The role of non-fig-wasp insects on fig tree biology, with a proposal of the F phase (Fallen figs)

Abstract

The two seminal papers by Galil and Eisikowitch describing the development of Ficus flowers and their sycophilous wasps (i.e., phases A-E) have been adopted in several ecological and evolutionary studies on a wide range of fig tree-insect interactions. Their classification, however, is not inclusive enough to encompass all the diversity of insects associated with the fig development, and the impact of this fauna on the fig-fig wasp mutualism is still unexplored. Here we describe the life history of the non-fig-wasp insects and propose an additional phase to fig-development classification, the F phase (Fallen figs). These figs are not consumed by frugivores while still on the parent tree, fall to the ground and turn into a resource for a diverse range of animals. To support the relevance of the F phase, we summarized a 5-years-period of field observations made on different biomes in three continents. Additionally, we compiled data from the literature of non-fig-wasp insects including only insects associated with inflorescences of wild fig tree species. We report 129 species of non-fig-wasp insects feeding on figs; they colonize the figs in different phases of development and some groups rely on the fallen figs to complete their life cycles. Their range of interaction varies from specialists – that use exclusively fig pulp or fig seeds in their diets – to generalists, opportunists and parasitoids species. The formalization of this additional phase will encourage new studies on fig tree ecology and improve our knowledge on the processes that affect the diversification of insects. It will also help us to understand the implications this fauna may have had on the origin and maintenance of mutualistic interactions.