Accueil

.

Qui sommes-nous ?

DGIMI est une unité mixte de recherche ayant pour tutelles INRAE et l'Université de Montpellier. Elle est située sur le campus Triolet de l'Université de Montpellier et accueille une trentaine de personnels INRAE et UM.

Les recherches développées dans l'UMR DGIMI visent à mieux comprendre les interactions entre les insectes et leur environnement biotique et abiotique dans les agrosystèmes, selon deux axes thématiques 

Lire la suite

HAL : Dernières publications

  • [hal-05855354] Experimental evolution at high temperature in a Lepidopteran host of an entomopathogenic nematode and its associated microbiota

    Abstract E ntomo p athogenic N ematodes (EPNs) have a great potential to control various insect crop pests, but their ability to perform their entire life-cycle in insects depends on environmental conditions. The insect killing ability of the endosymbiotic bacterial species (i.e., Xenorhabdus ) located in the EPNs’ gut ( Steinernema ) has been described for years. More recently, experimental data have suggested that other bacteria species of the nematode microbiota may also contribute to the parasitic success of the EPNs. EPNs and their associated bacteria should therefore be considered as holobionts. Global change, among its many predicted consequences, is expected to increase temperatures which may impair the parasitic success of these EPNs in the insect. Furthermore, higher environmental temperatures could modify the composition of the EPN-associated microbiota and could therefore also contribute to parasitic impairement. Using a S. carpocapsae strain originating from a French orchard, we investigated these hypotheses by experimentally evolving independent EPNs lineages in vivo in the lepidopteran species Galleria mellonella , at elevated and control temperatures. Several life-history traits of the evolved lineages were measured (insect killing ability, EPN emergence rate, EPN reproduction rate), and the bacterial microbiota of the evolved lineages was characterized by a metabarcoding approach. The EPNs’ lineages evolved at higher temperature showed impaired emergence rate and their reproduction rate was lower, when compared to lineages evolved at control temperature. The bacterial microbiota composition of these lineages was modified, with particular enrichment in bacteria of the genera Alcaligenes and Pseudomonas . Our results provide new evidence that modification of the environment (here, the abiotic parameter temperature) during several successive generations can modify the parasitic success of EPNs, concomitantly to a change in the microbiota composition. A better understanding of the life-history traits of these EPNs should help improve the biocontrol efficiency in a context of global warming.

    ano.nymous@ccsd.cnrs.fr.invalid (Nell Foucher) 06 Nov 2026

    https://hal.science/hal-05855354v1
  • [hal-04122847] Convergent origin and accelerated evolution of vesicle-associated RhoGAP proteins in two unrelated parasitoid wasps

    Animal venoms and other protein-based secretions that perform a variety of functions, from predation to defense, are highly complex cocktails of bioactive compounds. Gene duplication, accompanied by modification of the expression and/or function of one of the duplicates under the action of positive selection, followed by further duplication to produce multigene families of toxins is a well-documented process in venomous animals. This evolutionary model has been less described in parasitoid wasps, which use maternal fluids, including venom, to protect their eggs from encapsulation by the host immune system. Here, we evidence the convergent recruitment and accelerated evolution of two multigene families of RhoGAPs presumably involved in virulence in two unrelated parasitoid wasp species, Leptopilina boulardi (Figitidae) and Venturia canescens (Icheumonidae). In both species, these RhoGAPs are associated with vesicles that act as transport systems to deliver virulence factors, but are produced in different tissues: the venom gland in Leptopilina sp. and the ovarian calyx in V. canescens. We show that the gene encoding the cellular RacGAP1 is at the origin of the virulent RhoGAP families found in Leptopilina sp. and V. canescens. We also show that both RhoGAP families have undergone evolution under positive selection and that almost all of these RhoGAPs lost their GAP activity and GTPase binding ability due to mutations in key amino acids. These results suggest an accelerated evolution and functional diversification of these vesicle-associated RhoGAPs in the two phylogenetically distant parasitoid species. The potential new function(s) and the exact mechanism of action of these proteins in host cells remain to be elucidated.

    ano.nymous@ccsd.cnrs.fr.invalid (Dominique Colinet) 13 Oct 2026

    https://hal.inrae.fr/hal-04122847v1
  • [hal-05848235] N-terminal lysine as a critical determinant of odilorhabdin susceptibility to inactivation by the self-resistance acetyltransferase OatA

    Odilorhabdins (ODLs) are a novel class of peptide antibiotics that inhibit bacterial translation by binding to the 30S ribosomal subunit. Xenorhabdus nematophila , an ODL-producing bacterium, encodes a highly specialized self-resistance acetyltransferase, OatA, that inactivates ODLs via primary amine modification. In this study, we investigated the structural determinants governing susceptibility of the natural compound NOSO-95C to OatA-mediated inactivation. Using an alanine-scanning library, we identified N -terminal lysine (Lys 1 ) as the key structural determinant of acetyltransferase susceptibility. Expression of oatA in E. coli increased the MIC of NOSO-95C by 64-fold due to rapid OatA-mediated acetylation. In contrast, analog 1 (Lys1→Ala) was no longer discriminated between Oat-A expressing and non-expressing strains, and remained 95.4% unacetylated after 4 h of incubation. Functional assays confirmed that analog 1 retains potent translation inhibition and antibacterial activity despite enzyme exposure. Furthermore, OatA failed to inactivate other amine-containing clinical antibiotics such as aminoglycosides, penicillin, or polymyxins. These results indicate that the side chain of N -terminal lysine is essential for efficient OatA-mediated acetylation of ODLs. Moreover, this single residue can be modified to enable ODLs to evade enzymatic inactivation while preserving their primary mechanism of action. This work provides a clear structure-activity framework for the rational design of next-generation ODLs with enhanced stability against OatA-mediated enzymatic modification.

    ano.nymous@ccsd.cnrs.fr.invalid (Emilie Racine) 02 Nov 2026

    https://hal.science/hal-05848235v1

Actualités

Toutes les actualités
événement Du 03 oct. 2026 au 04 oct. 2026 Village des sciences de Montpellier

Fête de la science 2026

Pour cette édition 2026, le laboratoire DGIMI vous propose une animation sur la thématique "Insectes, plantes, vers, microbes : qui mange qui ?".
24 11
24 novembre 2026 Agropolis International - 1000, av. Agropolis, 34090 Montpellier

Journée scientifique du Vectopole Sud

En savoir plus

Cette année les présentations auront pour thématique "Le rôle des hôtes secondaires et des réservoirs (plantes, faune sauvage ou domestique) dans l'épidémiologie et la gestion des vecteurs et des ravageurs"

« RAVAGÉS »

En savoir plus

« Une conférence théâtralisée pour sauver ta culture »