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The honeybee population of the tropical Reunion Island is a genetic admixture of the Apis mellifera unicolor subspecies, originally described in Madagascar, and of European subspecies, mainly A. m. carnica and A. m. ligustica , regularly imported to the island since the late 19th century. We took advantage of this population to study genetic admixing of the tropical-adapted indigenous and temperate-adapted European genetic backgrounds. Whole genome sequencing of 30 workers and 6 males from Reunion, compared with samples from Europe, Madagascar, Mauritius, Rodrigues, and the Seychelles, revealed the Reunion honeybee population to be composed on an average of 53.2 6 5.9% A. m. unicolor nuclear genomic background, the rest being mainly composed of A. m. carnica andtoalesserextent A. m. ligustica . In striking contrast to this, only 1 out of the 36 honeybees from Reunion had a mitochondrial genome of European origin, suggesting selection has favored the A. m. unicolor mitotype, which is possibly better adapted to the island’s bioclimate. Local ancestry was determined along the chromosomes for all Reunion samples, and a test for preferential selection for the A. m. unicolor or European background revealed 15 regions significantly associated with the A. m. unicolor lineage and 9 regions with the European lineage. Our results provide insights into the long- term consequences of introducing exotic specimen on the nuclear and mitochondrial genomes of locally adapted populations

Globalisation has resulted in the movement of organisms outside their natural range, often with negative ecological and economic consequences. As cities are hubs of anthropogenic activities, with both highly transformed and disturbed environments, these areas are often the first point of entry for alien species. We compiled a global database of cities with more than one million inhabitants that data had on alien species occurrence. We then identified the most prominent pathways of introduction and vectors of spread of alien species in these cities. Most species were intentionally introduced to cities and were released or escaped from confinement. The majority of alien species then spread within cities through natural means (primarily unaided dispersal). Pathway prominence varied across the taxonomic groups of alien species: the most prominent pathway for plants and vertebrates was the escape pathway; for invertebrates the stowaway and contaminant pathways were most likely to facilitate introductions. For some organisms, pathway prominence varied with the geographical and climatic characteristics of the city. The characteristics of the cities also influenced the prominence of vectors of spread for alien species. Preventing the natural spread of alien species within cities, and into adjacent natural environments will be, at best, difficult. To prevent invasions, both the intentional and unintentional introduction of potentially harmful alien species to cities must be prevented. The pathways of introduction and vectors of spread identified here should be prioritised for management.

Rift Valley fever (RVF) is a major zoonotic and arboviral hemorrhagic fever. The conditions leading to RVF epidemics are still unclear, and the relative role of climatic and anthropogenic factors may vary between ecosystems. Here, we estimate the most likely scenario that led to RVF emergence on the island of Mayotte, following the 2006–2007 African epidemic. We developed the first mathematical model for RVF that accounts for climate, animal imports and livestock susceptibility, which is fitted to a 12-years dataset. RVF emergence was found to be triggered by the import of infectious animals, whilst transmissibility was approximated as a linear or exponential function of vegetation density. Model forecasts indicated a very low probability of virus endemicity in 2017, and therefore of re-emergence in a closed system (i.e. without import of infected animals). However, the very high proportion of naive animals reached in 2016 implies that the island remains vulnerable to the import of infectious animals. We recommend reinforcing surveillance in livestock, should RVF be reported is neighbouring territories. Our model should be tested elsewhere, with ecosystem-specific data., Author summary Rift Valley fever (RVF) is an arboviral hemorrhagic fever affecting primarily livestock in Africa and in the Arabian Peninsula. The conditions leading to RVF emergence are not fully understood, mainly because of data scarcity. Applied to the island of Mayotte (our ecosystem under study), for which 12 years RVF serological dataset are available, and by using a mechanistic model, we demonstrate that RVF epidemics related mainly to the introduction of infectious animals. Our work confirms that anthropogenic factors, such as livestock movements, need to be accounted for in order to understand the epidemiology of this disease. Our model should be tested elsewhere, with ecosystem-specific data.

