Breeding southern house wrens exhibit a threat-sensitive response when exposed to different predator models

We assessed the ability of southern house wrens (Troglodytes aedon musculus) to recognize and discriminate different birds of prey. We exposed nesting birds to stuffed specimens of two sympatric predator species, the chimango caracara (Milvago chimango, a nest predator) and the roadside hawk (Buteo magnirostris, a predator of adults and nests), and to a dummy of a non-sympatric predator, the double-toothed kite (Harpagus bidentatus, a predator of adults). Nesting wrens avoided going into their nest or took a longer time to resume their parental duties when exposed to the predators than when they were exposed to a control dummy (Chrysomus ruficapillus, a sympatric blackbird). Nest avoidance was higher when birds were exposed to the roadside hawk but no differences were detected when exposed to the chimango caracara or the double-toothed kite. The results indicate that southern house wrens are able to recognize a predator, responding in a graded manner. Our findings support the hypothesis that southern house wrens exhibit a threat-sensitive response during breeding. Also, individuals were able to recognize the unknown predator but failed to correctly assess the threat level represented by it. We propose that correct assessment of threat level by house wrens requires direct experience with the predator, which might mediate in the modulation of the response.     

Differential effects of native vs. invasive predators on a common Caribbean reef fish

Predators may have consumptive (lethal) and non-consumptive (sub-lethal) effects on prey. Non-consumptive effects include altered behavior and reduced growth and fecundity. Native prey may not recognize non-native predators as a threat, and therefore may suffer pronounced effects. Additionally, non-native predators may elicit different behavioral responses from prey compared to native predators. Theory predicts that consumptive effects should be greater for non-native predators (due to prey naiveté), and non-consumptive effects should be greater for native predators (due to predator recognition). To test these hypotheses, I monitored bicolor damselfish (Stegastes partitus) in the presence of invasive predatory Pacific lionfish (Pterois spp.), a native predator (graysby, Cephalopholis cruentata), and an egg predator (bluehead wrasse, Thalassoma bifasciatum). Body size and location of lionfish and graysby were monitored on reefs in the Bahamas. Bicolor fecundity was measured as the number and size of egg-masses that individual fish laid. Bicolor fecundity was negatively correlated with lionfish density but not graysby or bluehead density. Neither predator had a detectable effect on bicolor body size, but lionfish density was negatively correlated with the size of mature adult damselfish. I observed behavioral responses of bicolors to the two piscivores, to bluehead wrasse, and to two herbivorous fishes (Acanthurus coeruleus, Scarus spp.) as non-aggressive controls. Bicolors changed behavior (feeding and aggression) in the presence of all native fishes, but not in the presence of lionfish. Thus, differential effects exist between native and non-native predators, and invasive lionfish pose a non-consumptive threat to bicolor damselfish via reduced growth and fecundity.     

Biotic resistance of impact: a native predator (<Emphasis Type="Italic">Chaoborus</Emphasis>) influences the impact of an invasive predator (<Emphasis Type="Italic">Bythotrephes</Emphasis>) in temperate lakes

Introduced predators have caused some of the largest documented impacts of non-native species. Interactions among predators can have complex effects, leading to both synergistic and antagonistic outcomes. Complex interactions with native predators could play an important role in mediating the impact of non-native predators. We explore the role of the native predator context on the effect of the introduced predatory cladoceran Bythotrephes longimanus. While post-invasion impacts have been well described, studies have largely ignored the role of native predators. We used a field mesocosm experiment to determine whether Bythotrephes’ impact on prey communities is influenced by the presence of the ubiquitous native predatory insect larvae Chaoborus. The two predators exhibited niche complementarity as no change in total zooplankton prey abundance was detected across predator treatments. Rather, copepod abundances increased with decreasing abundances of Chaoborus, while cladocerans decreased with increasing abundances of Bythotrephes. Thus, the replacement of Chaoborus with Bythotrephes led to changes in the overall community structure of the zooplankton prey, but had little effect on prey total abundance. More interestingly, we found evidence of biotic resistance of impact, that is, the impact of Bythotrephes on the cladoceran community was altered when the two predators co-occurred. Specifically, the predation effect of Bythotrephes was more restricted to the shallower regions of the water column in the presence of Chaoborus, leading to a reduced impact on deeper dwelling prey taxa. Overall, our results demonstrate that the native predator context is important when trying to understand the effect of non-native predators and that variation in native predator abundances and assemblages could explain variation in impact across invaded habitats.     

