Éditeur(s) : HAL CCSD
Résumé :  
Les plantes qui présentent des structures anatomiques permettant de retenir de l'eau en permanence sont assez répandues en milieu tropical. Si beaucoup sont maintenant cultivées pour être vendues en jardineries, faisant le bonheur des amateurs, elles forment en milieu naturel des écosystèmes aquatiques encore très peu étudiés et renferment une biodiversité que l'on est loin d'avoir recensée. En Amérique centrale et du Sud, les broméliacées-citerne, qui représentent les plus nombreuses et les plus diversifiées de ces "plantes-mares", permettent à des organismes très variés d'accomplir leur cycle de vie.
Courrier de la Nature

hal-01019401
https://hal.archives-ouvertes.fr/hal-01019401

Éditeur(s) : HAL CCSD Ecological Society of America
Résumé : International audience
The main theories explaining the biological diversity of rain forests often confer a limited understanding of the contribution of interspecific interactions to the observed patterns. We show how two-species mutualisms can affect much larger segments of the invertebrate community in tropical rain forests. Aechmea mertensii (Bromeliaceae) is both a phytotelm (plant-held water) and an ant-garden epiphyte. We studied the influence of its associated ant species (Pachycondyla goeldii and Camponotus femoratus) on the physical characteristics of the plants, and, subsequently, on the diversity of the invertebrate communities that inhabit their tanks. As dispersal agents for the bromeliads, P. goeldii and C. femoratus influence the shape and size of the bromeliad by determining the location of the seedling, from exposed to partially shaded areas. By coexisting on a local scale, the two ant species generate a gradient of habitat conditions in terms of available resources (space and food) for aquatic invertebrates, the diversity of the invertebrate communities increasing with greater volumes of water and fine detritus. Two-species mutualisms are widespread in nature, but their influence on the diversity of entire communities remains largely unexplored. Because macroinvertebrates constitute an important part of animal production in all ecosystem types, further investigations should address the functional implications of such indirect effects.
Ecology

hal-00911501
https://hal.archives-ouvertes.fr/hal-00911501
https://hal.archives-ouvertes.fr/hal-00911501/document
DOI : 10.1890/09-1534.1
OATAO : 10118

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
ISSN: 0098-0331

hal-01083748
https://hal-agroparistech.archives-ouvertes.fr/hal-01083748
DOI : 10.1007/s10886-009-9673-x

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Myrmecophytes offer plant-ants a nesting place in exchange for protection from their enemies, particularly defoliators. These obligate ant-plant mutualisms are common model systems for studying factors that allow horizontally transmitted mutualisms to persist since parasites of ant-myrmecophyte mutualisms exploit the rewards provided by host plants whilst providing no protection in return. In pioneer formations in French Guiana, Azteca alfari and Azteca ovaticeps are known to be mutualists of myrmecophytic Cecropia (Cecropia ants). Here, we show that Azteca andreae, whose colonies build carton nests on myrmecophytic Cecropia, is not a parasite of Azteca-Cecropia mutualisms nor is it a temporary social parasite of A. alfari; it is, however, a temporary social parasite of A. ovaticeps. Contrarily to the two mutualistic Azteca species that are only occasional predators feeding mostly on hemipteran honeydew and food bodies provided by the host trees, A. andreae workers, which also attend hemipterans, do not exploit the food bodies. Rather, they employ an effective hunting technique where the leaf margins are fringed with ambushing workers, waiting for insects to alight. As a result, the host trees' fitness is not affected as A. andreae colonies protect their foliage better than do mutualistic Azteca species resulting in greater fruit production. Yet, contrarily to mutualistic Azteca, when host tree development does not keep pace with colony growth, A. andreae workers forage on surrounding plants; the colonies can even move to a non-Cecropia tree.
ISSN: 0028-1042

hal-00818203
https://hal.archives-ouvertes.fr/hal-00818203
DOI : 10.1007/s00114-010-0710-y
PUBMED : 20730522

