70 research outputs found
Application expérimentale de mycelium d'Erynia neoaphidis (Zygomycètes : entomophthorales) dans des populations de pucerons sur laitues en serre maraîchère : étude du suivi de l'inoculum par caractérisation enzymatique
Au cours d'une expérimentation réalisée en serre à Rennes, en 1983, on a éprouvé l'efficacité contre les pucerons de la laitue #Aulacorthum solani (Kaltenbach) et #Macrosiphum euphorbiae (Thomas) d'une biopréparation d'entomophtorale constituée de mycelium d'une souche de #Erynia neoaphidis introduite s'est implantée dans les populations aphidiennes, mais qu'elle est par la suite remplacée par un inoculum autochtone de la même espèce. On observe également le développement dès le début de l'expérimentation d'un inoculum de #C. obscurus$ qui ne correspond pas à la souche introduite 2 ans auparavant lors d'une précédente expérimentation. (Résumé d'auteur
An overview of the functioning of Sitobion avenea populations at three spatial scales in France
In this paper we give 3 snapshots of our recent work on S. avenae at field, landscape and country scales. From April to June wheat fields are continuously colonized by winged S. avenae and previously established colonies experience high extinction rates. This leads to changes in spatial distribution of aggregates of aphids and to a progressive spatial homogenisation of the populations in fields, and highlights the role of spring immigrants in the field dynamics of S. avenae. In the surrounding landscape, the S. avenae populations on cultivated cereals (wheat, maize, barley) do not differ genetically. Conversely, aphids from weed margins and pastures (mostly on Poeae) clearly differ from those on cereals, indicating a low level of gene flow between the ‘uncultivated’ (mostly perennial) and cultivated system (annual). Consequently weeds and pasture grasses are probably poor sources of S. avenae for further infestation of cereal fields. The role of surrounding crops and weeds as a source of aphids infesting wheat was assessed by stable isotopic ratios and population genetic tools. In autumn, up to the beginning of October, most S. avenae landing on wheat originated from maize and after this from cereal volunteers. In spring the influx from surrounding cereal volunteers varied between years, but uncultivated Poeae played a minor role. At country scale on cereals, clonal reproduction and parthenogenetic overwintering prevails everywhere in France, but there is a trend toward increasing sexuality northward. The weak genetic differentiation of the regional populations on cereals and the presence of many identical genotypes in most of the regions sampled confirm the high dispersal ability of S. avenae. The high occurrence of widespread genotypes in multiple copies, belonging to the same genetic pool, which persist over several years in France and other countries in Europe, indicates a homogenising effect of selection by millions of hectares of cereal
Rapport de synthese sur les activites du sous-groupe "Ecologie des pucerons des cereales".
National audienc
A twelve year study of cereal aphids on winter wheat in Brittany. Pest status of Sitobion avenae F., Metopolophium dirhodum Wlk. and Rhopalosiphum padi L. during spring.
International audienc
Pucerons et maladies a virus en rotations cerealieres intensives.
ISBN-85340-779-9National audienc
Pucerons des cereales et jaunisse nanisante de l'orge. Introduction.
ISBN-85340-779-9National audienc
L'appreciation et la prevision des risques en entomologie appliquee a l'agriculture: cas des grandes cultures
National audienc
Overwintering of primary parasites and hyperparasites of cereal aphids in western france
International audienc
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