INTRASPECIFIC DIVERSITY IN PAECILOMYCES-FUMOSOROSEUS

Two types of genetic markers, vegetative compatibility and RAPD, were evaluated for their ability to assess genetic variation among 38 isola tes of the entomopathogenic fungus, Paecilomyces fumosoroseus. Both ma rkers revealed significant polymorphisms. Nitrate non-utilizing mutant s were generated from chlorate-containing media and used as forcing ma rkers to observe heterokaryon formation and determine vegetative compa tibility. Nineteen separate vegetative compatibility groups (VCGs) wer e identified, only seven having at least two members and 12 represente d by single isolates. No correlation was observed between VCG and eith er insect host or geographic origin. Nine RAPD primers produced 365 un ique fragments and could distinguish three different phenetic groups. RAPD profiles conclusively showed that strains within some VCGs were g enetically unrelated, indicating that these strains were not clonal in origin. The large number of VCGs suggests that formation of heterokar yons and possible genetic exchange are uncommon. DNA fingerprinting wi th RAPD-PCR provides high resolution of genotype distribution and coul d be useful in tracking the fate of biocontrol agents released into th e environment.