Herbivore population suppression by an intermediate predator, <Emphasis Type="Italic">Phytoseiulus macropilis</Emphasis>, is insensitive to the presence of an intraguild predator: an advantage of small body size?

Recent work in terrestrial communities has highlighted a new question: what makes a predator act as a consumer of herbivores versus acting as a consumer of other predators? Here we test three predictions from a model (Rosenheim and Corbett in Ecology 84:2538–2548) that links predator foraging behavior with predator ecology: (1) widely foraging predators have the potential to suppress populations of sedentary herbivores; (2) sit and wait predators are unlikely to suppress populations of sedentary herbivores; and (3) sit and wait predators may act as top predators, suppressing populations of widely foraging intermediate predators and thereby releasing sedentary herbivore populations from control. Manipulative field experiments conducted with the arthropod community found on papaya, Carica papaya, provided support for the first two predictions: (1) the widely foraging predatory mite Phytoseiulus macropilis strongly suppressed populations of a sedentary herbivore, the spider mite Tetranychus cinnabarinus, whereas (2) the tangle-web spider Nesticodes rufipes, a classic sit and wait predator, failed to suppress Tetranychus population growth rates. However, our experiments provided no support for the third hypothesis; the sit and wait predator Nesticodes did not disrupt the suppression of Tetranychus populations by Phytoseiulus. This contrasts with an earlier study that demonstrated that Nesticodes can disrupt control of Tetranychus generated by another widely foraging predator, Stethorus siphonulus. Behavioral observations suggested a simple explanation for the differing sensitivity of Phytoseiulus and Stethorus to Nesticodes predation. Phytoseiulus is a much smaller predator than Stethorus, has a lower rate of prey consumption, and thus has a much smaller requirement to forage across the leaf surface for prey, thereby reducing its probability of encountering Nesticodes webs. Small body size may be a general means by which widely foraging intermediate predators can ameliorate their risk of predation by sit and wait top predators. This effect may partially or fully offset the general expectation from size-structured trophic interactions that smaller predators are subject to more intense intraguild predation.     

Predation on crown-of-thorns starfish larvae by damselfishes

Examining the functional response of predators can provide insight into the role of predation in structuring prey populations and ecological communities. This study explored feeding behaviour and functional responses of planktivorous damselfishes when offered captive reared larvae of crown-of-thorns starfish, Acanthaster sp., with the aim of determining whether these predators could ever play a role in moderating outbreaks of Acanthaster sp. We examined predatory behaviour of 11 species of planktivorous damselfish, testing: (1) the relationship between predator size and predation rate, both within and among fish species; (2) consumption rates on larvae of Acanthaster sp. versus larvae of a common, co-occurring coral reef asteroid Linckia laevigata; (3) maximal feeding rates upon both Acanthaster sp. and L. laevigata; and (4) functional responses of planktivorous fishes to increasing densities of Acanthaster sp. Consumption rates of crown-of-thorns larvae by damselfishes were independent of predator size; however, there was a significant negative relationship between predator size and consumption rate of L. laevigata, when pooling across all predatory species. Some damselfishes, including Acanthochromis polyacanthus and Amblyglyphidodon curacao, consumed larval Acanthaster sp. at a greater rate than for L. laevigata. Most predatory species (all except A. curacao and Pomacentrus amboinensis) exhibited a Type II functional response whereby the increasing feeding rate decelerated with increasing prey density. In addition to revealing that a wide range of planktivorous fishes can prey upon larvae of Acanthaster sp., these data suggest that planktivorous damselfishes may have the capacity to buffer against population fluctuations of Acanthaster sp. Importantly, predators with Type II functional responses often contribute to stability of prey populations, though planktivorous fishes may be swamped by an abnormally high influx of larvae, potentially contributing to the characteristic population fluctuations of Acanthaster sp.     

