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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 

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HAL : Dernières publications

  • [hal-05200267] Monitoring the molecular mechanisms of insecticide resistance in Spodoptera frugiperda populations from Thailand

    <div><p>Spodoptera frugiperda is a major crop pest that invaded Thailand in 2018 which cause significant damage, particularly to maize. In recent years, a loss of efficacy of certain insecticides has been observed, suggesting the emergence of resistance. The aim of our study was to investigate the molecular mechanisms of resistance in S. frugiperda populations collected in several regions in Thailand. Analysis of the presence of mutations in insecticide targets revealed three mutations (M944L, F1005C and I1011M) in the voltage-dependent sodium channel, and the F290V mutation in acetylcholinesterase (AChE). These mutations can confer resistance to pyrethroids, organophosphates and carbamates, respectively. The impact of the F290V as well as two other AChE mutations have been functionally validated by inhibition studies with recombinantly expressed AChE-1 variants. The potential involvement of metabolic resistance was also investigated by monitoring the expression level of several cytochrome P450 genes. Most of the CYP9A subfamily P450s were overexpressed, regardless of the geographical origin of the populations, a worrying situation given the demonstrated ability of these P450s to metabolize insecticides belonging to different chemical classes including pyrethroids. Transcription factors such as CncC and Maf were also overexpressed in these field populations. All these results should be taken into consideration in order to propose effective and sustainable control of this pest in Thailand. Our results also demonstrated the need to develop monitoring strategies that take into account the two main resistance mechanisms, target modification and metabolic detoxification.</p></div>

    ano.nymous@ccsd.cnrs.fr.invalid (Marlen Saladini Di Rovetino) 05 Aug 2025

    https://hal.science/hal-05200267v1
  • [hal-05279475] Pleiotropic role of PAX cyclolipopeptides in the Xenorhabdus bacterium mutualistically associated with entomopathogenic nematodes

    ABSTRACT Xenorhabdus is an entomopathogenic bacterium involved in a mutualistic relationship with Steinernema nematodes. Xenorhabdus produces a multitude of specialized metabolites by non-ribosomal peptide synthetase (NRPS) pathways to mediate bacterium-nematode-insect interactions. PAX cyclolipopeptides are a family of NRP-type molecules whose ecological role remains poorly understood. In this study, the pleiotropic role of PAX peptides in the life cycle of Xenorhabdus nematophila has been investigated. By mass spectrometry analysis, we first demonstrated that PAX peptides were detected from the pathogenic stage up to the necrotrophic stage. We discovered that the bromothymol blue adsorption phenotype historically used to discriminate Xenorhabdus variants was associated with the presence of PAX peptides. We found that PAX peptides were positively involved in biofilm formation and negatively involved in swimming motility. PAX peptides were also shown to promote in vivo the production of infective Steinernema juveniles, suggesting their involvement in the mutualistic relationship between Xenorhabdus and its nematode partner. Finally, we showed that the paxTABC cluster, as well as PAX peptide production, was conserved across the whole Xenorhabdus genus except in Xenorhabdus poinarii and Xenorhabdus ishibashii . This work has revealed multiple new ecological roles for NRP-type peptides. IMPORTANCE Xenorhabdus bacteria are models of particular interest for their mutualistic relationship with Steinernema nematodes and their ability to produce a wide range of natural NRP-type bioactive metabolites. These compounds are mostly studied for their medical or industrial applications, but their ecological role is poorly understood. This study provides a dynamic characterization of PAX cyclolipopeptide presence during the Xenorhabdus nematophila life cycle, as well as confirmation of their production by seven different strains within the Xenorhabdus genus. We revealed new multiple functions for PAX peptides in biofilm formation, swimming motility, and juvenile nematode production. A deeper understanding of how PAX peptides interact with the nematode host would provide a better insight into the role of these cyclolipopeptides in bacterial-nematode mutualism.

    ano.nymous@ccsd.cnrs.fr.invalid (Noémie Claveyroles) 23 Sep 2025

    https://hal.inrae.fr/hal-05279475v1
  • [hal-05248666] Global transcriptomics and targeted metabolite analysis reveal the involvement of the AcrAB efflux pump in physiological functions by exporting signaling molecules in Photorhabdus laumondii

    In Gram-negative bacteria, resistance-nodulation-division (RND)-type efflux pumps, particularly AcrAB-TolC, play a critical role in mediating resistance to antimicrobial agents and toxic metabolites, contributing to multidrug resistance. Photorhabdus laumondii is an entomopathogenic bacterium that has garnered significant interest due to its production of bioactive specialized metabolites with anti-inflammatory, antimicrobial, and scavenger deterrent properties. In previous work, we demonstrated that AcrAB confers self-resistance to stilbenes in P. laumondii TT01. Here, we explore the pleiotropic effects of AcrAB in this bacterium. RNA sequencing of ∆acrA compared to wild type revealed growth-phase-specific gene regulation, with stationary-phase cultures showing significant downregulation of genes involved in stilbene, fatty acid, and anthraquinone pigment biosynthesis, as well as genes related to cellular clumping and fimbrial pilin formation. Genes encoding putative LuxR regulators, type VI secretion systems, two-partner secretion systems, and contact-dependent growth inhibition systems were upregulated in ∆acrA. Additionally, exponential-phase cultures revealed reduced expression of genes related to motility in ∆acrA. The observed transcriptional changes were consistent with phenotypic assays, demonstrating that the ∆acrA mutant had altered bioluminescence and defective orange pigmentation due to disrupted anthraquinone production. These findings confirm the role of stilbenes as signaling molecules involved in gene expression, thereby shaping these phenotypes. Furthermore, we showed that AcrAB contributes to swarming and swimming motilities independently of stilbenes. Collectively, these results highlight that disrupting acrAB causes transcriptional and metabolic dysregulation in P. laumondii, likely by impeding the export of key signaling molecules such as stilbenes, which may serve as a ligand for global transcriptional regulators.

    ano.nymous@ccsd.cnrs.fr.invalid (Linda Hadchity) 10 Sep 2025

    https://hal.science/hal-05248666v1

Actualités

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vignette FDS 2025 DGIMI
événement Du 04 oct. 2025 au 05 oct. 2024

Village des sciences de Montpellier

Fête de la science 2025

Pour cette édition 2025, le laboratoire DGIMI a proposé une animation sur la thématique "Ravageurs malins et microbes futés".
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Nouvelle offre de poste en mobilité interne

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Un poste de technicien.ne en élevage, collectes et expérimentation appliqués aux insectes et autres invertébrés d’intérêt agronomique est ouvert en mobilité interne à INRAE. Les candidatures sont ouvertes du 16 juillet au 9 septembre.

Nouvelle publication scientifique

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Les populations invasives au Sénégal montrent des traces d’évolution adaptative sur des gènes CYP450 pouvant expliquer leur adaptation au maïs.

photo Peter Heeling

Site web en cours de maintenance

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Des modifications de structure et de contenus s'opèrent actuellement sur le site web DGIMI