‪Contexte - Depuis 2016, la noctuelle Spodoptera frugiperda, d'origine américaine, s'est établie en Afrique subsaharienne. Sa grande nuisibilité est constatée notamment sur le maïs. Présentation - Ses caractéristiques sont détaillées : morphologie et critères de différenciation d'avec les trois autres principales espèces de Spodoptera, biologie avec sa nuisibilité et sa longue liste de plantes-hôtes (dont le maïs, le sorgho, le riz, la canne à sucre et le cotonnier), cycle et dégâts. Analyse du risque - Dans un premier temps, les territoires français menacés sont ceux de l'océan Indien (La Réunion, Mayotte). Cependant, l'intensité des échanges internationaux et les capacités de dispersion naturelle du ravageur entraînent un risque plus étendu d'introduction. Une analyse climatique montre un risque d'établissement notable à élevé sur tout le pourtour méditerranéen, y compris le sud de la France, et un risque d'incursions plus au nord.

L'introduction et le transfert d'espèces de poissons entre continents et au sein de ceux-ci sont des pratiques qui remontent à l'antiquité et qui ont connu un développement considérable au XX e siècle. Les principales motivations de ces introductions sont l'amélioration de la production de la pêche et le développement de la pisciculture. Tous les continents ont fait l'objet de telles introductions \; les cas de l'Afrique et l'Asie sont plus particulièrement étudiés dans cet article. En Afrique, l'introduction d'espèces exotiques n'a pas significativement contribué à dynamiser le développement d'une filière aquacole demeurée à un très faible niveau de production, d'autant que la biodiversité des espèces de poissons autochtones est élevée. En Asie, en revanche, la production aquacole est fondée pour l'essentiel sur les carpes chinoises, les carpes indiennes et la carpe commune, largement transférées hors de leur aire d'origine. L'introduction, en même temps que ces espèces, du paquet technologique les concernant, a sans doute largement contribué au délaissement des ressources aquacoles autochtones, qui, elles, exigent un long travail de domestication. Les tilapias, originaires d'Afrique et produits principalement en Asie, constituent l'exemple remarquable d'une domestication et d'une production aquacole ex situ dont l'existence d'un marché international contribuera, certainement, à soutenir la progression. L'analyse de ces introductions à des fins aquacoles fait ressortir un impact écologique globalement faible et, en revanche, un bilan socio-économique largement bénéfique.

International audience; Comparing available paleontological, archaeological, historical, and former distributional data with current natural history and distributions demonstrated a turnover in the French vertebrate fauna during the Holocene (subdivided into seven sub-periods). To this end, a network of 53 specialists gleaned information from more than 1300 documents, the majority never cited before in the academic literature. The designation of 699 species as native, vanished, or non-indigenous in France or in one or more of its biogeographical entities during the Holocene period was investigated. Among these 699 species, 585 were found to belong to one or more of these categories. Among the 154 species that fit the definition of non-indigenous, 86 species were new species for France during the Holocene. Fifty-one that were autochthonous vanished from France during this period. Among these 51 species, 10 (two birds and eight mammals) are now globally extinct. During the last 11 millennia, the turnover in the French vertebrate fauna yielded a net gain of 35 species. On a taxon-by-taxon basis, there was a gain in the sizes of the ichthyofauna (19 : 27%), the avifauna (10 : 3%) and the herpetofauna (7 : 9%) and a loss in the mammalian fauna (−1 : 1%). Values of a per-century invasion index were less than 1 between 9200 BC and 1600 AD but increased dramatically after this date. An exponential model fits the trajectory of this index well, reaching the value of 132 invasions per century for the last sub-period, which encompasses 1945–2002. Currently, the local ecological and economic impacts of populations of 116 species (75% of the 154 that satisfied the criteria for non-indigenous) are undocumented, and the non-indigenous populations of 107 vertebrate species (69%) are unmanaged. The delay in assessing the ecological and economical impact of non-indigenous species, which is related to a lack of interest of French academic scientists in the Science and Action programmes, prevents the public from becoming informed and hinders the debates needed to construct a global strategy. For such a strategy to be effective, it will have to be elaborated at a more global scale than in just France – definitely at least in Europe.

