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Dive into the research topics where Pierre Jaisson is active.

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Featured researches published by Pierre Jaisson.


Current Biology | 2007

Individual Experience Alone Can Generate Lasting Division of Labor in Ants

Fabien Ravary; Emmanuel Lecoutey; Gwenaël Kaminski; Nicolas Châline; Pierre Jaisson

Division of labor, the specialization of workers on different tasks, largely contributes to the ecological success of social insects [1, 2]. Morphological, genotypic, and age variations among workers, as well as their social interactions, all shape division of labor [1-12]. In addition, individual experience has been suggested to influence workers in their decision to execute a task [13-18], but its potential impact on the organization of insect societies has yet to be demonstrated [19, 20]. Here we show that, all else being equal, ant workers engaged in distinct functions in accordance with their previous experience. When individuals were experimentally led to discover prey at each of their foraging attempts, they showed a high propensity for food exploration. Conversely, foraging activity progressively decreased for individuals who always failed in the same situation. One month later, workers that previously found prey kept on exploring for food, whereas those who always failed specialized in brood care. It thus appears that individual experience can strongly channel the behavioral ontogeny of ants to generate a lasting division of labor. This self-organized task-attribution system, based on an individual learning process, is particularly robust and might play an important role in colony efficiency.


Insectes Sociaux | 2004

Queen influence on worker reproduction in bumblebees (Bombus terrestris) colonies

Cédric Alaux; Pierre Jaisson; Abraham Hefetz

SummaryThe bumblebee Bombus terrestris is a good model in which to study the regulation of worker reproduction, because the onset of queen-worker conflicts regarding male production is constrained by the annual life cycle of the colony. Worker reproduction in this species is inhibited until late in colony development. The underlying proximate mechanism suggested for this delayed worker reproduction is queen control using combined pheromonal and behavioural determinants. The volatile queen pheromone hypothesis was tested by monitoring the length of time necessary for worker reproduction to occur when workers were separated from the queen by a double screen. These workers always reproduced before the onset of the competition phase in the queenright compartment (QRC), after the time lag required for egg maturation. Since the double-mesh-separated compartment was genuinely a queenless compartment, the volatile queen pheromone hypothesis was refuted.The possible involvement of a non-volatile pheromone and/or of physical intimidation by the queen was then tested using a queen excluder, which allowed the workers, but not the queen, to travel freely between two nest compartments, creating a “refuge from the queen”. Although worker reproduction in the queen-excluded compartment (QEC) was delayed compared to the queenless situation, it still occurred before the onset of the competition phase in the QRC and after the onset of queen production.These results indicate that workers autoregulate their reproduction rather than it being controlled by the queen (pheromonal or behavioural). The possible factors affecting this autoregulation may be 1) the workers’ perception of the queen and, possibly, her status through pheromonal emission and 2) the workers’ perception that the larvae are committed to become queens.


Insectes Sociaux | 2004

Absence of individual sterility in thelytokous colonies of the ant Cerapachys biroi Forel (Formicidae, Cerapachyinae)

F. Ravary; Pierre Jaisson

SummaryThe reproductive partitioning generates a persistent conflict within insects societies and a sustained theoretical and empirical attention is devoted to understand its resolution. In that context, thelytokous parthenogenesis by workers is an intriguing phenomenon where each individual is virtually reproducing. This reproductive strategy, scarce among Formicidae, was studied in C. biroi, an obligatory thelytokous cerapachyine ant. Particularly, we searched for a reproductive division of labour in colonies assumed to be clonal. The results revealed that no sterile caste was present in the colonies. However, reproduction was linked both to a temporal polyethism, in which older workers ceased to lay as they became foragers, and to a morphological polyethism, illustrated by two morphological types of individuals displaying different task allocations and ovary capacities. Evolutionary implication of this uncommon social structure, seemingly free of traditional conflict and characterised by a reproduction evenly distributed among nestmates, is discussed from comparisons to other ant species with extreme kin structure.


