Search results for "Predation"
showing 10 items of 589 documents
Maternal effects in vulnerability to eye-parasites and correlations between behavior and parasitism in juvenile Arctic charr
2017
Hatchery-reared fish show high mortalities after release to the wild environment. Explanations for this include potentially predetermined genetics, behavioral, and physiological acclimation to fish farm environments, and increased vulnerability to predation and parasitism in the wild. We studied vulnerability to Diplostomum spp. parasites (load of eye flukes in the lenses), immune defense (relative spleen size) and antipredator behaviors (approaches toward predator odor, freezing, and swimming activity) in hatchery-reared juvenile Arctic charr (Salvelinus alpinus) using a nested mating design. Fish were exposed to eye-fluke larvae via the incoming water at the hatchery. Fish size was positi…
Outside-host phage therapy as a biological control against environmental infectious diseases
2018
Background Environmentally growing pathogens present an increasing threat for human health, wildlife and food production. Treating the hosts with antibiotics or parasitic bacteriophages fail to eliminate diseases that grow also in the outside-host environment. However, bacteriophages could be utilized to suppress the pathogen population sizes in the outside-host environment in order to prevent disease outbreaks. Here, we introduce a novel epidemiological model to assess how the phage infections of the bacterial pathogens affect epidemiological dynamics of the environmentally growing pathogens. We assess whether the phage therapy in the outside-host environment could be utilized as a biologi…
Significance of butterfly eyespots as an anti-predator device in ground-based and aerial attacks
2003
Many butterfly genera are characterised by the presence of marginal eyespots on their wings. One hypothesis to account for an occurrence of eyespots is that these wing pattern elements are partly the outcome of visual selection by predators. Bicyclus anynana (Satyrinae) has underside spotting on its wings but there is also a seasonal form in which the eyespots are reduced in size or totally absent. This natural variation gives us a useful tool to test the hypothesis that marginal eyespot patterns can decoy the attacking predator by, at least sometimes, diverting attack from vital body parts to the edges of the wings. We used lizards, Anolis carolinensis, and pied flycatchers, Ficedula hypol…
Does Forest Fragmentation and Selective Logging Affect Seed Predators and Seed Predation Rates of Prunus africana (Rosaceae)?
2007
Forest fragmentation and selective logging can influence the life cycle of tropical tree species at several levels, e.g., by lowering pollination, by limiting seed dispersal, and by increasing seed predation. Understanding human-induced modifications in ecosystem processes such as seed predation is essential for conservation management of threatened species. We studied the impact of forest fragmentation and selective logging on seed predation of the endangered tree Prunus africana in the tropical rain forest of Kakamega, Kenya. We quantified the activity of seed predators in the main forest, forest fragments, and in sites of different logging intensity in the dry and rainy seasons of 2003 a…
Predation of two Mediterranean phytoseiid species (Parasitiformes, Phytoseiidae) upon eggs of tetranychid mites (Acariformes, Tetranychidae)
2012
Laboratory trials were carried out to verify the predatory capacity of two generic phytoseiid predators upon eggs of the two most important tetranychids damaging Citrus orchards in Sicily: Tetranychus urticae and Panonychus citri. Both Typhlodromus laurentii and Typhlodromus rhenanoides are autochthonous and common species on spontaneous and cultivated plants. The research aimed at investigating the predatory behaviour of the phytoseiids upon the prey stage considered more vulnerable. The predation rate of the two phytoseiids was different on the two prey eggs, both on each observation day and for the whole observation period. Both phytoseiids clearly preferred T. urticae eggs, on which the…
Predatory performance of two Mediterranean phytoseiid species, Typhlodromus laurentii and Typhlodromus rhenanoides fed on eggs of Panonychus citri an…
2013
Laboratory trials were carried out to determine the predatory capacity of two endemic to the Mediterranean area phytoseiid mites Typhlodromus (Typhlodromus) laurentii Ragusa et Swirski and Typhlodromus (Anthoseius) rhenanoides Athias-Henriot (Parasitiformes Phytoseiidae) upon the eggs of the two most important tetranychids damaging Citrus orchards in Sicily: Tetranychus urticae Koch and Panonychus citri (McGregor) (Acariformes Tetranychidae). The research aimed at investigating the predatory behaviour of the phytoseiids upon the prey stage considered the most vulnerable. The predation rate of the two phytoseiid species was different on the two prey eggs, both in every observation day and fo…
Predation of Typhlodromus longilaterus Athias-Henriot (Parasitiformes, Phytoseiidae) females on eggs and juveniles of the tetranychid mites Tetranych…
2013
Typhlodromus longilaterus is a generalist phytoseiid mite described by Athias-Henriot in 1957 and commonly found in Israel on spontaneous herbaceous plants. As very little is known about this species, the present study reports preliminary results on the predation capacity of phytoseiid females on eggs and juveniles of two tetranychid mites very common in the Mediterranean area, Tetranychus urticae and Panonychus citri. After 24 hours the phytoseiid females preyed on 15% of offered eggs of both tetranychids, while the prey ratio was higher on T. urticae eggs after this period (33.4% and 33.5% vs 20.8% and 16.2% after 2 and 3 days for T. urticae and P. citri respectively). The phytoseiid show…
Ground-level predation on artificial caterpillars indicates no enemy-free time for lepidopteran larvae
2017
Lepidoptera is one of the most diverse orders of insects, their larvae are very abundant in many habitats, and frequent prey of various predators. To decrease predation risk, caterpillars developed several means of defence, among them timing their activity to avoid predators (seeking enemy-free time). Although the enemy-free time hypothesis is often invoked to explain caterpillar behaviour, empirical evidence for it is scarce. We tested whether such enemy-free time exists in a temperate forest by comparing predation pressure on artificial caterpillars during day and night on the ground in forest fragments in Denmark. We found a high predation rate, 23.9% d(-1), and higher predation rate at …
Ocean acidification as a driver of community simplification via the collapse of higher-order and rise of lower-order consumers
2017
AbstractIncreasing oceanic uptake of CO2 is predicted to drive ecological change as both a resource (i.e. CO2 enrichment on primary producers) and stressor (i.e. lower pH on consumers). We use the natural ecological complexity of a CO2 vent (i.e. a seagrass system) to assess the potential validity of conceptual models developed from laboratory and mesocosm research. Our observations suggest that the stressor-effect of CO2 enrichment combined with its resource-effect drives simplified food web structure of lower trophic diversity and shorter length. The transfer of CO2 enrichment from plants to herbivores through consumption (apparent resource-effect) was not compensated by predation, becaus…
Native predators control the population of an invasive crab in no-take marine protected areas
2018
1. The resistance of an ecosystem to species invasion is considered to be related to the abundance and diversity of native species i.e. biotic resistance hypothesis). Theory predicts that the high native diversity in pristine systems can hinder the establishment and/or the spread of non‐native species through direct and indirect mechanisms (e.g. through competitive and/or predatory interactions). 2. Here we tested whether predation provides higher resistance to invasion by the Percnidae crab Percnon gibbesi (H. Milne Edwards, 1853) in protected native communities, compared with exploited ones. Specifically, this study aimed to compare: (i) the abundance and diversity of potential predator a…