Geographic Genetic Variation in the Introduced Insect Hyphantria cunea Drury in Japan Revealed by RAPD Analysis

The fall webworm Hyphantria cunea Drury (Lepidoptera: Arctiidae) is an invasive pest in Japan that has expanded its range since its accidental introduction in 1945. To investigate the genetic structure and potential source of a northern population recently established in Hirosaki (Aomori Prefecture), we analyzed five geographic populations using the random amplified polymorphic DNA (RAPD) method. Two primers revealed 18 polymorphic bands among 155 individuals collected across five prefectures. Cluster analysis based on Nei’s genetic distances grouped the populations into two major clusters corresponding to the Pacific coast and Sea of Japan coast, with the Hirosaki population showing close affinity to the Pacific coast group. These results suggest possible evolutionary divergence and local adaptation following invasion, and they highlight the utility of RAPD markers in assessing geographic genetic variation in introduced insect populations.