Population Structure and Dispersals of the Sulfur Butterfly Colias erate (Lepidoptera : Pieridae) in an Isolated Plain Located in a Cool Temperate Zone of Japan Population Structure and Dispersals of the Sulfur Butterfly Colias erate (Lepidoptera : Pieridae) in an Isolated Plain Located in a Cool Temperate Zone of Japan

Mark-release-recapture techniques were used to study natural populations of Colias erate in the isolated plain of Shirouma, Nagano Prefecture. Adults fed on and oviposited mainly on clovers, which are abundant on the ridges of the paddy fields. Males outnumbered females in each sampling day, but the estimated number indicated a 1 : 1 sex ratio. The butterfly had a low frequency of yellow morph in females (less than 15%). The yellow-white morph ratio in females did not differ much from the other localities sampled in Shirouma, such as the ski slope. Males, yellow morphs and white morphs showed similar stable age structures in the summer. Females tended to remate during their life span. Dispersal varied between sexes and between morphs in females. The resident times were similar for yellow and white morphs, but males had a higher recapture rate, suggesting site fidelity. Since most of the plain is occupied by cultivated fields for rice or cabbage, the available plants for larvae and adults in the ridges may not be a limiting resource for maintaining butterfly population.

Mark-release-recapture techniques were used to study natural populations of Colias erate in the isolated plain of Shirouma, Nagano Prefecture. Adults fed on and oviposited mainly on clovers, which are abundant on the ridges of the paddy fields. Males outnumbered females in each sampling day, but the estimated number indicated a 1 : 1 sex ratio. The butterfly had a low frequency of yellow morph in females (less than 15%). The yellow-white morph ratio in females did not differ much from the other localities sampled in Shirouma, such as the ski slope. Males, yellow morphs and white morphs showed similar stable age structures in the summer. Females tended to remate during their life span. Dispersal varied between sexes and between morphs in females. The resident times were similar for yellow and white morphs, but males had a higher recapture rate, suggesting site fidelity. Since most of the plain is occupied by cultivated fields for rice or cabbage, the available plants for larvae and adults in the ridges may not be a limiting resource for maintaining butterfly population.