Laboratoire Environnement and Sante

Lille, France

Laboratoire Environnement and Sante

Lille, France
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Devigne C.,University of Lille Nord de France | Devigne C.,Laboratoire Environnement and Sante | de Biseau J.-C.,Roosevelt University
Behavioural Processes | Year: 2012

It is well known that ants can use cuticular hydrocarbons (CHCs) as a specific recognition cue. Most previous studies addressed the perception of CHCs occurring on the cuticle. However, the presence of CHCs in the environment (e.g., on the substrate) and the role of these compounds as a signal cue are less clear.In this study of the ant L. niger, CHCs were extracted from corpses of workers, from the legs of workers and from filter paper marked by workers. Behavioural choice tests were then performed to study the reactions of workers and queens to CHC passively deposited on the substrate by walking workers.A GC-MS analysis of the CHCs revealed a complex mixture of 28 peaks composed of linear alkanes, alkenes and mono-, di- or trimethylalkane. This mixture was consistently present in the three sources tested (corpses of workers, the tarsus of workers and paper marked by walking workers). Nevertheless, discriminant analyses distinguished clearly among the three types of profiles.The results of our behavioural experiments showed that the workers were able to distinguish between marked and unmarked papers but that they exhibited no preferences for different types of marked papers (papers marked by workers from their own colony or papers marked by workers from a different colony).In queens, the perception of marked papers depended on age or physiological state. Just-mated queens did not discriminate between unmarked papers and papers marked by an alien colony. In contrast, the egg-laying queens 3. days after mating significantly favoured the marked papers. We discuss the ecological relevance of the differences in decision-making between castes. © 2012 Elsevier B.V.

Broly P.,University of Lille Nord de France | Broly P.,Laboratoire Environnement and Sante | Broly P.,Free University of Colombia | Deville P.,University of Lille Nord de France | And 5 more authors.
Evolutionary Ecology | Year: 2013

Living isopods of the suborder Oniscidea (commonly called woodlice) are the only group of Crustacea almost entirely composed of terrestrial forms. Furthermore, woodlice are completely independent from the aquatic environment from which they originally arose. From marine ancestors, woodlice are a key taxon to study the conquest of the land among arthropods because of their interesting gradation of morphological, physiological and behavioral adaptations for terrestriality. However, the origin and evolution of this model group are still poorly known. Herein, we provide a synthesis of the oniscidean fossil record to replace this group in a deep-time context. Because members of the Oniscidea are difficult to fossilize, their fossil record alone is undoubtedly fragmentary and not representative of their complete evolutionary history, but it maintains an important relevance by providing reference points. To date, the first attested occurrences of Oniscidea are recorded from the Early Cretaceous. At this time, woodlice were already widely distributed (from Western Europe to Eastern Asia) with several species. By evaluating phylogenetic studies, palaeobiogeographic context of fossil specimens and current biological considerations, we discuss and support a pre-Pangaean origin of the Oniscidea, in the Late Paleozoic-most likely during the Carboniferous. © 2012 Springer Science+Business Media Dordrecht.

Devigne C.,University of Lille Nord de France | Devigne C.,Laboratoire Environnement and Sante | Broly P.,University of Lille Nord de France | Broly P.,Laboratoire Environnement and Sante | Deneubourg J.-L.,Free University of Colombia
PLoS ONE | Year: 2011

Background: The aggregation of woodlice in dark and moist places is considered an adaptation to land life and most studies are focused on its functionality or on the behavioural mechanisms related to the individual's response to abiotic factors. Until now, no clear experimental demonstration was available about aggregation resulting from inter-attraction between conspecifics. Methodology/Main Findings: We present the dynamics of aggregation, not previously described in detail in literature, as being independent of the experimental conditions: homogeneous and heterogeneous environments with identical or different shelters. Indeed whatever these conditions, the aggregation is very quick. In less than 10 minutes more than 50% of woodlice were aggregated in several small groups in the homogeneous environment or under shelters in the heterogeneous environment. After this fast aggregation, woodlice progressively moved into a single aggregate or under one shelter. Conclusions/Significance: Here we show for the first time that aggregation in woodlice implies a strong social component and results from a trade-off between individual preferences and inter-attraction between individuals. Moreover, our results reveal that the response to the heterogeneities affects only the location of the aggregates and not the level of aggregation, and demonstrate the strong inter-attraction between conspecifics which can outweigh individual preferences. This inter-attraction can lead to situations that could seem sub-optimal. © 2011 Devigne et al.

Broly P.,University of Lille Nord de France | Broly P.,Laboratoire Environnement and Sante | Broly P.,Free University of Colombia | Mullier R.,University of Lille Nord de France | And 4 more authors.
ZooKeys | Year: 2012

Terrestrial isopods are known to be sensitive to humidity, brightness or temperature. Until now, aggregation was assumed to depend on these sensitivities as a result of individual preferences. In this paper, we show that the social component is also important in the isopod aggregation phenomenon. In experimental arenas with two identical shelters up to nearly 90% of woodlice aggregated under shelters. This aggregation was quick as in 10 minutes most of the animals aggregated, irrespective of their density. Nonetheless, 10-15% of the animals walked around the arena, rarely forming very small and short-lasting aggregates outside shelters. Woodlice aggregated preferably under one of the shelters in 77% of experiments. Indeed, almost 80% of the animals out of 40, 60 or 80 animals in the arena aggregated under one shelter. In arenas with 100 individuals the aggregations were proportionally smaller (70%). Our results revealed that 70 animals was a maximum number of woodlice in an aggregate. We concluded that the location of aggregates is strongly governed by individual preferences but the dynamics of aggregation and collective choice are controlled by social interaction between congeners. The tested densities of the animals in the arena did not impact the aggregation patterns. © Pierre Broly et al.

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