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PubMed2006

Evidence of leopard predation on bonobos (Pan paniscus).

Current models of social organization assume that predation is one of the major forces that promotes group living in diurnal primates. As large body size renders some protection against predators, gregariousness of great apes and other large primate species is usually related to other parameters. The low frequency of observed cases of nonhuman predation on great apes seems to support this assumption. However, recent efforts to study potential predator species have increasingly accumulated direct and indirect evidence of predation by leopards (Panthera pardus) on chimpanzees and gorillas. The following report provides the first evidence of predation by a leopard on bonobos (Pan paniscus).

Animals↗
PubMed2005

Variation in morphology and performance of predator-sensing system in wild cricket populations.

Even though variation in morphology is known to translate into variation in performance, studies looking at structural variability of a sensor to predict its consequences on the performance of animals are exceedingly rare. We investigated the morphological variability of air-flow-sensing receptors in wild populations of wood crickets (Nemobius sylvestris) sampled in a wide variety of habitats differing in latitude, litter structure, vegetation and predator communities. These hair receptors act as predator sensors. The observed levels of hair morphological variation were then incorporated into a biomechanical model of the hair canopy response to air flow to predict their influence on cricket predator perception. Cricket populations differ from each other, often strongly so, in the total number of hairs and in the number of hairs longer than 1 mm, which are the hairs most sensitive for the perception of approaching predators. The hair canopy response, the output of the biomechanical model, sums up over the entire canopy the angles of deflection at which a neurophysiological response is triggered and represents the sensitivity of the cercal system. It is 35% higher in the most sensitive population, compared with the least sensitive population. These large differences in perception sensitivity for a given predator signal translate into larger distances at which predators could be perceived. Thus, differences in morphology at the sensor level seem to be translated both at the perception level and subsequently at the performance level of crickets.

Air Movements↗
PubMedDate not supplied

Factors influencing predation of the waterbugs Sphaerodema annulatum (Fab). and S. rusticum (Fab.) on the disease transmitting snail Lymnaea (Radix) luteola (Lamarck).

Variations in the rate of predation of the waterbugs Sphaerodema annulatum and S. rusticum on the snails Lymnaea (Radix) luteola have been noted in respect to the morphs of the waterbugs, size of the prey individuals, densities of prey and predators, temperature and surface area of the waterbody concerned and the seasons. Consumption rate was highest (7.2 and 2.2 individuals per day per individual of S. annulatum and S. rusticum, respectively) in prereproductive ages of the waterbugs. This was followed by a gradual decline with the increase in age of the predators. The consumption rate was gradually higher with the increase of temperature from 20 degrees C to 35 degrees C. The bugs failed to survive beyond 35 days at 35 degrees C. Though the bugs prey upon the snails of all sizes preference for 6.5 x 4.5 mm to 8 x 5 mm individuals by S. annulatum and for 5 x 3 mm to 6.5 x 4.5 mm individuals by S. rusticum is established. The waterbugs, irrespective of species, consumed the snail individuals belonged to 3 x 2 - 4 x 3 mm size group maximum when supplied separately. The rate of predation gradually declined with the rise of predator's density irrespective of waterbug species. Predation rate increased with increasing prey density. This was level off when the prey snails were 1100 and 700 in number for S. annulatum and S. rusticum respectively. An adult S. annulatum and S. rusticum consumed 5.04, 3.7, 1.43 and 3.36, 2.49, 1.04 snails per day respectively in summer, monsoon and winter.

Age Factors↗
PubMed2000

Effect of nymphal diet on adult predation behavior in Orius majusculus (Heteroptera: Anthocoridae).

