栉颚榕小蜂在雌花期榕果内产卵及主动传粉行为的多样性

Diversity of oviposition and pollination behaviors of Ceratosolen spp.in female phase figs of subgenus Sycomorus

在雌雄同株榕树中,榕小蜂进入雌花期果后,既产卵于雌花子房繁殖后代,也同时为榕树传粉繁殖种子;而在雌雄异株榕树中,榕小蜂在雌果中传粉繁殖种子,在雄果中产卵繁殖后代,雌雄果内的繁殖任务各不相同。然而,在雌花期果内榕小蜂产卵和传粉行为是否存在种间差异及多样性、在不同行为上如何分配时间等问题目前还知之甚少。本研究选取既为雌雄同株又为雌雄异株传粉的栉颚榕小蜂类群(Ceratosolenspp.),适时引入寄主榕树雌花期果,跟踪观察、定量记录其在榕果内搜索、产卵、传粉的行为,以及测量与榕-蜂产卵传粉相关的特征,比较栉颚类榕小蜂在榕树不同繁殖系统和不同性别间的异同。结果显示:雌雄同株聚果榕(Ficusracemosa)以及雌雄异株木瓜榕(F.auriculata)、对叶榕(F.hispida)和鸡嗉子榕(F.semicordata)与其传粉榕小蜂均执行主动传粉模式。从榕小蜂产卵器长度与雌花花柱长度的匹配看,雌雄同株果内传粉榕小蜂在部分雌花产卵繁殖后代,并传粉部分雌花繁殖种子;而在雌雄异株的雄果内是产卵繁殖后代,在雌果内则是传粉繁殖种子。栉颚类榕小蜂搜索、产卵和传粉的行为和时间分配表现多样,在雌雄同株果内前6 h集中产卵,之后主要传粉,且单次传粉时间较短;而在雌雄异株的雌雄果内表现为:产卵末期进行传粉,之后拔出产卵器,然后循环相似行为,并且单次产卵时间越长,其传粉时间亦越长,但对叶榕和鸡嗉子榕传粉榕小蜂的产卵、传粉行为循环不规律。总之,栉颚榕小蜂单次产卵时间长于传粉时间,并且在榕树不同繁殖系统和性别的雌花期果内,传粉榕小蜂搜索、产卵和传粉的行为及时间分配存在差异、表现多样。研究结果首次展示了传粉榕小蜂在雌花期果内产卵和传粉行为的多样性及不同模式,将为其他传粉昆虫行为多样性的研究提供参考。

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.