Pierre Arnal, PhD candidate 2017-

Supervisors : R. Rougerie & M. Elias (MNHN / CNRS, Paris)

Funding : ANR project SPHINX

Spatial and Temporal dynamics of diversification in the silk and hawk moths (Saturniidae and Sphingidae)

Patterns of diversity and the understanding of mechanisms that drive them are fundamental questions, whose answers would allow setting up more efficient conservation programs. However, most current knowledge comes from Vertabrates or plants and no large-scale study on the Invertebrates have been conducted though they represent most of the diversity on Earth. This situation is largely due to a lack in taxonomic and biogeographic knowledge about these organisms especially in the intertropical region in which most of them occur. In this context, during his PhD, Pierre will analyse the spatial and temporal diversification of two families of Lepidoptera, the Sphingidae and Saturniidae (silk and hawk moths) that represent ca 5000 species and for which we have access to well documented worldwide pattern of diversity. We will test alternative hypotheses related to speciation, colonisation and extension events that may explain the actual diversity and distribution of these moths. We will for example investigate : i) the impact of past geological and climatic changes on the evolution of the moths to predict the possible impact of current changes, ii) the impact of biological features of the moths on their diversification (host spectrum, range size, short or long flyers etc.). Pierre is supervised by Rodolphe Rougerie and Marianne Elias from the Paris museum but will spend part of his time in our lab to build up a representative, robust and dated phylogeny of the two groups of moths based on Ultra Conserved Elements and RAD fragments. Pierre's PhD is part of our SPHINX project

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Perrine Cruaud, Postdoctoral fellow 2015-2016

Funding : COLEOTOOL Project

Development of a lab protocol and the associated bioinformatics pipeline for the multigenic characterisation of insect species

During her stay in our lab Perrine has set up a lab protocol and the associated bioinformatics pipeline for the identification of insect species, their possible parasitoids, preys and symbionts. Together we showed that a 2 step PCR approach targeting multiple gene regions followed by Illumina sequencing was a promising approach for barcoding and integrative taxonomy. We also illustrated the fact that Illumina approaches are not artefact-free and confirmed that Sanger databases can contain non-target genes. This highlights the importance of quality controls, working with taxonomists and using multiple markers for DNA-taxonomy or species diversity assessment. Read more in our publication 

 

 

Fernando Farache, Postdoctoral fellow 2017-

Funding :FAPESP / Univ. São Paulo, Ribeirao Preto, Brazil

Diversification and specialisation of fig wasps in the Neotropics

Fernando will work on the genera Pegoscapus (pollinators of the Ficus section Americana) and Idarnes (phytophagous/kleptoparasitic wasps also associated with these trees). He will study the species we already sampled during his PhD (several hundred species). We plan to reconstruct a phylogenetic hypothesis for Pegoscapus using ultra-conserved elements (UCE) and will use the multigene hypothesis on Idarnes inferred during his PhD. On a limited sampling, the genus Pegoscapus exhibits the highest number of lateral transferts of pollinators among fig tree species. Thus the co-diversification with their fig hosts appears less significant (see our last publication for a global test of cospeciation between the partners). We will seek to determine if this feature is still observed on a wider sampling. Our first results show that some clades remain associated with closely related fig trees, while other pollinatot clades pollinate phylogenetically distant fig trees. Idarnes are divided into three groups, exploiting fig flowers in different ways: i) a group of gall insects laying eggs before pollination, ii) a group of late gallers exploiting flowers before or shortly after pollination, iii) a group of cleptoparasitic wasps exploiting flowers that the pollinator or other wasps previously galled. These groups show different levels of specificity, and gallers appear globally more specific than cleptoparasites. From the inferred phylogenies we will i) analyse the relative impact of niche conservatism and host transferson the diversification of these phytophagous/parasitic species groups, ii) study the influence of main features of the host plants (fig size, wall thickness, niche, spatial and altitude distribution) on hostshift success, iii) compare the diversification patterns between Pegoscapus and Idarnes. Finally, Fernando will revise the genus Pegoscapus which includes about one hundred species. Fernando research project is part of our global project for a better understating of the interaction between fig trees and fig wasps in the Neotropics

 

 

Fernando Farache, PhD obtained in november 2014.

