Factors Influencing Realized Sex Ratios in Fig Wasps: Double Oviposition and Larval Mortalities

Pollinator fig wasps (Agaonidae) are a model system for studies of sex ratio evolution. They lay their eggs in galled ovules within figs. Only one adult emerges from each gall, suggesting that only one egg is always laid per ovule, but if double oviposition occurs then the assumption that adult (realised) sex ratios of fig wasps are representative of primary sex ratios may be violated. Many galls also fail to produce any wasps. If they initially contained eggs then differential mortality rates may also modify realized sex ratios. We investigated whether Kradibia (= Liporrhopalum) tentacularis foundresses in Ficus montana figs avoid laying in ovules that already contain eggs. Comparisons of oviposition frequencies and wasp emergence frequencies showed that most galls that failed to produce wasps will have had eggs laid in them, but few occupied ovules contained two eggs. Realised sex ratios therefore do not necessarily reflect primary sex ratios in this species, but double oviposition is not responsible.