Éditeur(s) : HAL CCSD Elsevier - Cachan : Lavoisier
Résumé : International audience
De par leur vie arboricole, les épiphytes sont soumis à des contraintes fortes, en particulier pour accéder aux nutriments. Ils y répondent par des adaptations morphologiques et anatomiques qui prennent également en compte les interactions directes et indirectes que ces plantes coupées du sol entretiennent avec d'autres organismes terrestres et aquatiques.
ISSN: 0294-3506

hal-00846263
https://hal.archives-ouvertes.fr/hal-00846263

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Establishing a direct link between climate change and fluctuations in animal populations through long-term monitoring is difficult given the paucity of baseline data. We hypothesized that social wasps are sensitive to climatic variations, and thus studied the impact of ENSO events on social wasp populations in French Guiana. We noted that during the 2000 La Niña year there was a 77.1% decrease in their nest abundance along ca. 5 km of forest edges, and that 70.5% of the species were no longer present. Two simultaneous 13-year surveys (1997-2009) confirmed the decrease in social wasps during La Niña years (2000 and 2006), while an increase occurred during the 2009 El Niño year. A 30-year weather survey showed that these phenomena corresponded to particularly high levels of rainfall, and that temperature, humidity and global solar radiation were correlated with rainfall. Using the Self-Organizing Map algorithm, we show that heavy rainfall during an entire rainy season has a negative impact on social wasps. Strong contrasts in rainfall between the dry season and the short rainy season exacerbate this effect. Social wasp populations never recovered to their pre-2000 levels. This is probably because these conditions occurred over four years; heavy rainfall during the major rainy seasons during four other years also had a detrimental effect. On the contrary, low levels of rainfall during the major rainy season in 2009 spurred an increase in social wasp populations. We conclude that recent climatic changes have likely resulted in fewer social wasp colonies because they have lowered the wasps' resistance to parasitoids and pathogens. These results imply that Neotropical social wasps can be regarded as bio-indicators because they highlight the impact of climatic changes not yet perceptible in plants and other animals.
ISSN: 1932-6203

hal-00825825
https://hal.archives-ouvertes.fr/hal-00825825
https://hal.archives-ouvertes.fr/hal-00825825/document
https://hal.archives-ouvertes.fr/hal-00825825/file/Dejean2011_Climate.pdf
DOI : 10.1371/journal.pone.0027004

Éditeur(s) : HAL CCSD
Résumé : International audience
Insect Conservation and Diversity

hal-01084030
https://hal-agroparistech.archives-ouvertes.fr/hal-01084030
DOI : 10.1111/j.1752-4598.2009.00060.x

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
ISSN: 0006-3606

hal-01093932
https://hal-agroparistech.archives-ouvertes.fr/hal-01093932
DOI : 10.1111/j.1744-7429.2009.00614.x

Éditeur(s) : HAL CCSD Museum Nationale d'Histoire Naturelle Paris
Résumé : International audience
ISSN: 1280-9551

hal-01084016
https://hal-agroparistech.archives-ouvertes.fr/hal-01084016
DOI : 10.5252/z2009n4a8

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Because group-hunting arboreal ants spread-eagle insect prey for a long time before retrieving them, these prey can be coveted by predatory flying insects. Yet, attempting to rob these prey is risky if the ant species is also an effective predator. Here, we show that trying to rob prey from Azteca andreae workers is a fatal error as 268 out of 276 potential cleptobionts (97.1 %) were captured in turn. The ant workers hunt in a group and use the "Velcro®" principle to cling firmly to the leaves of their host tree, permitting them to capture very large prey. Exceptions were one social wasp, plus some Trigona spp. workers and flies that landed directly on the prey and were able to take off immediately when attacked. We conclude that in this situation, previously captured prey attract potential cleptobionts that are captured in turn in most of the cases.
ISSN: 0028-1042

hal-00825764
https://hal.archives-ouvertes.fr/hal-00825764
DOI : 10.1007/s00114-012-0929-x
PUBMED : 22710934

