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International audience; The aim of our review was to examine the cases of Tephritidae invasions across island systems in order to determine whether they follow a hierarchical mode of invasion. We reviewed the literature on factors and mechanisms driving invasion sequences in Pacific and Southwest Indian Ocean islands and gathered every record of invasion by a polyphagous tephritid in island groups. From invasion date or period, we defined an invasion link when a new fruit fly established on an island where another polyphagous tephritid is already resident (that was indigenous or a previous invader). Across surveyed islands, we documented 67 invasion links, involving 24 tephritid species. All invasion links were directional, i.e., they involved a series of invasions by invaders that were closely related to a resident species but were increasingly more competitive. These sequential establishments of species are driven by interspecific competition between resident and exotic species but are also influenced by history, routes, and flows of commercial exchanges and the bridgehead effect. This information should be used to improve biosecurity measures. Interactions between trade flow, invasive routes, and the presence of invasive and resident species should be integrated into large-scale studies.

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.

International audience; Thirty-three species of aphids are now established in New Caledonia. All species appear to have been introduced accidentally by human activity in the last century. Here, 17 aphid species are recorded for the first time: Aphis eugeniae, Aphis glycines, Aphis odinae, Aulacorthum solani, Brachycaudus helichrysi, Cerataphis orchidearum, Greenidea psidii, Hyperomyzus carduellinus, Hysteroneura setariae, Lipaphis pseudobrassicae, Micromyzus katoi, Myzus ornatus, Pentalonia caladii, Rhopalosiphum nymphaeae, Rhopalosiphum rufiabdominale, Schizaphis rotundiventris, and Tetraneura fusiformis. Thirteen more species are also more or less regularly intercepted at the borders through biosecurity surveys, without further establishment. This demonstrates that aphids represent a major biosecurity threat, including a threat as potential plant virus vectors. The reinforcement of biosecurity is a priority for such biodiversity hotspots, from the perspectives of both agriculture and the native environment. Prioritisation and promotion of local development of vegetable and fruit production, rather than their risky importation from abroad, is desirable. Such an approach also should be promoted and extended to other Pacific islands, which all share the lack of native aphid fauna and their associated plant disease vector risks.; Trente trois (33) espèces de pucerons sont aujourd’hui recensées de Nouvelle-Calédonie. Toutes ces espèces sont exotiques et ont été introduites accidentellement par les activités humaines. Dix-sept (17) espèces y sont ainsi recensées pour la première fois : Aphis eugeniae, Aphis glycines, Aphis odinae, Aulacorthum solani, Brachycaudus helichrysi, Cerataphis orchidearum, Greenidea psidii, Hyperomyzus carduellinus, Hysteroneura setariae, Lipaphis pseudobrassicae, Micromyzus katoi, Myzus ornatus, Pentalonia caladii, Rhopalosiphum nymphaeae, Rhopalosiphum rufiabdominale, Schizaphis rotundiventris et Tetraneura fusiformis. Par ailleurs, au moins 13 autres espèces sont régulièrement interceptées par la biosécurité sans établissement actuel de populations. Les pucerons apparaissent donc comme une menace croissante pour la biosécurité de l’archipel. Aussi, le renforcement des mesures de biosécurité aux frontières apparaît prioritaire en association à une promotion du développement local de productions maraîchères et fruitières. Ainsi, la limitation de ces importations à risque, devrait contribuer à une meilleure protection des productions agricoles et de la biodiversité. Une telle approche devrait également être promue dans les pays insulaires du Pacifique, qui se caractérisent par la même disharmonie de peuplements, l’absence de communautés natives de pucerons et du risque associé de vectorisation de maladies phytopathogènes.

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.

Atelier Biodiversité en Océanie, Nouméa, NCL, 24-/06/2019 - 25/06/2019; Face à l’urgence de préserver la biodiversité, les aires protégées répondent à la nécessité d’appliquer un principe de précaution (valeur d’option) sur le vivant et son évolution à l’échelle mondiale. Dans le contexte océanien, pour être efficace en matière de préservation de la biodiversité et être soutenu socialement et politiquement, il est incontournable d’articuler l’agenda mondial de lutte contre l’effondrement de la biodiversité à la préservation des modes de vie locaux et des services que les populations tirent de la biodiversité.Préserver la biodiversité et les services écosystémiques à travers les aires protégées doit consolider la contribution de la nature au bien-être des Océaniens.

