Search results for "bee"

Microbial Community Structure and Density Under Different Tree Species in an Acid Forest Soil (Morvan, France)

2005

Overexploitation of forests to increase wood production has led to the replacement of native forest by large areas of monospecific tree plantations. In the present study, the effects of different monospecific tree cover plantations on density and composition of the indigenous soil microbial community are described. The experimental site of "Breuil-Chenue" in the Morvan (France) was the site of a comparison of a similar mineral soil under Norway spruce (Picea abies), Douglas fir (Pseudotuga menziesii), oak (Quercus sessiflora), and native forest [mixed stand dominated by oak and beech (Fagus sylvatica)]. Sampling was performed during winter (February) at three depths (0-5, 5-10, and 10-15 cm…

La lutte biologique contre l'ambroisie à feuilles d'armoise illustrée par l'exemple d'Ophraella communa: quels intérêts et quelles limites ?

2016

National audience; Common ragweed (Ambrosia artemisiifolia) was introduced in France over 150 years ago and its spreading across France now seems inexorable. The specific biology of this summer annual creates new problems for the managers of the various habitats where the plant can be found. The reduced possibility, or even the impossibility, to use traditional control means in certain environment conditions brings managers to consider biological control as one of the few possible means for slowing down the spread, or even pushing back the distribution area, of this invasive and allergenic plant. With Ophraella communa as an example, a reflection is presented on the benefit-risk balance of …

Pyrethroids alter sodium channel gating in honeybee olfactory receptor neurons

2010

International audience; Social structure in a domestic honeybee colony relies on inter-individual. chemical communication. Chemical communication is mediated. by odors and pheromones detected by olfactory receptor. neurons (ORN) localized in antennae. The Colony Collapse Disorder. (CCD) has been described in many countries around the world. and one of its main symptoms is the desertion of the hive by adult. worker bees, leaving the queen with brood and a small number of. young bees only. Our hypothesis is that such a desertion could be a. consequence of a disruption in the colony cohesion due to a defective. peripheral olfactory system. Recent studies have shown that. several insecticides c…

Effets de la variabilité inter-individuelles et des interactions intra-guildes sur les stratégies d'approvisionnement de carabes consommateurs de gra…

2017

Making a choice requires, implicitly, an investment of time in one behaviour at the expense of an investment in another. Being choosy would increase the risk of losing many food item opportunities to competitors, and is directly in conflict with other essential tasks such as predator avoidance. Individuals are thus expected to adjust their level of choosiness in response to the competition and predation context. The available behavioural ecological theory and the empirical ecology of carabids would suggest that competition and predation interference induces changes in the foraging behaviour of carabid individuals. Carabids typically operate within communities in which competition and predat…

Influence de la biodégradation dans l’atténuation des pesticides sur un bassin versant viticole : potentialité des différents éléments du paysage et …

2013

Nos travaux ont montré que les différents compartiments d'un paysage viticole du site atelier de la Morcille (sol de la parcelle, bande enherbée et sédiments) connectés le long du continuum sol-eau, présentaient une aptitude à minéraliser le diuron. La capacité épuratrice de ces différents compartiments évolue en fonction du niveau d’exposition au contaminant. Ainsi la zone tampon exposée présente une meilleure aptitude à épurer le diuron que la zone tampon témoin. Les sédiments de la Morcille situés à proximité de la zone tampon présentent également une capacité épuratrice présentant un gradient amont-aval coïncidant avec le gradient amont-aval observé également pour la qualité chimique de…

Contribution des pollinisateurs dans la production de colza et de tournesol en zone atelier « Plaine et Val de Sèvre »

2018

Insect pollination is essential for over 70% of crops around the world. However, the contribution of pollinators to crop production and the insects involved in crop pollination have rarely been studied. Moreover, assessments of pollinator contributions have mostly been conducted on a small scale or under simplified conditions, which do not represent the real contributions at the field scale and do not take into account possible interactions between pollinators and farming practices. The aim of this study is to quantify directly under field conditions, the contribution of pollinators in two crops frequently cultivated in Europe: oilseed rape and sunflower. Estimations are realized both at th…

Elucidating the genetic determinism of the plasticity of seed proteins in response to the environment using Medicago truncatula

2019

International audience; Legumes are able to produce high-protein seeds without nitrogen fertilizer through root symbiosis with nitrogen-fixing rhizobia. Rich in lysine, these proteins are used for human nutrition and animal feed. However, instability of seed protein yield and quality due to environmental fluctuations limits the wide adoption of legumes in Europe. Breeding efforts are needed to optimize and stabilize seed nutritional quality. We have studied the plasticity of protein content and composition of seeds from a collection of 200 ecotypes of Medicago truncatula grown under four controlled conditions (optimal, drought, and winter/spring sowing). A quantitative analysis of one-dimen…

Place des prairies permanentes dans les élevages allaitants de Bourgogne, projet de recherche PSDR Bourgogne. Rapport final

2006

Beticolins: chemistry and biological activities

2010

Part II: Biology of Cercospora beticola C)Toxins of Cercospora

Mechanisms involved in spatial and temporal mobility of disease patches caused by Rhizoctonia solani in sugar beet field : Induction of antagonists w…

2008

National audience; Rhizoctonia solani AG 2-2 causes damping-off and root rot on sugar beet in patches that are highly mobile both on spatial and temporal scales. They never occur in the same place where they were in the previous season. The aim of the present study was to uncover the mechanisms underlying the dynamics of disease patches. It was observed that soil inoculum potential was higher within diseased patch than in healthy area. However, the dormant pathogen in healthy area was stimulated by addition of buckwheat meal more than that in diseased patch. In addition soil from diseased area was more suppressive towards the disease. We did not observe significant differences in bacterial …