Body size and group size of Cuban tree frog (<Emphasis Type="Italic">Osteopilus septentrionalis</Emphasis>) tadpoles influence their escape behaviour

Tadpoles risk attack from both aquatic and aerial predators. We investigated how body size and group size influenced the behaviour of tadpoles before and during a predatory attack from above to test the predictions of the theoretical economic escape model. We examined escape (swimming) response of small and large Cuban tree frog (Osteopilus septentrionalis) tadpoles kept under three density treatments and predicted that increased group size, body size and depth in the water column would all reduce perceived risk and, therefore, escape responses to simulated predation. Compared with the lower density groups, tadpoles in higher density groups moved shorter distances, and many individuals did not even move away in response to being touched. Contrary to our predictions based on the economic escape model, smaller tadpoles (which should be more vulnerable to a greater suite of predators) were less reactive than larger tadpoles, and this result may reflect different costs of escape. Finally, although tadpoles might be exposed to a wider range of predator species (aerial as well as aquatic predators), we found no effect of initial depth on escape responses. In conclusion, it appears that the main benefit of increased group density in O. septentrionalis tadpoles is likely to be predator dilution, and that variation in densities of tadpoles influences the escape behaviour of individual tadpoles, regardless of tadpole size.     

Shared behavioral responses and predation risk of anuran larvae and adults exposed to a novel predator

Invasive species are a regional and global threat to biological diversity. In order to evaluate an invasive predator species’ potential to harm populations of native prey species, it is critical to evaluate the behavioral responses of all life stages of the native prey species to the novel predator. The invasion of the African clawed frog (Xenopus laevis) into southern California provides an opportunity to evaluate the predation risk and behavioral responses of native amphibians. We performed predation trials and explored prey behavioral responses to determine how this invasive predator may impact native amphibian populations using Pacific chorus frogs (Pseudacris regilla) as a representative native California prey species. We found that X. laevis will readily prey upon larval and adult life stages of P. regilla. Behavior trials indicated that both larval and adult P. regilla exhibit prey response behaviors and will spatially avoid the novel invasive predator. The results suggest that native anurans may have a redundant predator response in both the larval and adult life stages, which could reduce the predatory impact of X. laevis but also drive emigration of native amphibians from invaded habitat.     

The Predation Strategy of the Recluse Spider <Emphasis Type="Italic">Loxosceles rufipes</Emphasis> (Lucas, 1834) against four Prey Species

Generalist predators have to deal with prey with sometimes very different morphologies and defensive behaviors. Therefore, such predators are expected to express plasticity in their predation strategy. Here we investigated the predatory behavior of the recluse spider Loxosceles rufipes (Araneae, Sicariidae) when attacking prey with different morphologies and defensive mechanisms. We expected L. rufipes to show different prey capture strategies and variable acceptance towards each prey type. Potential prey species were collected directly from the web or in the surroundings of the web-building site of L. rufipes. We collected and used the following in our experiments: termite workers (Nasutitermes sp.), lepidopteran larvae (Eurema salome), ants (Camponotus sp.) and isopods (Tylidae). We paired these prey with L. rufipes and recorded their behavior in captivity, quantifying acceptance rate, immobilization time and the sequence of behaviors by the predator. The acceptance rate was lower for isopods but not different among other prey. The immobilization time was higher for isopods than for termites and similar for the other pairwise comparisons. The behavioral sequence was similar for all prey except for isopods, which were also bit more often. Our combined results show plasticity in the behavior of L. rufipes and also show it subdues a potentially dangerous prey (ant) and an armored prey (isopod).     

