鸡嗉子榕内传粉小蜂与非传粉小蜂的繁殖稳定共存机制研究

Reproductive behaviors facilitating stable coexistence between pollinating and non-pollinating fig wasps in Ficus semicordata

【目的】榕-蜂系统是自然界协同进化和互利共生的典型模型,榕-蜂之间如何实现繁殖分配从而实现稳定共存一直是倍受研究者关注的问题,但对传粉小蜂和非传粉小蜂的繁殖稳定共存研究较少。【方法】本文选取分布在西双版纳地区的雌雄异株榕树鸡嗉子榕Ficus semicordata的雄果,通过对榕果内唯一的传粉小蜂Ceratosolen gravelyi Grandi以及4种非传粉小蜂Philotrypesis dunia Joseph,Apocrypta sp.,Platyneura sp.,Sycoscapter trifemmensis Joseph的产卵时序进行了观察,并对5种小蜂的种群数量进行统计,以及对每种小蜂产卵小花的空间分布、瘿花体积等特征进行了研究。【结果】发现:5种小蜂在产卵时间上存在分离,且传粉小蜂的种群数量远大于其他4种非传粉小蜂的种群数量之和。5种小蜂的瘿花特征也存在差异:瘿花的子房大小不同,且花梗长度即分布空间也有差异,传粉小蜂最接近果腔而非传粉小蜂则更多地利用中层和内层的小花。【结论】结果说明在鸡嗉子榕有限的空间内,5种小蜂通过产卵时间和生长空间的分离,实现了减少竞争以及长期共存的特征,维持了榕-蜂系统的稳定性。

[Objectives] The interaction between pollinating fig wasps（Agaonidae） and their host fig trees（Ficus） is a striking example of an obligate, pollination mutualism. The reproductive resources allocated for the stable coexistence of figs and fig wasps have attracted considerable research interest, but the reasons for the stable coexistence of pollinating, and non-pollinating, fig wasps remain poorly understood. [Methods] Male trees of the dioecious fig species Ficus semicordata were observed in Xishuangbanna to determine the timing of oviposition by the pollinating fig wasp（Ceratosolen gravelyi） and 4 non-pollinating fig wasp species（Philotrypesis dunia, Apocrypta sp., Platyneura sp. and Sycoscapter trifemmensis）. The community structure, spatial distribution of gall flowers, and gall volume, was also determined for the 5 fig wasps species. [Results] The results show that the 5 fig wasp species had distinct oviposition intervals. The population size of pollinating fig wasps was significantly larger than that of all 4 non-pollinating fig wasp species combined. Offspring of the 5 wasp species developed in female flowers with different characteristics, such as different gall size and different pedicel length. Pollinating fig wasps tended to utilize flowers near the fig cavity and non-pollinating wasps were more likely to oviposit in flowers near fig wall. [Conclusion] Although all 5 wasp species oviposit in Ficus semicordata syconia, the timing, and location, of oviposition differed among species. These differences may be the adaptions that facilitate the stable coexistence of different wasp species within the same host plant.