Le commerce des animaux vivants est l'un des principaux modes d'introduction de virus dans les zones indemnes à partir de leurs zones d'enzootie. Depuis quelques années, certains animaux sauvages sont considérés comme des animaux de compagnie, ce qui augmente la diversité des espèces d'animaux faisant l'objet d'un commerce international. Ceci pourrait permettre à des pathogènes présentant un large spectre d'hôtes, comme certains arbovirus, d'élargir leur aire de répartition. L'objectif de cette étude était d'analyser le risque posé par les importations d'animaux vivants pour l'introduction, dans l'Union européenne (UE), de quatre arbovirus affectant l'Homme et le cheval : les virus des encéphalites équines de l'est (EEEV) et de l'ouest (WEEV), de l'encéphalite vénézuélienne (VEEV) et de l'encéphalite japonaise (JEV). Des données d'importations, environnementales et des données de densité de population humaine et équine ont été combinées pour calculer des indicateurs spatialisés du risque d'introduction de ces virus et des conséquences potentielles de telles introductions. Les résultats montrent l'existence de zones à risque en Belgique, aux Pays-Bas et dans le nord de l'Italie, avec un niveau de risque plus élevé pour l'EEEV que pour les trois autres virus, risque principalement attribuable au commerce des animaux de compagnie importés par lots de petite taille d'origines variées. La diversité croissante des espèces et des origines de ces animaux pourrait avoir dans le futur un impact important sur le risque d'introduction d'arbovirus dans l'UE.

International audience; The castniid palm borer, Paysandisia archon (Burmeister) (Lepidoptera: Castniidae), is a South American moth that in the last ten years has become a major pest of palm trees in the Mediterranean region. Current knowledge on the reproductive behavior of this diurnal moth suggests the importance of both visual and chemical cues, in particular the production of a male pheromone emitted during a specific scratching behavior. Male-produced scents have diverse functions in lepidopteran sexual communication but generally act during courtship behavior, leading to complex, stereotyped courtship sequences. As a first step to understand the cues involved in mating behavior and the role of male scents in male mating success, we quantified sequences of P. archon courtship behavior using video filming. To distinguish behaviors leading to an approach of both partners from those involved in short-range courtship, sequences were divided into "approach" and "interaction" phases. Quantifications and analyses were first made by NPMANOVA analysis of behavioral event frequencies, followed by flowchart construction using transition matrix probabilities. In 90% of the observations, courting activities led to copulation, but successful sequences were highly variable and could be divided into two categories, "rapid" and "prolonged" courtship sequences. In both categories, approaches were performed by males but depended strongly on female movements, especially on female flights. The significant behavioral differences were observed after the first contact (i.e., interaction phase) where, in rapid sequences, males generally acceded to copulation without displaying scratching behavior. Conversely, in prolonged sequences, the female expressed evading behavior and male scratching frequency increased. The possible roles of male scent emission in female mate choice and the importance of visual cues in the mating behavior of P. archon are discussed.

Présentation de l'éditeur : Invasions de frelons asiatiques, de ragondins, d'ibis sacrés, de renouées du Japon... On entend souvent parler de ces nouvelles menaces pour l'environnement. Un raz de marée d'espèces venues d'ailleurs serait-il sur le point d'envahir nos villes et nos campagnes ? Le thème scientifique de l'invasion biologique est très émotivement connoté, et l'auteur propose ici de le dépassionner. D'une part, les bouleversements écologiques observés dans des écosystèmes fermés, lacs ou îles, ne sont pas généralisables aux milieux plus ouverts. D'autre part, les espèces invasives devraient-elles être considérées comme des espèces inutiles et contraires à l'écologie ? Et d'où vient cette conception étroite de la "nature" comme collection d'écosystèmes bien ordonnés ayant existé de toute éternité ? Non seulement les espèces, animales ou végétales, ne cessent d'évoluer, mais les invasions correspondent à un ajustement du vivant au monde réel que nous avons façonné et dans lequel nous vivons aujourd'hui. La clé du problème semble bien être dans la redéfinition d'une nature figée, idéalisée sur des bases erronées, au profit d'une nature en perpétuel renouvellement, sainement gérée et maîtrisée. Toutes les espèces "invasives" ne sont pas néfastes, et il importe, pour le bien de tous, d'accompagner les changements de l'environnement plutôt que de les combattre. La guerre des espèces n'aura pas lieu

