Abstract:

Aims: In monoecious Ficus species, fig wasps lay eggs in the ovaries to propagate their offspring while also pollinating female flowers to generate seeds after they reach the female phase figs. On the other hand, in dioecious Ficus, fig wasps lay eggs in the ovaries of male figs and pollinate female flowers in female figs, indicating their differential reproductive tasks in the male and female figs. Our study aims to investigate interspecific differences and diversity in the oviposition and pollination behaviors of pollinating fig wasps and quantify the time involved in different behaviors in female phase figs, a subject that has been scarcely studied.
Methods: We selected four partners belonging to Ceratosolen wasps and subgenus Sycomorus figs, comprising both monoecious and dioecious fig species. Initially, we determined the pollination modes by collecting anther/ovule ratios of Ficus species, observing pollination structures and behaviors of pollinating fig wasps. The length of wasp ovipositors and flower styles were measured under the microscope with a micrometer to verify their matching. Additionally, we observed and quantitatively record the searching, oviposition and pollination behaviors of Ceratosolen spp. in female phase figs using a Digital Microscope.
Results: Our study found that monoecious Ficus racemosa, dioecious F. auriculata, F. hispida and F. semicordata were actively pollinated by their respective Ceratosolen pollinating fig wasps, which exhibited an active pollination mode. The length of ovipositors and flower styles were found to be matching, with pollinating fig wasps in monoecious figs laying eggs in some female flowers for offspring reproduction and pollinating some other female flowers to produce seeds. In dioecious figs, pollinating fig wasps laid eggs in male figs to reproduce offspring and pollinated female flowers in female figs to produce seeds. Moreover, the searching, oviposition, and pollination behaviors of Ceratosolen spp. in female phase figs were diverse. In monoecious figs, pollinating fig wasps primarily laid eggs in the first six hours after entering the figs and then pollinated female flowers, with a short time cost per pollination behavior. However, in dioecious male and female figs pollinating fig wasps pollinated female flowers at the end of each oviposition behavior and then extracted the ovipositors before repeating a similar behavior. As pollinating fig wasps oviposited more times, they also pollinated female flowers more times. Nevertheless, irregularity was observed in the pollinating fig wasps’ behavior in the female figs of F. hispida and F. semicordata.
Conclusion: Our study found that the time cost of per oviposition for Ceratosolen spp. was longer than that of pollination, and the time costs of searching, oviposition and pollination behaviors varied in different reproductive systems and sexes. Our results shed light on the diversity and different patterns of pollination and oviposition behaviors of fig wasps in female phase figs, providing a valuable reference for studying the behavioral diversity of other pollinators.

Key words: Ceratosolen, oviposition behavior, active pollination, Sycomorus, reproductive system, behavioral difference