Naturwissenschaften | 2004

Does the queen win it all? Queen–worker conflict over male production in the bumblebee, Bombus terrestris

Cédric Alaux; Fabrice Savarit; Pierre Jaisson; Abraham Hefetz

Social insects provide a useful model for studying the evolutionary balance between cooperation and conflict linked to genetic structure. We investigated the outcome of this conflict in the bumblebee, Bombus terrestris, whose annual colony life cycle is characterized by overt competition over male production. We established artificial colonies composed of a queen and unrelated workers by daily exchange of callow workers between colony pairs of distinct genetic make-up. Using microsatellite analysis, this procedure allowed an exact calculation of the proportion of worker-derived males. The development and social behavior of these artificial colonies were similar to those of normal colonies. Despite a high worker reproduction attempt (63.8% of workers had developed ovaries and 38.4% were egg-layers), we found that on average 95% of the males produced during the competition phase (CPh) were queen-derived. However, in four colonies, queen death resulted in a considerable amount of worker-derived male production. The different putative ultimate causes of this efficient control by the queen are discussed, and we suggest a possible scenario of an evolutionary arms race that may occur between these two female castes.


Molecular Ecology | 2000

Population structure and mating biology of the polygynous ponerine ant Gnamptogenys striatula in Brazil

Tatiana Giraud; Rumsaïs Blatrix; Chantal Poteaux; M. Solignac; Pierre Jaisson

Gnamptogenys striatula is a polygynous ponerine ant, whose colonies contain either several differentiated queens or several gamergates. Population structure, queen mating frequency and deviation from random mating were investigated in a north‐eastern Brazilian population. Eight workers from each of 33 queenright colonies and 17 queens and their progeny (20–40 offspring) were genotyped using eight variable microsatellite markers. Population differentiation tests indicated limited gene flow at the scale of several kilometres, and tests of isolation by distance revealed population viscosity at the scale of a few metres. This population structure, together with the frequent colony migrations and fissions observed in the field, suggest that new nests are founded by budding in G. striatula. Genetic data showed that 13 of our 17 queens were single‐mated and four were double‐mated. The estimation of the range of maximal frequency of double‐mated queens in the population was 0.232–0.259, demonstrating that mating frequency is low in G. striatula. The low estimated mean relatedness between the 17 queens and their mates (−0.04 ± 0.49) indicated no evidence of inbreeding in G. striatula.


Current Biology | 2013

Enforcement of Reproductive Synchrony via Policing in a Clonal Ant

Serafino Teseo; Daniel J. C. Kronauer; Pierre Jaisson; Nicolas Châline

In insect societies, worker policing controls genetic conflicts between individuals and increases colony efficiency. However, disentangling relatedness from colony-level effects is usually impossible. We studied policing in the parthenogenetic ant Cerapachys biroi, where genetic conflicts are absent due to clonality and reproduction is synchronized through stereotyped colony cycles. We show that larval cues regulate the cycles by suppressing ovarian activity and that individuals that fail to respond to these cues are policed and executed by their nestmates. These individuals are genetically identical to other colony members, confirming the absence of intracolonial genetic conflicts. At the same time, they bear distinct cuticular hydrocarbon profiles, which could serve as proximate recognition cues for policing. Policing in C. biroi keeps uncontrolled reproduction at bay and thereby maintains the colony-level phenotype. This study shows that policing can enforce adaptive colony-level phenotypes in societies with minimal or no potential genetic conflicts. In analogy to immunosurveillance on cancer cells in genetically homogeneous multicellular organisms, colony efficiency is improved via the control of individuals that do not respond properly to regulatory signals and compromise the functioning of the higher-level unit.


Behavioral Ecology and Sociobiology | 2005

Reproductive decision-making in semelparous colonies of the bumblebee bombus terrestris

