Data from: Cascading effects of predator activity on tick-borne disease risk
Hofmeester, T.R. ; Jansen, P.A. ; Wijnen, H.J. ; Coipan, E.C. ; Fonville, Manoj ; Prins, H.H.T. ; Sprong, Hein ; Wieren, S.E. van - \ 2017
Wageningen University & Research
Borrelia burgdorferi - predators - carnivores - rodents
Predators and competitors of vertebrates can in theory reduce the density of infected nymphs (DIN)—an often-used measure of tick-borne disease risk—by lowering the density of reservoir-competent hosts and/or the tick burden on reservoir-competent hosts. We investigated this possible indirect effect of predators by comparing data from 20 forest plots across the Netherlands that varied in predator abundance. In each plot, we measured the density of questing Ixodes ricinus nymphs (DON), DIN for three pathogens, rodent density, the tick burden on rodents and the activity of mammalian predators. We analysed whether rodent density and tick burden on rodents were correlated with predator activity, and how rodent density and tick burden predicted DON and DIN for the three pathogens. We found that larval burden on two rodent species decreased with activity of two predator species, while DON and DIN for all three pathogens increased with larval burden on rodents, as predicted. Path analyses supported an indirect negative correlation of activity of both predator species with DON and DIN. Our results suggest that predators can indeed lower the number of ticks feeding on reservoir-competent hosts, which implies that changes in predator abundance may have cascading effects on tick-borne disease risk.
"Roofdiervoeding" meer spiegelen aan de natuur?
Huisman, T.R. - \ 2011
zoo animals - animal nutrition - animal welfare - carnivores - animal behaviour - animal health - teaching materials
Life-history traits of gaur Bos gaurus: A first analysis
Ahrestani, F.S. ; Iyer, S. ; Heitkonig, I.M.A. ; Prins, H.H.T. - \ 2011
Mammal Review 41 (2011)1. - ISSN 0305-1838 - p. 75 - 84.
sexual size dimorphism - population-dynamics - prey selection - southern india - bison - ungulate - ecology - buffalo - tiger - carnivores
In this first detailed analysis of gaur Bos gaurus life-history traits, data were collected from a 20-month field study in South India and from captive gaur populations. Mean age of females at first parturition was 3 years; females remained fertile beyond the age of 15 years. Adult females were three times more abundant than adult males in the wild; survival of females was greater than males beyond three years of age. Life span of both sexes has not exceeded 24 years in captivity. Gaur life-history traits are similar to those of other similar-sized Bovini species.
Factors affecting livestock predation by lions in Cameroon
Bommel, L. van; Vaate, M.D. bij de; Boer, W.F. de; Iongh, H.H. de - \ 2007
African Journal of Ecology 45 (2007)4. - ISSN 0141-6707 - p. 490 - 498.
wolf predation - panthera-leo - depredation - carnivores
Interviews were carried out in six villages south-west of Waza National Park, Cameroon, to investigate the impact of factors related to the occurrence of livestock raiding by lions. Data were analysed at the village and individual level. Livestock losses (cattle, sheep and/or goats) caused by lions differed between villages, ranging from eight to 232 animals per village per year, or 37 to 1115 US$ per livestock owner. At the village and individual level, season and distance to the park boundary were important factors determining the occurrence of livestock losses (R2 > 0.81). In villages close to the park attacks occurred irrespective of season and predation was high, and in villages farther from the park attacks mainly occurred during the rainy season and predation was low. Owning a large number of animals and attempting to chase away lions during an attack also increased predation on both village and individual level. At individual level, predation increased with the combined ownership of cattle and sheep and/or goats. Herding methods could be changed to decrease livestock predation, for example herding livestock with more than one herder, or building bomas for cattle at night.
|Hunter and hunted
Broekhuizen, S. - \ 2003
Lutra 46 (2003)1. - ISSN 0024-7634 - p. 75 - 76.
