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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-05410672] Transgenerational effects of a high temperature impair the resistance of the pest Spodoptera frugiperda to a parasitoid

    Insect parasitoids provide a useful ecosystem service to control pest insects. However, climate change could challenge this pest management, as insects are known to be sensitive to temperature. Furthermore, transgenerational effects, which are common in insects, could influence these effects of temperature on host-parasitoid systems. The present study therefore aimed to test the combined effects of developmental and host parental temperatures on a host-parasitoid system, using the fall armyworm (FAW) and the parasitoid Hyposoter didymator. We focused on mean temperatures of 25 and 29 °C, with a daily fluctuation of ±5 °C. The increase in mean temperatures had a significant effect on all the host parameters tested (survival, developmental rate, sex ratio, body mass) and on parasitoid success. Parasitoid success decreased between the developmental temperatures of 25 and 29 °C, and most effects of the increase in developmental temperature on FAW traits were detrimental to the parasitoid. Remarkably, we found transgenerational effects of temperature on the host resistance to parasitoids (the proportion of FAW escaping parasitism), as well as on host traits associated with the probability of parasitoids finding a host (effects on survival and developmental rates) and host quality (body mass, sex ratio). The parental temperature of 29 °C had a detrimental effect on the FAW resistance to parasitoids, but it reinforced the effects of developmental temperature on host traits that have a negative impact on parasitoids. The study shows the high thermal sensitivity of a host-parasitoid system and highlights that thermal transgenerational plasticity should be considered in host-parasitoid interactions.

    ano.nymous@ccsd.cnrs.fr.invalid (Shannon Alary) 11 Dec 2025

    https://hal.inrae.fr/hal-05410672v1
  • [hal-05374380] A characterization of piARNs, their biogenesis and their targets in Spodoptera frugiperda (Lepidoptera, Noctuidae)

    Abstract PIWI-interacting RNAs (piRNAs) and PIWI proteins were initially described as involved in gametogenesis and preservation of genome integrity through the control of transposable elements (TE). Expressed also in the soma and able to regulate protein coding gene expression, they are involved in multiple biological pathways including host-pathogens interaction, sex determination, reproductive isolation. Spodoptera frugiperda is a major invasive insect pest species consisting of two strains with different host-plant ranges. In this paper, we characterized proteins and genomic regions involved in their biogenesis as well as TE and gene transcripts regulated by piRNAs. By phylogenetic analysis, we identified two new Piwi genes conserved in the genus Spodoptera , compared to the Lepidopteran model Bombyx mori , one more than in Drosophila . One of them, more expressed in gonads then soma could be a functional homolog of Drosophila PIWI or replace AGO3. A pool of 11 sRNA-Seq libraries was used to annotate piRNA clusters with Shortstack in the genomes of the two strains of Spodoptera frugiperda . Identification of TE targeted by piRNAs revealed that active transposons differ between the two strains of S. frugiperda despite of a similar TE content, as putative cause or consequence of reproductive isolation. GO analysis of genes targeted by piRNAs shows that some are involved in protein translation initiation. A piRNA cluster in the Masc gene suggests that sex determination is regulated by piRNAs in Spodoptera frugiperda . Our analysis supports that piRNAs have additional roles than silencing of transposable elements and contributes to functional annotation of the two strains genomes of Spodoptera frugiperda .

    ano.nymous@ccsd.cnrs.fr.invalid (Imène Seninet) 20 Nov 2025

    https://hal.inrae.fr/hal-05374380v1
  • [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

News

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article

27 October 2025

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

Our new article makes the cover of AEM

Nematodes are used in biological control to combat insect pests. To complete their infectious cycle, they are assisted by their symbiotic bacteria Xenorhabdus, which produces a multitude of different metabolites. Among these metabolites, Xenorhabdus produces PAX cyclolipopeptides, whose role in the ecological cycle of the bacteria was poorly understood.
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Thesis defense : Shannon Alary

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Congratulations to Shannon Alary for her thesis defense on the effect of temperature on the plasticity of host-parasitoid interactions, supervised by Isabelle Darboux and Manuel Massot (iEES Paris) !

vignette FDS 2025 DGIMI
04 10

From 04 Oct. 2025 to 05 Oct. 2024

Montpellier Science Village (Village des sciences de Montpellier)

Science Festival 2025

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For the 2025 edition, DGIMI Lab, proposed an activity on the theme of “Clever pests and smart microbes.”

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