L'identité coloniale et sa "représentation " chez les fourmis

Dominique FRESNEAU, Christine ERRARD : Colonial identity and its " representation " in ants In ants, societies are closed to alio-as well as conspecific intruders. This phenomenon rests on the presence and identification of chemicals (cuticular hydrocarbons). Due to the great diversity of these compounds, each colony possesses its own chemical profile. Although this principle is well known in most ant species, the underlying mechanisms vary. In this work, we examine two examples in order to suggest two hypothetical models of interpretation. Ponerine ants which are considered as primitive ants, give a first example where colonial recognition is based on a simple discrimination without any reference to memory. In contrast, the second example is constituted by two advanced subfamilies engaged in interspecific associations with relations of social parasitism. Results show a surprisingly phenomenon of learning by early familiarization and irreversible memorization of the chemical signature of individuals of the associated species. These results shed a new original light on the recognition and the representation of the colonial identity. In fact, the social level implies necessarily the occurrence of an additional step of analysis and reasoning which has not been yet taken into account. Our purpose is to initiate a discussion on this topic.Chez les fourmis, les sociétés sont fermées à toutes intruses, y compris celles de la même espèce. Ce phénomène repose sur l'existence et l'identification de substances chimiques (hydrocarbures cuticulaires) dont la diversité permet à chaque colonie de posséder un profil chimique qui lui est propre. Si ce principe est vérifié chez la plupart des espèces de fourmis, les mécanismes aboutissant à ce résultat varient. Dans ce travail, nous examinons deux exemples nous permettant de proposer deux modèles hypothétiques d'interprétation. Les fourmis Ponérines, réputées primitives, donnent un premier exemple où la reconnaissance coloniale obéit à un modèle basé sur la simple discrimination sans qu'il soit fait appel à la mémoire. En revanche, un second exemple repose sur l'étude d'espèces appartenant à deux sous-familles supérieures qui pratiquent le parasitisme social sur la base d'associations interspécifiques. Les résultats montrent un étonnant phénomène d'apprentissage par familiarisation précoce et mémorisation irréversible de la signature chimique des individus de l'espèce associée. Ces résultats posent la question de la reconnaissance et de la représentation de l'identité coloniale d'une manière originale puisque le palier social introduit nécessairement un niveau supplémentaire d'analyse et de raisonnement qui jusqu'ici n'a que très peu été pris en compte. Notre propos est d'initier une discussion sur cette thématique.Fresneau Dominique, Errard Christine. L'identité coloniale et sa "représentation " chez les fourmis. In: Intellectica. Revue de l'Association pour la Recherche Cognitive, n°19, 1994/2. Organisation émergente dans les populations : biologie, éthologie, systèmes artificiels. pp. 91-115

Etude de la fourmi tetramorium bicarinatum (approches biologique et moléculaire)

TOURS-BU Sciences Pharmacie (372612104) / SudocSudocFranceF

Mutualisme chez les fourmis champignonnistes (Atta et Acromyrmex) (approches comportementale, chimique et enzymologique)

Les fourmis Atta et Acromyrmex sont caractérisées par la présence d'un champignon symbiote. Leur co-dépendance est nutritionnelle, physiologique et antibiotique. L'étude des relations entre les deux symbiotes par différentes approches(comportementales, chimiques, moléculaires et enzymologiques)est réalisée. Nos résultats montrent que le champignon intervient dans l'homogénéisation de l'odeur coloniale. Cette odeur fluctue selon la nature de l'alimentation(modifications comportementales et chimiques). Les fourmis discriminent des champignons selon leur origine coloniale contrairement au champignon cultivé in vitro. Les distances génétiques et les profils chimiques des champignons de différentes colonies sont fortement corrélés chez deux espèces d'Acromyrmex. Les contributions relatives des fourmis et de leur champignon dans la dégradation de la matière végétale ont été réalisées sur sept espèces et ont montré que les deux partenaires ont des activités enzymatiques complémentaires. Bien que les sept associations présentent des profils enzymatiques très proches il existe des différences dans les activités de dégradation des substrats.TOURS-BU Sciences Pharmacie (372612104) / SudocSudocFranceF

