ナミハダニとカンザワハダニの比較生態学

抄録

Tetranychus urticae long a cosmopolitan, and T. kanzawai originally limited to the Far East now occurs widely on a variety of horticultural crops in Japan. The latter also depends on wild host plants and there are frequent exchanges of individuals between crops and wild hosts. The two species have many host plants in common and show similar ecological performance. However, the host adaptability of T. kanzawai often differs among mite strains, forming host races, but not in T. urticae. In warmer areas of Japan, the distribution of T. urticae in the field is limited and the mites maintain their populations only if adequate hosts are available in both summer and winter. The incidence of diapause of T. urticae shows a latitudinal cline and in warmer areas the mites have very weak diapause. By contrast, populations in warmer areas, such as Kagoshima and Taiwan, of T. kanzawai show a high incidence of diapause. We then speculated the origin of the two spider mite species.