2018 Volume 21 Issue 4 Pages 211-229
In order to clarify the effects of artificial managements and/or meteorological factors on the butterfly diversity, butterfly assemblages were monitored by transect counts in the Forestry and Forest Products Research Institute, Tsukuba City, central Japan for 20 years (1997–2016). Sixty-three species and 21,699 individuals of butterflies were recorded. Thirty-six to 43 species were recorded each year. The total number of individuals recorded in a year significantly increased every year, especially, densities in April, May, June, July and October were increased. A significant positive correlation was observed between the number of individuals recorded in a year and the cumulative air temperature. The most abundant species was Zizeeria maha, followed by Neope goschkevitschii, Argyreus hyperbius, Eurema mandarina, Pieris rapae, Minois dryas, Lycaena phlaeas, Curetis acuta, Polygonia c-aureum and Parnara guttata. Population densities of 13 species (Argyreus hyperbius, Eurema mandarina, Minois dryas, Lycaena phlaeas, Lethe sicelis, Narathura japonica, Colias erate, Everes argiades, Damora sagana, Papilio memnon, Narathura bazalus, Hestina assimillis and Nymphalis xanthomelas) significantly increased every year, but those of eight species (Mycalesis gotama, Graphium sarpedon, Papilo protenor, Papilio machaon, Apatura metis, Potanthus flavus, Rapala arata and Taraka hamada) significantly decreased. The Shannon-Wiener function (H′) was 2.057–3.710, the Simpson biodiversity index (1−λ) was 0.466–0.836 and the Pielou measurement of evenness (J′) was 0.387–0.702. These diversity and evenness indices of grassland species became higher every year. Artificial managements, such as the methods of mowing and the frequency of spraying insecticide may be major causes of changing the butterfly assemblage.
