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The little fire ant, Wasmannia auropunctata, is an invasive species known to negatively affect many native species in its introduced range. Here, we studied the effect of little fire ant presence on the biomass of soil fauna in rainforest of New Caledonia to assess if little fire ants have an impact on an endangered endemic flightless bird, the kagu, Rhynochetos jubatus. The average biomass of soil fauna (except for millipedes) was lower in 53 sample plots with little fire ants than in 597 sample plots without little fire ants and the biomass decreased with increasing density of little fire ant nests. Millipedes on the contrary seemed to be positively impacted as their average biomass was higher in areas with fire ants than in areas without, but even millipede biomass decreased with increasing nest density of fire ants. Kagu density decreased with increasing area of rainforest invaded by little fire ants, suggesting, given their observed negative impact on soil fauna biomass, that they may limit food resources for kagu. Little fire ants might therefore transform rainforest into a less suitable habitat for the kagu by reducing the biomass of their prey and thus have a negative impact for kagu conservation.

New Caledonia was, until recently, considered an old continental island harbouring a rich biota with outstanding Gondwanan relicts. However, deep marine sedimentation and tectonic evidence suggest complete submergence of the island during the latest Cretaceous to the Paleocene. Molecular phylogenies provide evidence for some deeply-diverging clades that may predate the Eocene and abundant post-Oligocene colonisation events. Extinction and colonization biases, as well as survival of some groups in refuges on neighbouring paleo-islands, may have obscured biogeographic trends over long time scales. Fossil data are therefore crucial for understanding the history of the New Caledonian biota, but occurrences are sparse and have received only limited attention. Here we describe five exceptional fossil assemblages that provide important new insights into New Caledonia’s terrestrial paleobiota from three key time intervals: prior to the submersion of the island, following re-emergence, and prior to Pleistocene climatic shifts. These will be of major importance for elucidating changes in New Caledonia’s floristic composition over time.

The OCBIL theory comprises a set of hypotheses to comprehend the biota of old, climatically buffered, infertile landscapes (OCBILs). Here, we review evidence from the literature to evaluate the extent to which this theory could apply to the biodiversity hotspot of New Caledonia. We present geological, pedological and climatic evidence suggesting how the island might qualify as an OCBIL. The predictions of OCBIL theory are then reviewed in the context of New Caledonia. There is evidence for a high rate of micro-endemism, accumulation of relict lineages, a high incidence of dioecy, myrmecochory and nutritional specializations in plants. New Caledonian vegetation also exhibits several types of monodominant formations that reveal the importance of disturbances on the island. Fires and tropical storms are likely to be important factors that contribute to the dynamic of New Caledonian ecosystems. Although naturally infertile, there is archaeological evidence that humans developed specific horticultural practices in the ultramafic landscapes of New Caledonia. Further comparisons between New Caledonia and other areas of the world, such as South Africa and Southwest Australia, are desirable, to develop the OCBIL theory into a more robust and generalized, testable framework and to determine the most efficient strategies to preserve their outstanding biodiversity.

Land-use changes through urbanization and biological invasions both threaten plant-pollinator networks. Urban areas host modified bee communities and are characterized by high proportions of exotic plants. Exotic species, either animals or plants, may compete with native species and disrupt plant&ndash, pollinator interactions. These threats are heightened in insular systems of the Southwest Pacific, where the bee fauna is generally poor and ecological networks are simplified. However, the impacts of these factors have seldom been studied in tropical contexts. To explore those questions, we installed experimental exotic plant communities in urban and natural contexts in New Caledonia, a plant diversity hotspot. For four weeks, we observed plant&ndash, pollinator interactions between local pollinators and our experimental exotic plant communities. We found a significantly higher foraging activity of exotic wild bees within the city, together with a strong plant&ndash, pollinator association between two exotic species. However, contrary to our expectations, the landscape context (urban vs. natural) had no effect on the activity of native bees. These results raise issues concerning how species introduced in plant&ndash, pollinator networks will impact the reproductive success of both native and exotic plants. Furthermore, the urban system could act as a springboard for alien species to disperse in natural systems and even invade them, leading to conservation concerns.

