Intercrop movement of the two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) from chrysanthemum to pea field.

I studied the seasonal occurrence of the two-spotted spider mite, Tetranychus urticae KOCH (green form), in chrysanthemum and pea fields and the dispersal between fields in central Wakayama Prefecture, Japan. During the summer, before pea planting, T. urticae are never observed on weeds near the pea fields. However, the mites occurred at high densities on chrysanthemums throughout the year, including the cultivation and nursery period, and move into pea fields in September. T. urticae survive and oviposit prolifically on chrysanthemum under experimental conditions, whereas T. kanzawai fail to develop to adulthood. These results show that chrysanthemums are the principal host of T. urticae, from where the mites migrate to pea fields.