vleesetende dieren - prooi - predator prooi verhoudingen - boekbesprekingen - menselijke invloed - carnivores - prey - predator prey relationships - book reviews - human impact
Bespreking van het nieuwste boek van Hans Kruuk (University Press Cambridge, 2002) over landroofdieren en de invloed die ze hebben op hun prooidiersoorten, inclusief de mens, en over de invloed die de mens heeft en heeft gehad op de landroofdieren
|Milieuvervuiling en voortplantingsproblemen bij vogels
Roode, D.F. de - \ 1999
Natura 96 (1999)5. - ISSN 0028-0631 - p. 140 - 142.
vogels - vleesetende dieren - vis - voortplanting - fauna - schade - milieueffect - waterverontreiniging - besmetters - gechloreerde koolwaterstoffen - birds - carnivores - fish - reproduction - fauna - damage - environmental impact - water pollution - contaminants - chlorinated hydrocarbons
Een van de processen waarop milieucontaminanten een invloed kunnen hebben, is die van de voortplanting. In de rest van het het artikel wordt ingegaan op de siutatie van visetende vogels, met een nadruk op chloorhoudende koolwaterstoffen
|Alternatieve voedselbronnen voor schelpdier-etende vogels in Nederlandse getijdewateren
Smit, C.J. - \ 1994
Wageningen : IBN (IBN - rapport 077) - 80
vleesetende dieren - mollusca - nederland - noordzee - watervogels - waadvogels - carnivores - mollusca - netherlands - north sea - waterfowl - waders
Infochemicals in tritrophic interactions : origin and function in a system consisting of predatory mites, phytophagous mites and their host plants
Dicke, M. - \ 1988
Agricultural University. Promotor(en): J.C. van Lenteren, co-promotor(en): M.W. Sabelis. - Wageningen : Dicke - 235
trombidiidae - tetranychus urticae - bryobia - mesostigmata - dermanyssidae - phytoseiidae - lokstoffen - plantenplagen - gastheer parasiet relaties - parasitisme - herbivoren - vleesetende dieren - biologische bestrijding - ongewervelde dieren - nuttige organismen - trombidiidae - tetranychus urticae - bryobia - mesostigmata - dermanyssidae - phytoseiidae - attractants - plant pests - host parasite relationships - parasitism - herbivores - carnivores - biological control - invertebrates - beneficial organisms - cum laude
What are infochemicals?
Chemical compounds play an important role in interactions between organisms. Some of these chemicals are to the benefit (e.g. nutrients) or detriment (e.g. toxins) of an organism. Others are of benefit or detriment in an indirect way: through the behavioural response they elicit. The latter chemicals are termed infochemicals (chemicals that, in the natural context, convey information in an interaction between two individuals, evoking in the receiver a behavioural or physiological response that is adaptive to either one of the interactants or both; chapter 2). On an evolutionary time scale, the fate of an infochemical depends on selection pressures on each interactant. Selection pressure is determined by costs and benefits which result from all interactions of an organism in which the infochemical is involved. Yet, for pragmatic reasons, to analyse the function of an infochemical in the biology of an organism, a cost-benefit analysis is made for each interaction between two organisms separately. In this way the cost-benefit analysis is restricted to the smallest number of interactants possible, which ensures its simplicity. Consequently, for each interaction the infochemical is classified according to the corresponding costs and benefits for the two interactants (chapter 2; cf. Nordlund and Lewis, 1976). Moreover, classification also reflects whether the interaction under consideration is between conspecifics or between individuals of different species. This resulted in the terminology represented in Figure 1.1 and Table 1.1 (cf. chapter 2). Its structure and terms are based on those of semiochemicals. However, infochemical terminology differs from semiochemical terminology in two respects (chapter 2):
(1) Infochemical terminology regards compounds that convey information, whereas semiochemical terminology in addition also includes toxins (Whittaker and Feeny, 1971; Nordlund and Lewis, 1976; Nordlund, 1981). In some instances toxins or nutrients may convey information. If that is the case, these toxins and nutrients are classified as infochemicals when their role as information carrier is considered. When poisonous or nutritious aspects are considered, they are not classified as infochemicals, but as toxins and nutrients respectively.