Supervisors : R.A.S Pereira & J.-Y. Rasplus

Funding :FAPESP / Univ. São Paulo, Ribeirao Preto, Brazil

Taxonomy and molecular phylogeny of three Sycophaginae (Hymenoptera, Agaonidae) genera: Anidarnes Bouček, 1993; Idarnes Walker, 1843; and Pseudidarnes Griault, 1927

Fig pollinating wasps use fig inflorescences (syconia) as oviposition sites and pollinate fig trees in return in one of the most remarkable examples of plant-insect mutualisms. The relation between figs and pollinator wasps is very strict since figs are exclusively pollinated by these wasps and the wasps, on the other side, can only reproduce within fig syconia. Besides pollinators, several other lineages of Chalcidoidea utilize fig inflorescences as oviposition sites. They are capable of inducing galls or developing as parasitoids or kleptoparasites and are recognized as “non-pollinating fig wasps” (NPFW). Among the NPFW, the Sycophaginae comprise ca. 52 species in 5 genera (plus at least one genus not yet described): Anidarnes Bouček, Eukoebelea Ashmead, Idarnes Walker, Pseudidarnes Girault and Sycophaga Westwood. In this contribution, we taxonomically reviewed three genera of Sycophaginae: Anidarnes, Idarnes, and Pseudidarnes. We also performed molecular phylogenetic analyses on Anidarnes and Idarnes using two mitochondrial (COI, CytB) and two nuclear (28S, EF-1α ) genes. In the first chapter of this thesis, we reviewed the 24 recognised Idarnes species and described 13 additional species for the I. flavicollis species group and 17 new species for the I. incertus species group. The phylogeny was mostly well supported, especially under the Bayesian optimization criterion, and 11 clades are well recognized. For Anidarnes (Chapter 2), we redescribed all three previously described species and described nine new species. Moreover, phylogenetic relationships inferred using parsimony, Bayesian and maximum likelihood methods were discussed in the light of our morphological observations and the host fig tree taxonomy. For Pseudidarnes (Chapter 3), we redescribed the two previously described species and also described several species new to science, two from Australia and four from Papua New Guinea. We hope that this contribution may raise interest in the taxonomic study of fig wasps and in the establishment of more robust phylogenetic hypotheses for these groups and that the present work contributes with taxonomic information and phylogenetic frameworks for future ecological and evolutionary analyses of the genera of Sycophaginae treated here.

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Martin Godefroid, PhD obtained in december 2015.

Supervisors : J.-Y. Rasplus & J.-P. Rossi

Funding : INRA - metaprogram SMACH

Assessing the risk of invasion by quarantine arthropods in Europe: The role of climate, evolutionary history and life history traits

Correlative species distribution models (SDMs) are widely used to predict potential distributions of pests in new geographical spaces and/or under global climate change scenarios. SDMs link species occurrences and environmental data to depict their niches. These bioclimatic models are usually calibrated with all species occurrences without accounting the fact that (1) intraspecific entities may differ in ecological niche and/or (2) the geographic distribution of a pest may only constitute a subset of its fundamental niche. Moreover, these factors may generate large uncertainty in predictions and lead to over- or underestimation of potential distributions. In this work, we studied different pests, most of them included in the European list of quarantine species (bark beetles belonging to the genus Dendroctonus Erichson, true fruit flies belonging to the family Tephritidae Newman, the pine processionary moth Thaumetopoea pityocampa Den. & Schif. and the grape phylloxera Daktulosphaira vitifoliae Fitch). We firstly investigated whether phylogeographic lineages within these species show different climatic niches and whether this genetic diversity played a role during invasions of these pests. Then, we reconstructed the evolutionary history of the genus Dendroctonus with RAD markers (Restriction-Site Associated DNA markers) and integrated this information in our invasion risk analyses. This work provides predictions of potential distribution of a large number of pests and help understanding geographical drivers of geographical genetic diversity. Our work highlights that species level is not always the most adequate taxonomic unit to take into account in invasion management.

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Mélodie Ollivier, MSc obtained in september 2016 (Montpellier SupAgro)

Supervisor : J.-C. Streito

Funding : COLEOTOOL Project

Setting up tools for the morphological and molecular identifiaction of pests of oilseed rape and their parasitoids