Éditeur(s) : HAL CCSD Wiley
Résumé : Plant germination and development depend upon a seed's successful dispersal into a suitable habitat and its ability to grow and survive within the surrounding biotic and abiotic environment. The seeds of Aechmea mertensii, a tank-bromeliad species, are dispersed by either Camponotus femoratus or Neoponera goeldii, two ant species that initiate ant gardens (AGs). These two mutualistic ant species influence the vegetative and reproductive traits of the bromeliad through their divergent ecological preferences (i.e. light and substrate). We hypothesised that the seeds dispersed by these two ant species have underlying genetic differences affecting germination, growth and survival of A.mertensii seedlings in different ways. To test this, we used an experimental approach consisting of sowing seeds of A.mertensii: (i) taken from the two AG-ant associations (i.e. seed origin), (ii) in two contrasting light conditions, and (iii) on three different substrates. Light and substrate had significant effects on germination, survival and on eight key leaf traits reflecting plant performance. Seed origin had a significant effect only on germination and on two leaf traits (total dry mass and relative growth rate). Overall, this bromeliad performs better (i.e. high growth and survival rates) when growing both in the shade and in the carton nest developed by C.femoratus ants. These results suggest that the plasticity of the tank bromeliad A.mertensii is mainly due to environment but also to genetic differences related to seed origin, as some traits are heritable. Thus, these two ant species may play contrasting roles in shaping plant evolution and speciation.
ISSN: 1435-8603

hal-01606565
https://hal.archives-ouvertes.fr/hal-01606565
DOI : 10.1111/plb.12452
PRODINRA : 407514

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Because territoriality is energetically costly, territorial animals frequently respond less aggressively toneighbours than to strangers, a reaction known as the "dear enemy phenomenon" (DEP). The contrary,the "nasty neighbour effect" (NNE), occurs mainly for group-living species defending resource-basedterritories. We studied the relationships between supercolonies of the pest fire ant Solenopsis saevissimaand eight ant species able to live in the vicinity of its nests plus Eciton burchellii, an army ant predatorof other ants. The workers from all of the eight ant species behaved submissively when confrontedwith S. saevissima (dominant) individuals, whereas the contrary was never true. Yet, S. saevissima weresubmissive towards E. burchellii workers. Both DEP and NNE were observed for the eight ant species, withsubmissive behaviours less frequent in the case of DEP. To distinguish what is due to chemical cues fromwhat can be attributed to behaviour, we extracted cuticular compounds from all of the nine ant speciescompared and transferred them onto a number of S. saevissima workers that were then confronted withuntreated conspecifics. The cuticular compounds from three species, particularly E. burchellii, triggeredgreater aggressiveness by S. saevissima workers, while those from the other species did not.
ISSN: 0376-6357

hal-00913344
https://hal.archives-ouvertes.fr/hal-00913344
https://hal.archives-ouvertes.fr/hal-00913344/document
https://hal.archives-ouvertes.fr/hal-00913344/file/roux_10206.pdf
DOI : 10.1016/j.beproc.2013.04.014