Mortal combat between ants and caterpillars: an ominous threat to the endangered Schaus swallowtail butterfly (<Emphasis Type="Italic">Heraclides aristodemus ponceanus</Emphasis>) in the Florida Keys,USA

The federally endangered Schaus swallowtail butterfly (Heraclides aristodemus ponceanus) has reached critically low numbers. Exotic ants are a potential threat to H. a. ponceanus and other rare butterflies as they can attack immature stages. Ant surveys conducted in subtropical dry forests in Biscayne National Park documented ant species diversity and relative abundance. A caterpillar predator exclusion experiment using physical barriers in different combinations evaluated caterpillar survivorship of both early and late instar caterpillars exposed to different threats. Ant-caterpillar interactions were also documented by placing caterpillars on plants and observing physical interactions between caterpillars and ants. A total of 1418 ants comprising 25 ant species was captured and identified. In canopies of H. a. ponceanus host plants, 243 ants comprising 12 species were found. The four most common ants collected in the host plant canopies were Pseudomyrmex gracilis, Camponotus planatus, Cremastogaster ashmeadi, and Camponotus floridanus. The predator exclusion experiment revealed survivorship was significantly lower for early and late instar caterpillars without any physical barrier, as well as for early instars not protected by a mesh cage. Pseudomyrmex gracilis and C. floridanus were more aggressive towards caterpillars in comparison to other ant species; these two species ranked first and second in the “ant danger index” ranking predatory abilities of the four most common ant species. Pseudomyrmex gracilis is a common arboreal exotic ant in Biscayne National Park and presents a major threat to caterpillars during their earliest life stages.     

Population development of the predatory mite <Emphasis Type="Italic">Amblydromalus limonicus</Emphasis> is modulated by habitat dispersion,diet and density of conspecifics

Habitat dispersion, diet and density can influence the per capita population growth of predators, and dispersed habitat can provide a spatial refuge that reduces the possibility of cannibalism among predators, thereby increasing their realized population growth rate. We tested the influence of variable habitat dispersion (dispersed patches, general patches and aggregated patches), two diets (Typha orientalis pollen and Ephestia kuehniella eggs) and initial predator density—one or two Amblydromalus limonicus (Garman and McGregor) (Acari: Phytoseiidae) founder females—on the population growth of A. limonicus in 7 days. Dispersed patches resulted in a higher total number of A. limonicus than the other two types of habitat dispersion from days 3–7 when fed on either of the diets, and started with either one or two A. limonicus females. Compared with E. kuehniella eggs, T. orientalis pollen resulted in more A. limonicus regardless of one or two founder females. Compared with two founder females, beginning with one founder female on pollen produced significantly more predatory mite females in dispersed and aggregated patches. A four-way ANOVA showed that the main effects indicated that habitat, diet, density, and time significantly influenced the number of immature and female A. limonicus. Significant interactions between habitat dispersion and diet were detected on immature and female A. limonicus. Our findings suggest that increasing the dispersion of artificial shelters on crop leaves may stimulate the control efficiency of predators in greenhouses. Furthermore, T. orientalis pollen provides a high nutritional quality supplemental diet that could enhance the ability of A. limonicus to control pests.     

Variation in the population demographics of <Emphasis Type="Italic">Scolopsis bilineatus</Emphasis> in response to predators

Predatory fishes play critical roles in the trophodynamics of coral reefs, and the biomass of predatory fish can be a strong determinant of the structure of reef fish assemblages. In this study, we used variations in predator biomass between management zones on the Great Barrier Reef to examine how predators influence the biomass, mortality, condition, and reproductive potential of a common prey species Scolopsis bilineatus (bridled monocle bream; Nemipteridae). Despite no numerical differences in biomass or mortality, we found significant differences in a variety of demographic traits for S. bilineatus between multiple areas of high and low predator biomass. The size-at-age, condition, and reproductive potential of fish were reduced in marine reserves where predator biomass was high. The response of fish to predators was highly sex dependent; females suffered the greatest reductions in condition and reproductive potential. This study supports the notion that predators can play important roles in regulating prey dynamics and emphasises the importance of understanding top-down control by predators when considering fisheries management techniques and conservation strategies.     

