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Xylella fastidiosa (Xf) is a vector-borne plant bacterium native to the Americas, which causes severe diseases to agricultural crops, ornamental plants and forest trees. The bacterium is becoming a source of worldwide health plant concern and disease outbreaks associated with Xf have occurred outside of its native range (in Europe, Asia and the Middle East). Several studies have estimated risks associated with Xf outbreaks in invaded regions under current climate conditions, but future climate change has been seldom addressed. In the present study, we calibrated correlative models of bioclimatic species distribution to forecast the potential range and severity of two economically important Xf-related diseases (Pierce's disease and the bacterial leaf scorch of shade trees) by the period 2040–2060. Models predict that conditions could become highly favourable for Pierce's disease in economically important wine-producing regions of the world, highlighting the need to design control strategies. Similarly, models suggest that risk of bacterial leaf scorch of shade trees might increase in temperate regions where it is still apparently absent. However, we note that substantial uncertainty in predictions arises from high levels of correlation among climatic variables in the calibration data set. The inherent lack of knowledge concerning whether the distribution of Xf-related diseases is at climatic equilibrium or not in Europe may also influence our predictions. The models provide valuable information to identify regions where increased surveillance efforts should be made and where control strategies are required., This work was funded by the European Union Horizon 2020 research and innovation program under grant agreement no. 727987 XF-ACTORS and the Plant health department of the INRAE (French National Research Institute for Agriculture, Food and the Environment).

International audience; Ambrosia trifida L. (giant ragweed, Asteraceae) is native to the North American continent and was introduced into Europe and Asia at the end of the 19th century. In its native range, this tall annual species is common in riparian and ruderal habitats and is also a major weed in annual cropping systems. For nearly a century, A. trifida has also been of great concern in the U.S. for its highly allergenic pollen, necessitating targeted control measures to reduce its impact on human populations. Based on the distribution of A. trifida in North America and in its introduced range, riparian systems in the rest of the world may be particularly at risk to invasion, with potential negative consequences for their biodiversity. Currently, A. trifida has invaded Asia more widely than Europe, likely due to the more favourable local conditions in Asia. Throughout its introduced range, A. trifida is host to a limited number of invertebrates and pathogens and only a few biological agents are available for its control. The main impacts of A. trifida at a global level are on crop yield and human health, resulting in significant socio-economic impacts. The success of A. trifida invasion in areas in which it has been introduced is still unclear, but climate change may increase climate suitability, increasing the potential for A. trifida to spread. While effective management in cultivated fields seems potentially possible, the development and control of A. trifida in natural riparian habitats is of great concern due to the difficulty of management in these areas.

To investigate enemy pressure across the range of the pine processionary moth (Thaumetopoea pityocampa, Den. & Schiff.) as it spreads northwards in Europe because of climate change, a survey of 206 egg batches from historical and newly colonized areas at both the westernmost and the easternmost ends of the front was carried out in 2016–2018. Out of them, 97 egg batches were collected from nine locations in three regions in France and 109 from four localities in two regions in Bulgaria, both within historical and newly colonized ranges of the pest. The average number of eggs per batch collected in Bulgaria (226.6 ± 43.2) was higher than that in France (194.3 ± 50.1). However, the hatching percentage was higher in French samples, varying from 69.8 to 95.7, vs 49.8 to 85.2 per cent in Bulgarian samples. Four primary parasitoids (Ooencyrtus pityocampae, Baryscapus servadeii, Anastatus bifasciatus, Trichogramma sp.) and a hyperparasitoid (Baryscapus transversalis, found only in two regions of the historical range in Bulgaria) were identified. The oligophagous species B. servadeii was present at all sites within the historical range of the pest. In newly colonized areas, the impact of primary parasitoids on the host was distinctly low, suggesting that they lag behind the range expansion of pine processionary moth. In France, the most abundant species in the T. pityocampa parasitoid complex were B. servadeii in Ré Island and Orléans (97.3 and 87.4 per cent, respectively), and Trichogramma sp. (99.7 per cent) in a newly colonized locality in Fréhel. Ooencyrtus pityocampae prevailed in three of four Bulgarian localities (72.1 per cent in Sandanski, 89.7 per cent in Maglizh and 65.7 per cent in Sladak kladenets), whereas B. servadeii was the most abundant in Gega (75.4 per cent). Mortality of B. servadeii and O. pityocampae caused by the hyperparasitoid B. transversalis amounted to 4.8–6.2 per cent. The impact of predators on the pine processionary moth in the egg stage was negligible at most sites, reaching 12.5 per cent in only one site (Maglizh).

