|Budget Amount *help
¥3,900,000 (Direct Cost : ¥3,900,000)
Fiscal Year 2000 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1999 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1998 : ¥2,800,000 (Direct Cost : ¥2,800,000)
When the swallowtail butterflies, Papilio xuthus, are mated by the hand-pairing method, both types of sperm, eupyrene and apyrene sperm, are transferred from the male to the spermatheca via the spermatophore in the bursa copulatrix. This is demonstrated by two different kinds of experiments. The first set of experiments employed interrupted copulation, and the second set was examination of the sperm in the spermatophore and spermatheca after the termination of copulation. The sperm was transferred 30 min after the start of copulation. The eupyrene sperm was still in the bundle, the number of the bundles ranged from 9 to 108 (mean 42.7, n=27) . The bundles were gradually released after the completion of copulation, and then the free eupyrene spermatozoa remained in the spermatophore at least 2 h before migrating to the spermatheca. On the other hand, about 160,000 apyrene spermatozoa were transferred to the spermatophore and remained there for more than 1 h. 11,000 apyrene spermatozoa in the spermatheca were observed 12 h after the completion of copulation, but most of this type of sperm disappeared shortly thereafter. In contrast, the eupyrene sperm arrived in the spermatheca more than 1 day after the completion of copulation, and remained there at least one week. Therefore, these findings suggest that apyrene sperm migrate from the spermatophore to the spermatheca earlier than eupyrene sperm. Accordingly, if females mated multiply, the time difference might avoid the mixing of sperm. In addition, the predominance of sperm from the last mating session may occur not in the bursa copulatrix but in the spermatheca.