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International audience; Globally, the estimated total area planted with transgenic plants producing Bacillus thuringiensis (Bt) toxins was 12 million hectares in 2001. The risk of target pests becoming resistant to these toxins has led to the implementation of resistance-management strategies. The efficiency and sustainability of these strategies, including the high-dose plus refuge strategy currently recommended for North American maize, depend on the initial frequency of resistance alleles. In this study, we estimated the initial frequencies of alleles conferring resistance to transgenic Bt poplars producing Cry3A in a natural population of the poplar pest Chrysomela tremulae (Coleoptera: Chrysomelidae). We used the F2 screen method developed for detecting resistance alleles in natural pest populations. At least three parents of the 270 lines tested were heterozygous for a major Bt resistance allele. We estimated mean resistance-allele frequency for the period 1999–2001 at 0.0037 (95% confidence interval = 0.000 45–0.0080) with a detection probability of 90%. These results demonstrate that (i) the F2 screen method can be used to detect major alleles conferring resistance to Bt-producing plants in insects and (ii) the initial frequency of alleles conferring resistance to Bt toxin can be close to the highest theoretical values that are expected prior to the use of Bt plants if considering fitness costs and typical mutation rates.

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Classical biological control is often advocated as a tool for managing invasive species. However, accurate evaluations of parasitoid species complexes and assessment of host specificity are impeded by the lack of morphological variation. Here, we study the possibility of host races/species within the eulophid wasp Pediobius saulius, a pupal generalist parasitoid that parasitize the highly invasive horse-chestnut leaf-mining moth Cameraria ohridella. We analysed the population genetic structure, host associations and phylogeographic patterns of P. saulius in Europe using the COI mitochondrial gene. This marker strongly supports a division into at least five highly differentiated parasitoid complexes, within two of which clades with differing degrees of host specialization were found: a Balkan clade that mainly (but not only) attacks C. ohridella and a more generalist European group that attacks many hosts, including C. ohridella. The divergence in COI (up to 7.6%) suggests the existence of cryptic species, although this is neither confirmed by nuclear divergence nor morphology. We do not find evidence of host tracking. The higher parasitism rates observed in the Balkans and the scarcity of the Balkan–Cameraria haplotypes out of the Balkans open the possibility of using these Balkan haplotypes as biological control agents of C. ohridella elsewhere in Europe.

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International audience; Three genes encoding proteins showing sequence similarity and features typical of insect APNs were characterized in C. tremulae and designed as CtAPN1, CtAPN2 and CtAPN3. Expression analysis of the three C. tremulae APN genes showed that CtAPN2 transcript is more abundant in the fat body, whereas both CtAPN1 and CtAPN3 are specifically expressed in the midgut. Despite a similar genomic organization, lepidopteran and coleopteran APNs are phylogenetically distant, suggesting that APN gene duplication events occurred after these two insect orders split. Sequence and expression comparisons of CtAPN1, CtAPN2 and CtAPN3 cDNAs in a C. tremulae Bacillus thuringiensis (Bt)-susceptible and in a Bt-resistant strain did not show any polymorphism at the amino acid level or difference at the transcription level

International audience; Recent research suggests that genetic diversity in tree population may shape associated species assemblages and then drive ecosystem processes. Trees can support large numbers of insect species and some functional traits of trees have been shown to have major influence on insect communities and resultant damage. Studying the response of insect herbivore populations to the genetic diversity of tree populations is therefore a relevant approach to test community genetics hypotheses. The objective of our study was to evaluate how insect herbivory is affected by genotypes of Populus nigra, a dominant native poplar species in riparian forests of Europe. In a field experiment, we planted eight native P. nigra clones in plots of increasing genetic diversity with combinations of one to six clones. Insect herbivory was measured using visual estimation of leaf damage by six functional guilds of insects: chewers, skeletonisers, leaf miners, gall makers, leaf rollers, sap suckers and sap feeders. Response of insect herbivory to increasing genotypic diversity was analysed by considering the net diversity effect which was further divided in a complementary and a selection effects. Overall we observed slightly higher insect herbivory in poplar clone mixtures than in clone monocultures. This pattern was due to two opposite mechanisms. There was a positive complementary effect, with higher associational susceptibility in more genetically diverse mixtures. On the other hand, the selection effect also increased with the genetic diversity as the more diverse clone mixtures were more likely to comprise insect resistant clones.

