POPULATION-STRUCTURE IN THE SPIDER-MITE TETRANYCHUS-URTICAE (ACARI, TETRANYCHIDAE) FROM CRETE BASED ON MULTIPLE ALLOZYMES

The polymorphism of four isozymes was studied on single females of Tet ranychus urticae from Crete (Greece), using an isoelectric focusing te chnique. Genetic differentiation was found to be correlated with dista nce but not with the species of colonized host-plants. Thus no differe ntiation was observed between samples collected on citrus trees, tomat o, pumpkin, okra or weed plants located within a 50 m(2) area, showing that at this geographical scale T. urticae. populations are panmictic . In contrast, samples from plants at 150m or more from one another di splayed a significant genetic differentiation. These results are discu ssed in relation to the known pattern of migration in the species.