Masahiro Kon

Comparison of the mating behaviour between two sympatric species,Nezara antennata andN. viridula (Heteroptera: Pentatomidae), with special reference to sound emission

Mating behaviour and associated songs were compared between 2 sympatric congeneric species,Nezara antennata andN. 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 ofN. antennata. ForN. 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 (Čokl et al. 1972), American (Harris et al. 1982) and Japanese populations ofN. viridula. These variations were relatively inconspicuous when compared with the interspecific differences fromN. antennata.

Intra- and interspecific copulations in the two congeneric green stink bugs,Nezara antennata andN. viridula (Heteroptera, Pentatomidae), with reference to postcopulatory changes in the spermatheca

Intra- and interspecific copulations betweenNezara antennata andN. viridula were investigated, with reference to postcopulatory changes in the spermatheca. The duration of copulation was significantly shorter in the case ofN. viridula males andN. 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 someN. viridula females copulated with anN. antennata male, whereas no such substance was found in the case of theN. antennata females copulated with anN. viridula male. Most of the pulpy substance appeared to have been absorbed from the spermatheca within a 5-day period after the copulation. This absorption was observed for theN. viridula females copulated with anN. antennata male, as well as for the females of each of the species copulated with a conspecific male. It was suggested that this pulpy substance was a male-derived nutrient.

A new type of microhabitat, the interface between the log and the ground, observed in the passalid beetle of borneoTaeniocerus bicanthatus (Coleoptera: Passalidae)

The Passalidae are a pan-tropical family of Coleoptera, all species of which apparently live in rotting wood in colonies composed of both adults and larvae, though a few species have been known to live in other microhabitats (Schuster 1978; Reyes-Castillo & Halffter 1983). Since first being reported by Ohaus (1900), the subsocial behaviour of passalid beetles has often been cited in the entomological literature (Wheeler 1923; Gray 1946; Wilson 1971; Matthews & Matthews 1978; Eickwort 1981; Halffter 1982; Reyes-Castillo & Halffter 1983). However, all these studies were restricted to New World species. Although Gravely (1914) suggested that, in Oriental species also, adults of nearly all species lived in decaying wood in pairs with their young, relatively little is known about the life of Oriental passalid beetles. We had an opportunity to collect some passalid beetles in Sabah, North Borneo in August, 1985 and found the Bornean species, Taeniocerus bicanthatus, living on the ground under the log in colonies, not tunneling into the log. We report briefly its unique microhabitat, body shape and colony composition. Thirteen colonies were collected in the plantation at Brumas. They occurred in bisexual pairs or as pairs with their young, excepting one colony composed of one female adult and 2 larvae (Table 1), and were living in the interface between the log and the ground. In addition, 2 single females were collected in the same microhabitat, but it was not observed that the larvae occurred alone without adults. It has been reported by some authors (ReyesCastillo & Halffter 1983; Johki & Kon 1987) that, in passalid beetles, flatter species tend to be found under the bark, more convex species deeper in the log, while a few species occur in other microhabitats, e.g., among decaying vegetable refuse (Gravely 1914), under epiphytic bromeliads, in the nests of leaf-cutter ants, in caves with a large colony of oilbirds (Schuster 1978) and among the rhizomes of epiphytic ferns (Johki & Kon 1986). However, the microhabitat of the interface between the log and the