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Frontiers in Insect Science 2023The term "microbial control" has been used to describe the use of microbial pathogens (bacteria, viruses, or fungi) or entomopathogenic nematodes (EPNs) to control... (Review)
Review
The term "microbial control" has been used to describe the use of microbial pathogens (bacteria, viruses, or fungi) or entomopathogenic nematodes (EPNs) to control various insect pest populations. EPNs are among the best biocontrol agents, and major developments in their use have occurred in recent decades, with many surveys having been conducted all over the world to identify EPNs that may have potential in the management of insect pests. For nematodes, the term "entomopathogenic" means "causing disease to insects" and is mainly used in reference to the bacterial symbionts of and ( and , respectively), which cause EPN infectivity. A compendium of our multiannual experiences on EPN surveys and on their collection, identification, characterization, and use in agro-forestry ecosystems is presented here to testify and demonstrate once again that biological control with EPNs is possible and offers many advantages over chemicals, such as end-user safety, minimal damage to natural enemies, and lack of environmental pollution, which are essential conditions for an advanced IPM strategy.
PubMed: 38469514
DOI: 10.3389/finsc.2023.1195254 -
Insects Oct 2018causes considerable economic damage to small and thin-skinned fruits including cherry, blueberry, raspberry, grape and strawberry. Since it attacks fruits at the...
causes considerable economic damage to small and thin-skinned fruits including cherry, blueberry, raspberry, grape and strawberry. Since it attacks fruits at the ripening stage, the use of chemical pesticides is limited due to the high risk of residues on fruit. Biological control is thus expected to play an essential role in managing this pest. The Gram-negative bacterium, and its symbiotic spp. nematode have been shown to be highly pathogenic to insects, with a potential for replacing pesticides to suppress several pests. Insecticidal activity of at different bacterial cell concentrations and its cell-free supernatant were assessed against third-instar larvae and pupae of under laboratory conditions. suspensions had a significant oral and contact toxicity on larvae and pupae, with mortalities up to of 70⁻100% 10 days after treatment. Cell-free supernatant in the diet also doubled mortality rates of feeding larvae. Our results suggest that may be a promising candidate for biological control of , and its use in integrated pest management (IPM) programs is discussed.
PubMed: 30360545
DOI: 10.3390/insects9040148 -
Parasites & Vectors Jul 2020The control of insects of medical importance, such as Aedes aegypti and Aedes albopictus are still the only effective way to prevent the transmission of diseases, such... (Review)
Review
The control of insects of medical importance, such as Aedes aegypti and Aedes albopictus are still the only effective way to prevent the transmission of diseases, such as dengue, chikungunya and Zika. Their control is performed mainly using chemical products; however, they often have low specificity to non-target organisms, including humans. Also, studies have reported resistance to the most commonly used insecticides, such as the organophosphate and pyrethroids. Biological control is an ecological and sustainable method since it has a slow rate of insect resistance development. Bacterial species of the genera Xenorhabdus and Photorhabdus have been the target of several research groups worldwide, aiming at their use in agricultural, pharmaceutical and industrial products. This review highlights articles referring to the use of Xenorhabdus and Photorhabdus for insects and especially for mosquito control proposing future ways for their biotechnological applicability. Approximately 24 species of Xenorhabdus and five species of Photorhabdus have been described to have insecticidal properties. These studies have shown genes that are capable of encoding low molecular weight proteins, secondary toxin complexes and metabolites with insecticide activities, as well as antibiotic, fungicidal and antiparasitic molecules. In addition, several species of Xenorhabdus and Photorhabdus showed insecticidal properties against mosquitoes. Therefore, these biological agents can be used in new control methods, and must be, urgently considered in short term, in studies and applications, especially in mosquito control.
Topics: Aedes; Animals; Bacterial Toxins; Chikungunya Fever; Dengue; Genes, Bacterial; Insecta; Insecticides; Larva; Mosquito Control; Mosquito Vectors; Pest Control, Biological; Photorhabdus; Vector Borne Diseases; Xenorhabdus; Zika Virus Infection
PubMed: 32727530
DOI: 10.1186/s13071-020-04236-6 -
Journal of Invertebrate Pathology Jun 2023Locusts occasionally represent a danger in Africa despite intensive management measures, leading to severe yield loss and a commensurate loss of food and money. The...
Biochemical compositions and histopathology of the young and aged nymphs of the desert locust Schistocerca gregaria Forsskål (Orthoptera: Acrididae) affected by Photorhabdus luminescens (Enterobacterales: Morganellaceae).
Locusts occasionally represent a danger in Africa despite intensive management measures, leading to severe yield loss and a commensurate loss of food and money. The laboratory assessment of the toxicity of the Photorhabdus luminescens bacteria and its cell-free filtrate used Schistocerca gregaria nymphs in the second and fifth nymphs as test insects. Greater mortality was seen in locust nymphs of the second and fifth instars due to the high levels of toxicity produced by the bacterial suspension and its cell-free filtrate. The amounts of protein, fat, and carbohydrates in the treated locusts were drastically reduced. For the treated second and fifth instar nymphs of the desert locust, adverse effects on the muscular layers of the midgut and the muscles in the jumping legs were investigated.
