RFLP Analysis of PCR Amplified ITS and 26S Ribosomal RNA Genes of Selected Entomopathogenic Nematodes (Steinernematidae, Heterorhabditidae).

Abstract

This study examined the polymerase chain reaction (PCR) amplified internal transcribed spacer (ITS) and 26S ribosomal DNA (rDNA) regions of 15 entomopathogenic nematode isolates including Steinernema feltiae syn. bibionis, S. glaseri, seven strains of S. carpocapsae, four strains of Heterorhabditis bacteriophora, and two field isolates. RDNA length variation was not observed among the isolates examined. Restriction fragment length polymorphisms (RFLP) of PCR amplified ITS and 26S regions provided specific banding patterns for all isolates but S. feltiae syn. bibionis and S. glaseri. These two species were separated by zymograms of esterase and tetrazolium oxidase. A field trapping method retrieved two isolates of naturally occurring nematodes. One field isolate collected (F1) displayed banding patterns identical to those of S. carpocapsae DD136 released in the same location 1 year earlier. The second field isolate (F2) had unique PCR-RFLP profiles compared with all other strains. This study provides a rapid molecular taxonomic method to more fully establish species relationships among members of Steinernema and Heterorhabditis.