(2) Semiochemical terminology is based on origin of the compounds, in addition to the cost-benefit analysis. Although knowledge of the origin is Important to understand the interaction between two organisms, it may be very difficult to elucidate the origin (e.g. Brand et al., 1975; chapter 4). Therefore, application of the origin criterion may lead to ambiguities. Because the cost- benefit criterion by itself is good and useful, infochemical terminology is based on that criterion alone.
Infochemicals in tritrophic systems.
Infochemicals play a role in interactions between consecutive trophic levels (e.g plant-herbivore, phytophagous insect- entomophagous insect; Figure 1.2) (e.g. Nordlund et al., 1981; Visser, 1986). Moreover, infochemicals may also mediate interactions between other trophic levels (e.g. plant-entomophagous insect; Figure 1.2) (Price, 1981). Therefore, to understand the selection pressure on an organism, as a result of an infochemical, all trophic levels involved should be regarded. As a consequence, investigations of infochemicals in interactions between herbivores and their predators should also regard involvement of at least the first trophic level, the plant.
The tritrophic system of this study: predatory mites, phytophagous mites and their host plants.
The herbivore-predator system investigated most extensively in this thesis consists of phytophagous mites and predatory mites that occur in Dutch orchards. Figure 1.3a,b depicts the two most abundant phytophagous mites that occur as pest organisms in Dutch apple orchards: the apple rust mite, Aculusschlechtendali (Nalepa), and the European red spider mite, Panonychusulmi (Koch) (Van de Vrie, 1973; Van Epenhuijsen, 1981; Gruys, 1982).
Several species of predatory mites occur in Dutch orchards. The most abundant of these are Typhlodromuspyri Scheuten (Figure 1.3c), Amblyseiusfinlandicus (Oudemans) and A.potentillae (Garman) (McMurtry & Van de Vrie, 1973; Overmeer, 1981; Gruys, 1982). All three species feed on P.ulmi and A.schlechtendali , as well as on other food sources such as several pollens (Overmeer, 1981; Kropczynska, 1970; Overmeer, 1985).
In this system consisting of two phytophagous prey species and three predator species (Figure 1.4a), prey preference of the predators was investigated. Optimal foraging theory predicts that natural selection favours predators preferring prey species that are most profitable in terms of reproductive success (Krebs, 1978). Reproductive success is determined, among others, by development time, oviposition rate, mortality during development and offspring quality. Each of these components can be affected by the prey species consumed. As a first step in analysing which selection pressures may have moulded prey preference of the predatory mites in the system outlined above, I have tested whether prey preference is matched by the associated reproductive success. If this most simple explanation for prey preference does not hold, other explanations should be considered (see below).
Do infochemicals play a role in prey preference ?
Kairomones (Table 1.1, Figure 1.1) may inform predators on presence and identity of prey (Greany and Hagen, 1981) and thereby affect foraging decisions, such as where to search, how long to search at a specific site, which prey to accept and when to disperse on air currents (chapter 3).
Spider-mite kairomones in a tritrophic context.
Predatory mites distinguish plants infested by spider mites from clean plants by a volatile kairomone (e.g. Sabelis & Van de Baan, 1983). This kairomone seems to be a product of the interaction between plant and spider mites: after removal of spider mites from an infested plant, the plant remains attractive to the predators during several hours, whereas the mites alone do not remain attractive (Sabelis & Van de Baan, 1983; Sabelis et al., 1984a). Current data on spider mite - predatory mite interactions do not explain the role of this infochemical in the biology of the spider mites (cf. chapter 3 for a review). It may, for instance, be an inevitable byproduct of damage inflicted on the plant by the spider mite, and/or have an indispensable function in the biology of the spider mite. Moreover, the plant may be involved in production of the infochemical. To elucidate the role of this volatile infochemical, its effects in interactions between plant and spider mite, between plant and predatory mite and between spider mites of one species should be investigated. Before this can be done, chemical identification of the infochemical is a necessary first step.
These investigations were made for a tritrophic system consisting of Lima bean plants, the two-spotted spider mite, Tetranychusurticae Koch and the predatory mite Phytoseiuluspersimilis Athias-Henriot (Figure 1.4b). This system was chosen for practical reasons. The plant and phytophagous mite can be reared throughout the year and therefore, this system is much more suitable to develop a method for the chemical analysis of spider-mite kairomones than a system in which the plant is a perennial.