Temporal and spatial trends in the abundances of an apex predator,introduced mesopredator and ground-nesting bird are consistent with the mesopredator release hypothesis

Apex predator extirpation has been identified as a key driver of biodiversity losses. The mesopredator release hypothesis (MRH) predicts that reduced abundance of apex predators results in an increase in the abundance and predatory impact of mesopredators. Here we test predictions made according to the MRH that an apex predator, the dingo (Canis dingo), benefits a small ground-nesting bird, the little button-quail (Turnix velox), by reducing the abundance of introduced mesopredators, the red fox (Vulpes vulpes) and feral cat (Felis catus). We also examined an alternative hypothesis that herbivore grazing negatively affects little button-quail abundance by reducing ground cover. To test our predictions we compared dingo, mesopredator, quail, herbivore and ground cover abundances and predator diets over a 25 month period and across a 10,000 km² region encompassing areas where dingoes were common and rare, pastoral properties, and conservation reserves. Little button-quails were primarily observed where dingoes were common and foxes rare. Cats were detected at low numbers throughout the sample area irrespective of the index abundance of little button-quails, dingoes or foxes. Birds occurred less frequently in dingo than fox or cat scats. Ground cover and herbivore grazing activity were poor correlates of little button-quail abundance. Our results are consistent with the hypothesis that apex predators’ mesopredator-suppressive effects translate to population-level benefits for a ground-nesting bird. Positive associations between the abundances of dingoes and small-prey species suggests that positive management of dingoes could be incorporated into broad-scale biodiversity conservation programs as a strategy to alleviate the predatory impacts of foxes.     

Reaping benefits from an invasive species: role of <Emphasis Type="Italic">Harmonia axyridis</Emphasis> in natural biological control of <Emphasis Type="Italic">Aphis glycines</Emphasis> in North America

Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) is an invasive species present in numerous agroecosystems in North America. Despite adverse impacts as a threat to native biodiversity, a nuisance household invader and a pest in fruit production, H. axyridis also plays a beneficial role as a major component of assemblages of generalist predators in several agricultural crops. Here, we review the role of H. axyridis as a natural enemy of Aphis glycines Matsumura (Hemiptera: Aphididae), an invasive pest of soybean, Glycine max (L.) Merrill (Fabales: Fabaceae), in North America. Harmonia axyridis is often the most abundant predator species attacking A. glycines in soybean agroecosystems. This predator has the potential to both prevent and suppress A. glycines outbreaks. Further studies are needed to fully understand and utilize the potential of H. axyridis as a natural enemy in the management of A. glycines and other agricultural pests in agroecosystems worldwide.     

Predatory Versatility in Females of the Scorpion <Emphasis Type="Italic">Bothriurus bonariensis</Emphasis> (Scorpiones: Bothriuridae): Overcoming Prey with Different Defensive Mechanisms

Scorpions are dominant predators in some environments. Nevertheless, most studies of predatory behavior in scorpions have focused on diet composition whereas some other relevant aspects, such as predatory strategy, have been poorly explored. Herein we evaluate the prey acceptance and predatory strategy of the scorpion Bothriurus bonariensis against sympatric prey with different defenses. As prey, we selected earwigs (Forficula cf. auricularia) which use pincer-like defensive appendages, hard-bodied isopods (Armadillium vulgare) known for their conglobation defensive strategy, soft bodied isopods (Porcellio cf. scaber), which secrete noxious substances as defense mechanisms, cockroaches with limited defensive mechanisms (Blatta cf. orientalis.) and spiders (Lycosa cf. poliostoma) which possess venomous fangs. Prey were offered to 21 adults of B. bonariensis in random order until all prey had been offered to all scorpions. Prey consumption and the number of attempts needed for capture were recorded. We also evaluated the effect of sting use on immobilization time as well as the prey capture strategies on the most consumed prey. We found that despite using a similar number of attempts for capturing all prey, spiders and armadillid isopods were less consumed than other prey. Immobilization times were longer for earwigs than for armadillid isopods and cockroaches. Scorpions used alternative predatory strategies against these aforementioned prey, although the stinger was used against all of them. These results show that scorpions are able to use different predatory strategies which might allow them to include prey with diverse defensive strategies in their diet.     

