Mate locating strategies of the green carpenter bees Xylocopa (Lestis) aeratus and X. (L.) bombylans

Abstract

This paper describes the mate locating strategies of male Australian carpenter bees Xylocopa (Lestis) aeratus Smith and X.(L.) bombylans (F.). Males of X. aeratus display three different mate locating strategies: (1) non-territorial patrolling near nests or flowers; (2) territorial defence of nests that contain unmated females; (3) non-resource territoriality (hill-topping). At the onset of the mating season, non-territorial patrolling and territorial defence of nests were observed in three out of four populations that were studied, while in a fourth population only non-resource territoriality was observed. Later in the mating season both territorial defence of nests and non-resource territoriality were observed in one of the populations. Male X. bombylans have only been observed using the non-resource territoriality. Males of all size classes used the same strategy at any one time, but males that were observed more than once in a territory were significantly larger, suggesting that larger males have greater territory-holding capacity. Upon encountering males, receptive female X. aeratus alternated low zigzag flights through the vegetation with high-velocity flights well above the vegetation, while males followed closely. This behaviour is interpreted as a test of the flight capacity of males, and is indicative of pronounced female choice. The mate locating strategies of the two species are compared with literature data from other xylocopine bees, and factors that might affect the choice of a particular mate locating strategy are briefly discussed.