Genetic Changes in the Population Structure of the Two-Spotted Spider Mite, Tetranychus urticae KOCH (Acari: Tetranychidae), on Vinyl-House Strawberries

Abstract

Two alleles were detected at the phosphoglucoisomerase (PGI) locus of the two-spotted spider mite, Tetranychus urticae KOCH. For clarifying the temporal change in genetic structures of the mite population, we introduced two laboratory-selected strains of the mites which were homozygous for PGI alleles onto vinyl-house strawberries. The results revealed that mites initially tended to from breeding colonies on individual leaflets, but with an increase in their density, they dispersed all over the plants. As a result, the population became genetically homogeneous as a whole.