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; We provide an up-to-date catalogue of the Coccomorpha Rubsaamen, 1899 of New Caledonia based on studies of collected and curated specimens and on the literature. One hundred and eighteen species (118) in ten families have been recorded to date, in 70 genera. Five of the genera (7.2%) are endemic, belonging to Asterolecaniidae Berlese, 1898 (Oacoccus Williams, 2007), Eriococcidae Cockerell, 1899 (Chazeauana Matile-Ferrero, 1988, Choneochiton Hodgson, 2014) and Monophlebidae Maskell, 1880 (Insulococcus Bhatti, 1991, Tessarobelus Montrouzier, 1864). Twenty-nine (29) species are endemic to New Caledonia, giving a rate of endemism of 24.6%. Most of the species are apparently human-assisted introductions. We provide here first records from New Caledonia for ten (10) species: Aulacaspis rosarum Borchsenius, 1858; Chrysomphalus pinnulifer (Maskell, 1891); Diaspis echinocacti (Bouche, 1833); Fiorinia phantasma (Cockerell & Robinson, 1915); Labidaspis myersi Green, 1929; Palmicultor browni (Williams, 1960); Poliaspoides formosana (Takahashi, 1930); Pseudococcus gilbertensis Beardsley, 1966; Pseudococcus orchidicola Takahashi, 1939 and Rhizoecus cacticans (Hambleton, 1946). Despite two introduction attempts for the biological control of weedy cactus, Hypogeococcus festerianus (Lizer y Trelles, 1942) is still considered absent from New Caledonia. Literature records of five species are shown to be erroneous: Dactylopius tomentosus (Lamarck, 1801); Dysmicoccus cocotis (Maskell, 1890); Lindingaspis buxtoni (Laing, 1927); Nipaecoccus filamentosus (Cockerell, 1893) and Clavaspis herculeana (Cockerell & Hadden, in Doane & Hadden, 1909), which are therefore considered absent from New Caledonia.

International audience; Invasive alien species are a major threat to native insular species. Eradicating invasive mammals from islands is a feasible and proven approach to prevent biodiversity loss. We developed a conceptual framework to identify globally important islands for invasive mammal eradications to prevent imminent extinctions of highly threatened species using biogeographic and technical factors, plus a novel approach to consider socio-political feasibility. We applied this framework using a comprehensive dataset describing the distribution of 1,184 highly threatened native vertebrate species (i.e. those listed as Critically Endangered or Endangered on the IUCN Red List) and 184 non-native mammals on 1,279 islands worldwide. Based on extinction risk, irreplaceability, severity of impact from invasive species, and technical feasibility of eradication, we identified and ranked 292 of the most important islands where eradicating invasive mammals would benefit highly threatened vertebrates. When socio-political feasibility was considered, we identified 169 of these islands where eradication planning or operation could be initiated by 2020 or 2030 and would improve the survival prospects of 9.4% of the Earth’s most highly threatened terrestrial insular vertebrates (111 of 1,184 species). Of these, 107 islands were in 34 countries and territories and could have eradication projects initiated by 2020. Concentrating efforts to eradicate invasive mammals on these 107 islands would benefit 151 populations of 80 highly threatened vertebrates and make a major contribution towards achieving global conservation targets adopted by the world’s nations.

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; 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; We present an updated checklist of the ladybird beetle fauna of New Caledonia. Fifty species have been tracked from literature and collections, but six should be removed from the list as they represent false records, invalid or unestablished species: Coccinella boletifera Fauvel, Harmonia conformis (Boisduval), Menochilus duodecimpunctatus (Fauvel), Micraspis lineola (Fabricius), Orcus australasiae Boisduval, and Curinus coeruleus (Mulsant). After our investigations, the current described ladybird beetle fauna totals 44 named species, belonging to 18 valid genera. The endemism rate is 47.7% (21 species), with one endemic subgenus, Scymnus (Caledonus). Based on comparisons of the coccinellid faunas of surrounding regions, the New Caledonian fauna has affinities with Australia and Papua New Guinea more than with the rest of the Pacific area. At least 19 species (43.2%) seem to have been introduced by human activities (either deliberately or accidentally).

