Pollination and parasitism in functionally dioecious figs

Fig wasps (Agaonidae: Hymenoptera) are seed predators and their interaction s with Ficus species (Moraceae! range from mutualism to parasitism. Recentl y, considerable attention has been paid to conflicts of interest between th e mutualists and how they are resolved in monoecious fig species. However, despite the fact that different conflicts can arise, little is known about the factors that influence the persistence of the mutualism in functionally dioecious Ficus. We studied the fig pollinator mutualism in 14 functionall y dioecious fig species and one monoecious species from tropical lowland ra inforests near Madang, Papua New Guinea. Observations and experiments sugge st that (i) pollinating wasps are monophagous and attracted to a particular host species; (ii) pollinating and non-pollinating wasps are equally attra cted to gall (male) figs and seed (female) figs in functionally dioecious s pecies; (iii) differing style lengths between gall figs and seed figs may e xplain why pollinators do not develop in the latter; (iv) negative density dependence may stabilize the interaction between pollinating wasps and thei r parasitoids; and (v) seed figs may reduce the search efficiency of non-po llinators. This increased pollinator production without a corresponding dec rease in seed production could provide an advantage for dioecy in condition s where pollinators are limiting.