Natural association of the entomopathogenic nematode Heterorhabditis indica (Rhabditida: Heterorhabditidae) from the Philippines with the non-symbiotic bacterium Ochrobactrum anthropi (Proteobacteria: Brucellaceae)

Abstract

Background Entomopathogenic nematodes of the genera Heterorhabditis and Steinernema are widely used as biocontrol agents against diverse insect pests. Their association with symbiont bacteria is found to be the primary cause of insect mortality. The present study reported a comprehensive characterization of a local Philippine EPN isolate using congruent morpho-taxometrical and molecular data and the associated bacterium in the infective dauer juveniles. Results Using an insect-baiting technique, a nematode isolate labeled F2H was recovered from the sandy soils in the coastal area of southern Philippines. Based on morphology and morpho-taxometrics, the F2H isolate collected from Iligan City was identified as Heterorhabditis indica. Analysis of the ITS region of rDNA revealed the highest sequence match to H. indica. The sequences of the bacterial 16S rDNA gene showed that the symbiont of H. indica presented 100% similitude with the sequences of Ochrobactrum anthropi. Further, pairwise alignment and phylogenetic analysis demonstrated that O. anthropi, O. lupini and O. cytisi shared 100% similarity and form a monophyletic clade. These strains have not presented any differences in the phylogenetic and 16S rDNA data, and O. lupini and O. cytisi should be considered a later heterotypic synonym of O. anthropi. Conclusions The description of H. indica-O. anthropi association was the first report in the Philippines. This provides additional account and collection of naturally isolated EPN-bacteria, contributing to limited knowledge on its diversity in the Philippines, which can be utilized in the biocontrol of pests after further comprehensive assessments.

Taxonomic and molecular characterization of a new entomopathogenic nematode species, Heterorhabditis casmirica n. sp., and whole genome sequencing of its associated bacterial symbiont

“…Insects with nematode infestation symptoms were washed with double distilled H 2 O, sterilized with 0.1% NaOCl 2 , and then placed in White traps to recover the new generation of IJs [ 24 ]. Recovered nematodes were reared using Galleria mellonella larvae as hosts under laboratory conditions [ 25 , 26 ]. The IJs were stored in 250-mL tissue culture flasks in a biological oxygen demand incubator at 15 °C [ 27 , 28 ].…”

Isolation, identification of entomopathogenic nematodes with insights into their distribution in the Syrian coast regions and virulence against Tuta absoluta

“…EPN also exhibited a higher recovery frequency at altitudes below 200 m. Within this altitude range, as revealed in the COIA analysis, H. indica and H. bacteriophora were dominant, which aligns with findings from other global studies ( Hominick, 2002 ; Mauléon et al ., 2006 ; Leonar et al ., 2022 ) indicating that both species are commonly found at lower altitudes. Jaffuel et al .…”