Invasive and native populations of common ragweed exhibit strong tolerance to foliar damage.

8 pages; International audience; Tolerance and resistance are defence strategies evolved by plants to cope with damage due to herbivores. The introduction of exotic species to a new biogeographical range may alter the plant herbivore interactions and induce selection pressures for new plant defence strategies with a modified resource allocation. To detect evolution in tolerance to herbivory in common ragweed, we compared 3 native (North America) and 3 introduced (France) populations, grown in a common garden environment. We explored the effect of leaf herbivory on plant vegetative and reproductive traits. Plants were defoliated by hand, simulating different degrees of insect grazing by remo…

Weed-DATA Base de données ‘Traits’ des plantes adventices des agroécosystèmes

SPEEAECOLDURGEAPSIéquipe CAPA; absent

Eight microsatellite markers isolated from common ragweed (Ambrosia artemisiifolia L.) and cross-amplification with herbarium specimens

 ; Eight microsatellite markers were developed for population genetic analyses of the common ragweed, Ambrosia artemisiifolia. Markers were tested for amplification with three populations (two recent populations from France and North America, and one historical population from herbarium specimens). These loci revealed a high level of genetic variability (5-19 alleles per locus; expected heterozygosity, 0.48-0.92). No significant deviation from Hardy-Weinberg equilibrium and no linkage disequilibrium were observed. The data thus demonstrate their utility as efficient genetic markers for determining the genetic diversity, population differentiation, and gene flow among invasive, native, and h…

Assessing the role of megafauna in tropical forest ecosystems and biogeochemical cycles - the potential of vegetation models

21 pages; International audience; Megafauna (terrestrial vertebrate herbivores > 5 kg) can have disproportionate direct and indirect effects on forest structure, function, and biogeochemical cycles. We reviewed the literature investigating these effects on tropical forest dynamics and biogeochemical cycles in relation to ecology, paleoecology, and vegetation modelling. We highlight the limitations of field‐based studies in evaluating the long‐term consequences of loss of megafauna. These limitations are due to inherent space‐time restrictions of field‐studies and a research focus on seed dispersal services provided by large animals. We further present evidence of a research gap concerning t…

Arable-weed flora and its pollen representation: A case study from the eastern part of France

International audience; Local pollen deposition in human-influenced vegetation types is studied with the aim of establishing the relationship between arable-weed vegetation and its pollen representation as an aid in interpreting human presence and impact on vegetation from pollen assemblages. The study area is located in the Franche-Comté region, eastern part of France. The presence of plants within 100 m2 plots and their pollen representation in moss samples within the same plots was recorded from different crops and annual fallows. Patterns in the vegetation and pollen assemblages were investigated separately using principal coordinate analysis (PCoA). Procrustean co-inertia analysis (PCI…

Mise au point sur la présence de l'espèce Ambrosia artemisiifolia L. dans les départements de Côte-d'Or et de Sâone-et-Loire

National audience

L'ambroisie : chronique de l'extension d'un polluant biologique en France

National audience

Ecological services performed by the bonobo (Pan paniscus): seed dispersal effectiveness in tropical forest.

Abstract:Survival of Afrotropical primary forests depends not only on habitat protection but also on the protection of animal species such as frugivorous primates, recognized as the most important seed dispersers for many plants. Here we investigate seed-dispersal services by the bonobo (Pan paniscus) in an evergreen lowland tropical rain forest of the Congo Basin. In the long-term research site of LuiKotale, we investigated food habits and seed processing based on 22 mo of behavioural observation, seed trial experiment and long-term daily GPS tracking of a habituated ape community. Bonobos were mainly frugivores (66% of all feeding sessions), spending about 3.5 h d−1swallowing seeds that w…

Variability and cryptic heteromorphism of Ambrosia artemisiifolia seeds: What consequences for its invasion in France