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.

New Caledonia is a megadiverse tropical island in the southwest Pacific, however, inhabited by only one species of amphibian, Litoria aurea (Hylidae). We used both molecular (CO1 and ND4 gene sequencing) and morphometric data to explore its geographical origin and timing of colonisation. We tested whether this species arrived through transoceanic dispersal before human arrival in the island, or recently through anthropogenic introduction. We found a weak phylogeographical structure within this species, and lower haplotype diversity in New Zealand, New Caledonia and Wallis compared to Australia. No significant genetic differentiation was found between pairs of populations in New Caledonia and Wallis, or between pairs of population from these two islands. We observed a high level of morphometric differentiation between Australian and island populations, and a low level of morphometric differentiation between island populations. Our results support an Australian origin for insular frogs. The possibility of a trans-marine dispersal from Australia to New Caledonia and/or Wallis in-between the Eocene and the Pleistocene cannot be favoured, given the low level of genetic differentiation. Our results are consistent with a recent human introduction, most likely during European times. Our data support the historical absence of amphibians in the old island New Caledonia, and is consistent with the new biogeographical paradigm that this island was totally re-colonized after emergence in Eocene. More studies are necessary to explain the success of this frog in oceanic islands, where it is widespread and abundant, compared to Australia, where it is declining.

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.

National audience; 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.

International audience; The disproportionate impacts of invasive predators are often attributed to the naïveté (i.e., inefficient or nonexisting anti-predator behavior) of island native species having evolved without such predators. Naïveté has long been regarded as a fixed characteristic, but a few recent studies indicate a capacity for behavioral adaptation in native species in contact with alien predators. Here, we tested whether two reptiles endemic to New Caledonia, a skink, Caledoniscincus austrocaledonicus, and a gecko, Bavayia septuiclavis, recognized and responded to the odor of six introduced species (two rodents, the feral cat, and three species of ants). We used an experimental design in which reptiles had a choice of retreat sites with or without the odor of predators or aggressors. Skinks avoided two or three of the predators, whereas geckos avoided at most one. These results suggest that diurnal skinks are more responsive than nocturnal geckos to the odor of introduced predators. Neither skinks nor geckos avoided the three species of ants. Thus, the odors of alien predators are shown to influence retreat site selection by two native island reptiles. Moreover, the study suggests that this loss of naïveté varies among native species, probably as a consequence of the intensity of the threat and of time since introduction. These findings argue for rethinking the behavioral flexibility of ectothermic reptiles in terms of their responses to biological invasion.

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; We compared trapping and kill efficiency, and by-catch rate of a new reverse-bait trigger rat trap (Ka Mate) with conventional snap traps (Ezeset and Victor), and assessed methods for calculating abundance indices, over 2879 trap nights on Wallis & Futuna and New Caledonia. Ka Mate traps were most effective at killing larger (> 100 g) rats whereas Ezeset traps had the best capture rates of smaller (< 100 g) rodents. Victor mouse traps caught rodents up to 50 g, but were no more efficient than rat traps. Proportions of live captures were similar for Ka Mate and Ezeset traps, but the mass threshold for live rats in Ezeset traps was much lower than that of the Ka Mate traps. Ka Mate traps had much lower non-target by-catch rates than Ezeset traps in habitats free of land crabs. We developed a new rodent abundance index to standardise results of different trap systems.

We report the recent arrival and subsequent spread of the Sida Leafbeetle, Calligrapha pantherina Stål, 1859, in the archipelago of New Caledonia. The species seems to have a rapid spread as it is now recorded all along the west coast and also have spread to the Loyalty Islands. The first specimen was caught in November 2012. This is a biocontrol agent which was introduced in the Pacific Region against invasive Malvaceae (Sida spp.). This accidental arrival would help to control the alien weed, Sida acuta Burm. f., in New Caledonia. But this establishment raises some questions about potential threats on the two endemic New Caledonian Sida species. We also discuss this arrival and subsequent installation in the context of global change and biosecurity issues, particularly in such a biodiversity hotspot.

