RAPD-PCR FOR IDENTIFICATION OF ZOOPHTHORA RADICANS ISOLATES IN BIOLOGICAL-CONTROL OF THE POTATO LEAFHOPPER

Biological control studies require the ability to distinguish released pathogens from locally occurring isolates of the same species. We hav e developed a technique that differentiates genotypes using random amp lified polymorphic DNA (RAPD) for the apomictic species Zoophthora rad icans (Zygomycota: Entomophthorales), a pathogen of the potato leafhop per, Empoasca fabae (Homoptera: Cicadellidae). RAPD analysis was perfo rmed on Z. radicans isolates released in test plots in 1990 and 1991 f ar leafhopper control; isolates later recovered from the same plots an d diverse other isolates were included in the analysis. RAPD fragment profiles of five recovered isolates proved very similar to those of th e released isolates and different from all other isolates tested; they are probable descendants of the released isolates. One of the recover ed isolates had RAPD profiles similar to isolates derived from aphids and probably represents a population endemic at the release site. In a ddition to verifying the successful establishment of our experimental releases, RAPD analysis revealed clear relationships among isolates de rived from the same host taxon. We propose that this simple and relati vely inexpensive method will be valuable in determining the establishm ent and spread of organisms released in biological control studies. (C ) 1995 Academic Press, Inc.