Origin and function of T.urticae kairomone in a tritrophic system.
Two-spotted spider mites distinguish between a clean plant and a plant that is infested by conspecifics on the basis of a volatile infochemical (chapter 4). The spider mites move away from heavily infested leaves. This response is advantageous to spider mites on the infested leaf as well as to spider mites that avoid settling on these leaves: increased competition for food is avoided, cf. Wrensch and Young (1978). In addition, the spider mite that disperses thus avoids settling on a spot that has an increased risk of being detected by predatory mites (Sabelis and Van de Baan, 1983). Therefore, the infochemical in this interaction between conspecific spider mites is called a (+,+)dispersing pheromone. Biological evidence suggests that this pheromone is (at least partly) identical to the volatile kairomone to which predatory mites respond (chapter 4).
Volatiles emitted from plants infested by T.urticae were identified and subsequent behavioural analyses resulted in identification of four kairomone components that attract the predatory mite P.persimilis : linalool (3,7-dimethyl-1,6-octadiene- 3-ol), methyl salicylate, ( E )-β-ocimene (3,7-dimethyl-1,3( E ),6- octatriene) and 4,8-dimethyl-1,3( E ),7-nonatriene. The structure of these compounds is shown in Figure 1.5. At least two of these (linalool and methyl salicylate) are also components of a kairomone in the interaction between T.urticae and A.potentillae (when reared on V.faba pollen; see below) (chapter 4). Literature data on the behavioural response of T.urticae indicate that one of these kairomone components (linalool) is also a component of the (+,+)dispersing pheromone (Dabrowski and Rodriguez, 1971).
All identified kairomone components are well-known in the plant kingdom. This suggests that the plant is involved in production of the infochemical, but it is no proof. It may for Instance be that spider-mite enzymes injected into the plant break down a plant compound. Investigation of e.g. site and moment of production and possible storage of precursors are needed as a next step to elucidate the role of the plant in kairomone production. However, suppose that it is the spider mite who produces the infochemical to serve as a dispersing pheromone. Then, it is not clear why this pheromone should necessarily consist of volatiles. As a result of the production of volatiles the spider mites incur more risks of being detected by predators than by production of non-volatile chemicals. Detection by predators inevitably leads to local extermination of spider mites (Sabelis and Van der Meer, 1986). For this reason it seems more likely that the volatiles are plant produced and that the spider mite makes the best of a bad job by using them as information to decide where not to colonize. To understand the evolution of plant-produced volatiles after herbivore attack, it is crucial to assess how they are produced, how much it costs to produce them and what the benefits are in terms of a lowered probability of herbivore attack.
Involvement of volatile kairomones in prey preference of predatory mites.
The response of T.pyri and A.potentillae to volatile kairomones is dependent on the diet of the predators. When reared on a carotenoid-poor diet these predators respond to the kairomones of more prey species than when reared on a carotenoid-rich diet (chapters 6, 7 and 8). Carotenoids are indispensable to A.potentillae because of their function in diapause induction (Overmeer, 1985a). The function of these nutrients to T.pyri remains unknown (chapter 8). All prey species to whose kairomones carotenoid-deficient A.potentillae and T.pyri respond can relieve the lack of carotenoids. Carotenoid-containing A.potentillae and T. pyri only respond to the P.ulmi kairomone. The above observations were made for predators that were starved for 20 h. Longer starvation of predators reared on a carotenoid-rich diet also enlarges the number of prey species responded to. Investigations of the response to volatile kairomones indicates that A.potentillae and T.pyri (whether carotenoids are available or not) prefer P.ulmi to A.schlechtendali (chapters 6, 7 and 8) and that A.finlandicus has a reverse preference (chapter 11).
