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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-05734157] Exploratory study to identify factors affecting the presence of genus Steinernema entomopathogenic nematodes in maize fields in South-West France

    Entomopathogenic nematodes (EPNs) are soil-dwelling parasites with a large range of insect hosts. They are valuable components of biological control products against insect pests (in greenhouses, for example) but their large-scale use in field crops is often limited by prohibitive costs, poor persistence, and low efficacy in non-native soils. The use of EPNs in conservation biological control — the use of different agricultural practices to promote the presence of native EPNs in field soils — has recently been proposed. Expanding our previous research mapping the occurrence of Steinernema spp. in maize fields in South-West France, this study explores different methodological approaches for investigating the biotic and abiotic factors associated with Steinernema presence, including soil properties, agricultural practices, and soil nematofauna characteristics. We hypothesised that Steinernema spp. occurrence is primarily driven by soil abiotic properties, agricultural management practices affecting habitat disturbance, and soil nematofauna characteristics, and is further influenced by plant diversity through crop rotations and cover crops. We performed univariate (Spearman’s correlation analysis and Chi2 tests) and multivariate (ANOVA) analyses on 46 explanatory variables obtained from 41 maize plots. We also tested a generalized linear model (GLM). For this last approach, given the large number of explanatory variables relative to the number of plots, we conducted a preliminary selection procedure and reduced the number of variables to four: mean weight diameter (MWD), CaO content, main crop alternation and the diversity of plant species used as cover crops. The various approaches converged to identify maize monoculture over five years as the strongest potential explanatory variable for the presence of Steinernema. These results suggest that, in the maize fields of South-West France, EPNs require a certain stability of the vegetation covering agricultural soils. These findings require confirmation in future studies with additional datasets obtained in other agronomic and pedoclimatic contexts.

    ano.nymous@ccsd.cnrs.fr.invalid (Elisabeth Depuydt) 01 Sep 2026

    https://hal.science/hal-05734157v1
  • [hal-05727261] Differences in mainland–island genetic diversity in two moths suggest species-specific outcomes

    Genetic divergence along elevational gradients between mainland and island populations provides an opportunity to test the island genetic erosion model, which predicts reduced genetic diversity and increased differentiation in island populations. We examined two moth species, a geometrid moth ( Alcis angulifera ) and an erebid moth ( Hydrillodes morosa ), sampled along elevational gradients on Mt. Jirisan (mainland) and Mt. Hallasan (island) in southern South Korea. A total of 155 individuals were analyzed using mitochondrial cytochrome oxidase subunit I (mt COI) sequences. We identified 61 haplotypes across both species. A. angulifera exhibited similarly high genetic diversity on the mainland and island, whereas H. morosa showed overall lower diversity relative to A. angulifera but pronounced regional differences, with significantly higher haplotype and nucleotide diversity on the island. Mantel tests revealed significant genetic divergence between mainland and island populations but not within individual mountains, suggesting ongoing gene flow within elevational gradients. AMOVA indicated moderate differentiation in A. angulifera (F CT = 0.08) and stronger differentiation in H. morosa (F CT = 0.14), with most genetic variation occurring within populations. Gene flow estimates further highlighted contrasting patterns, with high connectivity in A. angulifera (Nm = 5.49) and restricted migration in H. morosa (Nm = 0.08). Together, these results indicate that while A. angulifera maintains genetic cohesion across regions, H. morosa exhibits stronger geographic and elevational structuring due to limited gene flow. Our findings do not support a universal reduction in genetic diversity in island populations; instead, they highlight the importance of species-specific ecological traits and geographic context in shaping genetic diversity patterns, suggesting that the island genetic-erosion pattern is more context-dependent than previously appreciated.

    ano.nymous@ccsd.cnrs.fr.invalid (Sei-Woong Choi) 26 Aug 2026

    https://hal.science/hal-05727261v1
  • [hal-05693311] MexXY-OprM efflux pump mediates resistance to odilorhabdins in Pseudomonas aeruginosa

    The urgent need for new antibiotic classes to treat infections caused by multidrug-resistant gram-negative pathogens has driven interest in odilorhabdins (ODLs), a novel class of cationic antimicrobial peptides that target the bacterial ribosome. NOSO-502, the first clinical candidate in this family, exhibits potent activity against multidrug-resistant Enterobacteriaceae but is inactive against Pseudomonas aeruginosa isolates. This study investigates the intrinsic resistance of P. aeruginosa to NOSO-502 using the reference strain PAO1. Our data indicate that NOSO-502 induces overexpres sion of the MexXY-OprM efflux pump, which mediates drug extrusion from the periplasm and limits antibacterial activity. To further explore the role of MexXY-OprM, we evaluated NOSO-95C, the first purified ODL from natural origin. Unlike NOSO-502, NOSO-95C does not induce overexpression of MexXY-OprM at subinhibitory concentrations, resulting in measurable antibacterial activity against PAO1. However, NOSO-95C remains susceptible to MexXY-OprM-mediated efflux, as evidenced by its limited efficacy against strains that constitutively overexpress this pump. To better understand the structural basis of these differences, we investigated the relationship between ODL structures and the ability to induce mexXY expression. Our results demonstrate that both the amino acid at position 7 and the C-terminal region of the ODL scaffold are critical determinants of MexXY induction and efflux susceptibility. These findings offer valuable insights for the design of next-generation ODLs with improved efficacy against P. aeruginosa. IMPORTANCE Pseudomonas aeruginosa is a major cause of hospital-acquired infections. Odilorhabdins (ODLs) are a novel class of ribosome-targeting antibiotics with promising activity against multidrug-resistant gram-negative bacteria. Unfortunately, their efficacy against P. aeruginosa remains limited. In this study, we identify the MexXY-OprM efflux pump as the primary determinant of intrinsic resistance of P. aeruginosa to ODLs. We show that the clinical candidate NOSO-502 strongly induces mexXY expression, resulting in active self-efflux and loss of antibacterial activity, whereas the natural ODL NOSO-95C displays reduced induction and partial activity. By combining microbiological, transcrip tional, uptake, and structure-activity analyses, we demonstrate that specific structural patterns of ODLs govern both efflux susceptibility and efflux pump induction. These findings pave the way for the design of the next ODL generation with improved activity against P. aeruginosa.

    ano.nymous@ccsd.cnrs.fr.invalid (Emilie Racine) 15 Jul 2026

    https://hal.science/hal-05693311v1

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event From 03 Oct. 2026 to 04 Oct. 2026 Montpellier Science Village (Village des sciences de Montpellier)

Science Festival 2026

For this 2026 edition, the DGIMI laboratory is offering an activity on the theme "Insects, plants, worms, microbes: who eats whom?".