Bagaud Island has been undergoing two major biological invasions by Carpobrotus spp. and the black rat Rattus rattus. For that reason, Port-Cros National Park initiated and implement an ecological restoration program through the eradication of those two taxa. The first post-eradication study reveals a significant increase in arthropod abundances. Decomposer communities surge while predator populations decline. Nonetheless, species richness remained stable overall., L'île de Bagaud a subi deux invasions biologiques majeures : par Carpobrotus spp. et par le rat noir (Rattus rattus). Le Parc national de Port-Cros a lancé un programme de res-tauration écologique impliquant l'éradication de ces deux taxons. Cette première étude post-éradication révèle une augmentation significative de l'abondance des arthropodes. Les communautés de décomposeurs explosent alors que les populations de prédateurs chutent. Cependant, la richesse spécifique reste globalement stable.

The biosphere is experiencing a biodiversity crisis, which for islands are the epicenter. Biological invasions are there, one of the main drivers, especially regarding the alteration of mutualistic relationships for the functioning and the maintenance of ecosystems. Thus, during our work in New Caledonia, we focused on a key group for ecosystem functions: ants, and their involvement in seed dispersal (myrmecochory). We carried out the first assessment of this mutualism in New Caledonia with the identification of indigenous myrmechorous plants, with a preponderance of species on ultramafic soils. Then, we evaluated the magnitude of seed dispersal by ants on these soils. After the characterisation of ant communities across an anthropic disturbance gradient, we evaluated seed dispersal capabilities of exotic ant compared to native ones. Solenopsis geminata appears to offer a more efficient seed dispersal than natives. On the other hand, Wasmannia auropunctata excludes native species without ensuring effective dispersal. In the context of an intense disturbance regime, our work illustrates a neo-assembled community of ants, dominated by exotic ones, some of which could provide a function relay with respect to maintaining the dynamic of maquis. Our work illustrates the “context dependency” of invasive species’ impacts as a function of anthropogenic disturbance’s level. It also discusses the possible contribution of these ants in a context of restoration after disturbance of habitats on ultramafic substrates, or even their use in ecological engineering program.; La biosphère traverse une crise de biodiversité pour laquelle les milieux insulaires sont l’épicentre. Les invasions biologiques y constituent l’un des principaux facteurs de forçage, notamment du point de vue de l’altération des mutualismes, pour le fonctionnement et le maintien des écosystèmes. Durant notre travail en Nouvelle-Calédonie, nous nous sommes intéressés à un groupe clé de voute pour le fonctionnement des écosystèmes, les fourmis, et leur implication vis-à-vis de la dispersion de graines (myrmécochorie). Nous avons réalisé la première identification de plantes autochtones myrmécochores, avec une prépondérance des espèces sur substrats ultramafiques. Puis, nous avons testé la dispersion par les fourmis sur ces substrats. Après avoir caractérisé les communautés selon un gradient de perturbation anthropique, nous avons évalué la dispersion et la contribution des fourmis invasives à ce service par rapport aux fourmis natives. Ainsi, Solenopsis geminata semble capable d'une meilleure dispersion que les espèces natives. A contrario, Wasmannia auropunctata exclue les espèces natives sans assurer de dispersion efficace. Dans le contexte d’un régime de perturbations intense, nos travaux illustrent une communauté néo-assemblée de fourmis, dominée par des exotiques dont certaines pourraient assurer un relai de fonction pour la dynamique des maquis. Nos travaux illustrent la « contexte dépendance » des impacts d’espèces invasives en fonction du niveau de perturbation anthropique. Ils permettent de discuter la contribution possible de ces fourmis pour la restauration après perturbation sur substrats ultramafiques, voire de leur valorisation en ingénierie écologique.