International audience; Lombardy poplar (Populus nigra cv ‘Italica’) has been planted all over Europe, mostly as single trees or in rows along roads or around squares. This clone represents a unique opportunity to study local effects (e.g. associated community diversity) on a single genotype. We investigated the effect of local environmental conditions (biogeographical species pools, site conditions, surrounding vegetation) and clines in environmental conditions (climate, latitude) on the diversity of associated organisms, notably insect species. Pairs of trees were selected on at least five sampling sites (mixture of rural and urban) in each of the following countries: France, Germany, Hungary, Italy and Poland. Fifty leaves per tree were selected randomly once a month from May until September and evaluated for damage by six functional groups of insect: chewers, skeletonizers, leaf miners, sucking and sap feedings, gall makers and leaf rollers. Insect species were also determined for leaf miners and gall makers. There was no significant difference in damage levels between pairs of trees at each site, but significant differences were found among sites and among countries for the means of leaves damaged by each functional group. The same leaf miner species were found in the five counties but at different frequencies. The dominant gall-maker species was the aphid, Pemphigus spyrothecae, in all countries; however both species composition and dominance varied strongly among sites. Remarkably, species diversity (Shannon-Wiener Index) of gall makers and leaf miners was higher on urban sites than on rural sites.

National audience; Des recherches récentes ont montré que la diversité génétique des arbres peut conditionner l’assemblage des communautés associées et ainsi façonner l’évolution des écosystèmes. Les arbres peuvent héberger une importante communauté d’insectes et certains de leurs traits fonctionnels (débourrement végétatif, surface foliaire...) peuvent avoir une influence majeure sur la consommation des insectes. L’objectif de cette étude est d’évaluer comment l’herbivorie interagit avec la diversité génétique intraspécifique de huit clones de peuplier noir du bassin de la Loire. Nous avons installé en avril 2009 un dispositif expérimental en milieu naturel au sein de la ripisylve à peuplier noir de l’ISS Loire (intensive study site, http://www.evoltree.eu/), comprenant 120 parcelles unitaires de 6 plants, en combinaison variable de 1 à 6 génotypes. Des dispositifs similaires ont été installés en Hongrie, Italie et Pologne dans le cadre du réseau d’excellence européen Evoltree. L’herbivorie a été mesurée par estimation visuelle des dommages foliaires de six guildes fonctionnelles d’insectes : brouteurs, squeletteurs, mineuses, enrouleurs, galligènes, piqueurs-suceurs. La réponse des insectes a été analysée en tenant compte du niveau de diversité et de la composition des parcelles. Les premiers résultats du dispositif de Loire montrent un effet positif de la diversité, principalement expliqué par une plus forte sensibilité des parcelles les plus diversifiées génétiquement.

International audience; We provide a comprehensive overview of those Lepidopteran invasions to Europe that result from increasing globalisation and also review expansion of species within Europe. A total of 97 non-native Lepidoptera species (about 1% of the known fauna), in 20 families and 11 superfamilies have established so far in Europe, of which 30 alone are Pyraloidea. In addition, 88 European species in 25 families have expanded their range within Europe and around 23% of these are of Mediterranean or Balkan origin, invading the north and west. Although a number of these alien species have been in Europe for hundreds of years, 74% have established during the 20th century and arrivals are accelerating, with an average of 1.9 alien Lepidoptera newly established per year between 2000 2007. For 78 aliens with a known area of origin, Asia has contributed 28.9%, Africa (including Macaronesian islands, Canaries, Madeira and Azores) 21.6%, North America 16.5%, Australasia 7.2% and the neotropics just 5.2%. The route for almost all aliens to Europe is via importation of plants or plant products. Most alien Lepidoptera established in Europe are also confined to man-made habitats, with 52.5% occuring in parks and gardens. We highlight four species in particular, Diaphania perspectalis, Cacyreus marshalli, Cameraria ohridella and Paysandisia archon, as the most important current economic threats.

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Invading Nature- Springer Series in Invasion Ecology by James A. Drake (Series Editor); International audience

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International audience; The horse-chestnut leaf miner, Cameraria ohridella Deschka and Dimic, is a moth of unknown origin that was first observed in Macedonia in 1984 and has now invaded most of Europe. It is now attacked by several native leaf miners' parasitoids. Despite the low parasitism rates observed in C. ohridella, populations are so high that an unusual amount of polyphagous parasitoids are produced in the vicinity of infested horse-chestnut trees two or three times per year. In spring, the bulk of the parasitoids emerge at least six weeks before the first suitable C. ohridella larvae or pupae are available. These parasitoids have the possibility to massively attack the first indigenous leaf miners developing in spring. Predators may also increase in numbers in the vicinity of C. ohridella outbreaks. ln the present study, carried out in Switzerland, France and Bulgaria, we test the hypothesis that the presence of C. ohridella has an influence on the populations of native leaf miners though shared naturai enemies. This indirect interaction between two or more species via their natural enemy complex is called "apparent competition". The first results show a general decrease in leaf miner richness in the presence of C. ohridella, particularly in spring. Population densities of some leaf miners sharing their parasitoid complex with C. ohridella, such as the beech and oak leaf mining weevils Orchestes fagi and Orchestes quercus in Switzerland and France, and several leaf mining moths in Bulgaria, significantly decreased in the vicinity of horse-chestnut trees infested by C. ohridella. Studies are presently carried out to investigate whether these decreases are due to parasitoids or predators associated with C. ohridella.