This corresponds to conclusions from predation experiments performed at different composition of prey supply (chapters 9 and 11). The observed predation rates when mixed prey supplies were offered, were compared with a model provided with parameters estimated from experiments with each of both prey species alone. Amblyseiuspotentillae and T.pyri fed more on P.ulmi and A.finlandicus fed more on A.schlechtendali than was predicted by the model. This difference between observed and predicted predation rates cannot be explained by a change in behaviour of the prey species as a result of being together, nor by a change in walking behaviour of the predator. Therefore, these data indicate that A. potentillae and T.pyri prefer P.ulmi and that A.finlandicus prefers A.schlechtendali , in terms of a change in acceptance/rejection ratio ('success ratio').
Analysis of prey preference under field conditions showed that most T.pyri collected from apple leaves that widely varied in P.ulmi : A.schlechtendali numbers contained P.ulmi esterase, whereas A.schlechtendali esterase was present in a minor fraction of predators (chapter 10). Rust-mite esterase and P.ulmi esterase were found equally frequent in A.finlandicus . The data for A.finlandicus , obtained over a narrower range of prey-number ratios than for T.pyri , do not allow a definite conclusion on prey preference. However, they certainly do not cause rejection of the conclusion on prey preference as obtained in the laboratory analyses (chapter 11). No field data are available for A.potentillae .
Prey preference and reproductive success of predatory mites in an orchard system with two species of phytophagous prey mites.
Analysis of reproductive success of these three predator species, when feeding on either P.ulmi or A.schlechtendali , indicates that A.finlandicus selects the best prey species in terms of reproductive success. This predator species suffers high larval mortality on P.ulmi , but not on A.schlechtendali . This results in a much higher intrinsic rate of population increase when feeding on apple rust mites (chapter 12).
Amblyseiuspotentillae and T.pyri would also do better by feeding preferentially on A.schlechtendali : development times when feeding on this prey species are shorter than when feeding on P.ulmi , whereas these prey species do not differentially affect mortality or oviposition rate (chapter 12). For A.potentillae this may not be the case at the end of the season because P.ulmi is a better prey species in terms of diapause induction. Thus, on the basis of current data, optimal prey-choice theory cannot satisfactorily predict actual prey peference of A.potentillae and T.pyri . Future investigations should concentrate on e.g. (1) possible effect of competition between prey species on prey availability, (2) possible effect of competition between predator species on prey availability, and (3) possible shift in prey preference during the season.
Optimum prey capture techniques in fish
Leeuwen, J.L. van - \ 1983
Landbouwhogeschool Wageningen. Promotor(en): J.W.M. Osse. - Wageningen : Van leeuwen - 161
dieren - vleesetende dieren - eten - voedingsgedrag - vissen - masticatie - animals - carnivores - eating - feeding behaviour - fishes - mastication - cum laude
In this thesis hydrodynamic principles are used to quantify relations between form and function in the prey capture mechanism of actinopterygian fish. This work is closely related to the papers on the hydrodynamics of fish feeding by Muller et al. (1982) and Muller & Osse (in press). The effectiveness of different head forms and movements for prey uptake (in various habitats) is investigated by model simulations and verified by flow visualization and pressure measurements.Chapter 1 presents a technique to visualize the flow in 3-D around the mouth of the fish, sucking its prey. An expanding and compressing cylindrical or conical model of the fish's mouth cavity is used to quantify the relation between head movements and swimming. The opercular and branchiostegal valves are shown to function as control devices to obtain an optimal flow rate through the mouth aperture. The theoretical predictions were verified experimentally for the rainbow trout ( Salmo gairdneri ). Likewise, data from the literature appeared to agree with these hypotheses.Chapter 2 quantifies the contributions of the forward movement of the fish, the expansion of the mouth cavity and a possible protrusion of the jaws to the velocity of the prey. Optimum sucking techniques (i.e. techniques maximizing the chance of prey capture) in relation to swimming speed and habitat properties are derived by model simulations. Maximization of the initial prey distance by an exact adjustment of mouth expansion is rather useless for a fish. Much more is gained if the fish abducts its opercula at the maximal rate when the prey enters the mouth.Chapter 3 discusses recording techniques for pressures in prey-sucking fish. The dynamic properties of different measurement systems are investigated by Fourier analysis. Also, the frequency content of records of the fluctuating pressure inside the fish's mouth during feeding is shown. Prey capture events of different fish species are simulated using the hydrodynamical model of Muller et al. (1982). Measured and simulated pressure curves are compared and the effects of the use of different boundary conditions in the model are discussed. The literature on pressure measurements in prey-sucking fish is reviewed.
