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Trejo‐Meléndez VJ, Ibarra‐Rendón J, Contreras‐Garduño J. The evolution of entomopathogeny in nematodes. Ecol Evol 2024; 14:e10966. [PMID: 38352205 PMCID: PMC10862191 DOI: 10.1002/ece3.10966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 12/06/2023] [Accepted: 01/02/2024] [Indexed: 02/16/2024] Open
Abstract
Understanding how parasites evolved is crucial to understand the host and parasite interaction. The evolution of entomopathogenesis in rhabditid nematodes has traditionally been thought to have occurred twice within the phylum Nematoda: in Steinernematidae and Heterorhabditidae families, which are associated with the entomopathogenic bacteria Xenorhabdus and Photorhabdus, respectively. However, nematodes from other families that are associated with entomopathogenic bacteria have not been considered to meet the criteria for "entomopathogenic nematodes." The evolution of parasitism in nematodes suggests that ecological and evolutionary properties shared by families in the order Rhabditida favor the convergent evolution of the entomopathogenic trait in lineages with diverse lifestyles, such as saprotrophs, phoretic, and necromenic nematodes. For this reason, this paper proposes expanding the term "entomopathogenic nematode" considering the diverse modes of this attribute within Rhabditida. Despite studies are required to test the authenticity of the entomopathogenic trait in the reported species, they are valuable links that represent the early stages of specialized lineages to entomopathogenic lifestyle. An ecological and evolutionary exploration of these nematodes has the potential to deepen our comprehension of the evolution of entomopathogenesis as a convergent trait spanning across the Nematoda.
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Affiliation(s)
- V. J. Trejo‐Meléndez
- Edificio de Investigación I, ENES, Unidad Morelia, UNAMMoreliaMichoacánMexico
- Posgrado en Ciencias Biológicas, ENES, Unidad Morelia, UNAMMoreliaMichoacánMexico
| | - J. Ibarra‐Rendón
- Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV) – IrapuatoIrapuatoGuanajuatoMexico
| | - J. Contreras‐Garduño
- Edificio de Investigación I, ENES, Unidad Morelia, UNAMMoreliaMichoacánMexico
- Institute for Evolution and BiodiversityUniversity of MünsterMünsterGermany
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Ogier JC, Akhurst R, Boemare N, Gaudriault S. The endosymbiont and the second bacterial circle of entomopathogenic nematodes. Trends Microbiol 2023; 31:629-643. [PMID: 36801155 DOI: 10.1016/j.tim.2023.01.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 01/11/2023] [Accepted: 01/13/2023] [Indexed: 02/19/2023]
Abstract
Single host-symbiont interactions should be reconsidered from the perspective of the pathobiome. We revisit here the interactions between entomopathogenic nematodes (EPNs) and their microbiota. We first describe the discovery of these EPNs and their bacterial endosymbionts. We also consider EPN-like nematodes and their putative symbionts. Recent high-throughput sequencing studies have shown that EPNs and EPN-like nematodes are also associated with other bacterial communities, referred to here as the second bacterial circle of EPNs. Current findings suggest that some members of this second bacterial circle contribute to the pathogenic success of nematodes. We suggest that the endosymbiont and the second bacterial circle delimit an EPN pathobiome.
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Affiliation(s)
| | | | - Noël Boemare
- DGIMI, Univ Montpellier, INRAE, Montpellier, France
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3
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Abstract
Entomopathogenic nematodes (EPNs) infect and kill insects and have been successfully used in the biological control of some insect pests. Slugs and snails are known to be significant pests of agriculture and serve as vectors for disease-causing microbes that can affect crops and humans. The potential of EPNs to be used in the biological control of gastropods has not been well-studied. The few studies that have been performed on the efficacy of EPNs in controlling gastropod pests and vectors were reviewed. Suggested criteria for further assessments of EPN-gastropod interactions are: Dose of EPNs used, length of infection assays, host biology, nematode biology and development, and Koch's postulates. There are provocative data suggesting that EPNs may be useful biological control agents against gastropod pests of agriculture and vectors of disease, though additional studies using the suggested criteria are needed, including the publication of negative data or studies where EPNs were not efficacious or successful in controlling gastropods.
