Nucleotide sequence differentiation of argentine isolates of the mosquito parasitic nematode Strelkovimermis spiculatus (Nematode: Mermithidae)

Abstract

Strelkovimermis spiculatus is an obligate parasite of mosquito larvae that breeds in environments of permanent flooding or in habitats subjected to periods of desiccation. Differences in epizootic levels within these habitats likely are due to variation at the genetic level. We evaluated whether nucleotide sequence variation levels might provide a basis for the development of molecular markers that correlate with infectivity phenotypes characteristic of different populations of S. spiculatus from La Plata, Buenos Aires province, Argentina. Partial DNA sequences from the nuclear 18S gene and the mitochondrial nd4 gene were analyzed. Nucleotide sequences from nematodes collected from temporary ponds (site 4), when aligned with sequences obtained from isolates found in permanent (site 1 and site 2) and temporary environments (site 3), revealed a modest number of substitutions the 18S and nd4 genes over short sequence expanses. Our results indicate that an expanded sampling of both nuclear and mitochondrial genes, with a special reference to nuclear genes encoding host range infectivity phenotypes, may be useful in the development of biomarkers for studying the population dynamics of S. spiculatus, and for correlating isolates with phenotypic traits useful for durable biological control practices.