Pollinators for a syconium: How do wasps choose among syconia?

Abstract

Female agonid wasps, pollinators of monoecious figs, on entering a syconium (foundresses) are trapped in it and are committed to share the limited resources (flowers) with other foundresses. Hence, foundresses need to ensure that they choose the most suitable syconium. In three fig–wasp associations, we analysed if foundresses could indeed discriminate among syconia of different resource levels. In Ficus benghalensis, F. microcarpa and F. racemosa, the foundress wasps could easily discriminate between the empty and wasp-laden syconia and preferred to enter the former than the latter. Further, in two of these species (F. benghalensis and F. microcarpa), the speciesspecific foundresses were also capable of quantitatively assessing loads of the foundresses in the syconia on the basis of wings left behind at and around the ostiole. The wings load on the ostiole was strongly correlated to the foundresses loads. Foundresses preferred entering those syconia from which the wings were removed to those on which the wings were retained. The extent to which the foundresses preferred to enter the syconia was found to be influenced by the density of wings at and around the ostiole. Adding wings artificially to the empty syconia also deterred the foundresses from entering them, suggesting that these residual wings serve as negative feedback regulators for the preference and entry of foundresses. Thus, we show that pollinator wasps of fig–wasp associations choose the most suitable syconia to enter as long as they have opportunity.