La crise environnementale actuelle s'accompagne d'une crise de la biodiversite, et d'une crise epidemiologique marquee par des emergences de maladies infectieuses nouvelles issues de la faune sauvage et domestique. Existerait-il des liens entre biodiversite et transmission des pathogenes ? Les pertes de biodiversite s'accompagnent-elles d'une augmentation des risques sanitaires infectieux ? A l'inverse, la faune sauvage et la biodiversite au sens large subissent-elles l'usage des antibiotiques ? Les services rendus par les ecosystemes comme la pollinisation assuree par les abeilles sont-ils menaces par les pesticides ? La faune sauvage est-elle devenue, a son corps defendant, sentinelle de la qualite sanitaire de notre environnement ? (Resume d'auteur)

International audience; Recent studies have produced new insight into the origin and distribution of some cattle ticks in the south-western Indian Ocean islands. Rhipicephalus appendiculatus, introduced from Tanzania in 2002, is now well established on Grande Comore but has not yet reached the other islands of the archipelago (Moheli, Anjouan and Mayotte). Only one of the two clades identified in Africa has settled so far. Amblyomma variegatum, which was not supposed to be able to persist in the Antananarivo region (1300 m) nor in other Malagasy regions of high altitude without regular introductions of ticks by infested cattle, is now endemic as a general rule up to 1600 m although other regions of lower altitude (1400 m) are still free of the tick. This species remains confined in a small area of the west coast on La Reunion Island. On the contrary, Hyalomma dromedarii could not settle on Madagascar where it was introduced in 2008 and Rhipicephalus evertsi evertsi is not yet present in Grande Comore despite regular introductions by infested cattle from Tanzania. A phylogeographic approach has been carried out at an intra-specific level for A. variegatum. This study has led to the identification of two main lineages, one covering all species distribution and one restricted to East Africa and the Indian Ocean area. These two lineages are in sympatry in Madagascar where a high genetic diversity has been described, whereas a lower genetic diversity is observed on other islands. These results seem to agree with the historical data concerning the introduction of the tick in the Indian Ocean area.

Paysandisia archon was accidentally introduced into Europe where it damages endemic and ornamental palms, also threatening the date palm from North Africa. Little was known about sex pheromones in the Castniidae day-flying moth before a recent paper that concluded on the absence of female sex pheromone in P. archon. A putative identification of a short-range male pheromone, present on fore- and hindwings, was reported. In this paper, we describe the original structure of the male androconia located on the tarsi of the mid-legs. The extracts of mid-legs were analysed by GC/MS and the chemical structure of the male androconia component was identified as E2,Z13-18:OH. After extraction in solvent, biological activity of the extracts was assessed by EAG. The chemistry and the morphology of the androconia reinforce the current classification of the Castniidae in the Cossoid/Sesioid assemblage and provide new information on the chemical ecology in day-flying Lepidoptera and suit the recent paper describing the courtship behaviour.

chapitre 2; National audience

Introduction events can lead to admixture between genetically differentiated populations and bottlenecks in population size. These processes can alter the adaptive potential of invasive species by shaping genetic variation, but more importantly, they can also directly affect mean population fitness either increasing it or decreasing it. Which outcome is observed depends on the structure of the genetic load of the species. The ladybird Harmonia axyridis is a good example of invasive species where introduced populations have gone through admixture and bottleneck events. We used laboratory experiments to manipulate the relatedness among H. axyridis parental individuals to assess the possibility for heterosis or outbreeding depression in F1 generation offspring for two traits related to fitness (lifetime performance and generation time). We found that inter-populations crosses had no major impact on the lifetime performance of the offspring produced by individuals from either native or invasive populations. Significant outbreeding depression was observed only for crosses between native populations for generation time. The absence of observed heterosis is indicative of a low occurrence of fixed deleterious mutations within both the native and invasive populations of H. axyridis. The observed deterioration of fitness in native inter-population crosses most likely results from genetic incompatibilities between native genomic backgrounds. We discuss the implications of these results for the structure of genetic load in H. axyridis in the light of the available information regarding the introduction history of this species.

chapitre 3; National audience

The risk of introduction of new insect pest species is growing with the increase in passenger travel and the trade in plant products worldwide. Though effective detection methods exist in a number of cases, only some of them are applied in practice through organized networks. This paper reviews the detection tools available for insect pests, based on commonly available attractants and trapping systems. Chemical attractants are divided into powerful attractants (such as pheromones and para-pheromones), attractants of lower intensity (such as kairomones and food attractants), and their combinations. Physical attractants are also considered, such as visual cues, which are generally used in combination with olfactory attractants, and light traps. Finally, the diversity of trapping systems is also presented in relation to attractants, trap design and target species.

