钝叶榕(Ficus curtipes)非传粉小蜂交配行为

The mating behaviors of the non-pollinating fig wasps of Ficus curtipes

榕树及其传粉榕小蜂繁殖上相互依存,被认为是生物界中协同进化时间最悠久,相互关系最密切的一对生物;在大多数榕树种类的隐头花序内,除了传粉榕小蜂外,还共存着多种非传粉小蜂,它们的繁殖行为直接影响着榕树和传粉榕小蜂的繁殖和互惠稳定。钝叶榕(Ficus curtipes Corner),是一种雌雄同株的绞杀性榕树。研究在西双版纳热带植物园里共收集钝叶榕100个隐头果内的榕小蜂,获得9493号标本;其中,包括1种传粉小蜂和5种非传粉小蜂,钝叶榕传粉小蜂Eupristinasp.占总数的44.66%,杨氏榕树金小蜂Diaziella yangi占46.13%,而其它4种非传粉小蜂(Lipothymussp.,Sycobiasp.,Philotrypesissp.和Sycoscoptersp.)仅占9.20%。前3种榕小蜂雌蜂进到果腔产卵,其余3种在果外产卵。观测23个钝叶榕榕果出蜂情况发现,6种榕小蜂在钝叶榕隐头花序内遵循严格的羽化出蜂顺序,首先是Sycobiasp.,次之是Lipothymussp.,再次之是杨氏榕树金小蜂,最后是钝叶榕传粉小蜂、Philotrypesissp.和Sycoscoptersp.。5种非传粉小蜂的交配场所与雄蜂翅型无关,雄蜂有翅型的杨氏榕树金小蜂大部分交配在果内完成,而且它们的雄蜂为争夺交配机会存在激烈的打斗行为;雄蜂无翅型的Lipothymussp.有部分雄蜂爬出隐头果,在果壁和附近的叶片背面交配;雄蜂有翅型的Sycobiasp.,其所有交配都发生在果外;Philotrypesissp.和Sycoscoptersp.雄蜂均无翅,它们的交配全发生在果内。局域配偶竞争使榕小蜂性比偏雌,杨氏榕树金小蜂雄蜂虽然有翅,但大部分交配发生在榕果内,这将影响其最佳的性比率。因此,依赖雄蜂翅型并不能很好地预测榕小蜂的交配场所和性比率。

Ficus and their species-specific pollinator wasps （Agaonidae） exhibit a remarkable obligate mutualism. Fig trees are typically pollinated only by female agaonids, whose offspring feed on the ovules of the plant. Figs also shelter numerous other, unrelated, fig wasps that usually exploit the fig pollinator mutualism. Ficus curtipes Comer is a monoecious strangler fig tree. At Xishuangbanna Tropical Botanical Garden, 9493 individual fig wasps were reared from 100 figs （syconia）. They included one species of agaonid wasp and five unrelated fig wasps. The agaonid Eupristina sp. was represented by 45% of the individuals, Diaziella yangi van Noort ＆ Rasplus by 46% and the remaining 9% by Lipothymus sp.,Philotrypesis sp. , Sycobia sp. and Sycoscopter sp. Females of the first three species enter the figs to oviposit whereas the others lay their eggs from the outside of the figs. In this study, the order of emergence of the fig wasps from their natal figs and their mating behavior were recorded. They followed a strict sequence of emergence, with Sycobia sp. emerging first, then Lipothymus sp. , followed by Diaziella yangi. Eupristina sp. , Philotrypesis sp. and Sycoscopter sp. emerged last. Contrary to expectations, the mating sites of the five species of non-agaonid fig wasps were not always linked to the presence or absence of wings in the males. D. yangi （ with winged males） mated mostly inside the figs and its males engaged in fatal fights for mating opportunities. Male Lipothymus sp. （with wingless males）, mated both inside and outside the figs whereas male Sycobia sp. （ with winged males） only mated outside. Males of Philotrypesis sp. and Sycoscopter sp. （ both with wingless males）, only mated inside the figs. Fig wasps often display highly female-biased sex ratios linked to local mate competition. D. yangi, despite having winged males, mated mainly inside the figs, which is likely to influence its optimal sex ratio. The presence of wings in male fig wasps is therefore not a good predictor of mating sites, nor sex ratio.