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Heidi Goodrichblair - One of the best experts on this subject based on the ideXlab platform.

  • xenorhabdus nematophila bacteria shift from mutualistic to virulent lrp dependent phenotypes within the receptacles of Steinernema carpocapsae insect infective stage nematodes
    Environmental Microbiology, 2020
    Co-Authors: Mengyi Cao, Heidi Goodrichblair
    Abstract:

    Xenorhabdus nematophila bacteria are mutualists of Steinernema carpocapsae nematodes and pathogens of insects. Xenorhabdus nematophila exhibits phenotypic variation between insect virulence (V) and the mutualistic (M) support of nematode reproduction and colonization initiation in the infective juvenile (IJ) stage nematode that carries X. nematophila between insect hosts. The V and M phenotypes occur reciprocally depending on levels of the transcription factor Lrp: high‐Lrp expressors are M+V− while low‐Lrp expressors are V+M−. We report here that variable (wild type) or fixed high‐Lrp expressors also are optimized, relative to low‐ or no‐Lrp expressors, for colonization of additional nematode stages: juvenile, adult and pre‐transmission infective juvenile (IJ). In contrast, we found that after the bacterial population had undergone outgrowth in mature IJs, the advantage for colonization shifted to low‐Lrp expressors: fixed low‐Lrp expressors (M−V+) and wild type (M+V+) exhibited higher average bacterial CFU per IJ than did high‐Lrp (M+V−) or no‐Lrp (M−V−) strains. Further, the bacterial population becomes increasingly low‐Lrp expressing, based on expression of an Lrp‐dependent fluorescent reporter, as IJs age. These data support a model that virulent X. nematophila have a selective advantage and accumulate in aging IJs in advance of exposure to insect hosts in which this phenotype is necessary.

  • studying the symbiotic bacterium xenorhabdus nematophila in individual living Steinernema carpocapsae nematodes using microfluidic systems
    mSphere, 2018
    Co-Authors: Matthew D Stilwell, Heidi Goodrichblair, Douglas B Weibel
    Abstract:

    ABSTRACT Animal-microbe symbioses are ubiquitous in nature and scientifically important in diverse areas, including ecology, medicine, and agriculture. Steinernema nematodes and Xenorhabdus bacteria compose an established, successful model system for investigating microbial pathogenesis and mutualism. The bacterium Xenorhabdus nematophila is a species-specific mutualist of insect-infecting Steinernema carpocapsae nematodes. The bacterium colonizes a specialized intestinal pocket within the infective stage of the nematode, which transports the bacteria between insects that are killed and consumed by the pair for reproduction. Current understanding of the interaction between the infective-stage nematode and its bacterial colonizers is based largely on population-level, snapshot time point studies on these organisms. This limitation arises because investigating temporal dynamics of the bacterium within the nematode is impeded by the difficulty of isolating and maintaining individual living nematodes and tracking colonizing bacterial cells over time. To overcome this challenge, we developed a microfluidic system that enables us to spatially isolate and microscopically observe individual, living Steinernema nematodes and monitor the growth and development of the associated X. nematophila bacterial communities—starting from a single cell or a few cells—over weeks. Our data demonstrate, to our knowledge, the first direct, temporal, in vivo visual analysis of a symbiosis system and the application of this system to reveal continuous dynamics of the symbiont population in the living host animal. IMPORTANCE This paper describes an experimental system for directly investigating population dynamics of a symbiotic bacterium, Xenorhabdus nematophila, in its host—the infective stage of the entomopathogenic nematode Steinernema carpocapsae. Tracking individual and groups of bacteria in individual host nematodes over days and weeks yielded insight into dynamic growth and topology changes of symbiotic bacterial populations within infective juvenile nematodes. Our approach for studying symbioses between bacteria and nematodes provides a system to investigate long-term host-microbe interactions in individual nematodes and extrapolate the lessons learned to other bacterium-animal interactions.