A mixture of herbivore-induced plant volatiles from multiple host plant species enhances the attraction of a predatory bug under field-cage conditions

Plants respond to herbivore attack by emitting a blend of volatiles called herbivore-induced plant volatiles (HIPVs), which attract arthropod natural enemies. Under natural conditions and multiple cropping agriculture systems, natural enemies are thought to encounter a mixture of HIPVs emanating from multiple plant species. The effect of such a mixture of HIPVs on the responses of natural enemies under field conditions has not been explored. Our study assessed whether a mixture of HIPVs from multiple host plant species influenced predator responses in field-cage conditions. We investigated (1) foraging behaviors of a predatory bug, Orius strigicollis, on cotton bollworm (Helicoverpa armigera) larvae-infested multiple host plant species, and (2) the attractiveness of a mixture of reconstituted HIPVs from multiple plant species to O. strigicollis in outdoor cages. Significantly, greater numbers of predators were attracted to H. armigera-infested multiple plant species. The predators exterminated significantly greater numbers of H. armigera larvae with the multiple versus single plant species treatments. Significantly, greater numbers of O. strigicollis were captured on traps baited with the mixture of reconstituted HIPVs from multiple versus single plant species. The enhanced attractiveness of a mixture of HIPVs from multiple plant species to O. strigicollis might be the result of an additive effect of HIPVs from the three plant species when combined in a mixture.     

Responses of a predatory bug to a mixture of herbivore-induced plant volatiles from multiple plant species

The attractiveness of herbivore-induced plant volatiles (HIPVs) from a specific plant species to natural enemies has been well established. However, under natural conditions and polycultural agriculture systems, the interactions among trophic levels are thought to be more complex. For instance, complex mixtures of volatiles emitted from diverse host plant species infested by polyphagous herbivores might affect responses of natural enemies. In this study, we investigated whether a mixture of HIPVs emitted from herbivore-damaged multiple host plant species affect responses of a predatory bug. Therefore, we report (1) olfactory responses of the predatory bug (Orius strigicollis) to volatiles emitted from cotton bollworm (Helicoverpa armigera) first instar larvae-damaged multiple plant species (tomato, French bean and sweet corn), (2) chemical analyses of volatiles emitted from the three plant species exposed to different treatments and (3) olfactory responses of the predators to a reconstituted HIPV blend from multiple plant species based on chemical analyses. O. strigicollis significantly preferred volatiles emanating from H. armigera-damaged multiple plant species to volatiles emanating from a single plant species. In all the three plant species, H. armigera-damaged seedlings emitted significantly a greater amount of volatiles as well as a larger number of volatile compounds than an undamaged or a mechanically injured seedling. The predators preferred the reconstituted HIPVs from multiple plant species to the reconstituted HIPVs from a single plant species. Thus, the mixture of HIPVs from multiple plant species enhanced the attractiveness to the predators.     

Chemosensory cues of predators and competitors influence search for refuge in fruit by the coconut mite <Emphasis Type="Italic">Aceria guerreronis</Emphasis>

Organisms are adapted to recognize environmental cues that can provide information about predation risk or competition. Non-vagrant eriophyoid mites mainly avoid predation by using habitats that are difficult for predators to access (galls or confined spaces in plants) such as the meristematic region of the coconut fruit, which is inhabited by the phytophagous mites Aceria guerreronis and Steneotarsonemus concavuscutum. The objective of this study was to investigate the response of A. guerreronis to cues from the predators Neoseiulus baraki and Amblyseius largoensis in coconut fruits, cues from conspecifics (A. guerreronis injured) and cues from the phytophage S. concavuscutum. The test was carried out through the release of about 300 A. guerreronis on coconut fruits previously treated with cues from predators, conspecific or heterospecific phytophagous. We also observed the walking behaviour of A. guerreronis exposed to the same chemical cues using a video tracking system. The infestation of fruits by A. guerreronis was greater in the presence of predator cues and reduced in the presence of S. concavuscutum cues, but cues from injured conspecifics did not interfere in the infestation process. In addition, the cues also altered the walking parameters of A. guerreronis: it walked more in response to cues from predators and the heterospecific phytophage. Aceria guerreronis spent more time in activity in the treatments with clues than in the control treatment. These results suggest that A. guerreronis recognizes cues from predators and competitors and modifies its behaviour to increase its fitness.     

