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  • 1
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Resume Les ouvrières deLeptothorax unifasciatus utilisent des repères chimiques et des repères visuels au cours des activités de fourragement. Cependant, une orientation ménotactique (ampoule lumineuse de 60 watt) et reposant sur des repères visuels ambiants domient une orientation chimique. Un trajet effectué vers la nourriture suffit aux ouvrières pour s'orienter ensuite sur une ampoule lumineuse. Les ouvrières tracent une piste au cours du fourragement n'ayant pas fonction de recrutement, mais agissant comme repère orientationnel individuel. Ces pistes sont distinguées et préférées même lorsqu'elles sont superposées à plusieurs autres. Néanmoins, les ouvrières acceptent de suivre les pistes de leurs congénères en l'absence de leur propre piste. Les ouvrières nouvellement recrutées sont incapables de s'orienter sur les pistes chimiques.
    Notes: Summary Leptothorax unifasciatus workers use both chemical and visual cues when foraging. A visual orientation based on menotactical cues (60 watt light-bulb) and environmental cues (laboratory surroundings) dominate over a chemical orientation. The learning response to a 60 watt light-bulb cue occurs after a single trip to the food source. Workers lay down a trail when foraging which helps them to orient themselves but does not recruit other nestmates. Such trails are distinguished and preferred even when superposed by several other nestmates' trails. Nevertheless, the foragers are able to follow their nestmates' trails if their own is somehow missing. Newly recruited ants are unable to orient along chemical trails.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Resume Les ouvrières deLeptothorax unifasciatus différencient de nouvelles aires de celles précédemment explorées. En effet, un comportement de «va-et-vient» apparaît plus fréquent sur un papier vierge que sur un papier familier à la colonie. La chute d'activité sur un papier vierge après quelques heures indique que ce dernier devient rapidement familier à la colonie dans le dispositif expérimental utilisé. Les expériences suggèrent que le territoire est modifié chimiquement par l'activité des fourmis, mais la possibilité d'un marquage chimique n'a toutefois pas été explorée. Trois facteurs contrôlent le niveau d'activité de fourragement chezL. unifasciatus: 1o la nature de l'aire de récolte (connue ou inconnue); 2o la taille de la société; 3o le temps de séjour de la société dans un même nid. Des sociétés établies récemment dans leur nid montrent un niveau d'activité de fourragement plus élevé sur une aire de récolte inconnue que sur une aire familière. Dans tous les cas, il existe une relation linéaire liant la taille de la société et son activité. Des sociétés établies depuis longtemps dans un même nid montrent toujours une activité inférieure aux sociétés récemment établies. Aucune différence n'est observée entre une aire de récolte inconnue et familière. De plus, la taille de la société apparaît être moins influente sur son activité générale que pour une société récemment établie dans son nid. Ces résultats sont interprétés en termes éco-éthologiques, tenant compte d'une caractéristique biologique essentielle des sociétés deL. unifasciatus: les déménagements fréquents, saisonniers ou liés à la précarité des nids.
    Notes: Summary Leptothorax unifasciatus workers differentiate new areas from those previously explored. Indeed, a “coming and going” behaviour appears more frequent on a virgin paper than on a familiar one. The decrease of activity on a new paper after some hours indicates that this species rapidly gets to known such an area in the experimental device used here. The experiments suggest that the area is chemically modified by the ants' activity, but the possibility of a specific marking behaviour was not further investigated. Three factors control the level of foraging activity inL. unifasciatus: 1o. The nature of the foraging area (familiar or virgin). 2o. The size of the society. 3o. The age of the nest-site. Societies newly established in their nest show a higher level of foraging activity on a virgin area than on a familiar one. In every case, there is a linear relation between the size of the society and its activity. Long-settled societies always show a lower activity than recently established ones, and no difference was observed when they recruited on a virgin and a familiar area. Moreover, the society size appears to be less important in determining the general level of activity than for recently-settled societies. These results are tentatively interpreted in eco-ethological terms, taking into account a main biological characteristic ofLeptothorax societies: frequent nest emigrations that are either seasonal or due to fragile nest-sites.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Insectes sociaux 39 (1992), S. 201-213 
    ISSN: 1420-9098
    Keywords: Foraging ; recruitment ; colonies ; social insects ; ants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A numerical model of an eusocial colony foraging for food showed that, for each set of values of resource density, resource size and recruitment system employed, a given optimal proportion of scouts in the colony maximize the amount of resources retrieved by a colony during a fixed period. The model predicts that ants using mass recruitment systems should have larger colonies with small foragers, and should forage on large food sources. Retrieval of small food sources by small colonies is best achieved with large workers using individual foraging strategies. For mass foragers, several food sources are best retrieved using democratic decision-making systems in recruitment, whereas for very large food sources at very low mean food patch density, autocratic decision-making systems are optimal. Some of the experimental evidence available is discussed in the light of these findings, as they confirm the prediction that large colonies with small workers have mass recruitment systems, whereas workers of small colonies with large workers are generally lone foragers.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Insectes sociaux 45 (1998), S. 191-195 