  • high levels of the xenorhabdus nematophila transcription factor lrp promote mutualism with the Steinernema carpocapsae nematode host
    Applied and Environmental Microbiology, 2017
    Co-Authors: Tilak Patel, Heidi Goodrichblair, Tara Rickman, Elizabeth A Hussa
    Abstract:

    Xenorhabdus nematophila bacteria are mutualistic symbionts of Steinernema carpocapsae nematodes and pathogens of insects. The X. nematophila global regulator Lrp controls expression of many genes involved in both mutualism and pathogenic activities, suggesting a role in the transition between the two host organisms. We previously reported that natural populations of X. nematophila exhibit variable levels of Lrp expression, and that cells expressing relatively low levels of Lrp are optimized for virulence in the insect Manduca sexta. The adaptive advantage of the high-Lrp-expressing state was not established. Here we used strains engineered to express constitutively high or low levels of Lrp to test the model that high-Lrp-expressing cells are adapted for mutualistic activities with the nematode host. We demonstrate that high-Lrp cells form more robust biofilms in laboratory media than do low-Lrp cells, which may reflect adherence to host tissues. Also, our data showed that nematodes cultivated with high-Lrp strains are more frequently colonized relative to those associated with low-Lrp strains. Taken together these data support the idea that high-Lrp cells have an advantage in tissue adherence and colonization initiation. Furthermore, our data show that high-Lrp expressing strains better support nematode reproduction than their low-Lrp counterparts in both in vitro and in vivo conditions. Our data indicate that heterogeneity of Lrp expression in X. nematophila populations provides diverse cell populations adapted to both pathogenic (low Lrp) and mutualistic (high Lrp) states. Importance: Host associated bacteria experience fluctuating conditions both during residence within an individual host and during transmission between hosts. For bacteria that engage in evolutionarily stable, long-term relationships with particular hosts these fluctuations provide selective pressure for the emergence of adaptive regulatory mechanisms. Here we present evidence that the bacterium Xenorhabdus nematophila uses variable levels of the transcription factor Lrp to optimize its association with its two animal hosts: nematodes and insects, with which it behaves as a mutualist and a pathogen, respectively. Building on our previous finding that relatively low cellular levels of Lrp are optimal for pathogenesis, we demonstrate that conversely, high levels of Lrp promote mutualistic activities with the Steinernema carpocapsae nematode host. These data suggest that X. nematophila has evolved to utilize phenotypic variation between high and low Lrp expression states to optimize its alternating behaviors as a mutualist and a pathogen.

  • microbial population dynamics in the hemolymph of manduca sexta infected with xenorhabdus nematophila and the entomopathogenic nematode Steinernema carpocapsae
    Applied and Environmental Microbiology, 2014
    Co-Authors: Swati Singh, Heidi Goodrichblair, Jordan M Reese, Angel M Casanovatorres, Steven Forst
    Abstract:

    ABSTRACT Xenorhabdus nematophila engages in a mutualistic association with the nematode Steinernema carpocapsae. The nematode invades and traverses the gut of susceptible insects. X. nematophila is released in the insect blood (hemolymph), where it suppresses host immune responses and functions as a pathogen. X. nematophila produces diverse antimicrobials in laboratory cultures. The natural competitors that X. nematophila encounters in the hemolymph and the role of antimicrobials in interspecies competition in the host are poorly understood. We show that gut microbes translocate into the hemolymph when the nematode penetrates the insect intestine. During natural infection, Staphylococcus saprophyticus was initially present and subsequently disappeared from the hemolymph, while Enterococcus faecalis proliferated. S. saprophyticus was sensitive to X. nematophila antibiotics and was eliminated from the hemolymph when coinjected with X. nematophila. In contrast, E. faecalis was relatively resistant to X. nematophila antibiotics. When injected by itself, E. faecalis persisted (∼103 CFU/ml), but when coinjected with X. nematophila, it proliferated to ∼109 CFU/ml. Injection of E. faecalis into the insect caused the upregulation of an insect antimicrobial peptide, while the transcript levels were suppressed when E. faecalis was coinjected with X. nematophila. Its relative antibiotic resistance together with suppression of the host immune system by X. nematophila may account for the growth of E. faecalis. At higher injected levels (106 CFU/insect), E. faecalis could kill insects, suggesting that it may contribute to virulence in an X. nematophila infection. These findings provide new insights into the competitive events that occur early in infection after S. carpocapsae invades the host hemocoel.