International audience; Background and Aims:Ambrosia artemisiifolia is a ruderal weed introduced from North America to Europe. It produces large amount of achenes which are highly heterogeneous in size. Due to the preponderant role of propagules in invasive plant processes, the achene mass variability related to germination, dispersal strategy and life history traits of offspring were investigated within this species. Methods:The variability in achene mass was quantified among six populations sampled in different habitats. The effects of achene mass variation on germination were studied. The percentages of floating and non-floating achenes were evaluated in the studied populations. The cons…

Spatial and temporal presence of grasslands maintain local weed diversity thanks to spatio-temporal dispersal process

EAGESTADINRA; In frequently disturbed environments, plant community assembly mainly results from spatial dispersal and temporal dispersal through seed bank. Here, we propose to quantify the relative contributions of temporal and spatial dispersal on weed species assembly in farmlands. Weeds are mostly annual plants that rely exclusively on seeds for perpetuation, the latter presenting various level of longevity and dispersal capacity according to the species. In farmland, arable fields surrounded by landscape with high proportion of grasslands harbor high level of weed diversity revealing important dispersal flux. Similarly, the presence of grasslands in the past history (i.e crop successio…

Growth and reproduction responses of French invasive and North American native populations of common ragweed, Ambrosia artemisiifolia L. to defoliation

Enemy release and Evolution of Increased Competitive Ability hypotheses have been put forward to explain invasion success of introduced plant species. These hypotheses assume that the loss of natural enemies could induce an evolutionary change in plant defence and in resource allocation allowing the introduced plant populations to increase in vigour and fitness. To detect changes in functional traits following defoliation, we compared native and introduced populations of common ragweed, grown in a common garden environment. We compared six populations of Ambrosia artemisiifolia L., three from the North American native range and three from the French introduction range. We explored the effec…

Seed bank dynamics of an invasive plant, Ambrosia artemisiifolia L.

AbstractThe seed-bank dynamics ofAmbrosia artemisiifolia(Asteraceae), an annual invasive plant introduced from North America to Europe, were studied in nine French populations developing in field crops, set-asides or wastelands. The vertical distribution of seeds was studied in two different depth sections (0–5 cm and 5–20 cm), and the spatial horizontal pattern of distribution was analysed for two selected field-crop and set-aside populations. The proportions of dormant, non-dormant and dead seeds, as well as the changes in seed-bank dormancy over time, were evaluated. Natural seedling recruitment and its variation under different disturbance treatments in competitive set-asides were also …

Ambrosia artemisiifolia Linnaeus, common ragweed (Asteraceae, Magnoliophyta)

Chapter 13: Species Accounts of 100 of the Most Invasive Alien Species in Europe ; International audience

Skylarks trade size and energy content in weed seeds to maximize total ingested lipid biomass

International audience; tThe trade-off between forage quality and quantity has been particularly studied in herbivore organisms,but much less for seed eating animals, in particular seed-eating birds which constitute the bulk of win-tering passerines in European farmlands. The skylark is one of the commonest farmland birds in winter,mainly feeding on seeds. We focus on weed seeds for conservation and management purposes. Weedseeds form the bulk of the diet of skylarks during winter period, and although this is still a matter fordiscussion, weed seed predation by granivorous has been suggested as an alternative to herbicides usedto regulate weed populations in arable crops. Our objectives wer…

La flore des milieux rudéraux et sa représentation pollinique : une nouvelle approche pour la reconstruction de l'environnement humain

National audience

Correction: Mbehang Nguema, P.P., et al. Characterization of ESBL-Producing Enterobacteria from Fruit Bats in an Unprotected Area of Makokou, Gabon. Microorganisms 2020,

