Search results for "Predator"

Host manipulation of a freshwater crustacean (Gammarus roeseli) by an acanthocephalan parasite (Polymorphus minutus) in a biological invasion context.

2006

8 pages; International audience; Several gammarid species serve as intermediate hosts for the acanthocephalan parasite Polymorphus minutus. This parasite influences gammarid behaviour in order to favour transmission to its ultimate host, generally a bird. We investigated this host manipulation in Gammarus roeseli, a gammarid species introduced in France 150 years ago which now coexists with several exotic species from different origins. In the field, vertical distribution of G. roeseli revealed a higher proportion of infected individuals close to the water's surface and the size distribution of infected gammarids revealed predation pressure on infected individuals. However, under laboratory…

Modification of hosts' behavior by a parasite: field evidence for adaptive manipulation.

2007

9 pages; International audience; Parasites relying on trophic transmission to complete their life cycles often induce modifications of their host's behavior in ways that may increase their susceptibility to predation by final hosts. These modifications have often been interpreted as parasite adaptations, but very few studies have demonstrated that host manipulation has fitness benefits for the parasite. The aim of the present study was to address the adaptive significance of parasite manipulation by coupling observations of behavioral manipulation to estimates of trophic transmission to the definitive host in the natural environment. We show that the acanthocephalan parasite Pomphorhynchus …

Manipulative parasites may not alter intermediate host distribution but still enhance their transmission: field evidence for increased vulnerability …

2013

SUMMARYBehavioural alterations induced by parasites in their intermediate hosts can spatially structure host populations, possibly resulting in enhanced trophic transmission to definitive hosts. However, such alterations may also increase intermediate host vulnerability to non-host predators. Parasite-induced behavioural alterations may thus vary between parasite species and depend on each parasite definitive host species. We studied the influence of infection with 2 acanthocephalan parasites (Echinorhynchus truttae and Polymorphus minutus) on the distribution of the amphipod Gammarus pulex in the field. Predator presence or absence and predator species, whether suitable definitive host or …

Carotenoid-based colour of acanthocephalan cystacanths plays no role in host manipulation.

2009

Manipulation by parasites is a catchy concept that has been applied to a large range of phenotypic alterations brought about by parasites in their hosts. It has, for instance, been suggested that the carotenoid-based colour of acanthocephalan cystacanths is adaptive through increasing the conspicuousness of infected intermediate hosts and, hence, their vulnerability to appropriate final hosts such as fish predators. We revisited the evidence in favour of adaptive coloration of acanthocephalan parasites in relation to increased trophic transmission using the crustacean amphipodGammarus pulexand two species of acanthocephalans,Pomphorhynchus laevisandPolymorphus minutus. Both species show car…

Les impacts du campagnol terrestre sur les systèmes fourragers : le cas de l’élevage bovin allaitant en Bourgogne

2014

EAAgroSupECOLDUR; Do vole outbreaks have the same effects on suckler beef farms in Burgundy as they do on daily farms in Auvergne and Franche-Comte? Semi-structured interviews were carried out with 19 farmers from Burgundy who had been affected by a water vole outbreak in 2011. The results indicate that, just like farmers in Auvergne and Franche-Comte, farmers in Burgundy witnessed a decrease in forage quantity and quality. Farmers used diverse measures to deal with the outbreak (e.g., avoidance strategies or the use of bromadiolone). Farmers that described water voles as pests were more likely to have used bromadiolone, while those who described water voles in morphological terms or in ter…

Widespread diminishing anthropogenic effects on calcium in freshwaters

2019

Calcium (Ca) is an essential element for almost all living organisms. Here, we examined global variation and controls of freshwater Ca concentrations, using 440 599 water samples from 43 184 inland water sites in 57 countries. We found that the global median Ca concentration was 4.0 mg L−1 with 20.7% of the water samples showing Ca concentrations ≤ 1.5 mg L−1 , a threshold considered critical for the survival of many Ca-demanding organisms. Spatially, freshwater Ca concentrations were strongly and proportionally linked to carbonate alkalinity, with the highest Ca and carbonate alkalinity in waters with a pH around 8.0 and decreasing in concentrations towards lower pH. However, on a temporal…

Predator-Induced Plasticity on Warning Signal and Larval Life-History Traits of the Aposematic Wood Tiger Moth, Arctia plantaginis

2021

Predator-induced plasticity in life-history and antipredator traits during the larval period has been extensively studied in organisms with complex life-histories. However, it is unclear whether different levels of predation could induce warning signals in aposematic organisms. Here, we investigated whether predator-simulated handling affects warning coloration and life-history traits in the aposematic wood tiger moth larva, Arctia plantaginis. As juveniles, a larger orange patch on an otherwise black body signifies a more efficient warning signal against predators but this comes at the costs of conspicuousness and thermoregulation. Given this, one would expect that an increase in predation…

Increasing intensity of deimatic behaviour in response to repeated simulated attacks: a case study on the mountain katydid (Acripeza reticulata)

2022

Abstract How and when deimatic behaviours are performed can change during encounters between predators and prey. Some predators attack repeatedly, investigating and manipulating prey, and in response, an individual’s deimatic behaviour may intensify or may diminish in favour of escaping. The presence of a resource can further force a trade-off between displaying and escaping. Here, we examined the intensity of the katydid’s deimatic behaviour, a visual display, the propensity of their escape response under repeated simulated attacks, and how these responses change in the presence of foraging resources. We found that display intensity increased with repeated simulated attacks and that femal…

Many forms of the wood tiger moth (Parasemia plantaginis) : selective heterogeneity favours polymorphic warning signals

2013

Predator proximity as a stressor in breeding flycatchers: mass loss, stress protein induction, and elevated provisioning.

2010

We investigated the physiological and behavioral consequences for prey breeding at different distances from a nesting predator. In a natural setting, Pied Flycatchers (Ficedula hypoleuca) made territory location decisions relative to established Sparrowhawk (Accipiter nisus) nests. From female flycatchers attending nests at different distances from Sparrowhawk nests, we measured body mass, blood stress protein (HSP60 and HSP70), and plasma immunoglobulin levels at the beginning (initial) and end (final) of the flycatcher breeding cycle, and provisioning rates during the nestling phase. We found that individuals breeding in closer proximity to Sparrowhawk nests, under higher perceived predat…