Topics: Animals; Grasshoppers; Photorhabdus; Insecta
PubMed: 37068730
DOI: 10.1016/j.jip.2023.107922 -
Nature Communications Jun 2020Toxin complex (Tc) toxins are virulence factors of pathogenic bacteria. Tcs are composed of three subunits: TcA, TcB and TcC. TcA facilitates receptor-toxin interaction...
Toxin complex (Tc) toxins are virulence factors of pathogenic bacteria. Tcs are composed of three subunits: TcA, TcB and TcC. TcA facilitates receptor-toxin interaction and membrane permeation, TcB and TcC form a toxin-encapsulating cocoon. While the mechanisms of holotoxin assembly and pore formation have been described, little is known about receptor binding of TcAs. Here, we identify heparins/heparan sulfates and Lewis antigens as receptors for different TcAs from insect and human pathogens. Glycan array screening reveals that all tested TcAs bind negatively charged heparins. Cryo-EM structures of Morganella morganii TcdA4 and Xenorhabdus nematophila XptA1 reveal that heparins/heparan sulfates unexpectedly bind to different regions of the shell domain, including receptor-binding domains. In addition, Photorhabdus luminescens TcdA1 binds to Lewis antigens with micromolar affinity. Here, the glycan interacts with the receptor-binding domain D of the toxin. Our results suggest a glycan dependent association mechanism of Tc toxins on the host cell surface.
Topics: Animals; Bacterial Toxins; Binding Sites; Cell Adhesion; Cell Membrane; HEK293 Cells; Heparin; Humans; Insecta; Lewis X Antigen; Models, Molecular; Molecular Docking Simulation; Morganella morganii; Photorhabdus; Polysaccharides; Xenorhabdus
PubMed: 32483155
DOI: 10.1038/s41467-020-16536-7 -
Experimental Parasitology Sep 2019Only two drugs are currently available for the treatment of Chagas disease and their effectiveness are unsatisfactory. Photorhabdus luminescens and Xenorhabdus...
Only two drugs are currently available for the treatment of Chagas disease and their effectiveness are unsatisfactory. Photorhabdus luminescens and Xenorhabdus nematophila, two enteric bacteria highly pathogenic to a broad range of insects, have been studied as potential source for bioactive metabolites against protozoa causing neglected tropical diseases. Therefore, we tested the in vitro anti-Trypanosoma cruzi activity of secreted metabolites from these bacteria. The conditioned medium of X. nematophila and P. luminescens showed significant parasiticidal activity in a concentration-dependent manner (ICXN = 0.34 mg/mL, ICPL = 1.0 mg/mL). The parasiticidal compound was identified as a small molecule stable to heating and pH changes ranging from 2 to 12. Moreover, anti-Trypanosoma molecules secreted by both bacteria stimulate the trypanocidal activity of macrophages by a mechanism independent of nitric oxide. Summarizing, our studies reveal that P. luminescens and X. nematophila are potential sources of putative novel drugs against Chagas disease.
Topics: Analysis of Variance; Animals; Bacterial Proteins; Biological Assay; Chagas Disease; Culture Media, Conditioned; Endopeptidase K; Humans; Hydrogen-Ion Concentration; Inhibitory Concentration 50; Photorhabdus; Temperature; Trypanocidal Agents; Trypanosoma cruzi; Xenorhabdus
PubMed: 31279930
DOI: 10.1016/j.exppara.2019.107724 -
Plants (Basel, Switzerland) Aug 2021The current approaches to sustainable agricultural development aspire to use safer means to control pests and pathogens. bacteria that are insecticidal symbionts of... (Review)
Review
The current approaches to sustainable agricultural development aspire to use safer means to control pests and pathogens. bacteria that are insecticidal symbionts of entomopathogenic nematodes in the genus can provide such a service with a treasure trove of insecticidal compounds and an ability to cope with the insect immune system. This review highlights the need of -derived insecticidal, fungicidal, pharmaceutical, parasiticidal, antimicrobial, and toxic materials to fit into current, or emerging, holistic strategies, mainly for managing plant pests and pathogens. The widespread use of these bacteria, however, has been slow, due to cost, natural presence within the uneven distribution of their nematode partners, and problems with trait stability during in vitro culture. Yet, progress has been made, showing an ability to overcome these obstacles via offering affordable mass production and mastered genome sequencing, while detecting more of their beneficial bacterial species/strains. Their high pathogenicity to a wide range of arthropods, efficiency against diseases, and versatility, suggest future promising industrial products. The many useful properties of these bacteria can facilitate their integration with other pest/disease management tactics for crop protection.
PubMed: 34451705
DOI: 10.3390/plants10081660 -
Microbial Ecology Jan 2021Photorhabdus spp. (Enterobacteriales: Morganellaceae) occur exclusively as symbionts of Heterorhabditis nematodes for which they provide numerous services, including...