Urbanization consist in a complex and deep human-driven environmental change that strongly impacts the ecology and evolution of living organisms, including pathogens, reservoir and vector species hence human health. Quantitative proxies of urban landscapes may be very useful to sum-up such a complexity and to guide fundamental and applied research as well as urban planning programs. Geographic Information Systems (GIS) provide landscape and uses metrics which can be investigated through multivariate analyses, thus providing pertinent synthetic landscape descriptors. As such, our study describes the fine-scale modelling of three urban neighborhoods of Cotonou city, Benin, using GIS, landscape metrics and Principal Component Analysis (PCA). Spatial variability between and within neighborhoods revealed different levels of variability, with elements differentiating the three areas from each other, while local neighbourhood-specific variations were also evidenced. We found that Cotonou landscapes are strongly influenced by their history, the natural environment in which they develop as well as the urban planning trajectories. This case study shows that PCA-analyzed of GIS-based metrics may be very relevant to describe and understand the variability of urban landscapes at different scales, thus constituting a valuable tool for urban management of African cities.

Biological invasions represent a major threat for biodiversity and agriculture. Despite efforts to restrict the spread of alien species, preventing their introduction remains the best strategy for an efficient control. In that context preparedness of phytosanitary authorities is very important and estimating the geographical range of alien species becomes a key information. The present study investigates the potential geographical range of the glassy-winged sharpshooter (Homalodisca vitripennis), a very efficient insect vector of Xylella fastidiosa, one of the most dangerous plant-pathogenic bacteria worldwide. We use species distribution modeling (SDM) to analyse the climate factors driving the insect distribution and we evaluate its potential distribution in its native range (USA) and in Europe according to current climate and different scenarios of climate change: 6 General Circulation Models (GCM), 4 shared socioeconomic pathways of gas emission and 4 time periods (2030, 2050, 2070, 2090). The first result is that the climate conditions of the European continent are suitable to the glassy-winged sharpshooter, in particular around the Mediterranean basin where X. fastidiosa is present. Projections according to future climate conditions indicate displacement of climatically suitable areas towards the north in both North America and Europe. Globally, suitable areas will decrease in North America and increase in Europe in the coming decades. SDM outputs vary according to the GCM considered and this variability indicated areas of uncertainty in the species potential range. Both potential distribution and its uncertainty associated to future climate projections are important information for improved preparedness of phytosanitary authorities.

Monitoring of plant pathogens is usually carried out by analyzing symptomatic plant material. However when plants are frequently asymptomatic, which is the case for Xylella fastidiosa (Xf), this approach is problematic because it limits our ability to early detect the bacterium hence to understand and control its spread. To complement plant survey and facilitate large-scale monitoring, we propose to generalize the use of insect vectors as sentinels. We tested this approach in Corsica using Philaenus spumarius, an ubiquitous insect vector, as sentinel. We will present a high throughput method based on a two-step PCR approach followed by Illumina sequencing. Two genes of the MLST of Xf were targeted to identify the three main subspecies of Xf (multiplex, pauca or fastidiosa). This approach enables larger screening than classic (nested) PCR approaches followed by Sanger sequencing. We used this approach to monitor the spatio-temporal prevalence of Xf within vector populations (27 populations of 30 specimens). Our results show that Xf occurs throughout Corsica with a prevalence in insects up to 43% depending on the region and the year of sampling. Moreover, we show that Xf is present in ecosystems assumed uncontaminated on the basis of plant monitoring. No spatial, temporal or vegetation-related pattern of Xf prevalence in insects seem to emerge from our first data. Our results confirm that Xf introduction in Corsica likely predates 2015, it suggests ecological resilience of ecosystems and argues in favor of using insect vectors for Xf survey at large scale in Europe., FR; PPT; pauline.farigoule@inrae.fr