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Affiliation(s)
- Jacob Schurkman
- Department of Nematology, University of California, Riverside, 900 University Ave, Riverside, CA, 92521
| | - Adler R Dillman
- Department of Nematology, University of California, Riverside, 900 University Ave, Riverside, CA, 92521
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Aujoulat F, Pagès S, Masnou A, Emboulé L, Teyssier C, Marchandin H, Gaudriault S, Givaudan A, Jumas-Bilak E. The population structure of Ochrobactrum isolated from entomopathogenic nematodes indicates interactions with the symbiotic system. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2019; 70:131-139. [PMID: 30790700 DOI: 10.1016/j.meegid.2019.02.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2018] [Revised: 10/14/2018] [Accepted: 02/16/2019] [Indexed: 02/02/2023]
Abstract
Entomopathogenic nematodes (EPNs) form specific mutualistic associations with bioluminescent enterobacteria. In Heterorhabditidis indica, Ochrobactrum spp. was identified beside the symbiont Photorhabdus luminescens but its involvement in the symbiotic association in the EPNs remains unclear. This study describe the population structure and the diversity in Ochrobactrum natural populations isolated from EPNs in the Caribbean basin in order to question the existence of EPN-specialized clones and to gain a better insight into Ochrobactrum-EPNs relationships. EPN-associated Ochrobactrum and Photorhabdus strains were characterized by multi-locus sequence typing, Pulsed-Field Gel Electrophoresis fingerprinting and phenotypic traits. Population study showed the absence of EPN-specialized clones in O. intermedium and O. anthropi but suggested the success of some particular lineages. A low level of genetic and genomic diversification of Ochrobactrum isolated from the natural population of Caribbean nematodes was observed comparatively to the diversity of human-associated Ochrobactrum strains. Correspondences between Ochrobactrum and P. luminescens PFGE clusters have been observed, particularly in the case of nematodes from Dominican Republic and Puerto Rico. O. intermedium and O. anthropi associated to EPNs formed less biofilm than human-associated strains. These results evoke interactions between Ochrobactrum and the EPN symbiotic system rather than transient contamination. The main hypothesis to investigate is a toxic/antitoxic relationship because of the ability of Ochrobactrum to resist to antimicrobial and toxic compounds produced by Photorhabdus.
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Affiliation(s)
- Fabien Aujoulat
- HydroSciences Montpellier, IRD, CNRS, Univ Montpellier, Montpellier, France
| | - Sylvie Pagès
- Diversité, Génomes & Interactions Microorganismes-Insectes, INRA, Univ Montpellier, Montpellier, France
| | - Agnès Masnou
- HydroSciences Montpellier, IRD, CNRS, Univ Montpellier, Montpellier, France
| | - Loic Emboulé
- CHU de Pointe-à-Pitre/Abymes, Pointe-à-Pitre, Guadeloupe, France
| | | | - Hélène Marchandin
- HydroSciences Montpellier, IRD, CNRS, Univ Montpellier, Montpellier, France
| | - Sophie Gaudriault
- Diversité, Génomes & Interactions Microorganismes-Insectes, INRA, Univ Montpellier, Montpellier, France
| | - Alain Givaudan
- Diversité, Génomes & Interactions Microorganismes-Insectes, INRA, Univ Montpellier, Montpellier, France
| | - Estelle Jumas-Bilak
- HydroSciences Montpellier, IRD, CNRS, Univ Montpellier, Montpellier, France.
