RFLP ANALYSIS OF PCR AMPLIFIED ITS AND 26S RIBOSOMAL-RNA GENES OF SELECTED ENTOMOPATHOGENIC NEMATODES (STEINERNEMATIDAE, HETERORHABDITIDAE)

This study examined the polymerase chain reaction (PCR) amplified inte rnal transcribed spacer (ITS) and 26S ribosomal DNA (rDNA) regions of 15 entomopathogenic nematode isolates including Steinernema feltiae sy n. 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 f ragment length polymorphisms (RFLP) of PCR amplified ITS and 26S regio ns provided specific banding patterns for all isolates but S. feltiae syn. bibionis and S. glaseri. These two species were separated by zymo grams of esterase and tetrazolium oxidase. A field trapping method ret rieved two isolates of naturally occurring nematodes. One field isolat e collected (F1) displayed banding patterns identical to those of S. c arpocapsae DD136 released in the same location 1 year earlier. Thr sec ond 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 Steiner nema and Heterorhabditis.