Comparative population studies of threePieris butterflies,P. rapae, P. melete andP. napi, living in the same area

Summary

The adult populations of threePieris butterflies,P. rapae, P. melete andP. napi, were studied in an area of their coexistence throughout the flight seasons by using the mark-and-recapture method. The study area, about 3×1.5 km, was set up in a farm village surrounded by the mountainous area in Inabu, Aichi Prefecture.

The habitats were qualified by the four factors, i. e., oviposition plants, adult nector plants, roosting-sites and light conditions. BetweenP. rapae andP. napi, there were sharp differences with regards to overall habitat preferences.P. melete had the widest preferences for all the habitat resources, which overlapped greately with requirements ofP. rapae andP. napi. P. melete andP. rapae showed similar preferences for oviposition plants, but the former preferred shaded habitats while the latter preferred sunny places.P. melete andP. napi, having similar preferences for shaded situations, showed differences in the preferences for oviposition plants. Moreover, three species ofPieris were different in their preferences for adult nector plants. Thus, they were more likely to partition habitat resources rather than competing for them.

The habitat structures of each species in respect of time, space and stability to weather changes were much different each other in the same area. The habitat ofP. rapae was temporary, localized and unstable. While, that ofP. melete was more permanent, widespread and stable than that ofP. rapae. P. napi seemed to live in the intermediate habitat, i. e., permanent, localized and stable one.