    ISSN: 1420-9098
    Keywords: Key words: Group effect, latency time, fungus-growing termites, building behavior, bees, aggressiveness.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary: We suggest that group effect need not be invoked to explain the differences in latency times exhibited by groups of different sizes in the initiation of building in the termite Macrotermes subhyalinus (Rambur). A simple, alternative, model is presented, that is fully consistent with experimental data.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Insectes sociaux 24 (1977), S. 117-130 
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Summary We propose a mathematical method based on non linear differential equations and the concept of order by fluctuations, with the aim of simulating the collective behavior of insect societies. The example studied the first stages in the building of termites' nest show the importance of such a formulation. The essential points are: 1o Knowing the interactions mechanism between the different elements of the system or by making a series of hypotheses it is possible to formulate a system of differential equations the study of which gives an image of the collective behaviour of the group. 2o The innovations and fluctuations of the elements of the system (concentrations of individuals, odor, nest's elements, etc.) constitute an essential element of the structuration of such systems which seems to be in perfect agreement with the experimental observations showing the role of fluctuating elements of a colony.
    Notes: Résumé Nous proposons une méthode mathématique basée sur les équations différentielles non linéaires et le concept d'ordre par fluctuations, visant à la simulation du comportement collectif des sociétés d'insectes. L'exemple traité, les premières phases de la construction du nid chez les termites, montre l'intérêt qu'une telle formulation présente. Les points essentiels que nous retiendrons sont: 1o Connaissant les mécanismes d'interaction entre les éléments du système ou moyennant une série d'hypothèses sur ceux-ci, il est possible de formuler un système d'équations différentielles dont l'étude va nous donner une image du comportement collectif du groupe. 2o Outre les innovations introduites dans le système, les fluctuations de ses éléments (concentrations d'individus, d'odeurs, de matériaux...) constituent un des moteurs essentiels de la structuration des systèmes. Ce point semble être en parfait accord avec les observations expérimentales, qui montrent le rôle que jouent les éléments fluctuants d'une colonie.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Insectes sociaux 36 (1989), S. 339-347 
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Resume On présente un modèle simple de choix du secteur de fourragement par des fourmis. Ce choix se fait en fonction de la quantité de phéromone associée à chaque secteur, et est autocatalytique puisque les fourrageuses qui trouvent de la nourriture dans un secteur y ajoutent de la phéromone. Quand la nourriture d'un secteur est épuisée, les fourrageuses transfèrent spontanément leur activité vers le secteur adjacent. Si la richesse en nourriture augmente, le modèle passe d'un fourragement aléatoire à la formation d'une piste qui tourne autour du nid. Plus la richesse est élevée, plus la piste tourne lentement, jusqu'à devenir figée en un secteur. Ces résultats correspondent aux observations faites sur la fourmiMessor pergandei parBernstein (1975),Rissing etWheeler (1976). reconcilient une apparente contradiction entre eux.
    Notes: Summary A simple model is described wherein ant foragers choose a foraging sector as a function of the pheromone concentration associated with each sector. The choice is autocatalytic, as foragers that find food in a sector add to its pheromone. As a sector's food runs out, the foragers spontaneously switch to the adjacent sector. With increasing food abundance, the model passes from random foraging to the formation of a trail that rotates about the nest. The greater the abundance the more slowly the trail rotates until it finally becomes fixed on one sector. These results agree with experimental observations made on the harvester antMessor pergandei byBernstein (1975) andRissing andWheeler (1976), and reconcile an apparent contradiction between them.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Insectes sociaux 37 (1990), S. 258-267 
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Resume Nous présentons une série d'expëriences qui montrent comment la fourmiLasius niger peut utiliser son système des recruitement par piste afin de sélectionner une dfes deux sources de nourriture. Sil on leur offire simultanément deux solution 1M de saccharose, la sojciét'e concentre son activité sur l'une des deux. Si l'on offre deux solutions, une de 1M et l'autre de 0.1M, elle sélectionne la plus riche, à mons que la piste qui mène à la source 0.1M soit déjà bien développée au moment où l'on introduit la source 1M. Face à la même situation, la fourmiTetramorium caespitum, qui recrute par groupe/masse, utilise son mode de transmission d'information plus, individuel pour changes son exploitation vers la source 1M. Un modèle mathématique décrit ces processus, dont la dynamique correspond bien aux observations expérimentales.