Philaenus spumarius (Hemiptera: Aphrophoridae) is a major vector of Xylella fastidiosa (Xf) in Europe. However, the drivers influencing its abundance are still poorly known. In Corsica from 2018 to 2020, we monitored the abundance of P. spumarius three times a year in 64 permanent plots distributed along vegetation and altitudinal (0-600m) gradients. The vegetation gradient ranged from shrubland to oak forest and accounted for the density of Cistus monspeliensis on which P. spumarius usually develops and feed in Corsica. Abundance of P. spumarius was estimated through visual counting of foams and sweep netting of adults. Both vegetation composition and climate descriptors were recorded at each sampling location. We used partial least squares path modelling and generalized linear mixed models to unravel the relationships between vegetation / climate descriptors and P. spumarius abundance. Philaenus spumarius abundance significantly decreases with increasing average temperature. Abundance of P. spumarius was significantly and positively correlated with C. monspeliensis density, confirming difference in host plant preference between Corsica and mainland France. A significant effect of vegetation structure was also found with forests hosting lower P. spumarius abundance. The strong association observed between P. spumarius and C. monspeliensis suggests that Xf expansion may have been facilitated by firebreaks or disturbed habitats where C. monspeliensis is abundant as an early colonizer. Managing C. monspeliensis in the vicinity of agricultural areas may constitute an essential component of prophylaxis against Xf in Corsica.

Global change is currently inducing shifts in the distribution of many species, including harmful pests. In the present study, we addressed the potential future response of Xylella fastidiosa-related diseases to ongoing climate change. Using available data documenting the worlwide Xf distribution and bioclimatic data, we fitted correlative species distribution models to depict the climatic niche of harmful Xf-related diseases (e.g. Pierce’s disease). We then predicted the potential climatic suitability in Europe for these diseases under future climate conditions simulated by global circulation models considering various future scenario of greenhouse gas emissions. Models predict that some region including economically important agricultural areas (e.g. most of wine-producing regions of Western Europe) might likely experience an important increase in climatic suitability for the pathogen by the period 2040-2060. These results are crucial for European agriculture and, are important for the design of future control and monitoring strategies as well as the implementation of research projects., ES; PDF; martin.godefroid@gmail.com

Since the detection of Xylella fastidiosa (Xf) in Italy, European research interest into this bacterium has considerably increased. Research mainly focusses on Xf biology, evolution and epidemiology. However, managing the spread of Xf also requires the mobilization of other actors, whose action supports research driven strategy. Indeed, people who are directly impacted (arboriculturalist, winegrowers) must be involved to slow down the spread of Xf. We propose an interdisciplinary work that combines the production of knowledge in ecology with the analysis of the construction, use and diffusion of this knowledge to stakeholders using social studies of science and technology practices. In ecology, field observations, statistical and biomolecular analyses are conducted to characterize plant - insect vector and insect vector - Xf interactions. In sociology, an analysis of scientific production is carried out through the implementation of participatory observation to understand how scientific activities are linked with epidemiological surveillance. In addition, an analysis of the preparedness of stakeholders (professionals from agriculture, research and institutions involved in the French epidemiological surveillance system) based on semi-directive interviews is implemented. This interdisciplinary study, whose approach and first results will be presented has two objectives i) to propose prophylactic and control methods to slow down or prevent the establishment of Xf in the uncontaminated territories and ii) to provide recommendations for the dissemination and implementation of these practices with an evaluation of the preparedness in France. This approach could also lead to a reflexive understanding of how sciences and public management might be articulated to understand Xf disease as a socio-pathosystem., FR; PDF; jean-pierre.rossi@inrae.fr