  • the xenorhabdus nematophila nilabc genes confer the ability of xenorhabdus spp to colonize Steinernema carpocapsae nematodes
    Journal of Bacteriology, 2008
    Co-Authors: Charles Eugene Cowles, Heidi Goodrichblair
    Abstract:

    Members of the Steinernema genus of nematodes are colonized mutualistically by members of the Xenorhabdus genus of bacteria. In nature, Steinernema carpocapsae nematodes are always found in association with Xenorhabdus nematophila bacteria. Thus, this interaction, like many microbe-host associations, appears to be species specific. X. nematophila requires the nilA, nilB, and nilC genes to colonize S. carpocapsae. In this work, we showed that of all the Xenorhabdus species examined, only X. nematophila has the nilA, nilB, and nilC genes. By exposing S. carpocapsae to other Xenorhabdus spp., we established that only X. nematophila is able to colonize S. carpocapsae; therefore, the S. carpocapsae-X. nematophila interaction is species specific. Further, we showed that introduction of the nilA, nilB, and nilC genes into other Xenorhabdus species enables them to colonize the same S. carpocapsae host tissue that is normally colonized by X. nematophila. Finally, sequence analysis supported the idea that the nil genes were horizontally acquired. Our findings indicate that a single genetic locus determines host specificity in this bacteria-animal mutualism and that host range expansion can occur through the acquisition of a small genetic element.

Josep A. Jacas - One of the best experts on this subject based on the ideXlab platform.

  • short communication susceptibility of phoenix theophrasti palmae coryphoideae to rhynchophorus ferrugineus coleoptera curculionidae and its control using Steinernema carpocapsae in a chitosan formulation
    Spanish Journal of Agricultural Research, 2011
    Co-Authors: Oscar Dembilio, Filitsa Karamaouna, Dimitrios C Kontodimas, M Nomikou, Josep A. Jacas
    Abstract:

    The invasive red palm weevil, Rhynchophorus ferrugineus Oliv. (Coleoptera: Curculionidae) is the most destructive pest of palms in the world. It has been reported on 19 palm species belonging to 15 different genera. The host status of the Cretan Date Palm, Phoenix theophrasti, remains unclear. Therefore, the present study was carried out to ascertain the host status of this protected palm species. Additionally, the efficacy of entomopathogenic nematodes in a chitosan formulation to control this pest in P. theophrasti was assessed. Our results showed that healthy 4-yr-old P. theophrasti palms were not infested by adult females after 9 days exposure in a population density of 3 adults per plant. However, infestation was successful when neonate larvae were artificially introduced in palms. Therefore, natural populations of P. theophrasti could be at risk. Gummy secretion was observed in both naturally and forced infested palms indicating the existence of antibiosis in this species. Curative applications with the entomopathogenic nematode Steinernema carpocapsae in a chitosan formulation in early infested P. theophrasti palms managed to reduce insect’s activity and could help the palms to recover. Additional key words: antibiosis; antixenosis; entomopathogenic nematodes; Phoenix canariensis.

  • field efficacy of imidacloprid and Steinernema carpocapsae in a chitosan formulation against the red palm weevil rhynchophorus ferrugineus coleoptera curculionidae in phoenix canariensis
    Pest Management Science, 2010
    Co-Authors: Oscar Dembilio, Elena Llacer, Maria Del Mar Martinez De Altube, Josep A. Jacas
    Abstract:

    BACKGROUND: The invasive red palm weevil, Rhynchophorus ferrugineus (Olivier), has become the major pest of palms in the Mediterranean Basin. Chemical control against this species is difficult because of its cryptic habits and is mainly based on the repeated application of large quantities of synthetic insecticides. The aim of this work has been to evaluate in the field the efficacy of imidacloprid (Confidor® 240 OD) and Steinernema carpocapsae Weiser with chitosan (Biorend R® Palmeras) as soil and stipe treatments respectively, alone or in combination, against this pest. RESULTS: All treatments significantly reduced the mean number of immature stages of R. ferrugineus per palm. However, there were no significant differences among the different treatments considered. Efficacies ranged from 83.8 to 99.7% for the mean number of immature stages found in the palms and resulted in a significant increase in palm survival compared with the untreated control (75.0–90.0% versus 16.5% respectively). CONCLUSION: Both imidacloprid and S. carpocapsae in a chitosan formulation proved highly effective against R. ferrugineus in the field, and their efficacies did not significantly change when used in combination. Copyright © 2009 Society of Chemical Industry