International audience; A new genus and species of skink, Kuniesaurus albiauris, is here described from the Île des Pins off southern New Caledonia. This new taxon possesses a unique suite of morphological apomorphies (scalation) that does not allow it to be placed in any existing Australasian eugongylid genus. It is known only from a single area in dense coastal forest on limestone, on the main island of the Île des Pins. The species area of occupancy is restricted, and the habitat occupied under threat from the spread of the highly invasive Little Red Fire Ant Wasmannia auropunctata. These factors place this new skink at a level of risk sufficient for it to be listed as Critically Endangered under IUCN Red List criteria. The affinities of the lizard fauna of the Île des Pins with respect to that present on southern New Caledonia are also discussed, most notably the absence from the Île des Pins of taxa typically restricted to ultramafic surfaces.

Workshop Biodiversity in Oceania, Nouméa, NCL, 24-/06/2019 - 25/06/2019; As we are facing the urgency of safeguarding biodiversity, protected areas address the need to apply a precautionary principle (option value) to living things and their evolution at a global scale. In Oceania, for effective, socially and politically sustainable conservation of biodiversity, it is essential to reconcile the global agenda, designed to prevent the collapse of biodiversity, with the preservation of local lifestyles and the services that people get from biodiversity. Preserving biodiversity and ecosystem services using protected areas must consolidate Nature's contribution to the well-being of Oceanians.

International audience; Compared to other archipelagos of the Pacific, the New Caledonian Odonata fauna is rich and diverse with 56 valid species or subspecies (23 endemics, 41%) from eight families (four Zygoptera: Argiolestidae, Coenagrionidae, Isostictidae, Lestidae, and four Anisoptera: Aeshnidae, Corduliidae, Synthemistidae, Libellulidae) and 31 genera (including four endemics, 13%). In Zygoptera, we record 19 species including 12 endemics (63%), and among Anisoptera, we record 37 species or subspecies, including 11 endemics (30%). we removed five species from the list that had been erroneously recorded also doubtful, but we were unable to clarify to which taxon this record referred hence we excluded it from our update. From a biogeographic perspective, the New Caledonian fauna has mostly Australian affinities with some connections with southeast Asia and the Pacific region. we provide for each species, whenever information was available, a distribution map with a brief review of its known ecology, behaviour and phenology. we also evaluated each species' conservation status, in light of known threats (range restriction, scarcity and human activity including altered water flow). we consider seventeen species (30%) endangered. The most immediate threats concern water pollution including alteration to the flow of water courses caused by mining, deforestation and fires. Invasive species, such as alien fish, may be predators of concern for odonata larva, although this has not yet been proven in New Caledonia.; Par rapport aux autres archipels du Pacifique, la faune des Odonates de Nouvelle-Calédonie est riche et diversifiée avec 56 espèces ou sous-espèces valides (23 espèces endémiques, 41 %) de huit familles (quatre de Zygoptères: Argiolestidae, Coenagrionidae, Isostictidae, Lestidae et quatre d'Anisoptères: Aeshnidae, Corduliidae, Synthemistidae, Libellulidae) et 31 genres (dont quatre endémiques, 13 %). Parmi les Zygoptères, nous comptons 19 taxa dont 12 endémiques (63%). Parmi les Anisoptères, nous comptons 37 espèces ou sous-espèces, dont 11 endémiques (30%). Nous avons retiré 5 espèces de la liste faunistique de Nouvelle-Calédonie, celles-ci ayant été attribuées de façon erronée à l'archipel: une mention douteuse et n'a pas été incluse dans cet inventaire, faute d'une clarification de l'identité du taxon concerné. Cette faune montre de très nettes affinités biogéografiques avec l'Australie, avec quelques influences du sud-est asiatique et de la région Pacifique. Pour chaque espèce, nous proposons une carte de distribution et une synthèse des données disponibles sur l'écologie, l'éthologie et la phénologie. Pour chacune des espèces, nous proposons une évaluation du niveau de menaces (en fonction de leur distribution, de leur rareté et des menaces consécutives aux activités humaines) et un statut provisoire. Dix-sept espèces (30%) sont considérées en danger d'extinction. Les menaces les plus immédiates concernent la pollution des cours d'eau notamment par l'activité minière, la déforestation et les incendies qui changent le régime d'écoulements des cours d'eau. Des espèces envahissantes, comme les poissons exotiques, peuvent être prédateurs importants pour les larves d'odonates, bien que cela n' aie pas encore été prouvé en Nouvelle Calédonie.

