ALLOZYME VARIATIONS AMONG POPULATIONS OF THE 2-SPOTTED SPIDER-MITE, TETRANYCHUS-URTICAE KOCH, IN JAPAN

Genetic variations in two esterases, MDH and PGI were studied among Ja panese populations of the two-spotted spider mite, Tetranychus urticae KOCH, through polyacrylamide gel electrophoresis. Esterases and MDH w ere polymorphic in the majority of populations studied. Geographic pat terns in esterases and MDH allele frequencies were observed among popu lations 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 i n any enzyme variation in populations from herbaceous hosts, and the a llele frequencies differed greatly even among geographically neighbori ng populations.