The predatory bug Orius majusculus (Reuter) was reared on 2 different diets during the nymphal stages. The 1st group was exclusively offered eggs of Ephestia kuehniella Zeller (Lepidoptera: Pyralidae), a standard diet for O. majusculus production. The 2nd group was exclusively offered 4th instars of the pea aphid, Acyrtosiphon pisum (Harris). Subsequently, adult predatory behavior in experimental arenas containing A. pisium was recorded using 2 video cameras. One camera permitted observation of the predator's contact with the prey, where the 2nd camera viewed the arena from above to record the path taken by O. majusculus adults before and after contact with prey. When O. majusculus were reared on aphids, adult bugs successfully located and consumed 55% of experimental prey and continued prey search behavior after each aphid meal. O. majusculus adults that had no experience of aphid predation as nymphs, did not prey on aphids in the experimental arena. The mean walking speed of this group of predators increased from 5.9 +/- 1.2 mm/s to 9.8 +/- 0.7 mm/s after contact or detection of prey, indicating that predators rapidly moved away from unfamiliar prey. Moreover, for egg-reared O. majusculus, all contacts between aphid and predator were lateral, along the side of the prey and were effectively repelled by an aphid kicking response. In contrast, 83% of attacks by aphid-reared O. majusculus were directed at the head or posterior abdomen for which the prey could not defend themselves adequately. When egg-reared O. majusculus were exposed to novel aphid prey for 1-8 d, the frequency of aphid attack increased significantly. We conclude that the standard diet used for rearing O. majusculus may adversely affect the efficiency of this predator as an agent of biological control.

Animals↗
PubMed2004

Effects of Microphallus turgidus (Trematoda: Microphallidae) on the predation, behavior, and swimming stamina of the grass shrimp Palaemonetes pugio.

The effect of the trematode Microphallus turgidus on its second intermediate host, the grass shrimp, Palaemonetes pugio, was tested. To do so, we measured the susceptibility of infected and uninfected shrimp to predation by the mummichog, Fundulus heteroclitus. Shrimp behavior was compared in the presence and absence of a fish predator, and the swimming stamina and backthrust escape responses of infected and uninfected shrimp were measured. Infected shrimp were more likely to be eaten by a predator than uninfected shrimp, had lower swimming stamina, and spent more time swimming and less time motionless in the presence of a predator. There was no difference between backthrust distances traveled in response to a stimulus by either infected or uninfected shrimp. Thus, M. turgidus may increase the predation of P. pugio in the wild, possibly by affecting the swimming stamina and predator avoidance responses of the shrimp.

Analysis of Variance↗
PubMed2006

Warmer does not have to mean sicker: temperature and predators can jointly drive timing of epidemics.

Ecologists and epidemiologists worry that global warming will increase disease prevalence. These fears arise because several direct and indirect mechanisms link warming to disease, and because parasite outbreaks are increasing in many taxa. However, this outcome is not a foregone conclusion, as physiological and community-interaction-based mechanisms may inhibit epidemics at warmer temperatures. Here, we explore this thermal-community-ecology-based mechanism, centering on fish predators that selectively prey upon Daphnia infected with a fungal parasite. We used an interplay between a simple model built around this system's biology and laboratory experiments designed to parameterize the model. Through this data-model interaction, we found that a given density of predators can inhibit epidemics as temperatures rise when thermal physiology of the predator scales more steeply than that of the host. This case is met in our fish-Daphnia-fungus system. Furthermore, the combination of steeply scaling parasite physiology and predation-induced mortality can inhibit epidemics at lower temperatures. This effect may terminate fungal epidemics of Daphnia as lakes cool in autumn. Thus, predation and physiology could constrain epidemics to intermediate temperatures (a pattern that we see in our system). More generally, these results accentuate the possibility that warmer temperatures might actually enhance predator control of parasites.

Animals↗
PubMed2006

When r-selection may not predict introduced-species proliferation: predation of a nonnative oyster.