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Spatiotemporal expression of the putative MdtABC efflux pump of Phtotorhabdus luminescens occurs in a protease-dependent manner during insect infection. PLoS One 2019; 14:e0212077. [PMID: 30763358 PMCID: PMC6375597 DOI: 10.1371/journal.pone.0212077] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Accepted: 01/25/2019] [Indexed: 11/19/2022] Open
Abstract
Photorhabdus luminescens is an enterobacterium establishing a mutualistic symbiosis with nematodes, that also kills insects after septicaemia and connective tissue colonization. The role of the bacterial mdtABC genes encoding a putative multidrug efflux system from the resistance/nodulation/cell division family was investigated. We showed that a mdtA mutant and the wild type had similar levels of resistance to antibiotics, antimicrobial peptides, metals, detergents and bile salts. The mdtA mutant was also as pathogenic as the wild-type following intrahaemocoel injection in Locusta migratoria, but had a slightly attenuated phenotype in Spodoptera littoralis. A transcriptional fusion of the mdtA promoter (PmdtA) and the green fluorescent protein (gfp) encoding gene was induced by copper in bacteria cultured in vitro. The PmdtA-gfp fusion was strongly induced within bacterial aggregates in the haematopoietic organ during late stages of infection in L. migratoria, whereas it was only weakly expressed in insect plasma throughout infection. A medium supplemented with haematopoietic organ extracts induced the PmdtA-gfp fusion ex vivo, suggesting that site-specific mdtABC expression resulted from insect signals from the haematopoietic organ. Finally, we showed that protease inhibitors abolished ex vivo activity of the PmdtA-gfp fusion in the presence of haematopoietic organ extracts, suggesting that proteolysis by-products play a key role in upregulating the putative MdtABC efflux pump during insect infection with P. luminescens.
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Nematobacterial Complexes and Insect Hosts: Different Weapons for the Same War. INSECTS 2018; 9:insects9030117. [PMID: 30208626 PMCID: PMC6164499 DOI: 10.3390/insects9030117] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 08/22/2018] [Accepted: 09/06/2018] [Indexed: 12/12/2022]
Abstract
Entomopathogenic nematodes (EPNs) are widely used as biological control agents against insect pests, the efficacy of these organisms strongly depends on the balance between the parasitic strategies and the immune response of the host. This review summarizes roles and relationships between insect hosts and two well-known EPN species, Steinernema feltiae and Steinernema carpocapsae and outlines the main mechanisms of immune recognition and defense of insects. Analyzing information and findings about these EPNs, it is clear that these two species use shared immunosuppression strategies, mainly mediated by their symbiotic bacteria, but there are differences in both the mechanism of evasion and interference of the two nematodes with the insect host immune pathways. Based on published data, S. feltiae takes advantage of the cross reaction between its body surface and some host functional proteins, to inhibit defensive processes; otherwise, secretion/excretion products from S. carpocapsae seem to be the main nematode components responsible for the host immunosuppression.