In Gabon, terrestrial mammals of protected areas have been identified as a possible source of antibiotic-resistant bacteria. Some studies on antibiotic resistance in bats have already been carried out. The main goal of our study was to detect extended-spectrum beta-lactamases (ESBLs) that are produced by enterobacteria from bats in the Makokou region in Gabon. Sixty-eight fecal samples were obtained from 68 bats caught in the forests located 1 km from the little town of Makokou. After culture and isolation, 66 Gram-negative bacterial colonies were obtained. The double-disk diffusion test confirmed the presence of ESBLs in six (20.69%) Escherichia coli isolates, four (13.79%) Klebsiella pneu…

Tracking zoonotic pathogens using blood-sucking flies as 'flying syringes'

About 60% of emerging infectious diseases in humans are of zoonotic origin. Their increasing number requires the development of new methods for early detection and monitoring of infectious agents in wildlife. Here, we investigated whether blood meals from hematophagous flies could be used to identify the infectious agents circulating in wild vertebrates. To this aim, 1230 blood-engorged flies were caught in the forests of Gabon. Identified blood meals (30%) were from 20 vertebrate species including mammals, birds and reptiles. Among them, 9% were infected by different extant malaria parasites among which some belonged to known parasite species, others to new parasite species or to parasite …

Characterisation of phenotypic plasticity in seedling stage of native and invasive populations in Ambrosia artemisiifolia L.

Increased phenotypic plasticity has often been invoked as an hypothesis to explain the capacity of alien invasive plant species to colonize new environments, because it may enhance the ability of plants to cope with new biotic and abiotic conditions. Following this hypothesis, alien invasive populations should be represented by more plastic genotypes than populations in the native range. In annual species, the seedling stage is of crucial importance for population dynamics but surprisingly very few studies have investigated differences in phenotypic plasticity on seedling traits. Based on populations from the native range (North America) and the invasive range (France) of Ambrosia artemisii…

Gene flow and population admixture as the primary post-invasion processes in common ragweed (Ambrosia artemisiifolia) populations in France

*An improved inference of the evolutionary history of invasive species may be achieved by analyzing the genetic variation and population differentiation of recently established populations and their ancestral (historical) populations. Employing this approach, we investigated the role of gene flow in the post-invasion evolution of common ragweed (Ambrosia artemisiifolia). *Using eight microsatellite loci, we compared genetic diversity and structure among nine pairs of historical and recent populations in France. Historical populations were reconstructed from herbarium specimens dated from the late 19th to early 20th century, whereas recent populations were collected within the last 5 yr. *Re…

Doom of the elephant-dependent trees in a Congo tropical forest.

9 pages; International audience; In an evergreen lowland rain forest of the Cuvette Centrale, DR Congo, at the LuiKotale Max-Planck research site, forest elephants (Loxodonta cyclotis) are close to extinction. Between January 2009 and June 2011 we investigated the influence of elephant decline on sustainability of elephant-dispersed tree populations. For this, we explored how trees with the megafaunal syndrome reproduce without seed dispersal by elephants and how does this affect the demography and spatial distribution of these tree species. We studied alternative partners for functional replacement of the elephant. Overall, 18 tree species presenting the megafaunal syndrome were identified…

Determination of fatty acids content, global antioxidant activity and energy value of weed seeds from agricultural fields in France.

18 pages; International audience; The ecological consequences of seed size variation have been studied extensively in plants. Curiously, little attention has been paid to the qualitative and quantitative variation of the seed-stored molecules and on their ecological significance. Here, we analysed the oil content and oil composition of ca. 200 weed seed species from agricultural fields in France based on single seed accessions, concentrating on interspecies differences and ignoring within-species variation. The relationships between seed weight, oil %, fatty acids (FAs) and the energetic value of the seed and its antioxidant properties were also investigated. The antioxidant activity could …

Problématique de la dispersion des semences d'ambroisie en France

National audience

Estimation of the pollen and seed production of common ragweed in Europe

International audience; Common ragweed (Ambrosia artemisiifolia L.) is an invasive weed of fieldcrops and human-disturbed habitats in Europe. As well as in its natural range (NorthAmerica), common ragweed is a threat to human health due to its abundant allergenicpollen release. Most studies have been focused on airborne pollen monitoring, but todate, no data have been available on precise individual plant pollen and seed productionrelated to plant traits growing in natural environment and on their corresponding sourceof variation. The aim of this study was to evaluate pollen and seed production of commonragweed plants in several populations in France. Seasonal pollen production per plantran…

Détermination de la potentialité du stock de semences en messicoles rares d'une friche calcaire

National audience

Can the large ecological amplitude of Ambrosia artemisiifolia explain its invasive success in France?

