Abstract
Genetic variations in two esterases, MDH and PGI were studied among Japanese populations of the two-spotted spider mite, Tetranychus urticae KOCH, through polyacrylamide gel electrophoresis. Esterases and MDH were polymorphic in the majority of populations studied. Geographic patterns in esterases and MDH allele frequencies were observed among populations collected from fruit trees and roses. A dendrogram constructed by the phenetic cluster analysis based on the genetic distance values showed that these populations could be divided into three geographic groups. However, there seemed to be no particular geographic pattern in any enzyme variation in populations from herbaceous hosts and the allele frequencies differed greatly even among geographically neighboring populations.