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Death Becomes Them: Bacterial Community Dynamics and Stilbene Antibiotic Production in Cadavers of Galleria mellonella Killed by Heterorhabditis and Photorhabdus spp. Appl Environ Microbiol 2016; 82:5824-37. [PMID: 27451445 DOI: 10.1128/aem.01211-16] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 07/14/2016] [Indexed: 12/19/2022] Open
Abstract
UNLABELLED Insect larvae killed by entomopathogenic nematodes are thought to contain bacterial communities dominated by a single bacterial genus, that of the nematode's bacterial symbiont. In this study, we used next-generation sequencing to profile bacterial community dynamics in greater wax moth (Galleria mellonella) larvae cadavers killed by Heterorhabditis nematodes and their Photorhabdus symbionts. We found that, although Photorhabdus strains did initially displace an Enterococcus-dominated community present in uninfected G. mellonella insect larvae, the cadaver community was not static. Twelve days postinfection, Photorhabdus shared the cadaver with Stenotrophomonas species. Consistent with this result, Stenotrophomonas strains isolated from infected cadavers were resistant to Photorhabdus-mediated toxicity in solid coculture assays. We isolated and characterized a Photorhabdus-produced antibiotic from G. mellonella cadavers, produced it synthetically, and demonstrated that both the natural and synthetic compounds decreased G. mellonella-associated Enterococcus growth, but not Stenotrophomonas growth, in vitro Finally, we showed that the Stenotrophomonas strains described here negatively affected Photorhabdus growth in vitro Our results add an important dimension to a broader understanding of Heterorhabditis-Photorhabdus biology and also demonstrate that interspecific bacterial competition likely characterizes even a theoretically monoxenic environment, such as a Heterorhabditis-Photorhabdus-parasitized insect cadaver. IMPORTANCE Understanding, and eventually manipulating, both human and environmental health depends on a complete accounting of the forces that act on and shape microbial communities. One of these underlying forces is hypothesized to be resource competition. A resource that has received little attention in the general microbiological literature, but likely has ecological and evolutionary importance, is dead/decaying multicellular organisms. Metazoan cadavers, including those of insects, are ephemeral and nutrient-rich environments, where resource competition might shape interspecific macrobiotic and microbiotic interactions. This study is the first to use a next-generation sequencing approach to study the community dynamics of bacteria within a model insect cadaver system: insect larvae parasitized by entomopathogenic nematodes and their bacterial symbionts. By integrating bioinformatic, biochemical, and classic in vitro microbiological approaches, we have provided mechanistic insight into how antibiotic-mediated bacterial interactions may shape community dynamics within insect cadavers.
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Lechowicz L, Chrapek M, Czerwonka G, Korzeniowska-Kowal A, Tobiasz A, Urbaniak M, Matuska-Lyzwa J, Kaca W. Detection of ureolytic activity of bacterial strains isolated from entomopathogenic nematodes using infrared spectroscopy. J Basic Microbiol 2016; 56:922-8. [PMID: 26972384 DOI: 10.1002/jobm.201500538] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 02/27/2016] [Indexed: 11/10/2022]
Abstract
The pathogenicity of entomopathogenic nematodes (EPNs) depends directly on the presence of bacteria in the nematode digestive tracts. Based on 16S rRNA and MALDI-TOF analyses 20 isolated bacteria were assigned to 10 species with 10 isolates classified as Pseudomonas ssp. Six strains (30%) show ureolytic activity on Christensen medium. Spectroscopic analysis of the strains showed that the ureolytic activity is strongly correlated with the following wavenumbers: 935 cm(-1) in window W4, which carries information about the bacterial cell wall construction and 1158 cm(-1) in window W3 which corresponds to proteins in bacterial cell. A logistic regression model designed on the basis of the selected wavenumbers differentiates ureolytic from non-ureolytic bacterial strains with an accuracy of 100%. Spectroscopic studies and mathematical analyses made it possible to differentiate EPN-associated Pseudomonas sp. strains from clinical Pseudomonas aeruginosa PAO1. These results suggest, that infrared spectra of EPN-associated Pseudomonas sp. strains may reflect its adaptation to the host.
