Permeability of receptive fig fruits and its effects on the re‐emergence behaviour of pollinators

Abstract

1. Figs and pollinating fig wasps provide a model system for studying mutualism. The permeability of the syconium changes during receptivity or between seasons, which may affect the behaviour of pollinators. Fig fruits are permeable during receptivity, and in some species, pollinators can enter and re-emerge after oviposition/pollination. We studied the relationship between fig permeability and pollinator re-emergence behaviour with a functional dioecious fig, Ficus hispida and the obligate pollinator Ceratosolen solmsi marchali. 2. The relationship reflects the interaction of figs and pollinators in the mutualism and also the conflicts of interests between the two partners: figs benefit from the enclosed fig fruits which have low permeability, but pollinators benefit from their re-emergence behaviour, which requires high fig permeability.3. The results showed that at the end of receptivity, the permeability of fig fruits lowered rapidly with changes to the ostiole structures, and re-emergence rate was low, with more re-emerging pollinators trapped in the ostiolar bracts. Our results also showed that in the rainy season, the length of receptivity was shorter and fig permeability was lower. The re-emergence rates were also lower than those in the dry season. The results elucidated that figs' interests dominated in the conflicts between fig and pollinating wasp.4. Based on a new criteria which employed the classification of pollinators found dead in the ostiolar bracts and which involved a survey of 6 monoecious and 12 dioecious fig species, we found that re-emergence behaviour was prevalent among fig species, and was more prevalent in functional dioecious figs than monoecious ones.

Interactions Between Figs and Gall-Inducing Fig Wasps: Adaptations, Constraints, and Unanswered Questions

“…Glands on ostiolar bracts release volatiles (Souza et al, 2015;Hu et al, 2020) that attract pollinators to pollen-receptive syconia (Hossaert-McKey et al, 2010;Borges, 2016Borges, , 2018. The ostiole usually shuts after pollinators enter, but loosely arranged bracts sometimes allow the now wingless female pollinators to exit and visit other syconia on the same plant (Hu et al, 2010). The ostiole may also re-open at the wasp dispersal stage (Verkerke, 1989) so that the next generation of pollen-carrying females exit through the ostiole rather than through a passage through the syconium wall excavated by wingless males.…”