歪叶榕非传粉小蜂的繁殖策略及其对榕-蜂共生系统的影响

2004年8月至2005年8月在西双版纳热带植物园内，通过广泛收集歪叶榕榕小蜂标本、非传粉小蜂产卵行为学观察和阻止传粉者入果等实验方法，研究了我国西双版纳热带雨林下的一种榕树——歪叶榕Ficus cyrtophylla的榕小蜂群落组成结构、非传粉小蜂的繁殖策略以及它们对榕-蜂共生系统的影响。结果表明，歪叶榕中除了具有唯一传粉榕小蜂Blastophag sp.以外，还具有3种非传粉小蜂Platyneura sp.、Philotrypesis sp.和Sycoscapter sp.。在歪叶榕榕小蜂群落中，传粉榕小蜂占整个群落总数的92.21%，是群落的最主要组成者；主要的非传粉小蜂是Sycoscaptersp.，占5.78%； 其次是Philotrypesissp.，占1.84%，而Platyneurasp.仅占群落总数的0.17%。歪叶榕中的非传粉小蜂通过各自产卵时间和食性分化的策略来利用榕果中的资源繁殖后代。非传粉小蜂寄生使传粉榕小蜂的总数和其雌蜂数量都显著地降低，但是对传粉小蜂雄蜂数量没有显著影响，从而导致传粉榕小蜂的雄性性比显著地增加。这说明非传粉小蜂在选择寄居宿主时具有明显的倾向性，而且更多地将卵产于含有雌性传粉小蜂的瘿花之中。因此，非传粉小蜂通过减少雌性传粉小蜂的数量而降低了榕树的雄性适合度，从而在一定程度上对榕 蜂共生系统的稳定存在和发展产生了负面影响。

The reproductive strategies of non-pollinating fig wasps in Ficus cyrtophylla and their effects on the fig-wasp mutualism

Through extensive collecting, behavioral observation and test of obstructing fig wasps from entering figs, the community structure of fig wasps, the reproductive strategies of non-pollinating fig wasps (NPFW) and the effects of non-pollinating fig wasps on the fig-wasp mutualism of Ficus cyrtophylla, an understory fig species in the tropical rain forest of Xishuangbanna, were studied. Except the obligate pollinator-Blastophaga sp. for F. cyrtophylla, there were three non-pollinating fig wasp species in its syconia, i.e., Platyneura sp., Philotrypesis sp. and Sycoscapter sp. In the fig wasp community, Blastophaga sp., as the dominant species, accounted for 92.21% of the total fig wasps, while Sycoscapter sp. accounted for only 5.78%, Philotrypesis sp. 1.84% and Platyneura sp. 0.17% of the total fig wasps. Sycoscapter sp. was the primary non-pollinating fig wasp. All these non-pollinators oviposited outside the figs, and they produced their offsprings through co-inhabiting and competing with pollinators for reproductive sites or food resources. Platyneura sp. was the gall-maker while Philotrypesis sp. and Sycoscapter sp. were both inquilines. If no pollinators entered the figs, all the non-pollinators would fail to produce their offsprings. The non-pollinators performed some significantly negative effects on the pollinator population size and the number of female pollinators, but not on the number of male pollinating fig wasps, and thus resulted in a significant increase of the ratio of males to the total number of the pollinators. These results show that non-pollinators usually prefer the galls of female pollinators to the galls of male pollinating fig wasps when they oviposit. Because the female pollinators are the only vectors for figs, the non-pollinators may negatively affect the stable existence and development of the fig-wasp mutualism.