  • evaluation of the efficacy of Steinernema carpocapsae in a chitosan formulation against the red palm weevil rhynchophorus ferrugineus in phoenix canariensis
    Biocontrol, 2009
    Co-Authors: Elena Llacer, M Martinez M De Altube, Josep A. Jacas
    Abstract:

    The red palm weevil, Rhynchophorus ferrugineus (Olivier) (Coleoptera, Curculionidae), is an important pest of palms. It has recently colonized the Mediterranean Basin, where it is a serious problem on ornamental Phoenix canariensis (Chabaud) palms. The efficacy of Steinernema carpocapsae (Weiser) (Nematoda: Steinernematidae) in a chitosan formulation (Biorend R®) against this weevil in a semi-field trial including both preventative and curative assays has been studied. Our results prove the potential of this nematode to control R. ferrugineus. Efficacies around 80% were obtained in the curative assay, and up to 98% in the preventative treatment. Applications repeated every 2–3 weeks during the critical flight periods could prove effective to protect palms from this weevil in the Mediterranean Basin.

Bernard Duvic - One of the best experts on this subject based on the ideXlab platform.

  • Spodoptera frugiperda immune response to the nematobacterial complex Steinernema carpocapsae-Xenorhabdus nematophila
    2019
    Co-Authors: Louise Huot, Nicolas Negre, Pierre-alain Girard, Audrey Bigourdan, Sylvie Pages, Bernard Duvic
    Abstract:

    [i]Spodoptera frugiperda[/i] immune response to the nematobacterial complex [i]Steinernema carpocapsae-Xenorhabdus nematophila[/i]. Conférences Jacques Monod "Immunologie Intégrative des Insectes : Contrôle des Infections

  • spodoptera frugiperda transcriptional response to infestation by Steinernema carpocapsae
    bioRxiv, 2019
    Co-Authors: Louise Huot, Nicolas Negre, Simon George, Pierre-alain Girard, Dany Severac, Bernard Duvic
    Abstract:

    Abstract Steinernema carpocapsae is an entomopathogenic nematode (EPN) used in biological control of agricultural pest insects. It enters the hemocoel of its host via the intestinal tract and releases its symbiotic bacterium Xenorhabdus nematophila, which kills the insect in less than 48 hours. Although several aspects of its interactions with insects have been extensively studied, still little is known about the immune and physiological responses of its different hosts. In order to improve this knowledge, we examined the transcriptional responses to EPN infestation of the fat body, the hemocytes and the midgut in the lepidopteran pest model Spodoptera frugiperda (Lepidoptera: Noctuidae). Our results indicate that the tissues poorly respond to the infestation at an early time post-infestation of 8 h, even though the proliferation of the bacterial symbiont within the hemocoel is detected. Only 5 genes are differentially expressed in the fat body of the caterpillars. However, strong transcriptional responses are observed at a later time point of 15 h post-infestation in all three tissues. While few genes are differentially expressed in the midgut, tissue-specific panels of induced metalloprotease inhibitors, immune receptors and antimicrobial peptides together with several uncharacterized genes are up-regulated in the fat body and the hemocytes. In addition, among the most up-regulated genes, we identified new potential immune effectors, unique to Lepidoptera, for which we present evidence of acquisition by Horizontal Gene Transfer from bacteria. Altogether, these results pave the way for further functional studies of the mobilized genes’ involvement in the interaction with the EPN. Author summary The Fall Armyworm, Spodoptera frugiperda, is a major agricultural pest. The caterpillars cause extensive damage to crops of importance such as corn, rice, sorghum and cotton. Originally from the Americas, it is currently becoming invasive in other parts of the world, first in Africa in 2016, then in India and now in south-east Asia. Programs of biological control against insect pests are increasingly encouraged around the world and include the use of pathogens. Entomopathogenic nematodes such as Steinernema carpocapsae are already commercialized as organic pesticides. These nematodes live in the soil and enter the body of their insect preys. Once within the insects, they release their symbiotic bacteria (Xenorhabdus nematophila in this case), which infect and kill the host in a few hours. The nematodes can then feed on the dead insects, reproduce and resume their life cycle. It is a major challenge to understand how EPN achieve their pathogenicity as well as how the insects can resist them. Here we provide the foundation for such an interaction between EPN and a Lepidoptera. We analyzed the dynamic of transcriptional response in three insect tissues (midgut, fat body and hemocytes) upon infestation by EPN. Not many studies have been performed genome-wide on such an interaction, and none on a Lepidopteran model of economical importance. Our transcriptomic approach revealed some specificities of the Lepidopteran defense mechanisms. In particular, we discovered a set of genes, acquired in Lepidoptera from bacteria by Horizontal Gene Transfer, that probably encode proteins with antibiotic activity.

