Distribution and seasonal occurrence of the lycaenid, Zizina emelina (de l'Orza) (Lepidoptera, Lycaenidae), around the Osaka International Airport, central Japan

Abstract

The distribution and seasonal occurrence of the lycaenid butterfly, Zizina emelina (previously Zizina otis emelina), were investigated at 99 sites of grassy sites, including known previous locations around the Osaka International Airport (OIA) on the boundary between Osaka and Hyogo Prefectures, central in Japan between 2000 and 2007. In addition, eggs obtained from 31 field-collected females were reared into adults under quasi-natural conditions in different seasons to infer the developmental period in the field. Zizina emelina were seen at 43 of the 99 survey sites. Of the 43 sites, 15 and 21 were on or near embankments of the Inagawa River and in the grass of the urbanized region around the OIA, respectively. In contrast, this species was recorded from only seven survey sites in the Send Hills, located to the northeast of the OIA. The density of adults was especially high at 12 sites in the vicinity of the OIA and at one in the Senri Hills. The population living around the OIA depends on white clover, Trifolium repens (Fabaceae), and/or Japanese clover, Kummerovia striata (Fabaceae), as larval food plants rather than the bird's-foot trefoil, Lotus corniculatus (Fabaceae), the major food plant of Z. emelina in Japan, which was not found in the area around the OIA. In contrast, in the Senri Hills, Z. emelina and L. corniculatus were observed to cooccur at two sites, where the eggs of the butterfly were found on the plant. From the results of field observations and rearing experiments, we inferred Z. emelina has 6-7 generations in the field around the OIA, with the adult flight season being between April and November. Intriguingly, some field-collected females produced no male offspring (i. e. all F_1 adults were female).