Predicting outcomes of species introductions may be enhanced by integrating life-history theory with results of contained experiments that compare ecological responses of exotic and analogue native species to dominant features of the recipient environment. An Asian oyster under consideration for introduction to the Chesapeake Bay, USA, the rapidly growing Suminoe oyster (Crassostrea ariakensis), may not be as successful an invader as its r-selected life history suggests if the trade-off for rapid growth and maturation is lower investment in defenses against blue crab (Callinectes sapidus) predation than the native Eastern oyster (Crassostrea virginica). In laboratory trials, blue crabs simultaneously offered equal numbers of Suminoe and Eastern oysters consumed more nonnatives, irrespective of whether the crabs had previous experience with Suminoe oysters as prey. Satiated blue crabs consumed nearly three times as many Suminoe oysters as Eastern oysters of 25-mm shell height, and eight times as many of 35-mm shell height. Despite blue crabs consuming small (30 mm) Suminoe oysters at twice the rate of large (40 mm) Suminoe oysters, when 40-mm Suminoe were paired with 30-mm Eastern oysters, seven times as many of the larger (Suminoe) oysters were consumed. The greater susceptibility of C. ariakensis than C. virginica to blue crab predation appears to be based upon the biomechanics of shell strength rather than active selection of a more attractive food. Much less force was required to crush shells of Suminoe than Eastern oysters of similar shell height. Tissue transplant experiments demonstrated greater predation on oyster tissues in weaker C. ariakensis shells independent of tissue identity, and duration of handling time before rejection of C. virginica exceeded the time to crush C. ariakensis. These results, coupled with the present importance of blue crab predation in limiting recovery of native Eastern oysters, imply a role for blue crabs in inhibiting Suminoe oysters, if introduced, from attaining high adult densities required to restore a fishery, provide appreciable reef habitat, and reduce turbidity through filtration. Thus, in high-predation environments, allocation of resources to rapid growth and development rather than to predation defenses reflects a life-history trade-off that may promote early stages of invasion, yet prevent attainment of dense adult populations.

Animals↗
PubMed2004

Development of a model microbial predator-prey system suitable for studies of the behavior of toxic trace metals.

Interactions between microbial predators and their prey can significantly influence the behavior of toxic trace metals. Ingested bacterial prey-bound metals can either accumulate within a predator or be excreted and potentially reintroduced into the dissolved phase. A defined predator-prey system suitable for developing a more fundamental understanding of metal behavior in simple microbial food chains was designed and tested by using lead (Pb) as a representative cationic transition metal. Desired features of this system were the ability to define the chemical speciation of dissolved metals as well as to distinguish between prey- and predator-bound metals. Pseudomonas putida and the ciliate protozoan Tetrahymena thermophila were selected as representative bacterial prey and predator species, respectively. In addition, the use of fluorescent microspheres was evaluated as an experimental surrogate for bacterial prey. Filtration techniques for size-selective separation were developed so that the distribution of Pb between cells of T. thermophila, cells of P. putida or microspheres, and the dissolved phase could be assessed. Filtration units were selected based on their ability to perform separations with minimal metal loss at circumneutral pH. Five-micron polycarbonate filter membranes successfully separated T. thermophila from P. putida with good cell retention and low metal loss. Centrifuge filters successfully separated dissolved and particle-bound metal (<5,000 nominal molecular wt limit). Exemplary experimental results are presented and show that predation on Pb-exposed cells of P. putida or microspheres increases uptake of Pb by T. thermophila.

Animals↗
PubMed2001

Differential predation of the planarian Dugesia tigrina on two mosquito species under laboratory conditions.

Two experiments were performed on the predation of the planarian Dugesia tigrina (Girard) upon 2 mosquito prey species, Aedes albopictus and Culex quinquefasciatus. Bioassays were carried out in sectioned tires with 2 liters of water. In the 1st experiment, predation was evaluated using 4, 8, and 12 mature planarians against 40 2nd-stage larvae of each mosquito species alone. In the 2nd experiment, the same 3 predator densities were used with a pool composed of 20 2nd-stage larvae of each mosquito species. In the 1st experiment, final corrected mortality of Ae. albopictus reached 89.1, 98.8, and 99.6% and final corrected mortality of Cx. quinquefasciatus reached 29.4, 48.0, and 53.0%, respectively, with 4, 8, and 12 planarians. In the 2nd experiment and when subjected to the density of 4 planarians, Ae. albopictus was more susceptible to predation, with a selectivity index of 0.87, whereas this index was 0.13 for Cx. quinquefasciatus. Predation was more intensive during the 1st 4 days of the experiments, when most larvae were in the 2nd and 3rd stages. We observed that Cx. quinquefasciatus larvae were faster than Ae. albopictus in reacting to planarian contacts, resulting in more success in escaping from the predator attacks.