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Although ants may induce community-wide effects via changes in physical habitats in terrestrial environments, their influence on aquatic communities living in plant-held waters remains largely underexplored. The neotropical tank-bromeliad Aechmea mertensii (Bromeliaceae) occurs along forest edges in ant-gardens initiated by Camponotus femoratus or by Pachycondyla goeldii. Its leaves form wells that hold rainwater and provide suitable habitats for many aquatic organisms. We postulated that these ant-plant mutualisms indirectly affect the microbial community structure via changes in the environmental conditions experienced by the plants. To test this hypothesis, we analyzed the protist communities from 63 tank-bromeliads associated with either C. femoratus or P. goeldii (hereafter Cf-Aechmea and Pg-Aechmea) along a forest edge in French Guiana. For each plant, a large number of environmental variables (including habitat structure, food resources, incident radiation and the presence of aquatic invertebrates) were quantified to determine their relative importance in driving any observed differences across ant-associated plants. Pg-Aechmea are located in sun-exposed areas and hold low volumes of water and low amounts of detritus, whereas Cf-Aechmea are located in partially shaded areas and accumulate higher amounts of water and detritus. Protists (i.e., protozoa and algae) inhabiting Cf-Aechmea exhibit greater richness and abundances than those in Pg-Aechmea. Variations in detritus content, number of leaves, incident radiation, and the epiphyte richness of the ant-garden were the main factors explaining the variation in protist richness. A shift in the functional group composition of protists between bromeliads tended by different ant species suggested that mutualistic ants indirectly mediate changes in the microbial food web.
Basic and Applied Ecology

hal-00913126
https://hal.archives-ouvertes.fr/hal-00913126
https://hal.archives-ouvertes.fr/hal-00913126/document
DOI : 10.1016/j.baae.2012.10.002
OATAO : 10190

Éditeur(s) : HAL CCSD Springer Verlag
Résumé :  
In studying the ant genus Azteca, a Neotropical group of arboreal species, we aimed to determine the extent to which the ants use predation and/or aggressiveness to protect their host plants from defoliating insects. We compared a territorially dominant, carton-nester, Azteca chartifex, and three plant-ant species. Azteca alfari and Azteca ovaticeps are associated with the myrmecophyte Cecropia (Cecropiaceae) and their colonies shelter in its hollow branches; whereas Azteca bequaerti is associated with Tococa guianensis (Melastomataceae) and its colonies shelter in leaf pouches situated at the base of the laminas. Whereas A. bequaerti workers react to the vibrations transmitted by the lamina when an alien insect lands on a leaf making it unnecessary for them to patrol their plant, the workers of the three other species rather discover prey by contact. The workers of all four species use a predatory behaviour involving spread-eagling alien insects after recruiting nestmates at short range, and, in some cases, at long range. Because A. alfari and A. ovaticeps discard part of the insects they kill, we deduced that the workers' predatory behaviour and territorial aggressiveness combine in the biotic defence of their host tree.
ISSN: 0028-1042

hal-01032079
https://hal.archives-ouvertes.fr/hal-01032079
DOI : 10.1007/s00114-008-0448-y

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Mutualisms, or interactions between species that lead to net fitness benefits for each species involved, are stable and ubiquitous in nature mostly due to "byproduct benefits" stemming from the intrinsic traits of one partner that generate an indirect and positive outcome for the other. Here we verify if myrmecotrophy (where plants obtain nutrients from the refuse of their associated ants) can explain the stability of the tripartite association between the myrmecophyte Hirtella physophora, the ant Allomerus decemarticulatus and an Ascomycota fungus. The plant shelters and provides the ants with extrafloral nectar. The ants protect the plant from herbivores and integrate the fungus into the construction of a trap that they use to capture prey; they also provide the fungus and their host plant with nutrients. During a 9-month field study, we over-provisioned experimental ant colonies with insects, enhancing colony fitness (i.e., more winged females were produced). The rate of partial castration of the host plant, previously demonstrated, was not influenced by the experiment. Experimental plants showed higher δ¹⁵N values (confirming myrmecotrophy), plus enhanced vegetative growth (e.g., more leaves produced increased the possibility of lodging ants in leaf pouches) and fitness (i.e., more fruits produced and more flowers that matured into fruit). This study highlights the importance of myrmecotrophy on host plant fitness and the stability of ant-myrmecophyte mutualisms.
PLoS ONE

hal-00913754
https://hal.archives-ouvertes.fr/hal-00913754
https://hal.archives-ouvertes.fr/hal-00913754/document
DOI : 10.1371/journal.pone.0059405
OATAO : 10202

