pest control.

Nutrient intake and influence on markers of oxidative stress in zoo-managed male snow leopards (Uncia uncia).

Oxidative stress (OS) results from the overproduction of reactive species. Nutrient intake can contribute positively or negatively to OS, and the lack of established nutrient requirements for most of the exotic species managed in zoos exacerbates the possibilities for nutrient imbalances that potentially could lead to reactive species production. The objective of this study was to evaluate the influence of nutrient intake and nutritional husbandry on markers of OS in male snow leopards (n = 14) maintained in U.S. facilities (n = 12). Diet samples and husbandry information were obtained and snow leopards were immobilized once for collection of blood. Samples were analyzed for chemical composition (diet and blood), antioxidant capacity (blood), and markers of OS (blood). Correlations between weekly nutrient intakes and markers of OS were analyzed by linear regression. Analyzed markers of OS included antioxidant enzymes (superoxide dismutase [SOD] and glutathione peroxidase [GPx]) and ferric reducing antioxidant potential that are protective against OS, and protein carbonyls, thiobarbituric acid reactive substances, and DNA/RNA damage that are indicative of oxidative damage. Weekly copper intake (10.1 to 80.2 mg) was negatively correlated with DNA/RNA damage (R2 = 0.44; P = 0.01). Weekly sodium intake (4.4 to 12.7 g) was positively correlated with GPx activity (R2 = 0.43; P = 0.04). More frequent feeding of whole prey (0.3 to 3 times/wk) was correlated with increased blood SOD activity (R2 = 0.55; P < 0.01). In conclusion, greater dietary copper intake and more frequent feeding of whole prey may reduce OS in snow leopards. Dietary sodium intake and relationship with GPx activity should be further evaluated to determine benefit or detriment. No cause and effect can be inferred from our results, but our data suggest altering dietary form and nutrient concentrations may influence OS in snow leopards.

Plant-feeding may explain why the generalist predator Euseius stipulatus does better on less defended citrus plants but Tetranychus-specialists Neoseiulus californicus and Phytoseiulus persimilis do not

The generalist predator Euseius stipulatus (Athias-Henriot) and the Tetranychidae-specialist predators Neoseiulus californicus (McGregor) and Phytoseiulus persimilis Athias-Henriot play a key role in the regulation of Tetranychus urticae Koch in Spanish citrus orchards. Previous studies have shown that sour orange (Citrus aurantium L.) and Cleopatra mandarin (Citrus reshni hort. ex Tan.) display extreme resistance and susceptibility to T. urticae, respectively. When offered a choice between these two genotypes infested by T. urticae, E. stipulatus preferred Cleopatra mandarin, whereas the specialists did not show any preference. The present study was undertaken to check whether these preferences could be related to the feeding of E. stipulatus on the host plant and/or to differences in prey feeding on the two plants. Our results demonstrate that E. stipulatus is a zoophytophagous mite, which can engage in direct plant feeding in sour orange and Cleopatra mandarin, whereas neither N. californicus nor P. persimilis do so. Whereas Cleopatra mandarin provided a higher-quality prey/feeding substrate for E. stipulatus, which may be related to its phytophagy, no differences were observed for the two specialists. As higher constitutive and faster inducible defense against T. urticae in sour orange relative to Cleopatra mandarin plants result in sour orange supporting lower T. urticae densities and plant damage, our results demonstrate that pest regulation by specialist natural enemies may be more effective when prey feed on better defended plants.

What makes a fang? Phylogenetic and ecological controls on tooth evolution in rear-fanged snakes

