Caracterización molecular y filogenética del gen 18S ARNr del nemátodo entomopatógeno Heterorhabditis indica aislado en el norte de Perú

The molecular and phylogenetic characterization of entomopathogenic nematode (EPN) species allows for the differentiation of circulating genotypes as well as the mapping of their geographic distribution, including the identification of the most aggressive genotypes in insect infection. The aim of this study was to perform the molecular and phylogenetic characterization of in 18S rRNA gene of the entomopathogenic nematode Heterorhabditis indica isolated from northern Peru. A total of 851 nucleotides from a consensus sequence of the 18S rRNA gene of a H. indica strain, collected from algarrobo (carob tree) forests in northern Peru and previously shown to exhibit entomopathogenic activity against Galleria mellonella (wax moth), were analyzed. The consensus sequence was subjected to a similarity search using the BLAST tool from the NCBI GenBank database, applying a threshold of 90% for both identity and coverage. Sequences meeting these criteria were aligned with the consensus sequence through multiple sequence alignment using MEGA v.11 software. The resulting alignment was then analyzed using DnaSP v.5 software to assess monomorphic and polymorphic variability, allowing the identification and differentiation of haplotypes. During the alignment process, 74 unaligned bases at the sequence ends were removed, and 10 gap positions were excluded, yielding a final matrix of 767 aligned bases for molecular and phylogenetic analysis. The similarity analysis identified six sequences with identity ranging from 84.89% to 85.11% and coverage values between 92% and 99%. In the molecular characterization, 658 sites were found to be conserved (monomorphic), while 109 were variable (polymorphic), representing potential mutational events. Additionally, six distinct haplotypes (Hap-1 to Hap-6) were identified, with a haplotype diversity index (Hd) of 0.9524, indicating that the analyzed consensus sequence belonged to a single haplotype (Hap-2), to which a genotypic differentiation code (C05HI) was assigned. In the phylogenetic analysis, the sequence was closely related to a registered sequence in GenBank (accession number OK493747.1), forming a monophyletic group. It is recommended that further studies be conducted on H. indica C05HI, which may be present in algarrobo forest soils in northern Peru. Likewise, it is suggested that governmental institutions incorporate this nematode species into their training, technical assistance, and/or pest control programs.