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Experimental studies show that early sensory experience often affects subsequent sensory preference, suggesting that the heterogeneity of sensory cues in nature could induce significant inter-individual behavioral variation, potentially contributing to maintain intraspecific diversity. To test this hypothesis, we explored the behavioral effect induced by variation in the levels of a self-produced chemical, acetoin, and its link with intraspecific diversity. Acetoin is a pheromone-like substance produced by gut-associated microorganisms in Drosophila. Using wild-type Drosophila melanogaster populations producing variable acetoin levels, we (i) characterized factors involved in this variation and (ii) manipulated some of these factors to affect acetoin responses in larvae. We found that increased and decreased variations in acetoin levels were caused by microorganisms associated with the outside and inside of the egg, respectively. Wild-type larvae preferred acetoin-rich food only when they both produced and were exposed to substantial amounts of acetoin. The removal of the outside of the egg or the genetic alteration of olfaction abolished this preference. In contrast, larvae exposed to high doses of synthetic acetoin were repulsed by acetoin. The similar effects obtained with freshly caught wild-type lines suggest that this acetoin "production-preference" link underlies the diversity of acetoin-producing microorganisms among natural D. melanogaster populations.

In eusocial insect species, the nest represents the fundamental element of the colony. Extranidal activities (foraging, nest maintenance, defence) are fundamental for the development and the survival of the colony. Therefore, they may represent interesting targets to disrupt to limit their expansion in case of pest species such as Vespa velutina, an alien predator of domestic honeybees in Europe. An accurate knowledge of the pattern of activity of this pest’s colonies is therefore required. Due to the highly defensive nature of this hornet, a video monitoring was realized on two colonies during their growth from August to November. Three major behaviours were monitored: nest maintenance, patrolling on the nest and foraging flights. Although of different size and monitored during different years, the two colonies exhibited similar patterns of daily and seasonal variation. This work is a first step in the study of this pest especially in view of control program.

Notre étude visait à (i) identifier les aspects dégradés et/ou variables du bien-être des vaches laitières en fermes commerciales et (ii) pour chaque variable du bien-être, les caractéristiques des fermes associées à une dégradation du bien-être. Les observations ont été conduites à l’aide du protocole Welfare Quality® dans 131 exploitations laitières échantillonnées selon leur localisation, la taille et la race du troupeau, le logement, le système de traite. Des scores ont été calculés pour chaque ferme, exprimant le degré de conformité à 11 critères de bien-être (absence de faim, de soif, de maladies, comportement normal…). Des modèles linéaires multivariés ont été utilisés pour évaluer l'association entre les caractéristiques des fermes et les scores. Pour sept critères, les scores étaient dégradés (< 50 sur une échelle de 0 à 100): « Absence de faim prolongée », « Etat émotionnel positif », « Bonne relation homme-animal », « Expression du comportement social », « Confort de couchage », « Absence de maladies" et « Absence de douleurs liées aux pratiques d’élevage ». Les scores variaient selon les caractéristiques des fermes, excepté pour le critère « Bonne relation homme-animal ». L’étude a permis de mieux connaitre les risques de dégradation du bien-être auxquels sont exposées les vaches laitières et ouvre la voie vers des plans d’action ciblés., The objectives of the study were i) to highlight negative and variable aspects of dairy cow welfare in commercial farms, and ii) to determine which farm characteristics were associated with impaired welfare. We assessed welfare using the Welfare Quality ® protocol in 131 commercial farms that differed in location (highlands vs. lowlands), cow breed (Holstein vs. Montbéliarde), herd size (fewer than vs. more than 50 lactating cows), housing (cubicles vs. deep bedding), or milking system (milking parlor vs. robot). Within each farm, scores that express the degree of farm compliance with 11 welfare criteria were calculated (absence of hunger, thirst, diseases, normal behavior...). We used linear models to assess the association between farm characteristics and criterion scores. Six criteria had low scores (

Amélioration génétique des variétés cidricoles. Cider apple breeding (résumé en anglais). European Symposium on Apple Processing

Resume Reproductive cycle and fecundity in Hoplostemum littorale (Siluriforme), reared in French Guiana. The timing of the reproductive cycle of the atipa, Hoplosternum littorale (Hancock, 1828), in ponds (batches of fishes) or in cages (isolated couples), is similar to that obsewed under natural conditions. Recordings of nests and spawning show a reproductive cycle extending from early November to the end of May. The reunion of spawners dunng the second part of the breeding season does not extend the reproductive cycle. The high density of fry in the ponds, a few months after the first spawnings, might lead to the interruption of reproduction. The breeding of isolated couples shows : a decrease in the spawn weight from the first to the third spawning to a stable value (28.5 to 23.9 g for females of average weight 89 g, and 66.7 to 21.9 g for females with average weight 207 g). The number of spawnings for a female can reach 14 over the complete reproductive cycle. The mass of eggs laid in one annual cycle by a single female, can be 180 g (48 600 eggs) for one weighing 89 g and 340 g (91 900 eggs) for one of 207 g weight. These estimations for the number of eggs, founded on the weight of an egg of 3.7 mg established in the present paper, are far beyond what had been previously mentioned. The average loss of weight of males (0.4 % of initial weight for 185 g and 9 % for 292 g males) and females (10% of initial weight for 89 g and 23 % for 207 g females) over a complete reproductive cycle shows the extent of the investment of both sexes in reproduction. In ponds, 48 % of the nests are not used for spawning. The high proportion of nests without spawn is observed during the periods preceding and following the period of maximum spawning activity (JanuaryFebmary). There is no relation between the proportion of nests without spawn and rainfall. 49% of the nests hold eggs laid by at least 2 females. Five or more females can spawn in the sarne nest. The conclusion attempts to integrate the presents results in a general view of the reproductive strategy of the atipa. It points out the need for detailed ethological studies in order to reach a better understanding of the reproductive biology of this species.

Six variétés apparentées à Golden Delicious, toutes issues de semis, de maturité nettement plus précoces, ont été expérimentées sur le Centre Ctifl de Balandran, près de Nîmes. Cette étude se situe dans le cadre de l'expérimentation stade A pommier (action concertée INRA/Ctifl, coordonnée par la station d'arboriculture d'Angers).