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La populiculture est souvent mise en cause dans la gestion des zones humides. Si certains cortèges faunistiques et floristiques sont en effet directement menacés à cause des interventions humaines dans ces zones sensibles, ceux associés à l’agrosystème peupleraie sont presque inconnus et notamment en ce qui concerne l’entomofaune. Une étude a été réalisée de 2001 à 2003 pour évaluer la diversité des Coléoptères carabiques des peupleraies en Picardie. Cet article présente la liste et l’écologie des espèces répertoriées et considère certains facteurs abiotiques impliqués dans la biodiversité carabologique des peupleraies picardes., Biodiversity of ground beetles in the Picardy poplar plantations (Coleoptera Carabidae). The populiculture is often blamed in the management of the wetlands. Indeed some wetland assemblages are directly threatened by anthropic disturbance.However, there is only a few data on poplar assemblages and in particular on the insect fauna. A study was carried out from 2001 to 2003 to evaluate the ground beetle diversity of poplar stands in Picardy. First this article provides the list and the ecology of the inventoried species, and then considers some abiotic factors involved in the carabid biodiversity of poplar plantations in Picardy.

International audience; The invasion of species outside their native range is increasingly frequent and can have serious impact on biodiversity and cause health risks and economical damage to agriculture and forestry. The rapid spread of these alien invasive species has mainly been investigated from an ecological point of view. Little is known about the evolutionary aspects of invasions. lnvasions are rapid evolutionary events in which populations are unusually subjected to founder effects during colonization events followed by a rapid expansion. Thus newly arrived populations are likely to be less variable than the original population from which they derived. This represents a paradox since successful invading species are likely to be genetically depauperate compared to their source populations. We study this paradox using Cameraria ohridella, an invasive microlepidoptera, whose origin is unknown as a model system. Since its discovery in Macedonia, twenty years ago, this insect has progressively colonized all western and central Europe. Here we use molecular markers to study the genetic variability of c. ohridella, across its geographical distribution. The main objectives of this study are (i) to study the genetic structure of both the area of origin and invaded areas of c. ohridella; (ii) to see whether the invasion process and associated demographic expansion is due to changes in the genetic structure of the populations; (iii) to assess whether both invasive insects show a loss of genetic diversity associated with the process of invasion and for the presence of "invasive" haplotypes.

National audience; The horse-chestnut leaf miner, Cameraria ohridella Deschka and Dimic is a lepidopteran of unknown origin. This species was first obseгved in Macedonia more than 20 years ago and since then, it had spread over almost al Europe. It causes outbreaks on the European horse-chestnut Aesculus hippocastanum L., but other horse chestnut and maple species may be attacked. The damages do not lead to immediate plant health problem but pose aesthetical and economical problem on urban trees. The rapid growth of moth populations, the great host plant availability in urban environnement, and the lack of predators and specific parasitoides make the control of this insect difficult. The possibilities and limits of the use of the different control methods аге discussed.; La mineuse du marronnier Cameraria ohridella Deschka and Dimic est un lépidoptère dont l'origine est inconnue. Cette espèce, découverte en macédoine il y a plus de 20 ans, a ensuite colonisé progressivement toute l'Europe. Elle provoque d'importants dégâts sur le marronnier d'inde Aesculus hippocastanum L., mais d'autres espèces de marronniers et d'érables peuvent être attaquées. Les dégâts n'entraînent pas de risques immédiats de déclin des arbres mais posent des problèmes esthétiques et économiques pour les arbres urbains. L'accroissement rapide des populations de la mineuse, la grande disponibilité de la plante hôte dans les villes, l'absence de prédateurs, et de parasites spécifiques ne facilitent pas la lutte contre cet insecte. Les possibilités et les limites de l'application des différentes stratégies de lutte sont discutées.

