RFLP ANALYSIS OF RIBOSOMAL-RNA INTERGENIC SPACER REGIONS OF 23 ISOLATES OF THE ENTOMOPATHOGEN PAECILOMYCES-FARINOSUS

Genetic relationships between 23 eastern Canadian isolates of the ento mopathogen Paecilomyces farinosus (Helm ex S.F. Gray) Brown & Smith we re investigated by comparison of DNA fragments produced by restriction enzyme digestion of polymerase chain reaction amplified ribosomal RNA intergenic spacer regions. The variation observed was limited to 40% or less of these regions. All P. farinosus isolates were very dissimil ar to isolates of the entomopathogens Beauveria bassiana (Bals.) Vuill . and Paecilomyces fumosoroseus (Wize) Brown & Smith. Seventeen P. far inosus isolates from six different hosts and diverse habitats yielded identical or nearly identical results. Two groups, each with three iso lates from two different hosts, were distinct from the main Stoup of i solates. Each of the three P. farinosus groups included some isolates that produced synnemata and some that did not, indicating multiple evo lutionary losses of the ability to produce this sporulation structure. We conclude that eastern Canadian P. farinosus, while genetically and phenotypically variable, is not composed largely of strains with stri ct ecological requirements.