In Europe, many potential and confirmed vectors of Xylella fastidiosa (Xf) are polyphagous but appear to aggregate on their preferred host plants at local scales. For example, Philaenus spumarius is found most often on Asteraceae on the Californian coast, or on Apiaceae and Rubiaceae in the meadows of central Italy. However, vectors keep the ability to exploit multiple host-plants, which can be crucial in primary Xf transmission to crops. In this study, we assessed the habitat preferences of spittlebugs on and in the vicinity of Corsican clementine and olive groves, focusing on four habitats: Cistus monspeliensis border, Dittrichia viscosa cover, crop foliage and grove ground vegetation. Spittlebug abundance was assessed three times a year during two years on five to nine clementine and olive organic groves. Nymph and adult abundances were quantified based on spittle mass counts and nymph identification in April and sweep net sampling in June and October. Habitat preferences were inferred based on generalized linear mixed models. Overall, 6647 spittle masses and 1714 adults belonging to four species were found. Philaenus spumarius had a significant preference for Cistus monspeliensis, and to a lesser extent for Dittrichia viscosa. Neophilaenus campestris mostly occurred on ground vegetation of the grove and on Dittrichia viscosa. Lepyronia coleoptrata was less abundant on crop foliage than on ground vegetation and Aphrophora alni showed an even abundance in all habitats. This study demonstrates the specialization of P. spumarius on C. monspeliensis in the diversified Corsican landscape as well as strong habitat preferences for N. campestris. All recorded species were able to colonize clementine or olive foliage, but rarely, and in similar abundancies for all species. Should they be proven equivalent effective vectors, this suggests similar roles of these four species in Xf transmission to crops.

The current climate change has marked impacts on the phenology of species, i.e., the timing of the various stages of their life cycle. Yet, to fully understand how phenological patterns are modified by the changes of temperature regimes, it is of prime importance to rely on high quality historical data. We here document a very valuable data set including the individual monitoring of the end of the larval phase and the date of adult emergence in the pine processionary moth Thaumetopoea pityocampa. A total of 46 479 caterpillars were followed between 1970 and 1984 in 6 sites along an altitudinal gradient in southern France. As optional prolonged diapause occurs in this species, i.e. some individuals experience one or more years of diapause before emerging, the caterpillars sampled any given year were monitored during up to 5 years. The goal was to give precise information about phenology in this species to further analyse its spatial and temporal patterns of variation.This dataset is unique by its richness and the type of data it contains. Phenology in the pine processionary moth is often monitored by the use of pheromone traps in the field, which does not provide all the necessary information because it is then not possible to trace back the exact origin of the moth trapped, nor to characterise other steps of the life cycle. More, as it corresponds to historical data dating back to the 70s and the 80s, it provides a historical baseline of trends in the pre-warming period.

Trilateration is a popular approach in localization. Many related geometric approaches have been proposed for 2D scenarios. In general, each approach has a standard case in which the main solution is applied, and many specific cases. Each specific case has a particular solution, which makes the algorithm more complex. This paper introduces a novel geometric approach that covers all the cases considered by previous algorithms. It turns out though that this approach is a special case of an existing approach, for which we hence provide a geometric interpretation. Numerical results illustrate the method in RSS-based localization while estimating simultaneously the path loss component.

Fastq paired reads for analyzed samples are available as a NCBI Sequence Read Archive (ID#PRJNA606284). Custom script to detect cross-contamination is available from https://github.com/DNAdiversity/UCE-Cross-Contamination-Check.Datasets (morphological matrix, concatenated UCEs) and trees have been uploaded on Zenodo (https://doi.org/10.5281/zenodo.3666638).; International audience; Recent technical advances combined with novel computational approaches have promised the acceleration of our understanding of the tree of life. However, when it comes to hyperdiverse and poorly known groups of invertebrates, studies are still scarce. As published phylogenies will be rarely challenged by future taxonomists, careful attention must be paid to potential analytical bias. We present the first molecular phylogenetic hypothesis for the family Chalcididae, a group of parasitoid wasps, with a representative sampling (144 ingroups and seven outgroups) that covers all described subfamilies and tribes, and 82% of the known genera. Analyses of 538 Ultra-Conserved Elements (UCEs) with supermatrix (RAxML and IQTREE) and gene tree reconciliation approaches (ASTRAL, ASTRID) resulted in highly supported topologies in overall agreement with morphology but reveal conflicting topologies for some of the deepest nodes. To resolve these conflicts, we explored the phylogenetic tree space with clustering and gene genealogy interrogation methods, analyzed marker and taxon properties that could bias inferences and performed a thorough morphological analysis (130 characters encoded for 40 taxa representative of the diversity). This joint analysis reveals that UCEs enable attainment of resolution between ancestry and convergent/divergent evolution when morphology is not informative enough, but also shows that a systematic exploration of bias with different analytical methods and a careful analysis of morphological features is required to prevent publication of artifactual results. We highlight a GC content bias for maximum-likelihood approaches, an artifactual mid-point rooting of the ASTRAL tree and a deleterious effect of high percentage of missing data (>85% missing UCEs) on gene tree reconciliation methods. Based on the results we propose a new classification of the family into eight subfamilies and ten tribes that lay the foundation for future studies on the evolutionary history of Chalcididae.