International audience

International audience; Invasive species are a major concern for the maintenance of ecosystem services and biodiversity but are difficult to mitigate. Upstream solutions to prevent their impact, including their detection, are needed. Wasmannia auropunctata, an invasive ant living in vagile supercolonies, is especially hard to track and is a major threat for tropical ecosystems and local animal communities. As part of such tropical communities, crickets are sensitive to ecological conditions, easy to collect, detectable and identifiable through their species-specific calls. Here, we evaluated the use of an acoustic community of crickets as an indicator of the presence of W. auropunctata in New Caledonia. We evaluated the dominance of the crickets in the soundscape, describe the cricket community structure and diversity along a shrubland to forest gradient, characterize these cricket communities structure and diversity in the light of ongoing invasion by W. auropunctata, and identify cricket species' indicators of the invasion. Acoustic recordings collected on 24 sites were described using human-listening and spectrographic visualization. The results demonstrated a clear dominance of the cricket group in the New Caledonian nocturnal soundscapes. Each habitat harbored a specific acoustic cricket community related to specific environmental attributes including vegetation height, daily variation of humidity and temperature. The presence of W. auropunctata was significantly associated with a lower cricket acoustic activity and species richness at night. Of the 19 species detected, four nocturnal species were identified as indicator of non-invaded forests and preforests. This work supports the use of acoustic as an alternative method to detect invasion.

International audience

International audience; Squamata are one of the most threatened groups among island vertebrates, facing high pressure from exotic species. However, the contribution of small terrestrial reptiles in invasive rodents' diet remains poorly investigated, partly because of the lack of tools for accurately identifying chewed prey fragments in gut contents. The New Caledonia archipelago (South Pacific) hosts an exceptional terrestrial squamata fauna (105 species, 91.6% endemic) that are faced with many invasive species (rodents, feral cats, feral pigs, ants) and strong human pressures. Our study aimed to evaluate the frequency of occurrence of endemic skink remains by gut content analysis of two species of invasive rodents. Four rodent trapping sessions were implemented at two ultramafic sites and for two distinct habitats (closed canopy forest and open shrubland habitat). A total of 284 rats were trapped from two species (the ship rat Rattus rattus and the Pacific rat R. exulans) over 1200 trap nights. Combined analysis of stomach and caecum contents provided far more information than traditional stomach analysis alone. Analyses showed that 15.9% of rat samples included remains of at least 12 different skink species out of the 23 present. Six species are classified as threatened by the IUCN, the most endangered being Marmorosphax taom (CR) and Kanakysaurus viviparus (EN). This study provides new prospects for the assessment of invasive rodent impacts and new insights into the respective impacts of two sympatric invasive rodent species on native skinks.

Crickets (Insecta, Orthoptera, Gryllidea) are amongst the most abundant and diverse insects in New Caledonia: 40 genera are recorded today from the Archipelago and 180 cricket species have been reported; 19 genera and more than 90% of the species are endemic. Owing to this diversity, crickets prove an interesting model to test evolutionary hypotheses about New Caledonia and its fauna. They also reveal useful ecological indicators to survey and manage New Caledonian biodiversity. Both research and conservation developments need however that crickets are properly identified. In the present paper, an illustrated key to the identification of New Caledonian cricket genera is proposed, based on specimen examination; an emended diagnosis is given for each genus, using general morphology, coloration and the main traits of male genitalia, together with available data on habitat and biology. The genus Paora Gorochov, 1986 n. stat. is restored from its synonymy with Apteronemobius Chopard, 1929, Trigonidomo...

Among invasive species, ants are a particularly prominent group with enormous impacts on native biodiversity and ecosystem functioning. Globalization and on-going climate change are likely to increase the rate of ant invasions in the future, leading to simultaneous introductions of several highly invasive species within the same area. Here, we investigate pairwise interactions among four highly invasive species, Linepithema humile, Lasius neglectus, Pheidole megacephala and Wasmannia auropunctata, at the whole colony level, using a laboratory set-up. Each colony consisted of 300 workers and one queen. The number of surviving workers in the competing colonies was recorded daily over 7 weeks. We modelled the survival of each colony during pairwise colony interactions, using a nonlinear model characterizing the survival dynamics of each colony individually. The least dominant species was P. megacephala, which always went extinct. Interactions among the three other species showed more complex dynamics, rendering the outcome of the interactions less predictable. Overall, W. auropunctata and L. neglectus were the most dominant species. This study shows the importance of scaling up to the colony level in order to gain realism in predicting the outcome of multiple invasions., This paper was supported by Région Ile-de-France (03-2010/GV-DIM ASTREA), ANR (2009 PEXT 010 01) and BiodivERsa Eranet grants, FFII Project.