    Notes: Summary A series of experiments shows how the andLasius niger uses its trail recruitment system to select between two food sources. Simultaneously presented with to 1M sucrose solution it concentrates on one of them. When offered a 1M solution together with a 0.1M solution it selects the richer source, unless the trait to the 0.1M source had become well-developed before the 1M source was introduced. In the same situation, however, the group/mass recruiting antTetramorium caespitum uses its more individual transmission of information to switch to the 1M source. A mathematical model describes these processes and its dynamics reflect the experimental results.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Insectes sociaux 39 (1992), S. 59-72 
    ISSN: 1420-9098
    Keywords: Hymenoptera ; Formicidae ; Lasius niger ; food recruitment ; trail laying behaviour ; collective decision making
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The trail-laying behaviour of foragers of the antLasius niger was observed in the laboratory on a 20 cm bridge between the nest and the food source. We measured both the frequency of trail laying, as defined by the proportion of trips during which trail laying occurred, and its intensity, as defined by the number of marks laid during one bridge crossing. Foragers do not exhibit trail-laying behaviour until a food source is discovered. Trail laying then occurs more or less equally both to and from the nest, and both its frequency and intensity decrease as the recruitment proceeds. Foragers from very small colonies less than a year old appear to have quantitatively the same trail laying behaviour as those from older and much larger colonies. Groups of recruiters and recruits were individually marked. Their trail laying intensity was similar, both for trips to and from the nest, and for an ant's first, second, third and fourth trip. The frequency diminished rapidly with the number of trips made by each individual, and was 2–3 times higher for recruiters than for recruits, for trips both to and from the nest. Even though foragers stop marking after a variable number of passages, they continue to move between the nest and the food source, and other ants start marking. Different foragers appear to have widely different levels of trail laying, although we cannot say whether these differences are stable between different recruitments. Trail laying is strongly affected by the foragers' position on the bridge, especially for ants returning to the nest which lay up to five times more on the segment closest to the source than that closest to the nest. Foragers on a weakly marked trail appear to mark more than those on a well-marked trail. However, this effect is weak and could partly be attributed to their lower speed. Finally, a model using the experimental data gathered on the individuals' trail-laying behaviour reproduced satisfactorily the colony's overall trail laying.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1420-9098
    Keywords: Orientation ; individual memory ; chemical communication ; Formicidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The relative contribution of visual and chemical components in the orientation ofLasius niger andIridomyrmex humilis (Argentine ant) workers during mass recruitment to newly discovered food sources is analyzed over short time intervals. While both species orient in response to the trail pheromone, a large number ofL. niger foragers rapidly switch to a more individual orientation, based on their memory of environmental cues.I. humilis workers, on the other hand, predominantly use collective chemical cues. The effect of the number of reinforcements on visual learning and its interference with chemical communication show that olfactory cues always prevail in the Argentine ant. InL. niger, the proportion of ants orienting to visual cues is independent of the trail concentration. Detailed observations of the trail-laying behavior of individually marked foragers show that nearly all theI. humilis workers initially lay a trail, whereas only half theL. niger foragers do so. This proportion decreases considerably with the number of trips performed byL. niger workers, while remaining constant for the Argentine ants. These results are interpreted with respect to the species' behavioral ecology.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Insectes sociaux 35 (1988), S. 310-315 
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Resume Un modèle qui génère une activité périodique et synchrone par un comportement autocatalytique suivi d'une période de repos est présenté et discuté pour les insectes sociaux et arthropodes vivant en groupe.
    Notes: Summary A model that generates synchronised rhythmical activity from autocatalytic behaviour followed by a rest period is presented and discussed with respect to social insects and group-living arthropods.
    Type of Medium: Electronic Resource
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