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Affiliation(s)
- Lukasz Lechowicz
- Department of Microbiology, Jan Kochanowski University, Kielce, Poland
| | - Magdalena Chrapek
- Department of Probability and Statistics, Jan Kochanowski University, Kielce, Poland
| | | | - Agnieszka Korzeniowska-Kowal
- Department of Immunology of Infectious Diseases, Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wroclaw, Poland
| | - Anna Tobiasz
- Department of Immunology of Infectious Diseases, Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wroclaw, Poland
| | - Mariusz Urbaniak
- Division of Organic Chemistry, Jan Kochanowski University, Kielce, Poland
| | - Joanna Matuska-Lyzwa
- Department of Zoology and Biological Didactics, Jan Kochanowski University, Kielce, Poland
| | - Wieslaw Kaca
- Department of Microbiology, Jan Kochanowski University, Kielce, Poland
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Govindan JA, Jayamani E, Zhang X, Breen P, Larkins-Ford J, Mylonakis E, Ruvkun G. Lipid signalling couples translational surveillance to systemic detoxification in Caenorhabditis elegans. Nat Cell Biol 2015; 17:1294-303. [PMID: 26322678 PMCID: PMC4589496 DOI: 10.1038/ncb3229] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 07/24/2015] [Indexed: 12/17/2022]
Abstract
Translation in eukaryotes is followed to detect toxins and virulence factors and coupled to the induction of defence pathways. Caenorhabditis elegans germline-specific mutations in translation components are detected by this system to induce detoxification and immune responses in distinct somatic cells. An RNA interference screen revealed gene inactivations that act at multiple steps in lipid biosynthetic and kinase pathways upstream of MAP kinase to mediate the systemic communication of translation defects to induce detoxification genes. Mammalian bile acids can rescue the defect in detoxification gene induction caused by C. elegans lipid biosynthetic gene inactivations. Extracts prepared from C. elegans with translation deficits but not from the wild type can also rescue detoxification gene induction in lipid-biosynthesis-defective strains. These eukaryotic antibacterial countermeasures are not ignored by bacteria: particular bacterial species suppress normal C. elegans detoxification responses to mutations in translation factors.
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Affiliation(s)
- J Amaranath Govindan
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
- Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Elamparithi Jayamani
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
- Division of Infectious Diseases, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island 02903, USA
| | - Xinrui Zhang
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
| | - Peter Breen
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
| | - Jonah Larkins-Ford
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
| | - Eleftherios Mylonakis
- Division of Infectious Diseases, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island 02903, USA
| | - Gary Ruvkun
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
- Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA
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Campos-Herrera R, El-Borai FE, Duncan LW. Real-time PCR as an effective technique to assess the impact of phoresy by Paenibacillus sp. bacteria on Steinernema diaprepesi nematodes in nature. Mol Ecol Resour 2012; 12:885-93. [PMID: 22672645 DOI: 10.1111/j.1755-0998.2012.03159.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Quantitative real-time PCR (qPCR) is a powerful tool to study species of cryptic organisms in complex food webs. This technique was recently developed to detect and quantify several species of entomopathogenic nematodes (EPNs), which are widely used for biological control of insects, and some natural enemies of EPNs such as nematophagous fungi and the phoretic bacteria Paenibacillus sp. and Paenibacillus nematophilus. A drawback to the use of primers and TaqMan probes designed for Paenibacillus sp. is that the qPCR also amplified Paenibacillus thiaminolyticus and Paenibacillus popilliae, two closely related species that are not phoretically associated with EPNs. Here, we report that the detection of Paenibacillus sp. DNA in nematode samples was two orders of magnitude greater (P < 0.001) when the bacterium was added to soil together with its EPN species-specific host Steinernema diaprepesi than when it was added concomitantly with other EPNs or with species of bacterial-feeding nematodes. Just 6% of samples detected trace amounts of P. thiaminolyticus and P. popilliae exposed to the same experimental conditions. Thus, although the molecular assay detects Paenibacillus spp. DNA in nonphoretic associations, the levels are essentially background compared to the detection of Paenibacillus sp. in association with its nematode host.
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Affiliation(s)
- R Campos-Herrera
- Entomology and Nematology Department, Citrus Research and Education Center, University of Florida, IFAS, 700 Experiment Station Road, Lake Alfred, FL 33850-2299, USA.
