Xenorhabdus spp.: An Overview of the Useful Facets of Mutualistic Bacteria of Entomopathogenic Nematodes

Abstract

Mounting concern over the misuse of chemical pesticides has sparked broad interest for safe and effective alternatives to control plant pests and pathogens. Xenorhabdus bacteria, as pesticidal symbionts of the entomopathogenic nematodes Steinernema species, can contribute to this solution with a treasure trove of insecticidal compounds and an ability to suppress a variety of plant pathogens. As many challenges face sound exploitation of plant–phytonematode interactions, a full useful spectrum of such interactions should address nematicidal activity of Xenorhabdus. Steinernema–Xenorhabdus complex or Xenorhabdus individually should be involved in mechanisms underlying the favorable side of plant–nematode interactions in emerging cropping systems. Using Xenorhabdus bacteria should earnestly be harnessed to control not only phytonematodes, but also other plant pests and pathogens within integrated pest management plans. This review highlights the significance of fitting Xenorhabdus-obtained insecticidal, nematicidal, fungicidal, acaricidal, pharmaceutical, antimicrobial, and toxic compounds into existing, or arising, holistic strategies, for controlling many pests/pathogens. The widespread utilization of Xenorhabdus bacteria, however, has been slow-going, due to costs and some issues with their commercial processing. Yet, advances have been ongoing via further mastering of genome sequencing, discovering more of the beneficial Xenorhabdus species/strains, and their successful experimentations for pest control. Their documented pathogenicity to a broad range of arthropods and pathogens and versatility bode well for useful industrial products. The numerous beneficial traits of Xenorhabdus bacteria can facilitate their integration with other tactics for better pest/disease management programs.

Entomopathogenic Nematodes: Integrated Pest Management and New Vistas

“…(Machado et al, 2021) and Xenorhabdus spp. (Castaneda-Alvarez et al, 2021), while detecting more of the beneficial species/strains of both genera (Abd-Elgawad, 2021, 2022. The high pathogenicity of Photorhabdus and Xenorhabdus species to a broad range of arthropods, effectiveness against certain pests and diseases, and versatility bode well for opening new horizons for their advantageous products (Bock et al, 2013;Wu et al, 2022).…”

“…EPNs have been isolated from all continents around the world except Antarctica. Also, their symbionts have recently been recorded as 20 Photorhabdus (Abd-Elgawad, 2021) and 27 Xenorhabdus species (Abd-Elgawad, 2022). A specialized third stage juvenile, usually called the dauer juvenile or infective juvenile (IJ) is the only free living stage that can actively invade the insect host.…”

“…Therefore, even Xenorhabdus bacterial species individually should earnestly be utilized to manage plant pathogens/pests within integrated pest management (IPM) programs. The importance of fitting Xenorhabdus-obtained insecticidal, antimicrobial, fungicidal, nematicidal, pharmaceutical, acaricidal, and toxic compounds into present and arising IPM strategies for management of numerous pests/pathogens was recently highlighted (Abd-Elgawad, 2022). Nonetheless, the relevant practical usage of Xenorhabdus spp.…”

Genome analysis of secondary metabolite‑biosynthetic gene clusters of Photorhabdus akhurstii subsp. akhurstii and its antibacterial activity against antibiotic-resistant bacteria

“…temperata Meg1 (7), P. khanii subsp. khanii strain HGB1456 (10) and P. cinerea strain DSM19724 (14).…”

“…They are associated with the infective juveniles of entomopathogenic nematodes in the genera Steinernema and Heterorhabditis, respectively. Currently, 27 species of Xenorhabdus and 21 species of Photorhabdus were documented worldwide [4][5][6][7][8][9][10]. These bacteria are known to produce numerous secondary metabolites that show bioactivity against bacteria, fungi, insects, nematodes, and protozoa [11][12][13].…”