  • Transcriptional analysis of the Spodoptera frugiperda immune response to the nematobacterial complex Steinernema carpocapsae-Xenorhabdus nematophila
    2019
    Co-Authors: Louise Huot, Nicolas Negre, Pierre-alain Girard, Audrey Bigourdan, Sylvie Pages, Bernard Duvic
    Abstract:

    Transcriptional analysis of the [i]Spodoptera frugiperda[/i] immune response to the nematobacterial complex [i]Steinernema carpocapsae[/i]-[i]Xenorhabdus nematophila[/i]. Grande Conférence de l'Académie des Sciences

  • Spodoptera frugiperda transcriptional response to infestation by Steinernema carpocapsae
    Scientific Reports, 2019
    Co-Authors: Louise Huot, Nicolas Negre, Simon George, Pierre-alain Girard, Dany Severac, Bernard Duvic
    Abstract:

    Steinernema carpocapsae is an entomopathogenic nematode (EPN) used in biological control of agricultural pest insects. It enters the hemocoel of its host via the intestinal tract and releases its symbiotic bacterium Xenorhabdus nematophila. In order to improve our knowledge about the physiological responses of its different hosts, we examined the transcriptional responses to EPN infestation of the fat body, the hemocytes and the midgut in the lepidopteran pest Spodoptera frugiperda. The tissues poorly respond to the infestation at an early time post-infestation of 8 h with only 5 genes differentially expressed in the fat body of the caterpillars. Strong transcriptional responses are observed at a later time point of 15 h post-infestation in all three tissues. Few genes are differentially expressed in the midgut but tissue-specific panels of induced metalloprotease inhibitors, immune receptors and antimicrobial peptides together with several uncharacterized genes are up-regulated in the fat body and the hemocytes. Among the most up-regulated genes, we identified new potential immune effectors, unique to Lepidoptera, which show homology with bacterial genes of unknown function. Altogether, these results pave the way for further functional studies of the responsive genes' involvement in the interaction with the EPN.

  • Spodoptera frugiperda tissue-specific transcriptional response to infestation by Steinernema carpocapsae
    2017
    Co-Authors: Louise Huot, Nicolas Negre, Simon George, Pierre-alain Girard, Marc Ravallec, Bernard Duvic
    Abstract:

    [i]Spodoptera frugiperda[/i] tissue-specific transcriptional response to infestation by [i]Steinernema carpocapsae[/i]. Congrès IMMUNINV 2017

Oscar Dembilio - One of the best experts on this subject based on the ideXlab platform.

  • short communication susceptibility of phoenix theophrasti palmae coryphoideae to rhynchophorus ferrugineus coleoptera curculionidae and its control using Steinernema carpocapsae in a chitosan formulation
    Spanish Journal of Agricultural Research, 2011
    Co-Authors: Oscar Dembilio, Filitsa Karamaouna, Dimitrios C Kontodimas, M Nomikou, Josep A. Jacas
    Abstract:

    The invasive red palm weevil, Rhynchophorus ferrugineus Oliv. (Coleoptera: Curculionidae) is the most destructive pest of palms in the world. It has been reported on 19 palm species belonging to 15 different genera. The host status of the Cretan Date Palm, Phoenix theophrasti, remains unclear. Therefore, the present study was carried out to ascertain the host status of this protected palm species. Additionally, the efficacy of entomopathogenic nematodes in a chitosan formulation to control this pest in P. theophrasti was assessed. Our results showed that healthy 4-yr-old P. theophrasti palms were not infested by adult females after 9 days exposure in a population density of 3 adults per plant. However, infestation was successful when neonate larvae were artificially introduced in palms. Therefore, natural populations of P. theophrasti could be at risk. Gummy secretion was observed in both naturally and forced infested palms indicating the existence of antibiosis in this species. Curative applications with the entomopathogenic nematode Steinernema carpocapsae in a chitosan formulation in early infested P. theophrasti palms managed to reduce insect’s activity and could help the palms to recover. Additional key words: antibiosis; antixenosis; entomopathogenic nematodes; Phoenix canariensis.

  • field efficacy of imidacloprid and Steinernema carpocapsae in a chitosan formulation against the red palm weevil rhynchophorus ferrugineus coleoptera curculionidae in phoenix canariensis
    Pest Management Science, 2010
    Co-Authors: Oscar Dembilio, Elena Llacer, Maria Del Mar Martinez De Altube, Josep A. Jacas
    Abstract:

    BACKGROUND: The invasive red palm weevil, Rhynchophorus ferrugineus (Olivier), has become the major pest of palms in the Mediterranean Basin. Chemical control against this species is difficult because of its cryptic habits and is mainly based on the repeated application of large quantities of synthetic insecticides. The aim of this work has been to evaluate in the field the efficacy of imidacloprid (Confidor® 240 OD) and Steinernema carpocapsae Weiser with chitosan (Biorend R® Palmeras) as soil and stipe treatments respectively, alone or in combination, against this pest. RESULTS: All treatments significantly reduced the mean number of immature stages of R. ferrugineus per palm. However, there were no significant differences among the different treatments considered. Efficacies ranged from 83.8 to 99.7% for the mean number of immature stages found in the palms and resulted in a significant increase in palm survival compared with the untreated control (75.0–90.0% versus 16.5% respectively). CONCLUSION: Both imidacloprid and S. carpocapsae in a chitosan formulation proved highly effective against R. ferrugineus in the field, and their efficacies did not significantly change when used in combination. Copyright © 2009 Society of Chemical Industry

Louise Huot - One of the best experts on this subject based on the ideXlab platform.

  • Spodoptera frugiperda immune response to the nematobacterial complex Steinernema carpocapsae-Xenorhabdus nematophila
    2019
    Co-Authors: Louise Huot, Nicolas Negre, Pierre-alain Girard, Audrey Bigourdan, Sylvie Pages, Bernard Duvic
    Abstract:

    [i]Spodoptera frugiperda[/i] immune response to the nematobacterial complex [i]Steinernema carpocapsae-Xenorhabdus nematophila[/i]. Conférences Jacques Monod "Immunologie Intégrative des Insectes : Contrôle des Infections

  • spodoptera frugiperda transcriptional response to infestation by Steinernema carpocapsae
    bioRxiv, 2019
    Co-Authors: Louise Huot, Nicolas Negre, Simon George, Pierre-alain Girard, Dany Severac, Bernard Duvic
    Abstract:

    Abstract Steinernema carpocapsae is an entomopathogenic nematode (EPN) used in biological control of agricultural pest insects. It enters the hemocoel of its host via the intestinal tract and releases its symbiotic bacterium Xenorhabdus nematophila, which kills the insect in less than 48 hours. Although several aspects of its interactions with insects have been extensively studied, still little is known about the immune and physiological responses of its different hosts. In order to improve this knowledge, we examined the transcriptional responses to EPN infestation of the fat body, the hemocytes and the midgut in the lepidopteran pest model Spodoptera frugiperda (Lepidoptera: Noctuidae). Our results indicate that the tissues poorly respond to the infestation at an early time post-infestation of 8 h, even though the proliferation of the bacterial symbiont within the hemocoel is detected. Only 5 genes are differentially expressed in the fat body of the caterpillars. However, strong transcriptional responses are observed at a later time point of 15 h post-infestation in all three tissues. While few genes are differentially expressed in the midgut, tissue-specific panels of induced metalloprotease inhibitors, immune receptors and antimicrobial peptides together with several uncharacterized genes are up-regulated in the fat body and the hemocytes. In addition, among the most up-regulated genes, we identified new potential immune effectors, unique to Lepidoptera, for which we present evidence of acquisition by Horizontal Gene Transfer from bacteria. Altogether, these results pave the way for further functional studies of the mobilized genes’ involvement in the interaction with the EPN. Author summary The Fall Armyworm, Spodoptera frugiperda, is a major agricultural pest. The caterpillars cause extensive damage to crops of importance such as corn, rice, sorghum and cotton. Originally from the Americas, it is currently becoming invasive in other parts of the world, first in Africa in 2016, then in India and now in south-east Asia. Programs of biological control against insect pests are increasingly encouraged around the world and include the use of pathogens. Entomopathogenic nematodes such as Steinernema carpocapsae are already commercialized as organic pesticides. These nematodes live in the soil and enter the body of their insect preys. Once within the insects, they release their symbiotic bacteria (Xenorhabdus nematophila in this case), which infect and kill the host in a few hours. The nematodes can then feed on the dead insects, reproduce and resume their life cycle. It is a major challenge to understand how EPN achieve their pathogenicity as well as how the insects can resist them. Here we provide the foundation for such an interaction between EPN and a Lepidoptera. We analyzed the dynamic of transcriptional response in three insect tissues (midgut, fat body and hemocytes) upon infestation by EPN. Not many studies have been performed genome-wide on such an interaction, and none on a Lepidopteran model of economical importance. Our transcriptomic approach revealed some specificities of the Lepidopteran defense mechanisms. In particular, we discovered a set of genes, acquired in Lepidoptera from bacteria by Horizontal Gene Transfer, that probably encode proteins with antibiotic activity.

  • Transcriptional analysis of the Spodoptera frugiperda immune response to the nematobacterial complex Steinernema carpocapsae-Xenorhabdus nematophila
    2019
    Co-Authors: Louise Huot, Nicolas Negre, Pierre-alain Girard, Audrey Bigourdan, Sylvie Pages, Bernard Duvic
    Abstract:

    Transcriptional analysis of the [i]Spodoptera frugiperda[/i] immune response to the nematobacterial complex [i]Steinernema carpocapsae[/i]-[i]Xenorhabdus nematophila[/i]. Grande Conférence de l'Académie des Sciences

  • Spodoptera frugiperda transcriptional response to infestation by Steinernema carpocapsae
    Scientific Reports, 2019
    Co-Authors: Louise Huot, Nicolas Negre, Simon George, Pierre-alain Girard, Dany Severac, Bernard Duvic
    Abstract:

    Steinernema carpocapsae is an entomopathogenic nematode (EPN) used in biological control of agricultural pest insects. It enters the hemocoel of its host via the intestinal tract and releases its symbiotic bacterium Xenorhabdus nematophila. In order to improve our knowledge about the physiological responses of its different hosts, we examined the transcriptional responses to EPN infestation of the fat body, the hemocytes and the midgut in the lepidopteran pest Spodoptera frugiperda. The tissues poorly respond to the infestation at an early time post-infestation of 8 h with only 5 genes differentially expressed in the fat body of the caterpillars. Strong transcriptional responses are observed at a later time point of 15 h post-infestation in all three tissues. Few genes are differentially expressed in the midgut but tissue-specific panels of induced metalloprotease inhibitors, immune receptors and antimicrobial peptides together with several uncharacterized genes are up-regulated in the fat body and the hemocytes. Among the most up-regulated genes, we identified new potential immune effectors, unique to Lepidoptera, which show homology with bacterial genes of unknown function. Altogether, these results pave the way for further functional studies of the responsive genes' involvement in the interaction with the EPN.

  • Spodoptera frugiperda tissue-specific transcriptional response to infestation by Steinernema carpocapsae
    2017
    Co-Authors: Louise Huot, Nicolas Negre, Simon George, Pierre-alain Girard, Marc Ravallec, Bernard Duvic
    Abstract:

    [i]Spodoptera frugiperda[/i] tissue-specific transcriptional response to infestation by [i]Steinernema carpocapsae[/i]. Congrès IMMUNINV 2017