Oilseed rape in France is the arable crop the most treated against pests. Seven species of weevils (Ceutorhynchus sp., Aulacobaris sp. and Melanobaris sp.) are known to attack oilseed rape all along its biological cycle, but the expression of their pest potential differs among species. Sixteen parasitoids contribute to the natural regulation of these pests. Conservation biological control is the sustainable approach supported by the COLEOTOOL project, as an alternative to the use of insecticides. Indeed, the rape winter stem weevil (C. picitarsis) already started to develop resistance to pyrethroids in France. The lack of recent data about host/parasitoids interactions and the difficulty to identify weevils and their parasitoids constitute the issue that the CBGP and the agronomical institute Terres Inovia, must solve by the development of molecular and morphological identification tools. Terres Inovia directed the sampling campaign over nine collection sites in France. The specimens have been identified by taxonomists at the CBGP, and the cytochrome c oxidase subunit 1 (COI) of the mitochondrial gene has been sequenced for some of the specimens of the species identified. Phylogenetic inference, using maximum likelihood, has been employed to delineate species and study the congruence of morphological and molecular data. Further observations of vouchers permitted to correct identification errors, even describe new species characters for close species. The sequences of 108 weevils have been validated. They mostly belong to the four species the most represented in samplings (C. napi, C. obstrictus, C. pallidactylus and C. picitarsis). 145 sequences of parasitoids hymenoptera have been validated, belonging to 12 different species. Among them, ten did not present any sequence accessible on global database. A reference collection of specimen accompanies the sequence database. Tow digital polytomous keys has been created using LUCID software, dedicated to weevils and their parasitoids. They integrate a larger spectrum of species and characters newly reviewed. Thanks to these tools Terres Inovia will be able to analyse samples coming from a large network of plots in France, aiming at studying the favourable factors to conservation biological control of rape weevils. 

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Luciano Palmieri, PhD obtained in may 2017

Supervisors : R.A.S Pereira (Univ. São Paulo, Ribeirao Preto, Brazil)

Funding : Univ. São Paulo, Ribeirao Preto, Brazil

Systematics and biogeography of weevils (Curculionoidea; Coleoptera) associated with figs (Ficus; Moraceae)

Among the number of examples of broad radiations of insects on classes of plants, the fig – fig wasp system is one of the most remarkable. Although this interaction has frequently been used as a model for studies of mutualism and coevolution, other groups of insects associated with fig trees have received less attention and have been neglected by researchers. The weevils (Coleoptera: Curculionidae) associated with figs are one notable example. Being the largest family of animals, weevils achieved great evolutionary success due to their early association with their host plants. Despite few reports in literature, there is strong evidence of the specialization of weevils on figs. The main objective of this thesis was to understand how diversification of Curculionidae took place in fig trees. Previous studies have never addressed the systematics and biogeography of fig weevils under a phylogenetic framework. Therefore, we analyzed the tempo of diversification of Curculionidae lineages that use fig trees as host in order to reconstruct their historical biogeography. To gather information on fig weevils, we collected 325 fruit sets from more than 12% of the total Ficus species, from the Neotropical, Afrotropical and Oriental regions. We also examined seven entomological collections (AMNH, BMNH, INBIO, MNHN, MZUSP, NMNH, SAMC) searching for weevil specimens collected on figs. At least 80 weevil species from five genera (Cetatopus, Omophorus, Carponinus, Curculio, and Indocurculio) were found to be associated with figs. The radiation of curculionids on figs occurred at least three times independently. The tempo of diversification of the crown fig weevils is congruent with the diversification of figs during the Upper-Cretaceous/Lower-Eocene period. We hypothesize that the variation on the sea level and warmer climate in the past had great influence on the evolution of the species. Our results encourage future research on the biology and ecology of these species and will help us to understand the role weevils may have played in the evolution of the fig- fig wasp mutualism.

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Lillian Rodriguez, PhD obtained in december 2016

Supervisors : J.-Y. Rasplus & F. Kjellberg (CNRS, Montpellier)

Funding : Univ. Montpellier France & Institute of Biology, University of the Philippines Diliman, Quezon City, Philippines

Evolution and ecology of Philippine Ceratosolen pollinating fig trees under subgenus Sycomorus

Evolution in islands is affected by many factors such as geology and topography. Using figs (genus Ficus) and fig wasps (order Hymenoptera: genus Ceratosolen) as models, we found that, like most Philippine biodiversity, these small and short-lived wasps arrived from the south (mainly Borneo) through hip-hopping along island chains. Moreover, many wasp groups underwent speciation once they arrived in the Philippines. We also showed how fig trees directly affected fig wasp form and behaviour. For example, some species of fig trees have lots of liquid inside the figs. As a response, pollinators of these species were seen to have hairy, water-repelling legs, allowing them to breathe despite the presence of liquid. Also, we showed that wasp species that should recognize the same host were able to detect similar odour compounds. On the contrary, wasp species that did not share a host detected different odour compounds. These results point to the many intricate processes governing the fig-wasp mutualism.