Aedes↗
PubMed2002

Habitat size: a factor determining the opportunity for encounters between mosquito larvae and aquatic predators.

Occurrence patterns of mosquito immatures and insect predators in containers of various sizes were surveyed in summer (June-July) and autumn (September) of 1998 in a rural area of Saga, southwestern Japan. Mosquitoes were categorized into three types in relation to habitat size. First, Aedes (Stegomyia) spp. and Tripteroides bambusa occurred mostly in small containers of < 0.1 m2. Second, Ae. japonicus and Culex kyotoensis occurred in larger container sizes, compared with the first group. Third, Cx. tritaeniorhynchus and Anopheles sinensis occurred in rice fields in summer and in large containers in the autumn. Predators such as Notonectidae, Anisoptera nymphs, and Chaoborus sp. and a predaceous mosquito Cx. halifaxii occurred mainly in large (> or = 0.1 m2) containers. The mosquitoes of the third group showed similarities with predators in the occurrence of each habitat type, and they frequently co-occurred with predators. The mosquitoes of the first group showed less similarity with predators in habitat type preference, and they rarely co-occurred with predators. The second group mosquitoes showed intermediate patterns of the first and the third groups.

Animals↗
PubMed2003

Predation of Cryptosporidium oocysts by protozoa and rotifers: implications for water quality and public health.

Predation by free-living protozoa and rotifers was investigated as a possible mechanism for the removal of Cryptosporidium parvum oocysts in aquatic ecosystems including wastewater treatment plants. Free-living ciliated protozoa (Stylonychia mytilus, Paramecium caudatum and an unidentified wastewater wetland ciliate), an amoeba (Acanthamoeba culbertsoni) and rotifers, all commonly found in aquatic ecosystems, were exposed to varying doses of C. parvum oocysts. All organisms investigated ingested oocysts. Predation activity and rates of ingestion varied with predator species and prey density. Ciliated protozoa demonstrated greater predation activity than A. culbertsoni or rotifers when exposed to 2 x 10(5) oocyst/mL for up to 3 h. Greatest predation after 1 h exposure was observed in P. caudatum, the largest ciliate, with on average 1.9 oocysts/cell (range 0-9 oocysts/cell). Stylonychia mytilus and the wetland ciliate had a similar mean ingestion of around 0.3 oocysts/cell, with numbers internalised ranging from 0-3 oocysts/cell. Rotifers ingested on average 1.6 oocysts/individual (range 0-7 oocysts/individual) whilst amoebae ingested on average 1.8 oocysts/cell after 2 h exposure (up to 3 oocysts/cell). Grazing activity by P. caudatum was demonstrated at a variety of prey levels ranging from 9 to 9,000 oocysts. Numbers of oocysts internalised by Paramecium frequently exceeded the reported human infective dose of 30 oocysts. In general, numbers of internalised oocysts increased with incubation time of up to 20-30 min although the rate of accumulation was slower at lower dose levels. The significance of predation on the fate of Cryptosporidium oocysts in the environment is discussed.

Animals↗
PubMed2003

Mercury effects on predator avoidance behavior of a forage fish, golden shiner (Notemigonus crysoleucas).

Mercury contamination of fish is widespread in North America and has resulted in the establishment of fish consumption advisories to protect human health. However, the effects of mercury exposure to fish have seldom been investigated. We examined the effects of dietary mercury exposure at environmental levels in a common forage species, golden shiner (Notemigonus crysoleucas). Fish were fed either an unaltered diet (12 ng/g wet wt methylmercury [MeHg] as Hg), a low-Hg diet (455 ng/g Hg), or a high-Hg diet (959 ng/g Hg). After 90 d mean fish whole-body total Hg concentrations were 41, 230, and 518 ng/g wet wt, respectively, which were within the range of concentrations found in this species in northern U.S. lakes. There were no mortalities or differences in growth rate among groups. Groups of fish from each treatment were exposed to a model avian predator and their behavioral response videotaped for analysis. Brain acetylcholinesterase (AChE) activity was determined in fish after behavioral testing. Fish fed the high-Hg diet had significantly greater shoal vertical dispersal following predator exposure, took longer to return to pre-exposure activity level, and had greater shoal area after return to pre-exposure activity than did the other treatments, all of which would increase vulnerability of the fish to predation. There were no differences in brain AChE among treatments. We conclude that mercury exposure at levels currently occurring in northern United States lakes alters fish predator-avoidance behavior in a manner that may increase vulnerability to predation. This finding has significant implications for food chain transfer of Hg and Hg exposure of fish predators.

