Search results for " prey"
showing 10 items of 29 documents
Effect of pollens and preys on various biological parameters of the generalist mite Cydnodromus californicus
2009
The generalist phytoseiid mite Cydnodromus californicus (McGregor) (Mesostigmata Phytoseiidae) is considered a very important biocontrol agent of the spider mite Tetranychus urticae Koch both in greenhouses and field. Its capacity to feed alternative foods allows the increase of the population in field, even when the primary prey is not available. To investigate the effect of various alternative food substances present in the Mediterranean agroecosystems on the biological parameters of C. californicus, laboratory trials were carried out using 17 pollens and 3 preys. As it was expected, T. urticae was the best food for both the postembryonic development and the oviposition rate (100% of atta…
Social transmission in the wild can reduce predation pressure on novel prey signals
2021
Funder: Suomen Kulttuurirahasto (Finnish Cultural Foundation); doi: https://doi.org/10.13039/501100003125
Effetti della cattività su alcuni parametri ematologici del grifone (Gyps fulvus)
2017
Haematological analysis is an essential field of veterinary medicine that provides inexpensive and reliable support to determinate animal health. The knowledge of how different factors affect the normal mean values of blood parameters is key to understand and improve animal health. In order to investigate how captivity can affect the haematological profile of birds of prey, the erythrocyte count, haemoglobin concentration, haematocrit, mean corpuscular volume, total leukocytes count of 123 griffon vultures (Gyps fulvus) were analysed. The birds were divided into 4 groups according to their life conditions: a control group of free-living griffons, 2 semi-captive groups held in an aviary for …
Experiments on Concurrent Artificial Environment
2001
We show how the simulation of concurrent system is of interest for both behavioral studies and strategies of learning applied on prey-predator problems. In our case learning studies into unknown environment have been applied to mobile units by using genetic algorithms (GA). A set of trajectories, generated by GA, are able to build a description of the external scene driving a predators to a prey. Here, an example of prey-predator strategy,based on field of forces, is proposed. The evolution of the corespondent system can be formalized as an optimization problem and, for that purpose, GA can be use to give the right solution at this problem. This approach could be applied to the autonomous r…
L'influence de l'hyperthyroidisation expérimentale sur le plumage des oiseaux carnivores: (note préliminaire) [Gaļas ēdāju putnu spalvojuma atkarība …
1931
Teksts franču valodā, kopsavilkums latviešu valodā.
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…
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 …
Feeding habits of the Short-toed Eagle Circaetus gallicus during the breeding period in Central Italy
2022
Short-toed Eagle Circaetus gallicus is the only snake eagle that nests in the Palearctic. Its diet has been studied in several European countries and it is essentially based on reptiles. The aims of this work were to characterise the feeding habits of Short-toed Eagle breeding in the Tolfa Mountains (Central Italy) including a comparison of the diet with that of other populations. Moreover, we assessed changes in the diet of the former population using published data collected more than 35 years ago. We monitored five nests and three roosts between 2020 and 2021. Using camera traps and the collection and analysis of feeding remains, a total of 247 prey items were identified. The diet of the…
Ultraviolet reflection and predation risk in diurnal and nocturnal Lepidoptera
2004
According to our extensive data on Lepidoptera (883 species), UV wing patterns are almost three times more common in nocturnal than in diurnal Lepidoptera. This might be due to predation, because the primary diurnal predators, birds, utilize UV light in foraging and even prefer UV-reflecting prey. To test this hypothesis, we conducted a field experiment with tethered living moths whose wings were artificially manipulated to reflect (UV+, reflection at UV wavelength: 15%) or absorb (UV - ) UV light, keeping longer wavelengths identical. Thus, any difference found in survival rates would be the result of the difference in wing patterns in UV spectrum. Significantly more UV+ moths th…
Disentangling local agronomic practices from agricultural landscape effects on pest biological control
2019
International audience; The biological control of crop pests is a valuable service provided by various beneficial organisms that are naturally present in agricultural landscapes. Semi-natural habitats has long been recognized as essential to preserve beneficial insects, but proof of their efficiency to enhance biological control of pests remains non conclusive. Here, we examined the variability of landscape effect on biological pest control and the way local agronomic practices may modulate it. Biological pest control was monitored in 80 commercial fields (arable crops and orchards) during three consecutive years in four contrasting French agricultural landscapes distributed along a double …