ANALYSIS OF CLONAL DIVERSITY OF THE PEACH-POTATO APHID, MYZUS-PERSICAE (SULZER), IN SCOTLAND, UK AND EVIDENCE FOR THE EXISTENCE OF A PREDOMINANT CLONE

Clones of the peach-potato aphid, Myzus persicae (Sulzer), mostly from Scotland, UK were examined using an rDNA fingerprinting technique. Ei ghty patterns (genotypes) were found amongst the 276 clones. A large n umber of clones (30%) from all sample areas in Scotland exhibited the same simple pattern, suggesting the presence of a single M. persicae c lone. There was no difference in genotype distributions between M. per sicae collected from brassica or potato crops, suggesting that host-ad apted genotypes have no advantage in the field. Different fingerprints were randomly distributed in the environment, although clones taken f rom the same leaf were more often the same fingerprint. Highly distinc tive fingerprints, which were more widely distributed, suggest that th is technique could be used to follow individual clones. In addition to the common clonal type, multiple fingerprint bands were found over su ccessive years, implying that, in Scotland, local overwintering asexua l populations are the most common source of M. persicae in the followi ng year.