BackgroundFangs are a putative key innovation that revolutionized prey capture and feeding in snakes, and – along with their associated venom phenotypes – have made snakes perhaps the most medically-significant vertebrate animals. Three snake clades are known for their forward-positioned fangs, and these clades (Elapidae, Viperidae, and Atractaspidinae) contain the majority of snakes that are traditionally considered venomous. However, many other snakes are “rear-fanged”: they possess potentially venom-delivering teeth situated at the rear end of the upper jaw. Quantification of fang phenotypes – and especially those of rear-fanged species – has proved challenging or impossible owing to the small size and relative rarity of many such snakes. Consequently, it has been difficult to understand the evolutionary history of both venom and prey-capture strategies across extant snakes. We quantified variation in the dentition of 145 colubriform (“advanced”) snake species using microCT scanning and compared dental characters with ecological data on species’ diet and prey capture method(s) to understand broader patterns in snake fang evolution.ResultsDental traits such as maxilla length, tooth number, and fang size show strong phylogenetic signal across Colubriformes. We find extreme heterogeneity and evolutionary lability in the rear-fanged phenotype in colubrid (colubrine, dipsadine, and natricine lineages) and lamprophiid snakes, in contrast to relative uniformity in the front fanged phenotypes of other groups (vipers and, to a lesser extent, elapids). Fang size and position are correlated with venom-use in vipers, elapids, and colubrid snakes, with the latter group shifting fangs anteriorly by shortening the entire maxillary bone. We find that maxilla length and tooth number may also be correlated with the evolution of dietary specialization. Finally, an ancestral state reconstruction suggests that fang loss is a recurring phenomenon in colubrid snakes, likely accompanied by shifts in diet and prey capture mode.ConclusionsOur study provides a framework for quantifying the complex morphologies associated with venom use in snakes. Our results suggest that fang phenotypes, and particularly the rear-fanged phenotype, in snakes are both diverse and labile, facilitating a wide range of ecological strategies and contributing to spectacular radiations of these organisms in tropical and subtropical biomes worldwide.

The Impact of Microplastic Particles on Population Dynamics of Predator and Prey: Implication of the Lotka-Volterra Model

Microplastic particles are widely distributed in a variety of ecosystems and can be transferred to predators along a food chain after being ingested by prey. However, how microplastic particles affect prey and predator populations is not fully understood. In this study, using the Lotka-Volterra model, we theoretically investigated predator-prey population dynamics in terms of toxicological response intensity (strength to population growth rate) to microplastic particles, and examined the negative effects on prey feeding ability and predator performance due to microplastic particles. Results of numerical simulations indicate the critical properties of the predator-prey system in response to microplastic particles: (i) predators are more vulnerable than prey under exposure to microplastic particles; (ii) the effect of microplastic particles on prey and predator population growths can be negligible when toxicological response intensities of prey and predator are small; (iii) this system is prey dependent for predator functional response, whose stability highly relies on the density of prey; (iv) the reduced feeding capacity of prey and predator induced by microplastic particles does not significantly affect the population dynamics of the predator-prey system. Moreover, our analysis suggests that dynamic Lotka-Volterra models can play a vital role in predicting ecological impacts of microplastic particles on predator-prey population dynamics.

Small mammal responses to long-term large-scale woodland creation: the influence of local and landscape-level attributes.

Habitat loss and fragmentation greatly affect biological diversity. Actions to counteract their negative effects include increasing the quality, amount and connectivity of seminatural habitats at the landscape scale. However, much of the scientific evidence underpinning landscape restoration comes from studies of habitat loss and fragmentation, and it is unclear whether the ecological principles derived from habitat removal investigations are applicable to habitat creation. In addition, the relative importance of local‐ (e.g., improving habitat quality) vs. landscape‐level (e.g., increasing habitat connectivity) actions to restore species is largely unknown, partly because studying species responses over sufficiently large spatial and temporal scales is challenging. We studied small mammal responses to large‐scale woodland creation spanning 150 yr, and assessed the influence of local‐ and landscape‐level characteristics on three small mammal species of varying woodland affinity. Woodland specialists, generalists, and grassland specialists were present in woodlands across a range of ages from 10 to 160 yr, demonstrating that these species can quickly colonize newly created woodlands. However, we found evidence that woodlands become gradually better over time for some species. The responses of individual species corresponded to their habitat specificity. A grassland specialist (Microtus agrestis) was influenced only by landscape attributes; a woodland generalist (Apodemus sylvaticus) and specialist (Myodes glareolus) were primarily influenced by local habitat attributes, and partially by landscape characteristics. At the local scale, high structural heterogeneity, large amounts of deadwood, and a relatively open understory positively influenced woodland species (both generalists and specialists); livestock grazing had strong negative effects on woodland species abundance. Actions to enhance habitat quality at the patch scale focusing on these attributes would benefit these species. Woodland creation in agricultural landscapes is also likely to benefit larger mammals and birds of prey feeding on small mammals and increase ecosystem processes such as seed dispersal.