The battle between humans and plant pests is as old as agriculture, but the movement of pests as a consequence of human activities has been exacerbated only recently. International research collaboration is increasingly important to tackle pests causing serious damage to economies.

Xylosandrus compactus and X. crassiusculus are two polyphagous ambrosia beetles originating from Asia and invasive in circumtropical regions worldwide. Both species were recently reported in Italy and further invaded several other European countries in the following years. We used the MaxEnt algorithm to estimate the suitable areas worldwide for both species under the current climate. We also made future projections for years 2050 and 2070 using 11 different General Circulation Models, for 4 Representative Concentration Pathways (2.6, 4.5, 6.0 and 8.5). Our analyses showed that X. compactus has not been reported in all potentially suitable areas yet. Its current distribution in Europe is localised, whereas our results predicted that most of the periphery of the Mediterranean Sea and most of the Atlantic coast of France could be suitable. Outside Europe, our results also predicted Central America, all islands in Southeast Asia and some Oceanian coasts as suitable. Even though our results when modelling its potential distribution under future climates were more variable, the models predicted an increase in suitability poleward and more uncertainty in the circumtropical regions. For X. crassiusculus, the same method only yielded poor results, and the models thus could not be used for predictions. We discuss here these results and propose advice about risk prevention and invasion management of both species.

Despite their ecological and evolutionary importance as key components of tropical ecosystems, the phylogeny of fig trees is still unresolved. We use restriction-site-associated DNA (RAD) sequencing (ca420kb) and 102 morphological characters to elucidate the relationships between 70 species ofFicusrepresenting all known subgenera and sections and five outgroups. We compare morphological and molecular results to highlight discrepancies and reveal possible inference bias. We analyse marker and taxon properties that may bias molecular inferences, with existing softwares and a new approach based on iterative principal component analysis to reduce variance between clusters of samples. For the first time, with both molecular and morphological data, we recover a monophyletic subgenusUrostigmaand a clade with all gynodioecious fig trees. However, our analyses show that it is not possible to homogenize evolutionary rates and GC content for all taxa prior to phylogenetic inference and that four competing positions for the root of the molecular tree are possible. The placement of the long-branched sectionPharmacosyceaas sister to all other fig trees is not supported by morphological data and considered as a result of a long branch attraction artefact to the outgroups. Regarding morphological features and indirect evidence from the pollinator tree of life, the topology that divides the genusFicusinto monoeciousversusgynodioecious species appears most likely. Active pollination is inferred as the ancestral state for all topologies, ambiguity remains for ancestral breeding system including for the favored topology, and it appears most likely that the ancestor of fig trees was a freestanding tree. Increasing sampling may improve results and would be at least as relevant as maximizing the number of sequenced regions given the strong heterogeneity in evolutionary rates, and to a lesser extent, base composition among species. Despite morphological plasticity and frequent homoplasy of multiple characters, we advocate giving a central role to morphology in our understanding of the evolution ofFicus, especially as it can help detect insidious systematic errors that tend to become more pronounced with larger molecular data sets.

International audience; Speciation is nowadays recognized as a dynamic process in which the respective roles of forces driving ecological differentiation and reproductive isolation can change through time and space. Incipient speciation events are particularly useful to follow such processes that are not tractable when considering well-differentiated taxa. A promising case study was discovered in the pine processionary moth, Thaumetopoea pityocampa, a Mediterranean defoliator of Pinus species, for which allochrony acting as an automatic magic trait was recognized as the major driver of an incipient speciation process. In Portugal, a unique population with a shifted phenology, known as the summer population (SP), co-occurs with a population following the typical life cycle, known as the winter population (WP). We monitored male activity of both populations in the Leiria region, i.e. over the whole SP distribution range using a systematic sampling along two transects, and studied Portuguese WPs at a larger geographical scale to explore their genetic diversity and spatial pattern of differentiation. Results showed that the WPs were genetically more diverse than the SP, with a strong pattern of isolation by distance both at large and small spatial scales, while the SP was very homogeneous over its whole range, without signature of its recent spatial expansion. Contrary to our expectations, no F1 hybrids were identified, even though we found an extended flight period of the SP, overlapping with the beginning of the WP reproductive period. Interestingly, the SP was found to be mostly limited to the sea shore where the WP is now scarce or absent, which could suggest competitive exclusion. Once clearly occurring in a sympatric context, the allochronic differentiation tends to develop nowadays in parapatry.