En 2009, le réseau CaribVET a réalisé une enquête au sein des Services vétérinaires des pays et territoires de la Caraïbe afin d'évaluer les perceptions associées à l'évaluation du risque et d'identifier les principales maladies exotiques d'intérêt pour la région ainsi que leurs modalités d'introduction. L'étude a montré que l'introduction d'animaux vivants était considérée comme la voie d'accès la plus probable des agents pathogènes exotiques affectant les animaux, suivie de l'introduction non contrôlée de produits d'origine animale par les passagers des navires. Ces résultats ont été utilisés pour définir une stratégie d'évaluation des risques pour la santé animale qui tienne compte de l'importance des échanges intra-régionaux.

Trade is important for economic development and growth; however, it is also the principal means of introducing invasive pests and disease vectors that can cause environmental damage and economic losses and pose a serious risk to biodiversity. Invasive pests and trade have created a two-way linkage, leading to perceptions that African countries are becoming a source of invasive pests in other countries via trade. What phytosanitary measures do African countries have to take therefore to reduce losses in economic and trade opportunities? Another important issue is the ability of African countries to reduce trade-related pest invasions from other countries and the impact of such invasions on African economies and the environment. Management strategies that can reduce the introduction of exotic pests, while not restricting the benefits of trade or causing protective trade barriers, are desirable. This paper reviews linkages between trade and invasive pests and the resulting effects on African agricultural exports, the economy, environment and biodiversity. Strategies and policies to deal with invasive pests, trade and trade barriers and protectionism are reviewed to assess how they may affect or can be used by African countries to address these problems.

We present the first review of Hymenoptera alien to Europe. Our study revealed that nearly 300 species of Hymenoptera belonging to 30 families have been introduced to Europe. In terms of alien species diversity within invertebrate orders, this result ranks Hymenoptera third following Coleoptera and Hemiptera. Two third of alien Hymenoptera are parasitoids or hyperparasitoids that were mostly introduced for biological control purposes. Only 35 phytophagous species, 47 predator species and 3 species of pollinators have been introduced. Six families of wasps (Aphelinidae, Encyrtidae, Eulophidae, Braconidae, Torymidae, Pteromalidae) represent together with ants (Formicidae) about 80% of the alien Hymenoptera introduced to Europe. The three most diverse families are Aphelinidae (60 species representing 32% of the Aphelinid European fauna), Encyrtidae (55) and Formicidae (42) while the Chalcidoidea together represents 2/3 of the total Hymenoptera species introduced to Europe. The first two families are associated with mealybugs, a group that also included numerous aliens to Europe. In addition, they are numerous cases of Hymenoptera introduced from one part of Europe to another, especially from continental Europe to British Islands. These introductions mostly concerned phytophagous or gall-maker species (76 %), less frequently parasitoids. The number of new records of alien Hymenoptera per year has shown an exponential increase during the last 200 years. The number of alien species introduced by year reached a maximum of 5 species per year between 1975 and 2000. North America provided the greatest part of the hymenopteran species alien to Europe (96 species, 35.3%), followed by Asia (84 species, 30.9%) and Africa (49 species, 18%). Three Mediterranean countries (only continental parts) hosted the largest number of alien Hymenoptera: Italy (144 spp.), France (111 spp.) and Spain (90 spp.) but no correlation was found with the area of countries. Intentional introduction, mostly for biological control, has been the main pathway of introduction for Hymenoptera. Consequently, the most invaded habitats are agricultural and horticultural as well as greenhouses. To the contrary, Hymenoptera alien in Europe are mostly associated with woodland and forest habitats. Ecological and economic impacts of alien Hymenoptera have been poorly studied. Ants have probably displaced native species and this is also true for introduced parasitoids that are suspected to displace native parasitoids by competition, but reliable examples are still scarce. The cost of these impacts has never been estimated.

National audience

Dans les îles, éradiquer pour protéger ?