International audience; Among New Caledonian cicada taxa, the endemic genus Kanakia Distant, 1892 appears as the most spectacular one, especially because of the large size of its species (length up to 50 mm for males). Recent new specimen collections helped to clarify the taxonomy of this spectacular genus. According to morphological characteristics, we were able to redefine and to split the present genus into three distinct genera: Kanakia Distant, 1892, Pseudokanakia Delorme gen. nov. and Panialna Delorme gen. nov. These two new genera are monotypic and have been respectively established from revision of Kanakia flavoannulata (Distant 1920) and Kanakia parva Boulard 1991. Also, the type species, Kanakia typica Distant, 1892, appears to be a complex of cryptic species. New acoustic and morphological observations allowed us to redefine K. typica and to describe four new species in this complex: Kanakia paniensis Delorme sp. nov., Kanakia rana Delorme sp. nov., Kanakia salesnii Delorme sp. nov. and Kanakia fuscocosta Delorme sp. nov. Kanakia gigas Boulard 1988 is also briefly discussed and the female is described. An identification key of the Kanakia species and allied genera is also provided.

International audience; Few studies have focused on the early colonization of New Caledonia by insects, after the re-emergence of the main island, 37 Myr ago. Here we investigate the mode and tempo of evolution of a new endemic cricket genus, Pixibinthus, recently discovered in southern New Caledonia. First we formally describe this new monotypic genus found exclusively in the open shrubby vegetation on metalliferous soils, named 'maquis minier', unique to New Cal-edonia. We then reconstruct a dated molecular phylogeny based on five mitochondrial and four nuclear loci in order to establish relationships of Pixibinthus within Eneopterinae crickets. Pixibinthus is recovered as thesister clade of the endemic genus Agnotecous, mostly rainforest-dwellers. Dating results show that the island colonization by their common ancestor occurred around 34.7 Myr, shortly after New Caledonia re-emergence. Pixibinthus and Agnotecous are then one of the oldest insect lineages documented so far for New Caledo-nia. This discovery highlights for the first time two clear-cut ecological specializations between sister clades, as Agnotecous is mainly found in rainforests with 19 species, whereas Pixibinthus is found in open habitats with a single documented species. The preference of Pixibinthus for open habitats and of Agnotecous for forest habitats nicely fits an acoustic specialization, either explained by differences in body size or in acoustic properties of their respective habitats. We hypothesize that landscape dynamics, linked to major past climatic events and recent change in fire regimes are possible causes for both present-day low diversity and rarity in genus Pixibinthus. The unique evolutionary history of this old New Caledonian lineage stresses the importance to increase our knowledge on the faunal biodiversity of 'maquis minier', in order to better understand the origin and past dynamics of New Caledonian biota.

International audience; The impact of alien predator species on insular native biota has often been attributed to island prey naïveté (i.e. lack of, or inefficient, anti-predator behavior). Only rarely, however, has the concept of island prey naïveté been tested, and then only a posteriori (i.e. hundreds or thousands of years after alien species introduction). The presence of native or anciently introduced predators or competitors may be crucial for the recognition and development of adaptive behavior toward unknown predators or competitors of the same archetype (i.e. a set of species that occupy a similar ecological niche and show similar morphological and behavioral traits when interacting with other species). Here, we tested whether two squa-mates endemic to New Caledonia, a skink, Caledoniscincus austrocaledonicus, and a gecko, Bavayia septuiclavis, recognized and responded to the odor of two major invaders introduced into the Pacific islands, but not yet into New Caledonia. We chose one predator, the small Indian mongoose Herpestes javanicus and one competitor, the cane toad Rhinella marina, which belong respectively to the same archetype as the following two species already introduced into New Caledonia in the nineteenth century: the feral cat Felis catus and the golden bell frog Litoria aurea. Our experiment reveals that geckos are naïve with respect to the odors of both an unknown predator and an unknown competitor, as well as to the odors of a predator and a competitor they have lived with for centuries. In contrast, skinks seem to have lost some naïveté regarding the odor of a predator they have lived with for centuries and seem " predisposed " to avoid the odor of an unknown potential competitor. These results indicate that insular species living in contact with invasive alien species for centuries may be, although not systematically, predisposed toward developing adaptive behavior with respect to species belonging to the same archetype and introduced into their native range.