La biosphère traverse une crise de biodiversité pour laquelle les milieux insulaires sont l’épicentre. Les invasions biologiques y constituent l’un des principaux facteurs de forçage, notamment du point de vue de l’altération des mutualismes, pour le fonctionnement et le maintien des écosystèmes. Durant notre travail en Nouvelle-Calédonie, nous nous sommes intéressés à un groupe clé de voute pour le fonctionnement des écosystèmes, les fourmis, et leur implication vis-à-vis de la dispersion de graines (myrmécochorie). Nous avons réalisé la première identification de plantes autochtones myrmécochores, avec une prépondérance des espèces sur substrats ultramafiques. Puis, nous avons testé la dispersion par les fourmis sur ces substrats. Après avoir caractérisé les communautés selon un gradient de perturbation anthropique, nous avons évalué la dispersion et la contribution des fourmis invasives à ce service par rapport aux fourmis natives. Ainsi, Solenopsis geminata semble capable d'une meilleure dispersion que les espèces natives. A contrario, Wasmannia auropunctata exclue les espèces natives sans assurer de dispersion efficace. Dans le contexte d’un régime de perturbations intense, nos travaux illustrent une communauté néo-assemblée de fourmis, dominée par des exotiques dont certaines pourraient assurer un relai de fonction pour la dynamique des maquis. Nos travaux illustrent la « contexte dépendance » des impacts d’espèces invasives en fonction du niveau de perturbation anthropique. Ils permettent de discuter la contribution possible de ces fourmis pour la restauration après perturbation sur substrats ultramafiques, voire de leur valorisation en ingénierie écologique., The biosphere is experiencing a biodiversity crisis, which for islands are the epicenter. Biological invasions are there, one of the main drivers, especially regarding the alteration of mutualistic relationships for the functioning and the maintenance of ecosystems. Thus, during our work in New Caledonia, we focused on a key group for ecosystem functions: ants, and their involvement in seed dispersal (myrmecochory). We carried out the first assessment of this mutualism in New Caledonia with the identification of indigenous myrmechorous plants, with a preponderance of species on ultramafic soils. Then, we evaluated the magnitude of seed dispersal by ants on these soils. After the characterisation of ant communities across an anthropic disturbance gradient, we evaluated seed dispersal capabilities of exotic ant compared to native ones. Solenopsis geminata appears to offer a more efficient seed dispersal than natives. On the other hand, Wasmannia auropunctata excludes native species without ensuring effective dispersal. In the context of an intense disturbance regime, our work illustrates a neo-assembled community of ants, dominated by exotic ones, some of which could provide a function relay with respect to maintaining the dynamic of maquis. Our work illustrates the “context dependency” of invasive species’ impacts as a function of anthropogenic disturbance’s level. It also discusses the possible contribution of these ants in a context of restoration after disturbance of habitats on ultramafic substrates, or even their use in ecological engineering program.

In the context of global biodiversity crisis at world scale, research of efficient environmental proxies are urgently required, especially in tropical island ecosystems, to better assess environment quality and select conservation priorities. In New Caledonia ecosystems, crickets have a dominant contribution to natural communities, according to their richness, diversity and range of colonized habitats. They are highly abundant in ecosystems and also have a high contribution to the soundscape with their ability to produce species-specific airborne signals. In this context of search of efficient environmental proxies, we measured the response of cricket communities in a ecological succession on utlramafic soils and facing the spread of 2 invasive ants (Wasmannia auropunctata and Anoplolepis gracilipes). Through both classical community census and bioacoustic approach through passive acoustic monitoring, we have been able to characterize specific cricket assemblage of species in each succession stage, with a striking sensitivity for biological invasions. Also, a global acoustic analysis of soundscape, greatly dominated by crickets, provides similar results without taxonomic or acoustic identification or knowledge. These preliminary results provide critical insights for the management of ecosystems, Our findings open up promising field of research in order to generalized innovative bio-indication concepts using cricket community in other cricket rich tropical regions; Plus de 150 espèces de grillons (Ensifères, Orthoptères) sont présentes en Nouvelle-Calédonie avec un taux d’endémisme de 90%. Cette microfaune, abondante dans les milieux forestiers et sensible aux conditions biotiques et abiotiques, peuvent être des bio-indicateurs de premier choix dans le suivi de la biodiversité. L’échantillonnage et l’enregistrement de l’activité acoustique (méta-acoustique) des communautés sous différentes conditions écologiques (invasions biologiques et dynamique forestière) est la base de ce travail de thèse.En bioacoustique : quelle est l’activité acoustique des communautés grillon en Nouvelle-Calédonie ? Cette activité varie-t-elle en fonction de la structure de la végétation (maquis, para-forestier et forêt dense) ? Finalement, est-ce que cette activité acoustique peut se décrire sous forme de « niches acoustiques », avec les paramètres du chant (temporels et spectraux), le nycthémère (l’heure de la journée) et les indices comportementaux (les postes de chants, le bruit ambiant) ?Fourmis invasives : est-ce que les fourmis envahissantes (Wasmannia auropunctata, Anoplolepis gracilipes et Pheidole megacephala) impactent les densités relatives et la diversité spécifique des populations d’Orthoptères ? Si oui, est-ce un phénomène de compétition par prédation directe (sur les œufs, juvéniles ou adultes) ou par compétition indirecte (site de chant et site de repos indisponible, accès à la reproduction réduit) ?Nous avons 3 principaux objectifs : (1) Taxonomie : accumuler des connaissances sur cette microfaune peu connue qui présente un taux d’endémisme supérieur à 90%. Créer et enrichir une collection de base et de référence sur les Orthoptères de Nouvelle-Calédonie ; (2) Ecologie fonctionnelle : déterminer l’impact des changements globaux (fourmis invasives et structure forestière) sur la dynamique et la structure des populations d’Orthoptères ; (3) Gestion du patrimoine : créer un outil de mesure non-invasif de la biodiversité des forêts néo-calédoniennes et de l’état des écosystèmes grâce à la bioacoustique de cette microfaune.