International audience; The bark beetle genus Dendroctonus contains some of the most economically important pests of conifers worldwide. Despite many attempts, there is no agreement today on the phylogenetic relationships within the genus, which limits our understanding of its evolutionary history. Here, using restriction-site associated DNA (RAD) markers from 70 specimens representing 17 species (85% of the known diversity) we inferred the phylogeny of the genus, its time of origin and biogeographic history, as well as the evolution of key ecological traits (host plants, larval behavior and adults’ attack strategies). For all combinations of tested parameters (from 6,444 to 23,570 RAD tags analysed), the same, fully resolved topology was inferred. Our analyses suggest that the most recent common ancestor (mrca) of all extant Dendroctonus species was widely distributed across eastern Palearctic and western Nearctic during the early Miocene, from where species dispersed to other Holarctic regions. A first main inter-continental vicariance event occurred during early Miocene isolating the ancestors of D. armandi in the Palearctic, which was followed by the radiation of the main Dendroctonus lineages in North America. During the Late Miocene, the ancestor of the ‘rufipennis’ species group colonized north-east Palearctic regions from western North America, which was followed by a second main inter-continental vicariance event isolating Pleistocene populations in Asia (D. micans) and western North America (D. murrayanae and D. punctatus). The present study supports previous hypotheses explaining intercontinental range disjunctions across the Northern Hemisphere by the fragmentation of a continuous distribution due to climatic cooling, host range fragmentation and geological changes during the late Cenozoic. The reconstruction of ancestral ecological traits indicates that the mrca bored individual galleries and mass attacked the boles of pines. The gregarious feeding behavior of the larvae as well as the individual attack of the base of trees have apparently independently evolved twice in North America (in the ‘rufipennis’ and the ’valens’ species groups), which suggests a higher adaptive potential than previously thought and may be of interest for plant protection and biodiversity conservation in a rapidly changing world.

The bacterium Xylella fastidiosa (Xf) is a plant endophyte native to the Americas that causes worldwide concern. Xf has been recently detected in several regions outside its natural range including Europe. In that context, accurate estimates of its response to climate change are required to design cost-efficient and environment-friendly control strategies. In the present study, we collected data documenting the native and invaded ranges of the three main subspecies of Xf: fastidiosa, pauca and multiplex, as well as two strains of Xf subsp. multiplex recently detected in southern France (ST6 and ST7). We fitted bioclimatic species distribution models (SDMs) to forecast their potential geographic range and impact in Europe under current and future climate conditions. According to model predictions, the geographical range of Xf as presently reported in Europe is small compared to the large extent of suitable areas. The European regions most threatened by Xf encompass the Mediterranean coastal areas of Spain, Greece, Italy and France, the Atlantic coastal areas of France, Portugal and Spain as well as the south-western regions of Spain and lowlands in southern Italy. Potential distribution of the different subspecies / strains are contrasted but all are predicted to increase by 2050, which could threaten several of the most economically important wine-, olive- and fruit-producing regions of Europe, warranting the design of control strategies. Bioclimatic models also predict that the subspecies multiplex might represent a threat to most of Europe under current and future climate conditions. These results may serve as a basis for future design of a spatially informed European-scale integrated management strategy, including early detection surveys in plants and insect vectors, quarantine measures as well as agricultural practices.

