Search results for " predation"
showing 10 items of 56 documents
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…
Intraguild interactions between two egg parasitoids exploring host patches
2010
Intraguild interactions between two egg parasitoids, Trissolcus basalis (Hymenoptera: Scelionidae) and Ooencyrtus telenomicida (Hymenoptera: Encyrtidae), exploring egg masses of the Southern Green Stink Bug (SGSB) Nezara viridula (Heteroptera: Pentatomidae), were investigated in laboratory conditions by single, simultaneous and sequential host attack experiments. Mortality of N. viridula eggs was higher in simultaneous and sequential releases compared to single species releases. In simultaneous host exploitations, T. basalis females displayed an aggressive behavior against O. telenomicida females. The outcome of multiparasitism showed that interspecific larval competition was dominated by O…
Plant-animal interactions in fire-prone ecosystems
2018
SÍNTESIS Estudiar cómo responden las interacciones ecológicas a las perturbaciones es clave para abordar la creciente pérdida de biodiversidad en diferentes ecosistemas. En la Tierra existen especies que han evolucionado ante la presencia recurrente de perturbaciones naturales, como ocurre en ecosistemas con incendios frecuentes. En ellos el fuego se originó poco después de la aparición de las primeras plantas terrestres y también algunos de los patrones de incendios característicos que todavía permanecen. Sin embargo, las actividades humanas están alterando los patrones naturales de incendios, lo que puede suponer una amenaza incluso para las especies que presentan una rápida recuperación …
John Bates Clark on trusts: New light from the Columbia archives
2005
Public concern over the so called “trust problem” in the United States between the end of the nineteenth century and 1914, the year of the passage of the Clayton and Federal Trade Commission (FTC) Acts, was reflected in the considerable contemporary literature on the subject. Not surprisingly, professional economists actively participated in this debate. Their thinking directly and indirectly influenced the legislation of 1914 in a way that cannot be said of the Sherman Act of 1890 (Mayhew 1998). A survey of the most important of these professional writings shows that, among the several voices animating the discussion, John Bates Clark's was perhaps the most influential. In this connection,…
The role of biotic interactions in a prey-predator system : the case of predation and regulation of weed seeds by carabids.
2020
For the transition towards agricultural production systems that are less dependent on herbicides, the use of weed regulation by seed-eating carabids is of great interest. Weed seed predation by carabids is variable and occurs within a complex context of many biotic interactions. This complexity partly explains our current inability to predict levels of in-field weed regulation. In this thesis, I analysed variations in the levels of predation and biological regulation of weeds and determined how they respond to two classes of biotic interactions: 1) the availability of alternative prey; and, 2) intra- and inter-specific interactions between the carabids themselves. Field measurements carried…
Effects of food abundance and early clutch predation on reproductive timing in a high Arctic shorebird exposed to advancements in arthropod abundance.
2016
12 pages; International audience; Climate change may influence the phenology of organisms unequally across trophic levels and thus lead to phenological mismatches between predators and prey. In cases where prey availability peaks before reproducing predators reach maximal prey demand, any negative fitness consequences would selectively favor resynchronization by earlier starts of the reproductive activities of the predators. At a study site in northeast Greenland, over a period of 17 years, the median emergence of the invertebrate prey of Sanderling Calidris alba advanced with 1.27 days per year. Yet, over the same period Sanderling did not advance hatching date. Thus, Sanderlings increasin…
Melanin-based colour polymorphism signals aggressive personality in nest and territory defence in the tawny owl (Strix aluco)
2013
Nest and territory defence are risky and potentially dangerous behaviours. If the resolution of life history trade-offs differs between individuals, the level of defence may also vary among individuals. Because melanin-based colour traits can be associated with life history strategies, differently coloured individuals may display different nest and territory defence strategies. We investigated this issue in the colour polymorphic tawny owl (Strix aluco) for which plumage varies from dark to light reddish melanic. Accordingly, we found that (1) our presence induced a greater response (flying around) from dark-coloured than light-coloured females and (2) dark reddish males suffered lower nest…
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…
Breeding success of the Great Tit Parus major in relation to attributes of natural nest cavities in a primeval forest
2015
An overlap in attributes of nest cavities used by Great Tit Parus major across Eurasia suggests similar nest site preferences within the geographical range, although the drivers of these preferences are unclear. To determine whether preferred cavities provide conditions enhancing successful reproduction, we investigated the breeding performance of Great Tits in relation to tree cavity characteristics using data collected during 2008–2011 in primeval conditions (Białowieża National Park, Poland). Here, tree cavities are diverse and superabundant but nesting birds are at risk from a variety of predators. According to expectations, nest losses were high (60 % of Great Tit nests failed), mostly…
Intraguild predation and interference competition on the endangered dragonfly Aeshna viridis
2003
We examined the effects of intraguild predation (IGP) and interference competition on an endangered dragonfly, Aeshna viridis Eversm. (Odonata: Anisoptera). A. viridis is rare in Europe due to the decrease in suitable habitats harboring the macrophyte Stratiotes aloides L. Stratiotes plants are the principal oviposition substrate for A. viridis females and protect the larvae of A. viridis from fish predation. In our study lakes A. viridis larvae are sympatric with larvae of Aeshna grandis and Aeshna juncea. The susceptibility of A. viridis larvae to IGP by similar-sized larvae of A. grandis and A. juncea was tested in a laboratory predation experiment. Microhabitat use of A. viridis and A. …