Éditeur(s) : HAL CCSD
Résumé : International audience
The presence of the frontal gland is well established in termite soldiers of Rhinotermitidae, Serritermitidae, and Termitidae. It is one of their main defensive adaptations or even an exclusive weapon. The gland was also occasionally reported in alate imagoes, but never in the worker caste. Here, we report the first observation of a frontal gland in workers of several Neotropical and one African species of Apicotermitinae. The ultrastructure of Aparatermes cingulatus and Anoplotermes nr. subterraneus is described in detail. In these two species, the gland is well-developed, functional and consists of class 1 secretory cells. The presence of envelope cells, wrapping the gland, is an unusual feature, as well as the presence of several zonulae adherens, connecting neighbouring glandular cells. The frontal gland of workers is homologous to this organ in soldiers and imagoes, as evidenced by the same position in the head and its connection to the same muscle. However, the defensive role of the frontal gland in workers remains to be confirmed.
Naturwissenschaften

hal-01095843
https://hal-agroparistech.archives-ouvertes.fr/hal-01095843
DOI : 10.1007/s00114-010-0664-0

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
Wasp nests range from simple to complex structures made of paper or mud. Here, we show that a Neotropical wasp of the genus Nitela builds its nest entirely by weaving endophytic fungal hyphae and spider silk harvested from the leaves growing in the understory of the rain forest in French Guiana.
ISSN: 0006-3606

hal-01095857
https://hal-agroparistech.archives-ouvertes.fr/hal-01095857
DOI : 10.1111/j.1744-7429.2010.00645.x

Éditeur(s) : HAL CCSD Royal Society, The
Résumé : Species engaged in multiple, simultaneous mutualisms are subject to trade-offs in their mutualistic investment if the traits involved in each interaction are overlapping, which can lead to conflicts and affect the longevity of these associations. We investigate this issue via a tripartite mutualism involving an ant plant, two competing ant species and a fungus the ants cultivate to build galleries under the stems of their host plant to capture insect prey. The use of the galleries represents an innovative prey capture strategy compared with the more typical strategy of foraging on leaves. However, because of a limited worker force in their colonies, the prey capture behaviour of the ants results in a trade-off between plant protection (i.e. the ants patrol the foliage and attack intruders including herbivores) and ambushing prey in the galleries, which has a cascading effect on the fitness of all of the partners. The quantification of partners' traits and effects showed that the two ant species differed in their mutualistic investment. Less investment in the galleries (i.e. in fungal cultivation) translated into more benefits for the plant in terms of less herbivory and higher growth rates and vice versa. However, the greater vegetative growth of the plants did not produce a positive fitness effect for the better mutualistic ant species in terms of colony size and production of sexuals nor was the mutualist compensated by the wider dispersal of its queens. As a consequence, although the better ant mutualist is the one that provides more benefits to its host plant, its lower host–plant exploitation does not give this ant species a competitive advantage. The local coexistence of the ant species is thus fleeting and should eventually lead to the exclusion of the less competitive species.
ISSN: 0962-8452

hal-01608641
https://hal.archives-ouvertes.fr/hal-01608641
DOI : 10.1098/rspb.2016.1679
PRODINRA : 405078

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Trophobiotic associations between Caternaultiella rugosa (Heteroptera; Plataspidae) and two ant species, Camponotus brutus (Formicidae) and Myrmicaria opaciventris (Myrmicinae), were recorded at the base of the trunks of Bridelia micrantha (Euphorbiaceae). The bug colonies were generally sheltered in pavilions built by the ants, but during periods of proliferation, part of the colonies developed outside the pavilions. We examined the protective activity of the two associated ant species against an encyrtid parasitoid wasp that parasitized egg masses of the bug. Egg masses situated outside the pavilions were significantly less parasitized on trees occupied by either ant species than on experimental trees where ants were excluded by a sticky barrier. Egg masses were significantly less parasitized on trees occupied by C. brutus than on those occupied by M. opaciventris, both inside and outside the pavilions. Moreover, they were less parasitized inside than outside the pavilions when protected by C. brutus. Inside the pavilions, parental care of the egg masses and first-instar nymphs was abandoned to the ants. In contrast, outside the pavilions, the females of C. rugosa guarded egg masses and clusters of first-instar nymphs. Furthermore, adults and last-instar nymphs grouped around and above first-instar nymphs, forming a protective shield. These groups formed and disintegrated daily, according to the attending ant's rhythm of activity
ISSN: 0029-8549