II existe désormais un domaine reconnaissable de la biologie de la réintroduction. Depuis le début des années 1980, les programmes de réintroduction sont en constante augmentation. Cependant, historiquement, ces projets ont connu un faible taux de réussite. L'objectif de cette synthèse bibliographique est de déterminer si la biologie de la réintroduction peut être considérée comme un outil de conservation des espèces. L'Union Mondiale pour la Nature (UICN), après sa prise de position relative aux transferts d'organismes vivants en 1987, publia en 1998 les Lignes Directrices Relatives aux Réintroductions, dont le plan a été utilisé pour mener à bien cette synthèse. Les objectifs d'un programme peuvent être multiples, le principal restant l'établissement d'une population viable, en liberté, dans son milieu naturel. De nombreuses activités préparatoires doivent être menées, qu'il s'agisse d'activités purement biologiques comme l'évaluation du site, le choix du stock d'individus et sa préparation, les risques sanitaires, les techniques de lâcher, ou d'activités annexes comme les conditions socio-économiques, juridiques, la création d'une équipe multidisciplinaire, les efforts de sensibilisation des communautés ou la recherche de financements. La majorité des difficultés n'est généralement pas rencontrée sur des questions biologiques. II est nécessaire d'établir un programme d'évaluation afin d'identifier clairement la rentabilité et la réussite du projet à travers une récolte minutieuse de données après le lâcher. De nombreux points restent à améliorer mais il semble évident que la réintroduction offre des potentiels de recherches énormes pour le futur. Une des priorités reste le développement de lignes directrices détaillées en fonction des espèces étudiées. De même, un effort est à faire dans la publication de résultats concernant les réintroductions, même si ces dernières sont des échecs.

Drosophila subobscura is a Palearctic species that was first observed in South and North America in the early 1980s, and that rapidly invaded broad latitudinal ranges on both continents. To trace the source and history of this invasion, we obtained genotypic data on nine microsatellite loci from two South American, two North American and five European populations of D. subobscura. We analysed these data with traditional statistics as well as with an approximate Bayesian computation (ABC) framework. ABC methods yielded the strongest support for the scenario involving a serial introduction with founder events from Europe into South America, and then from South America into North America. Stable effective population size of the source population was very large (around one million individuals), and the propagule size was notably smaller for the introduction into South America (i.e. high bottleneck severity index with only a few effective founders) but considerably larger for the subsequent introduction into North America (i.e. low bottleneck severity index with around 100-150 effective founders). Finally, the Mediterranean region of Europe (and most likely Barcelona from the localities so far analysed) is proposed as the source of the New World flies, based on mean individual assignment statistics.

International audience; New Caledonia has an exceptionally diverse and unique flora, and there is growing concern about the impacts of introduced wild rusa deer on native forests. The diets of free-ranging rusa deer from two native forest sites were studied using rumen content analysis. Samples (n = 61) from a sclerophyll forest site consisted principally of graminoids (64.6 ± 4.4% dry weight), mainly native grass, but the proportion of woody species increased during the dry season. In the rumen samples from the rainforest site (n = 56), woody species were the predominant plants (61.9 ± 3.7% dry weight), and the composition of the diet was more constant across seasons. Most of the food items found could not be identified to species level, but it is estimated that native plants represent 40–60% of rusa deer diet. Although more work is needed to assess diet preferences and impacts of rusa deer, we suggest that they represent a potentially important threat to some native plant species in New Caledonia.

Cette analyse de risque a été réalisée en utilisant les principes de la norme CIPV (NIMP n°11),sous la forme du "système pour l'évaluation du risque phytosanitaire"mise au point par l'OEPP, mais certaines questions ont été peu renseignées, par manque de données ou dans une volonté de simplification.Les données principales sont reprises selon un plan simplifié proposé par l'OEPP, favorisant une présentation rapide de l'organisme nuisible et du risque lié à son introduction :aux Antilles,en Guyane,à la Réunion. Au niveau des facteurs de risque, #N.octasema# est un bio-agresseur au comportement variable en fonction des lieux où on le rencontre.Dans certaines zones il n'est même pas une contrainte pour les bananiers alors que dans d'autres zones il commet de sérieux dégâts. Il est important de noter qu'il est très difficile de mener une lutte efficace. La probabilité d'entrée de cet insecte est très peu élevée contrairement à sa probabilité d'établissement très élevée. L'estimation de son impact économique potentiel est fort pour les Antilles, moyen pour la Guyane et la Réunion. Cet insecte est potentiellement extrêmement nuisible (par exemple en Australie dans le Queensland) à la culture de la banane et bien que son entrée dans les DOM paraisse peu probable, elle est toujours possible. Cet organisme mérite donc de figurer sur la liste de quarantaine pour les Antilles,la Guyane et la Réunion.

