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DGIMI - Diversity, Genomes and Insects-Microorganisms Interactions

DGIMI is a joint research unit supervised by INRAE and the University of Montpellier. It is located on the Triolet campus of the University of Montpellier, and houses staff from both INRAE and UM.

The research carried out by UMR DGIMI is devoted to the study of interaction mechanisms between insect crop pests, their pathogens and parasites, and their host plants. This research takes into account the diversity of the partners and is based on knowledge of their genomes.

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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-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
  • [hal-05213997] Lepidopteran Genomes Have Denser Transposable Elements in Smaller Chromosomes, Likely Driven by Non-allelic Homologous Recombination

    Transposable elements (TEs) drive major genome size and structural variations, yet evolutionary forces affecting their accumulation and removal remain unclear. Classical models predict that higher recombination rates lead to more efficient purifying selection, such as TE removal. However, in the painted lady butterfly (Vanessa cardui), smaller chromosomes harbor denser TE content than larger ones despite higher recombination rates. This unexpected pattern raises questions about whether similar trends occur across other Lepidoptera species and what evolutionary forces are behind this pattern. Across ten species spanning ten lepidopteran families, we investigated the relationship between chromosome size and TE organization using comparative genomics. We observed that smaller chromosomes consistently have higher TE densities in all the investigated species. Chromosome size had positive correlations with average inter-TE distance for both young (<5% divergence) and old TEs (5% to 10% divergence). However, the ratio of these distances (young/old TEs) was negatively correlated with chromosome size in eight of ten species, with two showing no statistically significant correlation, suggesting that smaller chromosomes have higher removal rates of sequence between TEs, potentially due to nonallelic homologous recombination, causing the loss of unique sequences between nonallelic homologs. Population genomics analyses showed inconsistent correlations between chromosome size and genetic diversity or selection coefficients between Danaus plexippus and Spodoptera frugiperda, ruling out the efficiency of purifying selection or selective constraint as the main driver. Taken together, we demonstrate that Lepidoptera has a unique genomic feature of denser TEs in smaller chromosomes, with nonallelic homologous recombination as a potential driving force.

    ano.nymous@ccsd.cnrs.fr.invalid (Hyerin An) 19 Aug 2025

    https://hal.inrae.fr/hal-05213997v1

News

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article

18 July 2025

By: A-N. Volkoff, N. Nègre , I. Seninet

A University of Montpellier's Associated Professor in microbiology position (sections 64-65) has been created in DGIMI

Applications must be submitted on Odyssée before 04/04/2025.
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A new scientific publication

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Invasive populations in Senegal show evidence of adaptive evolution on CYP450 genes that may explain their adaptation to maize

photo Peter Heeling

Website under restructuring

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Our website is currently being restructured.

Postdoctoral Position in CRISPR/Cas9 Gene Editing in Insects (University of Montpellier)

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Location: UMR-DGIMI, University of Montpellier, France / Duration: 18 months / Start Date: Preferably from April 2025