International audience; Ants figure prominently among the worst invasive species because of their enormous ecological and economic impacts. However, it remains to be investigated which species would be behaviourally dominant when confronted with another invasive ant species, should two species be introduced in the same area. In the future, many regions might have suitable environmental conditions for several invasive ant species, as predicted under climate change scenarios. Here, we explored interactions among several highly invasive ant species, which have been shown to have overlapping suitable areas. The aim of this study was to evaluate the performance in interference competition of seven of the world's worst invasive ant species (Anoplolepis gracilipes, Paratrechina longicornis, Myrmica rubra, Linepithema humile, Lasius neglectus, Wasmannia auropunctata and Pheidole megacephala). We conducted pairwise confrontations, testing the behaviour of each species against each of the six other species (in total 21 dyadic confrontations). We used single worker confrontations and group interactions of 10 versus 10 individuals to establish a dominance hierarchy among these invasive ant species. We discovered two different behavioural strategies among these invasive ants: three species displayed evasive or indifferent behaviour when individuals or groups were confronted (A. gracilipes, Pa. longicornis, M. rubra), while the four remaining species were highly aggressive during encounters and formed a linear dominance hierarchy. These findings contrast with the widespread view that invasive ants form a homogeneous group of species displaying the `invasive syndrome', which includes generally aggressive behaviour. The dominance hierarchy among the four aggressive species may be used to predict the outcome of future competitive interactions under some circumstances. Yet, the existence of several behavioural strategies renders such a prediction less straightforward.

International audience; Ants are among the most problematic invasive species. They displace numerous native species, alter ecosystem processes, and can have negative impacts on agriculture and human health. In part, their success might stem from a departure from the discovery-dominance trade-off that can promote co-existence in native ant communities, that is, invasive ants are thought to be at the same time behaviorally dominant and faster discoverers of resources, compared to native species. However, it has not yet been tested whether similar asymmetries in behavioral dominance, exploration, and recruitment abilities also exist among invasive species. Here, we establish a dominance hierarchy among four of the most problematic invasive ants (Linepithema humile, Lasius neglectus, Wasmannia auropunctata, Pheidole megacephala) that may be able to arrive and establish in the same areas in the future. To assess behavioral dominance, we used confrontation experiments, testing the aggressiveness in individual and group interactions between all species pairs. In addition, to compare discovery efficiency, we tested the species' capacity to locate a food resource in a maze, and the capacity to recruit nestmates to exploit a food resource. The four species differed greatly in their capacity to discover resources and to recruit nestmates and to dominate the other species. Our results are consistent with a discovery-dominance trade-off. The species that showed the highest level of interspecific aggressiveness and dominance during dyadic interactions.

International audience; The rarely collected gasteruptiid wasp fauna (Evanioidea: Gasteruptiidae) of New Caledonia is reviewed. Previously only two species of Pseudofoenus (Hyptiogastrinae) were known. Here, we record the subfamily Gasteruptiinae from New Caledonia for the first time and describe three new species of Gasteruption: G. lacoulee Jennings, Krogmann & Parslow, sp. nov., G. maquis Jennings, Krogmann & Parslow, sp. nov., and G. sarramea Jennings, Krogmann & Parslow, sp. nov. An identification key to the Gasteruptiidae of New Caledonia is provided.

International audience; Invasive species usually go through a period of reduced genetic variability due to a bottleneck. The genetic constitution of an invading population should therefore reflect the time since invasion and the number of introduction events. We studied genetic population structure of three rat species occurring sympatrically on the island of Futuna (46km(2)), where they were introduced recently (Rattus rattus), 80-170 years ago (R.norvegicus) and about 3000 years ago (R.exulans). From 2007 to 2012, we trapped 3900 rats during a rodent regulation programme over 20000 trap nights and took 565 rat tissue samples for genetic analyses. By examining genetic variation and spatial distribution of genetic resemblance, we evaluated the consequences of the time after introduction for genetic population structure. Observed heterozygosity, expected heterozygosity, number of alleles and allelic richness generally increased with increasing length of time a species was introduced to the island. The species with longer invasion history had also higher spatial admixture. However, in R.norvegicus, the observed heterozygosity was lower and inbreeding higher than expected by the invasion history. We relate this with the assumption that this species was introduced once or a few times and in low numbers, while R.exulans was intentionally introduced many times by Polynesian navigators and R.rattus had a high chance of being introduced on multiple occasions in recent times.

