Male mating tactics and lethal combat in the nonpollinating fig wasp Sycoscapter australis

Fatal fights are rare in the majority of animal species but are a common co mponent of mate competition between wingless males of some species of fig-a ssociated wasps. We investigated fatal fighting in Sycoscapter australis, a nonpollinating fig wasp found in the syconia (inflorescences) of the Moret on Bay fig, Ficus macrophylla. Overall, about 25% of males sustained fatal injuries during the mate competition period. Measurement and analysis of 34 9 males revealed a sevenfold difference in mandible size between the larges t and smallest individuals, as well as evidence for dimorphism in the mandi bles, which showed positive allometry in relation to other body parts. Smal l and large males did not differ significantly in their injury levels. Mand ibles are the main weapons used in fights and injury levels were highest in syconia where males on average had larger mandibles. Injury levels also in creased with the estimated operational sex ratio in a syconium, although th is variable explained little of the variation. In contrast to the usual ass umptions about wingless male fig wasps, a significant number (17%) of males emerged from their natal syconia. Females emerged at a fairly constant rat e over many hours, consistent with contest competition between males for ac cess to matings. In contrast, the more numerous females of the pollinating wasp species Pleistodontes froggatti showed a strong peak in emergence, con sistent with scramble competition between males for access to mates. (C) 20 01 The Association for the Study of Animal Behaviour.