Signalling receptivity: Comparison of the emission of volatile compounds by figs of Ficus hispida before, during and after the phase of receptivity to pollinators
Résumé
Figs and pollinating fig wasps are involved in highly specific mutualisms. Because associations between figs and their
pollinating wasps are horizontally transmitted, partner encounter is a crucial step, and is mediated by the emission by
receptive figs of the volatile compounds that are detected by the pollinator. However, pollinator attraction is probably not
the only function of the volatile compounds produced by figs. Other likely functions include signalling to wasps that a fig
has already been pollinated, and deterring or defending against visitors with negative effects on developing figs or the
pollinators they contain. The functions of volatile compounds will also change over the course of fig development, and the
composition of the odour bouquet is thus also likely to vary. However, this variation and its likely functional importance
have rarely been studied. To address these questions, we investigated changes in the composition of the bouquet of volatile
compounds, and in the rate of emission of odour components, before, during and after the phase of receptivity to pollinators
in Ficus hispida, in Yunnan (China). This first study of the dynamics of variation in signal composition throughout the cycle
of fig development, provides support for the hypothesis of chemical mimicry in dioecious figs.