Photorhabdus spp. (Enterobacteriales: Morganellaceae) occur exclusively as symbionts of Heterorhabditis nematodes for which they provide numerous services, including killing insects and providing nutrition and defence within the cadavers. Unusually, two species (Photorhabdus cinerea and Photorhabdus temperata) associate with a single population of Heterorhabditis downesi at a dune grassland site. Building on previous work, we investigated competition between these two Photorhabdus species both at the regional (between insects) and local (within insect) level by trait comparison and co-culture experiments. There was no difference between the species with respect to supporting nematode reproduction and protection of cadavers against invertebrate scavengers, but P. cinerea was superior to P. temperata in several traits: faster growth rate, greater antibacterial and antifungal activity and colonisation of a higher proportion of nematodes in co-culture. Moreover, where both bacterial symbionts colonised single nematode infective juveniles, P. cinerea tended to dominate in numbers. Differences between Photorhabdus species were detected in the suite of secondary metabolites produced: P. temperata produced several compounds not produced by P. cinerea including anthraquinone pigments. Bioluminescence emitted by P. temperata also tended to be brighter than that from P. cinerea. Bioluminescence and pigmentation may protect cadavers against scavengers that rely on sight. We conclude that while P. cinerea may show greater local level (within-cadaver) competitive success, co-existence of the two Photorhabdus species in the spatially heterogeneous environment of the dunes is favoured by differing specialisations in defence of the cadaver against differing locally important threats.
Topics: Animals; Anthraquinones; Grassland; Luminescent Measurements; Photorhabdus; Secondary Metabolism; Strongyloidea; Symbiosis
PubMed: 32827089
DOI: 10.1007/s00248-020-01573-y -
Journal of Invertebrate Pathology May 2015In this work, we primed Galleria mellonella larvae by haemocoel injection of lipopolysaccharide (LPS) extracted from Photorhabdus luminescens TT01 to determine whether...
In this work, we primed Galleria mellonella larvae by haemocoel injection of lipopolysaccharide (LPS) extracted from Photorhabdus luminescens TT01 to determine whether bacterial LPS can induce enhanced immune protection (recently called immune priming). We also analyzed the relationship between changes in the levels of innate immune elements and the degree of enhanced immune protection in the larvae at designated time points after priming. The larvae that received experimental doses (20.0, 10.0 and 5.0μg per larva) of LPS demonstrated increased resistance against lethal challenge with P. luminescens TT01; the degree and period of protection correlated positively with the priming dose. These results indicated that the P. luminescens TT01 LPS could induce typical immune priming in G. mellonella. Moreover, the levels of innate immune parameters (i.e. haemocyte density, phagocytosis, haemocyte encapsulation ability, and antibacterial activity of cell-free haemolymph) and endogenous enzyme activities (i.e. acid phosphatase, ACP; alkaline phosphatase, AKP; superoxide dismutase, SOD and lysozyme, LSZ) were significantly increased following priming of the larvae with LPS, whereas the activities of peroxidase (POD) and catalase (CAT) were significantly decreased. All of the parameters examined changed in a dose- and time-dependent manner. This study demonstrated that G. mellonella larvae could modulate their immune responses based on different doses of LPS used for priming, and that priming phenomenon in G. mellonella larvae elicited by LPS was mediated by the innate immune elements and enzyme activity.
Topics: Animals; Larva; Lipopolysaccharides; Moths; Photorhabdus
PubMed: 25796336
DOI: 10.1016/j.jip.2015.03.007 -
Cellular Microbiology Aug 2021Photorhabdus luminescens Tc toxins are large tripartite ABC-type toxin complexes, composed of TcA, TcB and TcC proteins. Tc toxins are widespread and have shown a...
Photorhabdus luminescens Tc toxins are large tripartite ABC-type toxin complexes, composed of TcA, TcB and TcC proteins. Tc toxins are widespread and have shown a tropism for a variety of targets including insect, mammalian and human cells. However, their receptors and the specific mechanisms of uptake into target cells remain unknown. Here, we show that the TcA protein TcdA1 interacts with N-glycans, particularly Lewis X/Y antigens. This is confirmed using N-acetylglucosamine transferase I (Mgat1 gene product)-deficient Chinese hamster ovary (CHO) Lec1 cells, which are highly resistant to intoxication by the Tc toxin complex most likely due to the absence of complex N-glycans. Restoring Mgat1 gene activity, and hence complex N-glycan biosynthesis, recapitulated the sensitivity of these cells to the toxin. Exogenous addition of Lewis X trisaccharide partially inhibits intoxication in wild-type cells. Additionally, sialic acid also largely reduced binding of the Tc toxin. Moreover, proteolytic activation of TcdA1 alters glycan-binding and uptake into target cells. The data suggest that TcdA1-binding is most likely multivalent, and carbohydrates probably work cooperatively to facilitate binding and intoxication.
Topics: Animals; Bacterial Toxins; CHO Cells; Cricetinae; Cricetulus; Humans; Photorhabdus; Polysaccharides
PubMed: 33720490
DOI: 10.1111/cmi.13326