Abstract
BackgroundEntomopathogenic nematodes (EPNs) harboring symbiotic bacteria are one of the safest alternatives to the chemical insecticides for the control of various insect pests. Infective juveniles of EPNs locate a target insect, enter through the openings, and reach the hemocoel, where they release the symbiotic bacteria and the target gets killed by the virulence factors of the bacteria. Photorhabdus with Heterorhabditis spp. are well documented; little is known about the associated bacteria.Main bodyIn this study, we explored the presence of symbiotic and associated bacteria from Heterorhabditis sp. (IISR-EPN 09) and characterized by phenotypic, biochemical, and molecular approaches. Six bacterial isolates, belonging to four different genera, were recovered and identified as follows: Photorhabdus luminescens, one each strain of Providencia vermicola, Pseudomonas entomophila, Alcaligenes aquatilis, and two strains of Alcaligenes faecalis based on the phenotypic, biochemical criteria and the sequencing of 16S rRNA gene.ConclusionP. luminescens is symbiotically associated with Heterorhabditis sp. (IISR-EPN 09), whereas P. vermicola, P. entomophila, A. aquatilis, and A. faecalis are the associated bacteria. Further studies are needed to determine the exact role of the bacterial associates with the Heterorhabditis sp.
Highlights
Materials and methods Entomopathogenic nematode and insect sources Infective juveniles (IJs) of Heterorhabditis sp. (IISR-Entomopathogenic nematodes (EPNs) 09) were cultured as per the procedure described by Woodring and Kaya (1988)
The ease of their production and exemption from registration requirements are the two big reasons for commercial developments of EPNs. They are widely distributed in different soil habitats and are diverse with respect to the conditions needed for their survival, infectivity potential, mode of replication, and host range (Ali et al 2005).Other major bacterial agents used in biological control of insect pests are Bacillus thuringiensis and B. sphaericus; these bacteria have been used in controlling insect pests belonging to the orders Diptera, Lepidoptera, and Coleoptera (Vega and Kaya 2012)
Bacteria were successfully isolated on NBTA (Supplementary Fig. 1) from the gut of EPNs, using all the 3 methods, but rate of recovery varied among the methods
Summary
Six bacterial isolates from the Heterorhabditis sp. (IISR-EPN 09) were identified and the latter is native to the spice plantation of the southern India. The bacteria were identified based on the phenotypic-biochemical criteria and the sequencing of 16S rRNA gene. From the Heterorhabditis sp., some associated bacterial species belonging to genera other than Photorhabdus, were isolated and identified. These species were not reported to have a symbiotic relationship with. Some associated bacteria have been found to augment the toxicity of the EPNs in some previous studies. Evaluation of the entomopathogenic potential of the symbiotic and associated bacteria against the insect pests shall be carried out to explore their toxicity potential
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