Biological control of two-spotted spider mites using phytoseiid predators
Sabelis, M.W. - \ 1982
Landbouwhogeschool Wageningen. Promotor(en): C.T. de Wit, co-promotor(en): J. de Wilde; R. Rabbinge. - Wageningen : Pudoc - ISBN 9789022007761
rosaceae - sierplanten - biologische bestrijding - ongewervelde dieren - nuttige organismen - plantenplagen - trombidiidae - tetranychus urticae - bryobia - predatie - vleesetende dieren - rosaceae - ornamental plants - biological control - invertebrates - beneficial organisms - plant pests - trombidiidae - tetranychus urticae - bryobia - predation - carnivores
The searching behaviour of individual predators of four phytoseiid species ( Phytoseiulus persimilis , Amblyseius p o tentillae , Amblyseius bibens , Metaseiulus occidentalis ) is investigated in relation to the two-spotted spider mite ( Tetranychus urticae ), which infests greenhouse roses. Especially the role of spider- mite webbing in the predator-prey relation is studied. Webbing interferes with searching, decreasing the rate of encounter per unit prey density. Low walking speeds and activity in webbing ensure that the predator is rarely disturbed after contact with other mites. Webbing also positively influences searching, as spider mites aggregate within the webbed area: prey density, defined here as the number of prey per square centimetre of webbed leaf area, is high, as is the rate of encounter with prey. The ability to capture a prey after tarsal contact depends on the food content of the gut, the prey-stage and, in two specific cases, the webbing; the success ratio of P. persimilis increased on a webbed substrate, that of A. potentillae decreased.
Models to simulate rate of predation on the basis of the dynamics of the motivational state and the state dependent rate of successful encounter are proposed. The food content of the gut is chosen as an indicator of the motivational state. A stochastic queueing model simulates predation as accurately as a Monte Carlo model or a compound simulation model. The queueing model is preferred because of its economic use of computer time and the relatively few variables used. The model was validated in predation experiments.
Systems analysis showed that the effect of temperature on the rate of predation is largely determined by its relation with the relative rate of food conversion into egg biomass and not by behavioural changes related to temperature. Also, it was shown that webbing has an important influence on the predation rate. A new model for the analysis of prey-stage preference is proposed.
Predators invade the webbed leaf area after contact with the silk strands, irrespective of the presence of prey. The residence time in the prey colony is determined by prey density. Simulation of experimentally defined walking behaviour shows that predators remain in profitable prey patches by turning at the edge of the webbed leaf area. However, when predator density increases, the tendency to leave the prey colony also increases, even at high prey densities. Only A. potentillae avoided the webbed leaf area, preferring the thickest parts of the leaf ribs or other protected places on the plant.
A survey of references on life history data is presented; emphasis is given to the role of food, temperature and relative humidity. Experiments by the author show that oviposition history of predatory females is a major factor in determining the actual rate of food conversion into egg biomass; and that the egg stage of the predators is very vulnerable to relative humidities below 70%, though the evapotranspiration of the plant and the hygroscopic properties of the webbing buffer this to some extent. As the juvenile mortality of the phytoseiids increases above 30°C, and that of the two-spotted spider mites above 35°C, spider-mite control at temperatures above 30°C is not effective.
The four phytoseiid species are ranked on their capacities for numerical increase and predation: P. persimilis , A. bibens , M. occidentalis and A. potentillae . On capacity to survive on alternative foods they are ranked: A. potentillae , A. bibens , M. occidentalis and P. persimilis . Some trials with alternative food supply did not improve survival rates established for prevailing greenhouse conditions.
The rate of increase of the webbed area per individual spider mite is quantified by experiment. This knowledge will enable continuous monitoring of the prey density during simulations of the predator-prey interactions on the population level.