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12
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Schwartz HT, Antoshechkin I, Sternberg PW. Applications of high-throughput sequencing to symbiotic nematodes of the genus Heterorhabditis. Symbiosis 2012. [DOI: 10.1007/s13199-012-0151-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Entomopathogenic nematodes, phoretic Paenibacillus spp., and the use of real time quantitative PCR to explore soil food webs in Florida citrus groves. J Invertebr Pathol 2011; 108:30-9. [DOI: 10.1016/j.jip.2011.06.005] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Revised: 06/09/2011] [Accepted: 06/14/2011] [Indexed: 11/23/2022]
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Vasanthakumar A, Handelsman J, Schloss PD, Bauer LS, Raffa KF. Gut microbiota of an invasive subcortical beetle, Agrilus planipennis Fairmaire, across various life stages. ENVIRONMENTAL ENTOMOLOGY 2008; 37:1344-1353. [PMID: 19036215 DOI: 10.1603/0046-225x(2008)37[1344:gmoais]2.0.co;2] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We characterized gut microbial communities in the emerald ash borer, Agrilus planipennis Fairmaire, an invasive phloem-feeding and wood-boring beetle that has caused extensive mortality to urban and forest ash trees. Analyses included both 16S rRNA gene-based and culture-based approaches. We estimated that the emerald ash borer gut harbors 44, 71, and 49 operational taxonomic units (OTUs(0.03)) in the larval, prepupal, and adult stages, respectively, and a total of 132 OTUs(0.03) when data from the three stages are pooled. The larval gut community shared all its OTUs(0.03) with either the adult or the prepupal gut community, and the adult and prepupal gut communities shared 27 OTUs(0.03). Twenty-two OTUs(0.03) were shared among the three life stages. Rarefaction analyses suggest that these gut microbial communities are close to being completely sampled at the phylum level. Culture-independent techniques yielded a higher diversity of bacteria than did culturing. Three species of bacteria inhabiting guts of emerald ash borer showed cellulolytic activity. The diverse, dynamic, and presumably multifunctional microbial community associated with emerald ash borer guts suggests that invasive insects should be viewed as multispecies complexes and that such an interpretation can improve our ability to develop more effective management approaches.
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Affiliation(s)
- Archana Vasanthakumar
- Department of Entomology, 1630 Linden Dr., 345 Russell Labs, University of Wisconsin-Madison, Madison, WI 53706, USA.
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Vasanthakumar A, Handelsman J, Schloss PD, Bauer LS, Raffa KF. Gut microbiota of an invasive subcortical beetle, Agrilus planipennis Fairmaire, across various life stages. ENVIRONMENTAL ENTOMOLOGY 2008. [PMID: 19036215 DOI: 10.1093/ee/37.5.1344] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
We characterized gut microbial communities in the emerald ash borer, Agrilus planipennis Fairmaire, an invasive phloem-feeding and wood-boring beetle that has caused extensive mortality to urban and forest ash trees. Analyses included both 16S rRNA gene-based and culture-based approaches. We estimated that the emerald ash borer gut harbors 44, 71, and 49 operational taxonomic units (OTUs(0.03)) in the larval, prepupal, and adult stages, respectively, and a total of 132 OTUs(0.03) when data from the three stages are pooled. The larval gut community shared all its OTUs(0.03) with either the adult or the prepupal gut community, and the adult and prepupal gut communities shared 27 OTUs(0.03). Twenty-two OTUs(0.03) were shared among the three life stages. Rarefaction analyses suggest that these gut microbial communities are close to being completely sampled at the phylum level. Culture-independent techniques yielded a higher diversity of bacteria than did culturing. Three species of bacteria inhabiting guts of emerald ash borer showed cellulolytic activity. The diverse, dynamic, and presumably multifunctional microbial community associated with emerald ash borer guts suggests that invasive insects should be viewed as multispecies complexes and that such an interpretation can improve our ability to develop more effective management approaches.
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Affiliation(s)
- Archana Vasanthakumar
- Department of Entomology, 1630 Linden Dr., 345 Russell Labs, University of Wisconsin-Madison, Madison, WI 53706, USA.