Cédric Alaux; Pierre Jaisson; Abraham Hefetz

Queen and worker Bombus terrestris have different optima for the timing of gyne production. Workers, being more related to their gyne-sisters than to their sons, should ascertain that gyne production has started before attempting to reproduce. Their optimal timing for gyne production will be as early as possible, while allowing sufficient ergonomic colony growth to support gyne rearing. Queen optimum, on the other hand, should be to postpone gyne production toward the end of colony life cycle, in order to minimize the time-window available for worker reproduction. Thus, the timing of gyne production may profoundly affect the outcome of queen–worker competition over male production. In this study we investigated some of the social correlates possibly affecting this timing. It was found that neither keeping colony size constant and as low as 20 workers, nor decreasing worker average age, influenced the onset of gyne production. To test the effect of queen age we created young colonies with old queens and vice versa. When colony social composition remained unchanged, in young colonies headed by old queens gynes were produced earlier than predicted, but in the inverse situation gyne production was not delayed. When colony social composition was completely standardized queen age had a decisive effect, indicating that the timing of gyne production is both under queen influence and affected by queen age. Furthermore, queens assess colony age from the time of first worker emergence rather than from their own first oviposition. In these experiments the factors affecting gyne production also affected the onset of queen–worker conflict for male production, suggesting that both are regulated by the same causal effect. Postponing gyne production as much as possible provides another mechanism, in addition to extensive oophagy, for the queen to outcompete her workers in male production.


Animal Behaviour | 1991

A post-eclosion early learning involved in host recognition by Dinarmus basalis rondani (Hymenoptera: Pteromalidae)

Yves Caubet; Pierre Jaisson

Abstract Host preference was induced during the early development of Dinarmus basalis , an ectoparasitoid of bruchid beetle larvae feeding inside bean seeds. A series of experiments at successive stages of the parasitoids development showed that host-preference depends on a learning process that takes place after the eclosion of the adult parasitoid but before it emerges from the chamber beneath the beans integument. During this period of a few hours the callow parasitoid may be affected by stimuli from the shrivelled remains of the host. The effect depends on the host species. Zabrotes subfasciatus provoked a change in host-preference but Acanthoscelides obtectus did not. Host-preference induction is strongly constrained, therefore, by factors endogenous to the parasitoid. This type of early learning appears to be novel in parasitoid wasps because of the time at which it occurs.


Animal Behaviour | 1995

Ontogeny of nestmate brood recognition in a primitive ant,Ectatomma tubercalutumOlivier (Ponerinae)

Renée Fénéron; Pierre Jaisson

Abstract The capacity of the primitive ant Ectatomma tubercalatum to discriminate between nestmate and alien conspecific larvae in choice situations in relation to workers age, social status and early experience was investigated. Brood discrimination was measured in terms of behavioural acts (licking, transport, antennation). Only 2-10-week-old adults preferred nestmate larvae, as they specialized in nursing. Younger as well as older workers were unable to discriminate brood. Teneral workers learned to recognize and prefer nestmate brood, even if it was unrelated (adopted from an alien conspecific colony). The familiarization learning was always very labile, however. A temporary estrangement from brood was enough for a worker to lose either the template of recognition cues, or the capacity to display preferential behaviour.


Behavioral Ecology and Sociobiology | 2006

Regulation of worker reproduction in bumblebees (Bombus terrestris): workers eavesdrop on a queen signal

Cédric Alaux; Pierre Jaisson; Abraham Hefetz

In the annual bumblebee Bombus terrestris, the onset of queen-worker conflict over male production is seasonally and socially constrained. Workers will do better if they start to reproduce (the so-called competition phase) only after ascertaining that larvae are committed to gyne development but before the season ends because they gain more by rearing sister-gynes than their own sons. Here, we tested two nonmutually exclusive hypotheses as to what triggers the onset of worker reproduction: Workers can directly monitor larval development and/or workers eavesdrop on the queen signal that directs gyne development. Exposing workers to gyne larvae through a double mesh did not advance the competition phase compared to control colonies. However, when workers, but not the queen, were allowed contact with gyne larvae, both the competition phase and gyne production were advanced. Thus, while larvae do not emit a volatile pheromone that discloses their developmental route, the physical contact of workers with such larvae triggers early competition phase. However, workers exclusively exposed to worker larvae (colonies prevented from producing gyne larvae) started to reproduce at the same time as control colonies. Replacing the resident queen with an older queen (from gyne-rearing colonies) advanced the competition phase, irrespective of worker age. The results are consistent with the hypothesis that workers eavesdrop on the queen pheromones. This is adaptive because it allows workers a broader time-window for reproduction and thus to gain fitness from rearing both sister-gynes and sons before the season ends without affecting colony development.

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Alain Lenoir

François Rabelais University

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