L'identité chimique des insectes

chapitre 10National audienc

Bumblebee inquilinism in Bombus (Fernaldaepsithyrus) sylvestris (Hymenoptera, Apidae): Behavioural and chemical analyses of host-parasite interactions

The bumblebee Bombus sylvestris is an obligate social inquiline of B. pratorum and nest-invading females are known to integrate themselves into host colonies, usually without any aggression. We investigated whether cuticular compounds could be involved in discrimination processes in common bumblebees, and whether they play a role in the social integration of inquilines in host nests. We tested nestmate recognition in B. terrestris workers, and analysed cuticular chemical profiles of hairs taken from allocolonial individuals. Bumblebees belonging to the same colony shared a common odour. Then, we investigated how B. sylvestris females integrated into colonies of natural and non-natural hosts, B. pratorum and B. terrestris, respectively. Inquiline females apparently succeeded in entering a host colony by expressing non-aggressive behaviours and had no chemical signature; subsequently, acquisition of a chemical signature similar to the host colony might facilitate their integration into the host nest. © INRA/DIB-AGIB/ EDP Sciences, 2005.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Naturwissenschaften ( Intercontinental chemical variation in the invasive ant Wasmannia auropunctata (Roger) (Hymenoptera Formicidae): a key to the invasive success of a tramp species

Abstract Unicoloniality emerges as a feature that characterizes successful invasive species. Its underlying mechanism is reduced intraspecific aggression while keeping interspecific competitiveness. To that effect, we present here a comparative behavioural and chemical study of the invasive ant Wasmannia auropunctata in parts of its native and introduced ranges. We tested the hypothesis that introduced populations (New Caledonia archipelago) have reduced intraspecific aggression relative to native populations (e.g., Ilhéus area, Brazil) and that this correlates with reduced variability in cuticular hydrocarbons (CHCs). As predicted, there was high intraspecific aggression in the Brazilian populations, but no intraspecific aggression among the New Caledonian populations. However, New Caledonian worker W. auropunctata remained highly aggressive towards ants of other invasive species. The chemical data corresponded with the behaviour. While CHCs of ants from the regions of Brazil diverged, the profiles of ants from various localities in New Caledonia showed high uniformity. We suggest that C. Errard (

Early learning of volatile chemical cues leads to interspecific recognition between two ant species

International audienceNestmate recognition in social insects generally involves matching a label to the template that is acquired through the early learning of non-volatile cuticular hydrocarbon cues. However, a possible role of the volatile chemical cues that exist in the nest, and which may also affect template formation, has not been studied. We investigated this possibility using experimental mixedspecies groups composed of the two ant species Manica rubida and Formica selysi. The experimental set-up either allowed full contact between workers of the two species or interspecific contact was hindered or prohibited by a single or a double mesh. After three months, workers of M. rubida ants were selected as focal ants for aggression tests including the following target ants: F. selysi workers from the same mixed-species group (for each of the three rearing conditions) or from a single-species group (control). Workers of M. rubida were always amicable towards their group-mates, irrespective of the experimental group (contact, single or double mesh). However, M. rubida that were not imprinted on F. selysi, expressed high levels of aggression towards the non-familiar F. selysi workers. The finding that F. selysi workers in the mixed-species groups appeared familiar to their M. rubida group-mates even without physical contact between them, suggests that the volatile cues produced by F. selysi affected nestmate recognition in M. rubida. In an attempt to identify these volatile cues we performed SPME analysis of the head space over groups of F. selysi workers. The findings revealed that F. selysi Dufour's gland constituents, with undecane as the major product, are released into the head space, rendering them likely candidates to affect template formation in M. rubida. Analysis of Dufour's gland secretion of F. selysi revealed a series of volatile alkanes, including undecane as a major product. These alkanes were not present in the glandular secretion of M. rubida, whose secretion was mainly composed of isomers of farnesene. We therefore hypothesize that callow M. rubida workers in the mixed-species groups had become imprinted by the above alkanes (in particular undecane, being the major heterospecific volatile in the head space