Assuming that a simple drowning model is applicable to all islands facing future climate change and sea-level rise (SLR), the future existence of up to 12% of islands is said to be compromised – and therefore these should not be considered for active management and protection [1,2]. This includes tropical atolls and their low-lying islands. However, we reject the triage strategy elaborated by Courchamp et al. [1]. Evidence from geology, sedimentology, and oceanography, and from the ecology of invasive species, shows that island conservation, especially of low islands, should remain a priority.

Simultaneous eradications of Black Rat (Rattus rattus) and Ice plants (Carpobrotus spp.) on Bagaud Island (Port-Cros National Park, Provence, France) : preliminary results on their impacts on Athropods communities. — Biological invasions are recognized as one of the major threats to island biodiversity conservation, and numerous studies have been conducted around the world to restore the biodiversity of islands submitted to invasive species impacts. However, few scientific post-eradication studies were piloted notably for the biodiversity assessment of Arthropod communities. Bagaud Island is an integral reserve of the Port-Cros National Park (PNPC), located in the îles d’Hyères Archipelago (Var, France). In the last centuries, it has undergone two major anthropogenic disturbances : the invasion of the Black Rat (Rattus rattus) and the Ice plants (Carpobrotus spp.), two alien taxa known for their particularly negative effects on the flora and fauna of the Mediterranean island ecosystems, including Arthropods. PNPC has launched a ten-year program of ecological restoration that involves the eradication of these two invasive taxa. The Arthropod communities of the island have been analysed in their initial state in spring 2011, eradications were conducted between September 2011 and January 2013, and the first post-eradication campaign began in spring 2013. The ground fauna was sampled using four transects of Barber traps distributed in different ecological contexts of the island. This first post-eradication study reveals an increase in the abundance of arthropods trapped between 2011 (4868 individuals in 74 traps) and 2013 (6892, n = 60). The average number of trapped Arthropods was significantly higher in areas where Carpobrotus spp. have been eradicated, but declined in the bush area that housed a high density of R. rattus. The communities of decomposers explode, in contrast to predator populations. However, the global specific richness remains stable (220 morphospecies in 2011, 216 in 2013). Scientific monitoring by the PNC must be continued to better determine the direct and indirect long-term impacts of these eradications upon the structure and the functioning of the Arthropods communities of the Bagaud Island., Les invasions biologiques sont reconnues comme l’une des principales menaces pour la conservation de la biodiversité, et de nombreux travaux ont été conduits à travers la planète pour restaurer la biodiversité insulaire par des programmes d’éradication d’espèces invasives. Cependant, peu d’études scientifiques post-éradication ont été conduites notamment pour l’évaluation de la biodiversité des communautés d’Arthropodes. L’île de Bagaud, située dans l’archipel des îles d’Hyères (Var, France), est une réserve intégrale du Parc national de Port-Cros (PNPC) qui a notamment été soumise à deux perturbations majeures d’origine anthropique au cours des derniers siècles : l’invasion du Rat noir (Rattus rattus) et celle des Griffes de sorcière (Carpobrotus spp.). Ces espèces allochtones engendrent des effets particulièrement néfastes sur la flore et la faune des écosystèmes insulaires méditerranéens, notamment sur les Arthropodes. Le PNPC a ainsi lancé un programme décennal de restauration écologique qui implique l’éradication de ces deux taxons invasifs. La communauté des Arthropodes de l’île a fait l’objet d’un état initial au printemps 2011, les éradications ont été effectuées entre septembre 2011 et janvier 2013, et la première campagne d’échantillonnage post-éradication a été réalisée au printemps 2013. L’échantillonnage de la faune épigée a été réalisé au moyen de quatre transects fixes de pièges Barber répartis dans différents milieux écologiques de l’île. Cette première étude post-éradication révèle une augmentation de l’abondance des Arthropodes piégés entre 2011 (4868 individus dans 74 pièges) et 2013 (6892, n = 60). Les effectifs moyens par piège augmentent significativement dans les zones où les Carpobrotus spp. ont été arrachés, mais chutent dans la zone de maquis qui abritait une forte densité de R. rattus. La richesse spécifique reste globalement stable (220 morpho-espèces en 2011, 216 en 2013), cependant les communautés de décomposeurs explosent a contrario des populations de prédateurs. Les suivis doivent être poursuivis afin de mieux déterminer les impacts directs et indirects à long terme de ces éradications s’exerçant sur la biodiversité des communautés d’Arthropodes de l’île., Braschi Julie,Ponel Philippe,Krebs Elise,Jourdan Hervé,Passetti Aurélie,Barselo Alain,Berville Laurence,Le Quilliec Patricia,Lorvelec Olivier,Matocq Armand,Meunier Jean-yves,Oger Pierre,Séchet Emmanuel,Vidal Éric. Éradications simultanées du rat noir (Rattus rattus) et des griffes de sorcière (Carpobrotus spp.) sur l’île de Bagaud (parc national de Port-Cros, Provence, France) : résultats préliminaires des conséquences sur les communautés d’arthropodes. In: Revue d'Écologie (La Terre et La Vie), supplément n°12, 2015. Les invasions biologiques et leur gestion au carrefour des sciences naturelles et des sciences humaines et sociales. Colloque organisé à Rennes (Université de Rennes 1) du 20 au 22 octobre 2014. pp. 91-98.