Larval skipper frogs recognise kairomones of certain predators innately

Recognising potential predators is critical for the survival and reproduction of prey animals. However, prey animals may possess an innate ability to recognise the signature odours (kairomones) of only certain native, sympatric predators, while requiring learning to recognise others. Our observations have shown that larval skipper frogs (Euphlyctis cyanophlyctis) fail to recognise kairomones of dragonfly nymph, a common predator of amphibian tadpoles with a cosmopolitan distribution. Hence, we wanted to determine if larval skipper frogs totally lack an innate mechanism to recognise kairomones of all aquatic predators, or have an innate ability to recognise kairomones of only certain predators. In a series of experiments, we tested the antipredator response of larval skipper frogs to kairomones of dragonfly nymph (Bradinopyga geminata); walking catfish (Clarias batrachus); Mozambique tilapia (Oreochromis mossambicus); two species of predatory tadpoles, Indian bullfrog (Hoplobatrachus tigerinus) and Jerdon’s bullfrog (Hoplobatrachus crassus); and the checkered keel back snake (Xenochrophis piscator). The results clearly indicate that larval skipper frogs have the innate ability to recognise kairomones of the walking catfish, both species of larval bullfrog and checkered keel back snake. However, they lack the innate ability to recognise kairomones of dragonfly nymph and Mozambique tilapia. Prey choice of the Mozambique tilapia and gape-limitation of dragonfly nymphs could be responsible for the lack of innate responses of larval skipper frogs to them. The study provides empirical evidence for the notion that prey can innately recognise certain predators.     

Threat-sensitive anti-predator defence in precocial wader,the northern lapwing <Emphasis Type="Italic">Vanellus vanellus</Emphasis>

Birds exhibit various forms of anti-predator behaviours to avoid reproductive failure, with mobbing—observation, approach and usually harassment of a predator—being one of the most commonly observed. Here, we investigate patterns of temporal variation in the mobbing response exhibited by a precocial species, the northern lapwing (Vanellus vanellus). We test whether brood age and self-reliance, or the perceived risk posed by various predators, affect mobbing response of lapwings. We quantified aggressive interactions between lapwings and their natural avian predators and used generalized additive models to test how timing and predator species identity are related to the mobbing response of lapwings. Lapwings diversified mobbing response within the breeding season and depending on predator species. Raven Corvus corax, hooded crow Corvus cornix and harriers evoked the strongest response, while common buzzard Buteo buteo, white stork Ciconia ciconia, black-headed gull Chroicocephalus ridibundus and rook Corvus frugilegus were less frequently attacked. Lapwings increased their mobbing response against raven, common buzzard, white stork and rook throughout the breeding season, while defence against hooded crow, harriers and black-headed gull did not exhibit clear temporal patterns. Mobbing behaviour of lapwings apparently constitutes a flexible anti-predator strategy. The anti-predator response depends on predator species, which may suggest that lapwings distinguish between predator types and match mobbing response to the perceived hazard at different stages of the breeding cycle. We conclude that a single species may exhibit various patterns of temporal variation in anti-predator defence, which may correspond with various hypotheses derived from parental investment theory.     

Ambush Predation of Stingless Bees (<Emphasis Type="Italic">Tetragonisca angustula</Emphasis>) by the Solitary-Foraging Ant <Emphasis Type="Italic">Ectatomma tuberculatum</Emphasis>

Social insect colonies are high-value foraging targets for insectivores, prompting the evolution of complex colony defensive adaptations as well as specialized foraging tactics in social insect predators. Predatory ants that forage on other social insects employ a diverse range of behaviors targeted at specific prey species. Here, we describe a solitary foraging strategy of the ant Ectatomma tuberculatum, on nest guards of the stingless bee Tetragonisca angustula. We observed multiple instances of E. tuberculatum ambushing and successfully capturing the hovering and standing guards of T. angustula near nest entrances. The unique hovering behavior of the guard caste of this bee species, an adaptation to frequent cleptoparasitism by other stingless bees, may make these guards particularly vulnerable to ground-based, ambush attacks by E. tuberculatum. Likewise, the behavior of the foraging ants appears to adaptively exploit the defensive formations and activity patterns of these bees. These observations suggest an adaptive and targeted predatory strategy aimed at gathering external guard bees as prey from these heavily fortified nests.