Acetylcholinesterase↗
PubMed2003

Effectiveness of predators and parasitoids for the natural control of Diuraphis noxia (Homoptera: Aphididae) on barley in central Ethiopia.

The Russian wheat aphid, Diuraphis noxia (Kurdj.), is a serious threat for the production of barley, Hordeum vulgare L., in Ethiopia. The pest can cause up to 100% yield losses in years of heavy infestation. Natural control of D. noxia by using predators and parasitoids might be the best alternative both from economical and ecological point of view. In this regard, a field investigation was conducted during the 2001 spring cropping season at Fitche, central Ethiopia to determine abundance of D. noxia and associated natural enemies and evaluate their effectiveness as natural control agents for this pest. In addition, the data collected during the 1995-1997 spring and summer cropping seasons at Chacha was analysed and presented. There was a highly significant difference (P < 0.01) on the population density of D. noxia between spring and summer and among sampling dates. The average aphid density was 23.1 and 0.7 aphids per tiller during spring and summer, respectively. The quantitative analyses based on predator units (PU) showed a highly significant difference (P < 0.01) among the predator groups, coccinellids and syrphids being more important, however, the coccinellid beetle, Hippodamia variegata Goeze, was the dominant species from all predator species or groups. Moreover, syrphid fly larvae were the only predators consistently found feeding on aphids within D. noxia rolled leaves. The polyphagous predators: Chrysopids, spiders and staphylinids were found to have less effect on D. noxia populations. Only two primary parasitoid species were recorded both during spring and summer cropping seasons: Aphidius colemani Vier. and Aphidius spp. Of these, A. colemani was more abundant in both seasons. The rate of parasitism was also generally low during the season. In general, the population build up of these natural enemies is slow and maximum population size is reached after the aphid population peaks and the crop has already been damaged. Further extensive work is necessary to maximize the effectiveness of natural enemies against this pest.

Animals↗
PubMed1987

A descriptive study of dairy goat predation in Louisiana.

Questionnaires concerning herd size, housing and management, and previous instances of predation were mailed to 124 goat owners in Louisiana. Postcards were mailed over a period of one year on a monthly basis, to the 84 individuals who responded to this questionnaire. Owners were asked to indicate whether they had seen predators on their property and whether any goats were injured or killed by the predators. Upon receipt of any postcard with a "yes" answer to either of these questions, a telephone interview was conducted to determine the exact circumstances of predator experience. The interview format included time, physical circumstances, and detailed questions about the actions of the predator and the goats. In 85% of the cases, the predators sighted were reported as dogs, and most of these were thought to be pets, rather than wild. Instances of attacks occurred most frequently during periods of reduced light. No clear seasonal pattern of attacks emerged. Four management factors were associated with a reduction in number of attacks; penning the goats at night, use of a night light, proximity of the herd to an occupied residence, and presence of a dog.

Animal Husbandry↗
PubMed1985

[Experimental study on the predation of Cionella lubrica Müller by Nesovitrea hammonis Ström].

The predation of C. lubrica by N. hammonis was studied under controlled laboratory conditions. Adult N. hammonis ate mainly prey measuring 2 to 4 mm in height. The predation rate was steady in spite of the increase in number of predators for the same number of prey. Vegetable food was indispensable to N. hammonis' predation. The predation was maximum at 20-25 degrees C. N. hammonis cannot be considered as an agent of biological control against C. lubrica owing to its limited predation.

Animals↗
PubMed2007

Age and seasonal effects on predator-sensitive foraging in squirrel monkeys (Saimiri sciureus): a field experiment.