New Caledonia is an important biodiversity hotspot with much undocumented biodiversity, especially in many insect groups. Here we used an integrative approach to explore species diversity in the tenebrionid genus Uloma (Coleoptera, Tenebrionidae, Ulomini), which encompasses about 150 species, of which 22 are known from New Caledonia. To do so, we focused on a morphologically homogeneous group by comparing museum specimens with material collected during several recent field trips. We also conducted molecular phylogenetic analyses based on a concatenated matrix of four mitochondrial and three nuclear genes for 46 specimens. The morphological study allowed us to discover and describe four new species that belong to the group of interest, the Uloma isoceroides group. Molecular analyses confirmed the species boundaries of several of the previously described species and established the validity of the four new species. The phylogenetic analyses also provided additional information on the evolutionary history of the group, highlighting that a species that was thought to be unrelated to the group was in fact a member of the same evolutionary lineage. Molecular species delimitation confirmed the status of the sampled species of the group and also suggested some hidden (cryptic) biodiversity for at least two species of the group. Altogether this integrative taxonomic approach has allowed us to better define the boundaries of the Uloma isoceroides species group, which comprises at least 10 species: Uloma isoceroides (Fauvel, 1904), Uloma opacipennis (Fauvel, 1904), Uloma caledonica Kaszab, 1982, Uloma paniei Kaszab, 1982, Uloma monteithi Kaszab, 1986, Uloma robusta Kaszab, 1986, Uloma clamensae sp. n., Uloma condaminei sp. n., Uloma jourdani sp. n., and Uloma kergoati sp. n. We advocate more studies on other New Caledonian groups, as we expect that much undocumented biodiversity can be unveiled through the use of similar approaches.

International audience; Key evolutionary events associated with invasion success are traditionally thought to occur in the introduced, rather than the native range of species. In the invasive ant Wasmannia auropunctata, however, a shift in reproductive system has been demonstrated within the native range, from the sexual non-dominant populations of natural habitats to the clonal dominant populations of human-modified habitats. Because abiotic conditions of human- modified habitats are hotter and dryer, we performed lab experiments on workers from a set of native and introduced populations, to investigate whether these ecological and genetic transitions were accompanied by a change in thermotolerance and whether such changes occurred before establishment in the introduced range. Thermotolerance levels were higher in native populations from human-modified habitats than in native populations from natural habitats, but were similar in native and introduced populations from human-modified habitats. Differences in thermotolerance could not be accounted for by differences in body size. A scenario based on local adaptation in the native range before introduction in remote areas represents the most parsimonious hypothesis to account for the observed phenotypic pattern. These findings highlight the importance of human land use in explaining major contemporary evolutionary changes.

Correspondence: E-mail: orivel@cict.fr; International audience; The biology of most invasive species in their native geographical areas remains largely unknown. Such studies are, however, crucial in shedding light on the ecological and evolutionary processes underlying biological invasions.The present study focuses on the little fire ant 2. Wasmannia auropunctata, a species native to Central and South America that has been widely introduced and which has become invasive throughout the tropics. We characterise and compare several ecological traits of native populations in French Guiana with those in one of its introduced ranges, New Caledonia.We found ecologically heterogeneous populations of 3. W. auropunctata coexisting in the species’ native geographical area. First, we found populations restricted to naturally perturbed areas (particularly floodplains) within the primary forest, and absent from the surrounding forest areas. These populations were characterised by low nest and worker densities. Second, we found dominant populations in recent anthropogenic areas (e.g. secondary forest or forest edge along road) characterised by high nest and worker densities, and associated with low ant species richness. The local dominance of W. auropunctata in such areas can be due to the displacement of other species (cause) or the filling-up of empty habitats unsuitable to other ants (effect). With respect to their demographic features and ant species richness, the populations of native anthropogenic habitats were to a large extent similar to the invasive populations introduced into remote areas.4. The results point to the need for greater research efforts to better understand the ecological and demographic features of invasive species within their native ranges