International audience; In order to understand the successful spread of Ambrosia artemisiifolia in France, the variability of colonised habitat by this species was studied at 48 locations, from its central to peripheral area of distribution. Each site was characterised by a vegetation survey, a description of the A. artemisiifolia population and a soil analysis. Differences in the number of species, Shannon diversity index, evenness index and plant life form spectra were compared among the sites. A total of 276 species occurring along with A. artemisiifolia was observed. Therophytes and hemicryptophytes represented more than 80% of all the species. The two most frequent species occurring al…

Développement de l’Ambroisie dans le Sud de la Bourgogne

International audience; L'ambroisie à feuilles d'armoise, (Ambrosia artemisiifolia L.) fait partie des espèces dites « invasives» sur le territoire français. Cette espèce a déjà été signalée dans le Sud de la Bourgogne, mais il n'existait pas de données récentes sur sa présence dans le Nord de la région. Le travail réalisé montre que l'espèce est en forte extension dans les départements de Saône-et-Loire et de Côte-d'Or principalement dans les parcelles cultivées. En Saône-et-Loire, l'espèce est maintenant très largement présente aussi bien en tant qu'adventice des cultures que de plante des bords de route. En Côte-d'Or, deux types de populations coexistent: des populations « agricoles» mar…

Écologie tropicale : de l'ombre à la lumière.

192 pages; National audience; Les événements écologiques survenus ces dernières années, notamment en raison des changements globaux, et du réchauffement climatique en particulier, ont fait prendre conscience à l'opinion publique des menaces qui planent sur les zones tropicales. Et les sciences, dans une nouvelle approche transversale et interdisciplinaire, se penchent aujourd'hui sur cette écologie unique qui abrite des écosystèmes d'une grande complexité. En effet, l'équilibre de notre planète repose en partie sur ces environnements fragiles où évolue le plus grand nombre d'espèces en densité et en diversité. Cette biodiversité et la gestion des ressources associées apparaissent comme l'un…

Do the high phenotypic plasticity of A. artemisiifolia L. explain its invasive success in France?

International audience; Ambrosia artemisiifolia (Asteraceae) is an invasive annual plant introduced from North America to Europe over 100 years ago. This plant species is now widespread in numerous countries all over the world, causing damages to agricultural crops and human health. Ambrosia artemisiifolia is spreading as a weed in many field crops but is also able to invade a wide range of areas such as various human disturbed habitats or riverbanks (Figure 1). A considerable variability of the life history traits of A. artemisiifolia was previously observed among and within different populations (Fumanal et al., 2007). Since the success of colonization of some invasive plant species may r…

The Bonobo-DialiumPositive Interactions: Seed Dispersal Mutualism

A positive interaction is any interaction between individuals of the same or different species (mutualism) that provides a benefit to both partners such as increased fitness. Here we focus on seed dispersal mutualism between an animal (bonobo, Pan paniscus) and a plant (velvet tamarind trees, Dialium spp.). In the LuiKotale rainforest southwest of Salonga National Park, Democratic Republic of Congo, seven species of the genus Dialium account for 29.3% of all trees. Dialium is thus the dominant genus in this forest. Dialium fruits make up a large proportion of the diet of a habituated bonobo community in this forest. During the 6 months of the fruiting season, more than half of the bonobos' …

Species Accounts of 100 of the Most Invasive Alien Species in Europe: Ambrosia artemisiifolia Linnaeus, common ragweed (Asteraceae, Magnoliophyta)

International audience

Extension d'Ambrosia artemisiifolia L. dans le département de la Côte d'Or

International audience

Characterization of ESBL-producing enterobacteria from fruit bats in an unprotected area of Makokou, Gabon.

