Host pollination mode and mutualist pollinator presence: net effect of internally ovipositing parasite in the fig–wasp mutualism

Abstract

The Ficus-their specific pollinating fig wasps (Chalcidoidea, Agaonidae) interaction presents a striking example of mutualism. Figs also shelter numerous non-pollinating fig wasps (NPFW) that exploit the fig-pollinator mutualism. Only a few NPFW species can enter figs to oviposit, they do not belong to the pollinating lineage Agaonidae. The internally ovipositing non-agaonid fig wasps can efficiently pollinate the Ficus species that were passively pollinated. However, there is no study to focus on the net effect of these internally ovipositing non-agaonid wasps in actively pollinated Ficus species. By collecting the data of fig wasp community and conducting controlled experiments, our results showed that internally ovipositing Diaziella bizarrea cannot effectively pollinate Ficus glaberrima, an actively pollinated monoecious fig tree. Furthermore, D. bizarrea failed to reproduce if they were introduced into figs without Eupristina sp., the regular pollinator, as all the figs aborted. Furthermore, although D. bizarrea had no effect on seed production in shared figs, it significantly reduced the number of Eupristina sp. progeny emerging from them. Thus, our experimental evidence shows that reproduction in Diaziella depends on the presence of agaonid pollinators, and whether internally ovipositing parasites can act as pollinators depends on the host fig's pollination mode (active or passive). Overall, this study and others suggest a relatively limited mutualistic role for internally ovipositing fig wasps from non-pollinator (non-Agaonidae) lineages.