In the context of global biodiversity crisis at world scale, research of efficient environmental proxies are urgently required, especially in tropical island ecosystems, to better assess environment quality and select conservation priorities. In New Caledonia ecosystems, crickets have a dominant contribution to natural communities, according to their richness, diversity and range of colonized habitats. They are highly abundant in ecosystems and also have a high contribution to the soundscape with their ability to produce species-specific airborne signals. In this context of search of efficient environmental proxies, we measured the response of cricket communities in a ecological succession on utlramafic soils and facing the spread of 2 invasive ants (Wasmannia auropunctata and Anoplolepis gracilipes). Through both classical community census and bioacoustic approach through passive acoustic monitoring, we have been able to characterize specific cricket assemblage of species in each succession stage, with a striking sensitivity for biological invasions. Also, a global acoustic analysis of soundscape, greatly dominated by crickets, provides similar results without taxonomic or acoustic identification or knowledge. These preliminary results provide critical insights for the management of ecosystems, Our findings open up promising field of research in order to generalized innovative bio-indication concepts using cricket community in other cricket rich tropical regions, Plus de 150 espèces de grillons (Ensifères, Orthoptères) sont présentes en Nouvelle-Calédonie avec un taux d’endémisme de 90%. Cette microfaune, abondante dans les milieux forestiers et sensible aux conditions biotiques et abiotiques, peuvent être des bio-indicateurs de premier choix dans le suivi de la biodiversité. L’échantillonnage et l’enregistrement de l’activité acoustique (méta-acoustique) des communautés sous différentes conditions écologiques (invasions biologiques et dynamique forestière) est la base de ce travail de thèse.En bioacoustique : quelle est l’activité acoustique des communautés grillon en Nouvelle-Calédonie ? Cette activité varie-t-elle en fonction de la structure de la végétation (maquis, para-forestier et forêt dense) ? Finalement, est-ce que cette activité acoustique peut se décrire sous forme de « niches acoustiques », avec les paramètres du chant (temporels et spectraux), le nycthémère (l’heure de la journée) et les indices comportementaux (les postes de chants, le bruit ambiant) ?Fourmis invasives : est-ce que les fourmis envahissantes (Wasmannia auropunctata, Anoplolepis gracilipes et Pheidole megacephala) impactent les densités relatives et la diversité spécifique des populations d’Orthoptères ? Si oui, est-ce un phénomène de compétition par prédation directe (sur les œufs, juvéniles ou adultes) ou par compétition indirecte (site de chant et site de repos indisponible, accès à la reproduction réduit) ?Nous avons 3 principaux objectifs : (1) Taxonomie : accumuler des connaissances sur cette microfaune peu connue qui présente un taux d’endémisme supérieur à 90%. Créer et enrichir une collection de base et de référence sur les Orthoptères de Nouvelle-Calédonie ; (2) Ecologie fonctionnelle : déterminer l’impact des changements globaux (fourmis invasives et structure forestière) sur la dynamique et la structure des populations d’Orthoptères ; (3) Gestion du patrimoine : créer un outil de mesure non-invasif de la biodiversité des forêts néo-calédoniennes et de l’état des écosystèmes grâce à la bioacoustique de cette microfaune.