A field experiment was conducted to examine the effect of perceived predation risk on the use of foraging areas by juvenile and adult primates under different conditions of local food abundance. Wild squirrel monkeys, Saimiri sciureus, were observed in an experiment conducted during the dry and the wet seasons at a site in Eastern Amazonia, Brazil. Animals were presented with feeding platforms that differed in food quantity and exposure to aerial predators through varying vegetative cover. In the dry season, juveniles and adults chose platforms based solely on food quantity. However, in the wet season, juveniles foraged preferentially on high-reward platforms only if cover level also was high (i.e., potentially offered greater concealment from predators). In contrast, adults showed the same pattern of platform use regardless of season. These results indicate that age and local resource availability based on seasonality affect whether primates forage in a predator-sensitive manner. Juveniles may be more sensitive to predation risk when foraging, and individuals may take fewer risks when resource abundance is high in their environment.

Age Factors↗
PubMed2007

Do cavity-nesting primates reduce scent marking before retirement to avoid attracting predators to sleeping sites?

The largest population of endangered golden lion tamarins (Leontopithecus rosalia, GLTs) decreased from approximately 330 to 220 individuals between 1995 and 2000 due to a dramatic increase in predation at sleeping sites. We used behavioral data from eight social groups in this population to test two hypotheses: First, if GLTs attempt to mitigate the risk of predation at sleeping sites, they should reduce their rates of scent marking just prior to retirement. Second, if the benefits of scent marking prior to entering the sleeping site merit an increase in the rate of marking, then tamarins should increase their rate of pre-retirement scent marking during the breeding season, when such behavior would have its greatest impact on reproductive fitness. We used a generalized linear model (GLM) repeated-measures analysis to compare rates of daytime scent marking with rates of marking just prior to retirement for males and females. In addition, we compared scent marking prior to retiring in the nonbreeding season to marking rates before retirement in the breeding season for males and both sexes considered concurrently. Contrary to our expectations, GLTs significantly increased their rates of scent marking during the 30 min prior to entering their sleeping site-an observation driven by an increase in male (but not female) rates of marking. Rates of marking before entering the sleeping site were greater in the nonbreeding season compared to the breeding season, when both sexes were considered concomitantly and when males were evaluated alone. We conclude that GLTs do not attempt to minimize predation risk by decreasing scent marking in the period before they enter their sleeping site, and that tamarins do not scent mark at this time of day in order to transmit information about reproductive status or to control reproduction of subordinates. We speculate that scent marking in the 30 min prior to entering sleeping sites may serve to reduce predation risk by enabling tamarin groups to return quickly to favored sleeping sites in the evening when crepuscular predators are active.

Animals↗
PubMed1998

Sedentary snakes and gullible geckos: predator-prey coevolution in nocturnal rock-dwelling reptiles.

We investigated (1) the importance of chemical cues for predator detection by the nocturnal, rock-dwelling velvet gecko, Oedura lesueurii, and (2) how the lizards' responses to snake odour may have exerted selection on the foraging behaviours of a nocturnal elapid snake. This snake species (broadheaded snake, Hoplocephalus bungaroides) feeds primarily on velvet geckos, and does so by means of a distinctive foraging behaviour: the snakes remain sedentary in rock crevices for days or weeks, waiting to ambush geckos. Behavioural assays showed that geckos that are sympatric with this sedentary 'ambush' predator can detect and respond to the scent of the snake. Retreat-site selection experiments showed that geckos are less likely to enter crevices if the snake's scent is distributed over the entire rock surface, rather than localized to a central portion. Together, these data support the notion that the 'ambush' predator benefits by remaining sedentary within a retreat-site for long periods, because it thereby minimizes the extent to which it spreads its scent over the rocks forming the crevice. Geckos from a population sympatric with the 'ambush' predator responded strongly to the snake scent, but those from an allopatric population did not. Additionally, geckos from sympatric populations were able to detect the scent of a nocturnal snake that does not eat geckos (small-eyed snake, Rhinoplocephalus nigrescens), but did not modify their retreat-site selection or locomotory behaviours in response to this cue. Lizards from allopatric populations apparently did not detect the scent of small-eyed snakes. Collectively, our findings support an interpretation of predator-prey coevolution in the present system, and emphasize the importance of chemosensory cues to these rock-dwelling reptiles. Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.

Journal Article↗