Perception of the ethical acceptability of live prey feeding to aquatic species kept in captivity.

Previous research into public perceptions of live prey feeding has been focused on terrestrial animals. The reasons for this likely relate to the difficulty humans have in being compassionate to animals who are phylogenetically distantly related. In order to test these assumptions, the general public (two groups; one who had just visited an aquarium; and one group who had just visited a zoo), aquarium professionals in the UK/US and terrestrial zoo animal professionals (UK) were investigated to see how they would differ in their responses when asked about feeding various live aquatic animals to one another. Likert based surveys were used to obtain data face to face and via online social media. Demographics in previous research identified a lower acceptance of live prey feeding by females, however in aquatic animals this was not reflected. Instead, separations in perception were seen to exist between participants dependent on whether they had just visited a zoo or aquarium, or worked with animals.

Drivers of stereotypic behaviour and physiological stress among captive jungle cat (Felis chaus Schreber, 1777) in India

Zoos play a vital role in managing and conserving a wide range of threatened species and in enhancing their populations in natural habitats through captive breeding and reintroduction programmes. Most small felids are poor breeders in zoos, owing to a range of issues such as spatial constraints, diet, disturbance from visitors, small population size, social grouping and other environmental factors in the exhibits. Many of these factors have also been found to influence the glucocorticoid levels among them. Chronic elevations in glucocorticoids can ultimately lead to psychological and physiological problems, eventually affecting reproduction and fitness. We assessed the influence of four biological and seven environmental factors on stress level linked to psychological (stereotype), and physiological (Faecal Glucocorticoid Metabolite, FGM) conditions and positive welfare behaviour (active and inactive) among 14 jungle cats Felis chaus managed at three zoos in Indian (two in Kerala and one in Maharashtra) during May 2014–March 2017. Stereotype, a behavioural indicator of stress, and welfare behaviour were assessed through 336 h daylight focal sampling and physiological stress following non-invasive FGM extraction using Enzyme-Immunoassay (EIA) from 63 fresh faecal samples. Overall, jungle cats spent more time on inactive (72%) compared to active behaviour (23%) and 5% on stereotypic behaviour. On average, the jungle cats had 43.3 ng/g of FGM. The Principal Component Analysis on 11 independent factors revealed that daylight hour did not influence active, inactive and stereotype behaviours. In addition, age also had no significant influence on FGM levels. Binary logistic regression revealed that active behaviour was more likely to be observed in cats fed live chicken, housed on natural substrate and in females. Inactive behaviour was significantly lower in younger cats, but higher in cats managed with hideouts. Our results suggest that cats housed with non-relatives and in enclosures lacking hideouts have higher rates of stereotype. Multiple regression analyses on behaviour indicate that active behaviour was significantly higher in cats when the arrival age at the zoo was <1 year, among females compared to males, fed live chicken compared to beef, when managed in natural compared to artificial enclosures and in enclosures without hideouts. Remarkably, inactive behaviour increased significantly with increase in visitor intensity and when cats fed beef compared to live chicken. The stereotypic behaviour was significantly lower in females and higher when the arrival age at the zoo was >1 year. It was also the case when the cats were fed beef vs. whole live chicken, when managed in enclosures without hideouts, and also when managed with unrelated conspecifics compared to those kept in enclosures with hideouts and in solitary condition. The FGM levels were significantly higher among males but lower among cats managed in natural and larger enclosures, and enclosures with hideouts, when compared to those managed in artificial, smaller enclosures and enclosures without hideouts. We recommend the provision of larger (>29 m2) natural enclosures with hideout facilities, management in solitary condition or in social groupings with related conspecifics and feeding of live prey to promote positive welfare and reduce psychological and physiological stress among the jungle cats in zoos.