La Nouvelle-Zélande, qui compte 1% des espèces animales du globe pour 0,17% seulement des surfaces émergées, est caractérisée par son haut niveau de spéciation et la forte originalité de sa faune, liée notamment à la quasi-absence de mammifères. Dans ce contexte, l'introduction souvent délibérée d'espèces animales a eu des conséquences particulièrement désastreuses sur l'environnement. En l'absence de compétiteurs, les animaux introduits ont aisément envahi, puis bouleversé les milieux naturels, jusqu'à entraîner parfois la disparition d'espèces indigènes. Face à cette situation, les Néo Zélandais sont passés maîtres dans la restauration écologique de milieux insulaires affectés par des invasions animales.

Cette mission fait suite à celle réalisée en juin 2001 (Vercambre, 2001) et octobre puis novembre - décembre 2002. Elle avait pour principaux buts: i/ la restitution des résultats de l'enquête réalisée par la F.D.G.D.O.N. entre juin et août 2003; ii/ la programmation des actions à entreprendre afin de poursuivre l'évaluation de la lutte biologique menée contre Hoplochelus marginalis à l'aide du champignon entomopathogène Beauveria brongniartii introduit une quinzaine d'années auparavant (Vercambre et al., 1990); iii/ la participation aux échanges de la réunion bipartite Maurice-Réunion concernant le Protocole Ver Blanc; celui-ci régit certains échanges aéroportuaires entre les deux pays durant la période de vol des scarabées afin d'éviter leur introduction accidentelle dans les deux îles. Les deux premiers points ont pu être abordés lors d'une réunion du Groupe de Travail Ver Blanc. Le dernier point a été l'occasion d'échanges fructueux avec nos collègues mauriciens. Le vol des adultes de H. marginalis a été faible durant les deux sorties réalisés à Pierrefonds et Gillot (4 adultes /piège). Mais les observations au Port ont montré que l'espèce Heteronychus ficas était trouvé en nombre non négligeable sur les ponts de bateaux. Par ailleurs, les prises de Alissonotum piceum sont maintenant régulières au piège lumineux de Gillot depuis la saison 2002-2003. Le détail des activités apparaît aux annexes 1 et 2. La mission a été financée par le Pôle 3P.

The capacity to react quickly to species introductions and to plan effective management countermeasures is always difficult, and methodology is lacking. This paper summarizes the different steps of a decision-making protocol applied to the recent establishment of an exotic species, the House Sparrow Passer domesticus, in the Lesser Antilles. This pest bird damages crops, fruits and stored food products and also competes with numerous hole-nesting birds in a large part of its range, and this requires more or less rapid management decision to limit its impact. In order to construct a base for decision-making in the Lesser Antilles case, we designed and conducted a brief biological study involving three spatial scales. At the regional scale, we defined the state of spread of House Sparrows throughout the West Indies. At the island scale, we estimated the number and distribution of breeding colonies. At the local scale, we estimated the numbers and behaviour of House Sparrows. To enable a quick decision to be made, we also suggested organizing a collective decision-making process applying a multi-actor guideline taking account of the different kinds of actors and levels of competence. We applied this method and we presented our results to a multi-actor workshop. The collective decision-making chose to apply the precautionary principle on one island (bird eradication) and to install both communications and monitoring plans. The procedure involving both multi-spatial scale assessment and a multi-actor workshop needs to be refined but its prospects are promising.

In the subantarctic French territory of the Kerguelen Islands, Atlantic salmon Salmo salar was stocked to create a new population in the Korrigans drainage system. The analysis of historical scale collections showed that hybrids were inadvertently introduced with the original Atlantic salmon stocks. Later colonization of the Korrigans system by brown trout Salmo trutta was followed by interspecific hybridization between the two species. Our results highlight the importance of both routine genetic monitoring of hatchery stocks and considering the possible influence of other species when stocking is envisaged.