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ffrench-Constant RH, Dowling A, Waterfield NR. Insecticidal toxins from Photorhabdus bacteria and their potential use in agriculture. Toxicon 2006; 49:436-51. [PMID: 17207509 DOI: 10.1016/j.toxicon.2006.11.019] [Citation(s) in RCA: 157] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2006] [Accepted: 11/17/2006] [Indexed: 10/23/2022]
Abstract
Most of the insecticidal toxins used in agriculture come from a single bacterium Bacillus thuringiensis or 'Bt'. Here we review our work on the array of toxins produced by Photorhabdus and Xenorhabdus bacteria that are symbiotic with entomopathogenic nematodes, and discuss their potential for use in agriculture as alternatives to Bt. Despite the fact that both Photorhabdus and Xenorhabdus are introduced directly into the insect blood stream by their nematode vectors, they produce a range of toxins with both oral and injectable insecticidal activity. The toxin complexes (Tc's) are large orally active toxins that are displayed on the outer surface of the bacterium. They require three components (A-C) for full toxicity and one 'A' component has been successfully expressed in transgenic Arabidopsis to confer insect resistance. One such group of Tc's, the PirAB binary toxins, have oral activity against mosquitoes and some caterpillar pests. Their mode of action is not known but they show significant sequence similarity to a recently described neurotoxin beta-leptinotarsin-h isolated from the blood of the Colorado potato beetle. Other toxins such as 'makes caterpillars floppy' (Mcf) and proteins encoded by the 'Photorhabdus virulence cassettes' (PVCs) only show injectable activity. Mcf1 promotes apoptosis in a wide range of cells and appears to mimic mammalian BH3 domain-only proteins in the mitochondrion whereas the mode of action of the PVCs remains undetermined. The likely biological reasons for the massive functional redundancy in Photorhabdus insecticidal toxins are discussed.
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Affiliation(s)
- Richard H ffrench-Constant
- Center for Ecology and Conservation, School of Biological Sciences, University of Exeter in Cornwall, Penryn, Cornwall TR10 9EZ, UK.
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Ffrench-Constant R, Waterfield N. An ABC Guide to the Bacterial Toxin Complexes. ADVANCES IN APPLIED MICROBIOLOGY 2005; 58C:169-183. [PMID: 16543033 DOI: 10.1016/s0065-2164(05)58005-5] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Richard Ffrench-Constant
- Center for Molecular Microbiology and Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, United Kingdom
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Enright MR, Griffin CT. Effects of Paenibacillus nematophilus on the entomopathogenic nematode Heterorhabditis megidis. J Invertebr Pathol 2005; 88:40-8. [PMID: 15707868 DOI: 10.1016/j.jip.2004.10.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2004] [Revised: 09/29/2004] [Accepted: 10/08/2004] [Indexed: 11/29/2022]
Abstract
The insect parasitic nematodes Heterorhabditis spp. are mutualistically associated with entomopathogenic bacteria, Photorhabdus spp. A novel association has been detected between H. megidis isolate EU17 and the endospore-forming bacterium Paenibacillus nematophilus. P. nematophilus sporangia adhere to infective juveniles (IJs) of H. megidis and develop in insect hosts along with the nematodes and their symbiont. We tested the effects of P. nematophilus on H. megidis. The yield and quality (size, energy reserves, and storage survival) of IJs were not affected by co-culture in insects with P. nematophilus. Dispersal of IJs in sand and on agar was inhibited by adhering P. nematophilus sporangia: fewer than 2% of IJs with P. nematophilus sporangia reached the bottom of a sand column, compared to 30% of the control treatment. Sporangia significantly reduced infectivity of H. megidis for wax moth larvae in sand, but not in a close contact (filter paper) assay. The results suggest that P. nematophilus may reduce the transmission potential of H. megidis through impeding the motility of IJs.
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Affiliation(s)
- Michael R Enright
- Department of Biology and Institute of Bioengineering and Agroecology, National University of Ireland, Maynooth, Co. Kildare, Ireland
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