In Gabon, terrestrial mammals of protected areas have been identified as a possible source of antibiotic-resistant bacteria. Some studies on antibiotic resistance in bats have already been carried out. The main goal of our study was to detect extended-spectrum beta-lactamases (ESBLs) that are produced by enterobacteria from bats in the Makokou region in Gabon. Sixty-eight fecal samples were obtained from 68 bats caught in the forests located 1 km from the little town of Makokou. After culture and isolation, 66 Gram-negative bacterial colonies were obtained. The double-disk diffusion test confirmed the presence of ESBLs in six (20.69%) Escherichia coli isolates, four (13.79%) Klebsiella pneu…

Les changements globaux

National audience

Artificial germination activation of Dialium corbisieri by imitation of ecological process.

11 pages; International audience; Species of the gender Dialium commonly are trees found in Central African rainforests. They produce tasty sugary fruits, feeding numerous frugivores, but are, despite their valuable nutritional value, rarely exploited by humans. A potential reason for this could be the complexity of symbiotic dependence between trees and pollinators, germination activators, and dispersers causing problems in ancestral and contemporary domestication. We investigated Dialium corbisieri reproduction in the Democratic Republic of the Congo, Bandundu Province. Here we give a key for an artificial activation of germination of these trees ecologically adapted to the digestive syst…

Bush pig (Potamochoerus porcus) seed predation of bush mango (Irvingia gabonensis) and other plant species in Democratic Republic of Congo.

4 pages; International audience

Can fruiting plants control animal behaviour and seed dispersal distance?

In an Afrotropical forest, we tested the hypothesis that fleshy-fruit plants with interspecific dif-ferences in fruit quality and quantity affect ranging behaviour of their seed dispersal vector. Iffruiting plants could affect their dispersal vector, the plants also affect their seed dispersal distanceand eventually their plant population biology. From 2007 to 2011, we measured seed transportby georeference daily bonobo group movements via GPS. Seed dispersal distance was estimatedwith mechanistic model, using 1200 georeferenced dispersal events and the average seed transittime through bonobo (24.00 h). We compared dissemination for eight plant species that deal withthis trade-off: attracti…

High level of intrinsic phenotypic antimicrobial resistance in enterobacteria from terrestrial wildlife in Gabonese national parks.

Data on the prevalence of antibiotic resistance in Enterobacteriaceae in African wildlife are still relatively limited. The aim of this study was to estimate the prevalence of phenotypic intrinsic and acquired antimicrobial resistance of enterobacteria from several species of terrestrial wild mammals in national parks of Gabon. Colony culture and isolation were done using MacConkey agar. Isolates were identified using the VITEK 2 and MALDI-TOF methods. Antibiotic susceptibility was analysed and interpreted according to the European Committee on Antimicrobial Susceptibility Testing guidelines. The preliminary test for ESBL-producing Enterobacteriaceae was performed by replicating enterobacte…

Author response: Tracking zoonotic pathogens using blood-sucking flies as 'flying syringes'

Response and effect traits of arable weeds in agro-ecosystems: a review of current knowledge.

25 pages; International audience; Integrating principles of ecological intensification into weed management strategies requires an understanding of the many relationships among weeds, crops and other organisms of agro-ecosystems in a changing context. Extensively used during the last two decades in weed science, trait-based approaches have provided general insights into weed community response to agricultural practices, and recently to understanding the effect of weeds on agro-ecosystem functioning. In this review, we provide a holistic synthesis of the current knowledge on weed response and effect functional traits. Based on the literature and recent advances in weed science, we review cur…

Possibilité de dissémination d'Ambrosia artemisiifolia L. via les semences de tournesol

National audience