-Mating behaviour and associated songs were compared between 2 sympatric congeneric species, Nezara antennata and N. viridula, between which interspecific mating was known to occur under natural conditions. The fundamental sequence of mating behaviour for these species was the same. Three kinds of songs were recorded from each sex of N. antennata. For N. viridula, 4 kinds of male songs and 3 kinds of female songs were recorded. The songs which corresponded with definite behavioural bouts were distinct between these species. Some consideration was made as to why interspecific differences in the songs did not sufficiently engender ethological isolation. In addition, some geographic variations in the songs were shown among Yugoslavian (~okl et al. 1972), American (Harris et al. 1982) and Japanese populations of N. viridula.These variations were relatively inconspicuous when compared with the interspecific differences from N. antennata.

--Intra-and interspecific copulations between Nezara antennata and N. viridula were investigated, with reference to postcopulatory changes in the spermatheca. The duration of copulation was significantly shorter in the case of N. viridula males and N. antennata females than it was in the other 3 combinations. Both sperm and pulpy substance were transferred into the spermatheca during the intraspecific copulation of each species. No sperm was found in the spermatheca after interspecific copulation. However, the pulpy substance was found in the dilated portion of spermathecal ducts of some

No abstract