New Caledonia has generally been considered a continental island, the biota of which largely dates back to Gondwanan times owing to its geological origin and the presence of phylogenetic relicts. This view is contradicted by geological evidence indicating long Palaeocene and Eocene submersions and by recent biogeographic and phylogenetic studies, with molecular or geophysical dating placing the biota no older than the Oligocene. Phylogenetic relicts do not provide conclusive information in this respect, as their presence cannot be explained by simple hypotheses but requires assumption of many ad hoc extinction events. The implication of this new scenario is that all the New Caledonian biota colonized the island since 37 Ma Local richness can be explained by local radiation and adaptation after colonization but also by many dispersal events, often repeated within the same groups of organisms. Local microendemism is another remarkable feature of the biota. It seems to be related to recent speciation mediated by climate, orography, soil type and perhaps unbalanced biotic interactions created by colonization disharmonies. New Caledonia must be considered as a very old Darwinian island, a concept that offers many more fascinating opportunities of study.

Due to the unbalanced distribution of their fauna and flora, which leads to the creation of a niche opportunities, it is generally accepted that island communities offer weak biotic resistance to biological invasion. In order to empirically test this statement, we compared resource use by ants in the understorey of an undisturbed New Caledonian rain forest recently invaded by the little fire ant, Wasmannia auropunctata. We tested the exploitation of: (1) food sources by placing baits on all trees with trunks greater than 5 cm in diameter; and (2) nesting sites on two tree species likely to shelter ant colonies. In non-invaded areas, the native ants occupied only 44.6% of the baits after 2 h of exposure, while in invaded areas all the baits were occupied by numerous W. auropunctata workers. Similarly, in non-invaded areas only 48.9% of Meryta coriacea (Araliaceae) trees and 64.5% of Basselinia pancheri (Arecaceae) sheltered ants, while in invaded areas W. auropunctata nested in 92.6–98.3% of these trees. Also, workers attended native Margarodidae (Hemiptera) for which they promoted the development of populations significantly larger than those attended by native ants. Thus native ants appear unable to efficiently exploit and defend several of the available food sources and nesting sites, providing a niche opportunity for an invader like W. auropunctata.

We examined intraspecific colonial aggressiveness in Wasmannia auropunctata (Roger), a tramp species originating from the neotropics. By observing the results of one-on-one confrontations, we compared the behavioral responses of workers originating from six New Caledonian locations (introduced range) and four Brazilian cocoa plantations (original range). We recorded interindividual “aggressive” behavior on four levels ranging from physical contact, with no aggressive response, to prolonged aggressiveness, including stinging by one or both ants. In Brazil, we often observed high intraspecific aggressiveness between populations originating from distant locations, indicating that W. auropunctata may behave as a multicolonial species in its native range. In New Caledonia, paired encounters resulted in low agonistic behavior, as shown by the absence of “full attacks” (which include stinging by one or both opponents). Our results suggest that W. auropunctata behaves as a single supercolony throughout New Caledonia and that the scale of its unicoloniality (widespread colonies with interconnected nests without aggressiveness between workers originating from distant areas) is different in introduced and native populations. According to the present study, it seems likely that differences in intraspecific aggressiveness between native and introduced populations of W. auropunctata contribute to its invasive success.

The antennal receptors of the adult male and female ladybird beetle, Semiadalia undecimnotata (Coleoptera: Coccinellidae), were examined by scanning and transmission electron microscopy. Twelve types of receptors were characterized and grouped into 5 morphological classes: Bohm, trichoid, coeloconic, basiconic, and chetiform sensilla. Sensory function was determined on the basis of sensillar ultrastructure and electrophysiological response. Olfactory sensilla are confined in both sexes to the 2 terminal antennal segments. In contrast, gustatory and mechanosensitive organs are present along the entire length of the antennae. Sexual dimorphism of antennal receptors is limited to the latter 2 functional classes. The principal characteristics of this dimorphism are the following: a) males possess 540 sensilla (all types), while females possess only 500; b) males exhibit 2 types of taste receptors not present in females; c) females exhibit one type of mechanoreceptor absent in males; d) the 3 sex-specific types of sensilla, which occupy the same position in males and females, are confined to the inner side of the antennae. The possible role of male-specific sensilla in intersexual communication is discussed.