Key message[br/] Despite variable dynamics of genetic diversification at the different altitudinal levels, strong gene flow tends to standardize larch genetic diversity: the larch forest distributed along the altitudinal gradient can be regarded as a single population.[br/] [br/] Context[br/] While in forest tree species many studies focus on the structure of the genetic diversity at the natural range and at the forest stand levels, few studies have worked at intermediate levels like the landscape level.[br/] [br/] Aims[br/] We tried to determine to what degree altitude variation can affect the genetic diversity and the local structure of the genetic diversity of European larch (Larix decidua Miller) at the landscape level.[br/] [br/] Methods[br/] Using microsatellite markers, we determined the between- and within-plot genetic structure and the spatial genetic structure (SGS) of four altitudinal plots distributed between 1,350 and 2,300 m a.s.l. in a European larch forest located in the French Alps.[br/] [br/] Results[br/] A homogenous neutral genetic structure was detected along this gradient. The intensity of the SGS was found to be stronger at 2,300 m and decreased at the 2,000-m plot. It was low or non-existent at the 1,700- and 1,350-m altitudinal levels.[br/] [br/] Conclusion[br/] Our results suggest that the genetic structure observed at the landscape level in this European larch forest was only slightly affected by climatic variation, human activities, or historical events. However, the variation of intensity of the SGS within the altitudinal plots indicates the existence of variable genetic dynamics, despite the globally uniform genetic structure along the altitudinal gradient.

We sampled ca 2500 specimens of Philaenus spumarius throughout Corsica without a priori on the presence of symptoms on plants. We screened 448 specimens for the presence of Xylella fastidiosa (Xf) using qPCR and a custom nested PCR. qPCR appeared versatile and under-estimated the prevalence of Xf. Nested PCR showed that Xf was present in all populations. Molecular results were validated by prediction on the distribution of Xf made from tests conducted on plants, which shows the pertinence of using vectors in risk assessment studies. Xf was detected in tenerals and adults. Thus, P. spumarius could acquire Xf from its host plant, mostly Cistus monspeliensis in Corsica, which may act as reservoir for the next season. This contrasts with other observations and suggests that management strategies may have to be adapted on a case-by-case basis. At least two genetic entities and several variants of Xf not yet identified on plants were present in the insects, which suggests ancient introductions of Xf and a probable underestimation of the current diversity of the strains present in Corsica. Interestingly 6% of the specimens carried two subspecies. Studies are wanted to better characterize the strains present in Corsica and know how the disease was introduced, spread and why no sign of a potential epidemic was detected earlier. This study shows that, when sensitive enough methods are implemented, insects can be used to predict and better assess the exact distribution of Xf. Insects are indeed easy to collect, Xf multiply only in their foregut and does not become circulative, which facilitates its detection., This work has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement N. 727987 "Xylella fastidiosa Active Containment Through a multidisciplinary-Oriented Research Strategy XF-ACTORS"

International audience; Trypanosomes are protozoan parasites found worldwide, infecting humans and animals. In the past decade, the number of reports on atypical human cases due to Trypanosoma lewisi or T. lewisi-like has increased urging to investigate the multiple factors driving the disease dynamics, particularly in cities where rodents and humans co-exist at high densities. In the present survey, we used a species distribution model, Maxent, to assess the spatial pattern of Trypanosoma-positive rodents in the city of Niamey. The explanatory variables were landscape metrics describing urban landscape composition and physiognomy computed from 8 land-cover classes. We computed the metrics around each data location using a set of circular buffers of increasing radii (20 m, 40 m, 60 m, 80 m and 100 m). For each spatial resolution, we determined the optimal combination of feature class and regularization multipliers by fitting Maxent with the full dataset. Since our dataset was small (114 occurrences) we expected an important uncertainty associated to data partitioning into calibration and evaluation datasets. We thus performed 350 independent model runs with a training dataset representing a random subset of 80% of the occurrences and the optimal Maxent parameters. Each model yielded a map of habitat suitability over Niamey, which was transformed into a binary map implementing a threshold maximizing the sensitivity and the specificity. The resulting binary maps were combined to display the proportion of models that indicated a good environmental suitability for Trypanosoma-positive rodents. Maxent performed better with landscape metrics derived from buffers of 80 m. Habitat suitability for Trypanosoma-positive rodents exhibited large patches linked to urban features such as patch richness and the proportion of landscape covered by concrete or tarred areas. Such inferences could be helpful in assessing areas at risk, setting of monitoring programs, public and medical staff awareness or even vaccination campaigns.