Prey capture and feeding behaviour in an endemic land flatworm from São Tomé Island

ABSTRACTTwo specimens of the endemic land flatworm species Othelosoma impensum Sluys & Neumann, 2017 from the volcanic island São Tomé were observed in the wild in Obo-National Park while they were preying on ants that had descended on a tree trunk after their nuptial flight. A maximum of 41 ants were assembled in a cluster by one of the flatworms, the insects being immobilised by mucus secreted by the worms. A strong cephalic retractor muscle facilitated capture of the mobile prey. Presence or absence of similar cephalic adaptations in other species of Othelosoma and other genera of land flatworms is discussed, as well as the effectiveness of the sticky mucus secreted by the worms during prey capture.

Deforestation May Trigger Black-and-Chestnut Eagle (Spizaetus isidori) Predation on Domestic Fowl

In anthropogenically transformed habitats, some birds of prey feed on domestic animals, triggering conflict between people and predators. To manage this conflict, it is important to understand the ecological circumstances associated with the predation of domestic animals. We studied variation in the diet of the endangered Black-and-chestnut Eagle ( Spizaetus isidori) in four different Andean landscapes in Colombia. We analyzed 261 prey items brought to five S. isidori nests during the period when the nestlings were being raised. Domestic fowl are relatively frequent prey in the diet of S. isidori in three of the four localities studied (frequency: 9.3%–36%), representing 12.2% to 37.1% of the total biomass of prey consumed. In terms of biomass, in Ciudad Bolívar, Jardín, and Campohermoso, the sites with the greatest forest cover, mammals were the most important prey in the diet of S. isidori, while in Gachalá, the most deforested site, domestic fowl were the most important prey. We recommend that forest cover be maintained and increased to provide habitat for wild prey in the breeding territories of S. isidori using the landscape management tools best suited to the specific socioecological contexts of this eagle’s territories. We also suggest that the management of domestic fowl under controlled conditions or the use of some deterrent be examined as strategies to mitigate or prevent conflict between people and S. isidori. Socioecological research and educational programs should be carried out to increase the public’s understanding of this eagle and its benefits to the ecosystem.

Functional response and prey stage preference of Neoseiulus barkeri on Trasonemus confusus

The fungivorous Tarsonemus confusus Ewing is a tarsonemid mite causing a so call ‘black-dot’ symptom on the bagged apple fruit in North China, and the phytoseiid mite Neoseiulus barkeri Hughes is a cosmopolitan generalist predator of many agricultural and horticultural pests. In the present study, we evaluated the biological control potential of N. barkeri on T. confusus, by determining its functional response type to prey density of and prey stage preference on both active and quiescent life stages of T. confusus (i.e., eggs, larvae, quiescent larvae and female adults). We found that N. barkeri exhibited all three types of functional response. When fed on eggs and quiescent larvae of T. confusus, N. barkeri had a Type II functional response (i.e., inverse density-dependent predation rate); however, a Type I functional response (i.e., density-independent predation rate) was detected when N. barkeri preyed on T. confusus larvae and a Type III functional response (i.e., sigmoid density-dependent predation rate) when preyed on T. confusus adults. We further showed that the ‘constant prey’ functional response models fit our data better than the ‘depleted prey’ models, as the predator left and reencountered the previously fed prey which reduced its searching efficiency. When all active and quiescent life stages of T. confusus were available, N. barkeri significantly preferred larvae over other prey stages for feeding. Our results imply that due to its quick response to the increasing prey larval and adult densities, N. barkeri could consume a great number of active prey and is thus capable to decline the current fruit damage caused by prey feeding and to potentially prevent the prey population build-up later in the season. Furthermore, predators with Type II response may be efficient at low prey densities, thus augmentative release of N. barkeri early in the season may also suppress the egg and quiescent larva populations of T. confusus. Knowledge from this study provides insights into our understandings in the biological control ecology of N. barkeri.