International audience; The horse chestnut leafminer cameraria ohridella Deschka & Dimic (Lepidoptera, Gracillariidae) is an invasive species of unknown origin first observed and identified in Macedonia in 1984 (Deschka & Dimic 19g6). The species has subsequently invaded much of central and westem Europe over the last 20 years at an approximate rate of 60 km year This species almost exclusively develops on leaves of white-flowered horse chestnut, Aesculus hippocastanum L., and can cause extensive dam- age' resulting in premature defoliation of trees in the summer- some infestations have also been recorded on maples : Acer pla- tanoides and Acer pseudoplatanus , but these appear to be opportunistic intestations adjacent to heavily infested horse chest- nut trees' However, considering the pressure on the moth to find new host plants after having defoliated host chestnut trees, it is suspected that damage on Acer sp. will increase. As a conseguence, we have studied the possible impact of this pest on maples' across Europe' we have canied out surveys in the Balkans, SwiEerland and France to record c. ohridella infestations on A- pseudoplatanus, and to study the parasitoid complex on both maple and hors€ chestnut tree€. Molecular analyses are being canied orÎ to study the possible presence of host races.

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International audience; The parasitism of the horse chestnut leafminer remains at a low level in Europe since many years. As a consequence, horse chestnuts in regions with more than 20 years of C. ohridella infestation still suffer from heavy leafminer attack.However, results of our investigations show changes in the parasitoid complex over the years, reflecting three different strategies exemplified by three parasitoidspecies. (1) The abundance of the most common parasitoid, Minotetrastichus frontalis, seems to remain at the same low level, indicating that the parasitoid does not actively search for special leafminer hosts but rather encounter them by chance. The relative impact of these species decreases as other parasitoids gain importance. (2) Other species, like Pediobius saulius, seem to undergo a slow adaptation process. Their relative importance in the parasitoid complex increases at many locations infested for a long time. In the long run, parasitism of these species may reach levels exhibiting a controlling effect on the leafminer's populations. (3) A third group of species seems to follow the spread of its new host and invade new regions. Starting in the year 2000, the originally eastern European species Cirrospilus talitzkii was recorded from C. ohridella in countries where it has never been found before on any other leafminer. Meanwhile, the species can be found as a regular element of the parasitoid complex of the horse chestnut leafminer in many south and central European countries. To the present, these changes in the parasitoid complex have no significant impact on overall parasitism of C. ohridella. However, there are measurable effects, like an increasing rate of pupal parasitism due to the action of P. saulius. In the long run, changes in the parasitoid spectrum of the horse chestnut leafminer may increase the impact of parasitism and contribute substantially to the control of the invasive species in future.

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National audience; Des inventaires réalisés dans des plantations de peupliers ont révélé une diversité surprenante de carabes, d’oiseaux et de végétation.

International audience; The very fast spread of the horse-chestnut leafminer Cameraria ohridella throughout Europe has been mainly attributed to a very high dispersal ability combined with wind or human passive transportationover long distances.However, the species effective dispersal characteristics remain to be better understood. Here we present data of experiments aiming to describe the decrease in population estimate as a function of distance to a population source. Firstly, we analysed the decrease in infestation level on horse-chestnut trees along three transect avenues departing from population source located in green areas in Brussels. Secondly, we describe the decrease in catches of pheromone traps disposed along two transects departing from an isolated group of infested chestnut trees. Results of these two experiments suggest that the active dispersal ability might be very short (approx. 100m), and that the largest part of the dispersal could be the result of infested leaves (or fragments) blown from population source during the winter.The evolutionary perspective of this hypothesis (i.e. do leafminers benefit from being dispersed with their leaves) and applied consequences for pest management at the scale of cities is discussed.

International audience; Although it is likely that the horse chestnut leaf miner Cameraria ohridella (Lepidoptera: Gracillaridae)entered France in the course of 1998, its first observation was recorded near Paris in 2000. The rapid spread of the leafminer throughout Europe suggested that the country would be quickly invaded, and surveys were carried out in 2001, 2002 and 2003 to follow its nationwide spread. Surveys aiming at detecting the presence of the pest by visual observation of leaf damages were carried out in late summer/early autumn in the centre and East of the country in 2001, whereas they were extended to the West in 2002 and 2003. The pattern of spread derived from the spatial analysis of these data is compared to the pattern of spread already described for Germany in term of spread rate and possible relationship with human population density.

International audience; Two Populus deltoïdes clones (P.deltoïdes Bartr.cl.'55/65'and P.deltoïdes Bartr. cl.'2KEN8') with high resistance to Anoplophora glabripennis (Resistant rate are 96.16 %,97.37 %, respectively) were used as parents and crossed by artificial controlled pollination, 37 among of which F1 progenies were planted in Shuyang, Jiangsu province and tested for insect resistance with the borer Apriona germari Hope. Under artificial inoculation and natural infestation with Apriona germari Hope, significant variations of oviposition and larval development were observed between progenies. Both artificial inoculation and natural infestation alow the characterization of plant resistance to insect, although insect behavioral responses sometimes differ between free choice (natural infestation) and no choice experiment (inoculation).

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149 ref. *INRA. Documentation, Orleans Diffusion du document : INRA. Documentation, Orleans Diplôme : Dr. d'Université

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