hal-01202757
https://hal.archives-ouvertes.fr/hal-01202757
DOI : 10.1007/s004420000479

Éditeur(s) : HAL CCSD
Résumé : The mosquito species Aedes (Stegomyia) aegypti (Linnaeus 1762) was introduced into the Americas some 400 years ago from the African continent. Currently, this species is the primary agent behind dengue and chikungunya outbreaks in the pan-tropical area and its widespread distribution has likely played an important role in the recent expansion of the Zika virus. The biology of Ae. (Stg.) aegypti is particularly well known, which is not the case for its ecology. By adopting a cross-disciplinary approach I attempted to understand the relative contribution of biotic and abiotic factors as well as some evolutionary processes in the distribution of this species at the local and regional scales in French Guiana.Initially, I was interested in revising the core knowledge concerning the diversity of mosquitoes in French Guiana. By combining traditional and molecular taxonomy, this step allowed my colleagues and I to discover several new species and to create the appropriate tools to manage this type of entomological data.Secondly, we studied the spatio-temporal structure of resident aquatic macroinvertebrate communities in urban areas. This highlighted the existence of antagonistic and mutualistic interactions. In particular, the native mosquito Limatus durhamii Theobald 1901 appears to prevent the sustainable establishment of Ae. (Stg.) aegypti in slightly urbanized environments via a mechanism of competitive exclusion.
Le moustique Aedes (Stegomyia) aegypti (Linnaeus 1762) a été introduit dans les Amériques depuis le continent africain il y a environ 400 ans. Actuellement, cette espèce est la principale responsable des épidémies de dengue et de chikungunya dans la zone pantropicale et sa large répartition a très probablement joué un rôle important dans l’expansion récente du virus Zika. La biologie d’Ae. (Stg.) aegypti est particulièrement bien connue, ce qui n’est pas le cas de son écologie, en particulier de ses interactions avec les communautés résidentes. En adoptant une démarche pluridisciplinaire je me suis intéressé à la contribution relative des facteurs biotiques et abiotiques ainsi que de certains processus évolutifs dans la distribution de cette espèce à différentes échelles en Guyane française.Dans un premier temps j’ai participé à la révision des connaissances fondamentales sur la diversité des moustiques de Guyane. En alliant la taxonomie classique et moléculaire, cette étape a permis de découvrir plusieurs nouvelles espèces et de mettre en place des outils adaptés à la gestion de ce type de données, notamment pour une utilisation future.Dans un second temps la structuration spatio-temporelle des communautés résidentes de macro-invertébrés aquatiques a été étudiée en milieu urbain. Cela a permis de mettre en évidence l’existence d’interactions antagonistes et mutualistes avec les taxons des communautés résidentes. En particulier, le moustique autochtone Limatus durhamii Theobald 1901 semble empêcher l’établissement durable d’Ae. (Stg.) aegypti dans les milieux faiblement urbanisés via un mécanisme d’exclusion compétitive.
https://tel.archives-ouvertes.fr/tel-01405425

NNT : 2016YANE0001
tel-01405425
https://tel.archives-ouvertes.fr/tel-01405425
https://tel.archives-ouvertes.fr/tel-01405425/document
https://tel.archives-ouvertes.fr/tel-01405425/file/These_Def_Talaga.pdf