聚果榕果内种子季节变化与聚果榕小蜂活动的关系

聚果榕与聚果榕小蜂有着种间专一的互惠共生关系。榕小蜂进聚果榕果内 ,结果表现为 2方面 :1)对长柱小花传粉受精后产生榕树种子 ,使聚果榕能正常进行有性繁殖 ;2 )在短柱花内产卵形成瘿花 ,产生榕小蜂后代 ,植食性 ,最后发育为聚果榕小蜂 ,并作为榕树传粉的媒体。对西双版纳地区 2个样地内不同季节的聚果榕果进行了 3年的连续解剖观察 ,统计了雄花期榕果内瘿花、种子、败育花的数量 ,比较了 3年中旱季和雨季各种小花的比率。结果表明 :不同季节 ,各种小花的比率不同。旱季的 1月和 11月 ,聚果榕产生的种子量最多 ,雨季末期的 9— 10月份次之 ,产生种子量最低的是 3月份。旱季和雨季 ,瘿花的寄生比率没有显著差异 ,但不同月份之间差别较大 ,寄生率最高在旱季的 1月份和雨季初期 5月份 ,最低是在 3月份。长花柱雌花和短花柱雌花的败育率 ,在气温最低的月份 (1— 2月 )和雨量最多的月份 (7— 8月 )结的榕果内最高 ,在雨季初期 (5月 )和旱季初期 (11月 )结的榕果内最低。造成聚果榕果小花败育的主要因素是低温、多雨的气候。除聚果榕小蜂外 ,榕果内还有造瘿类和重寄生 2类非传粉小蜂 ,它们对聚果榕的种子形成具有一定的影响。

Relationship between Activity of Ceratosolen fusciceps and Seasonal Changes of the Seed Number of Ficus racemosa

Figs and their pollinating fig wasps bear the obligate species-specific mutualism. The entering of pollinating Ceratosolen fusciceps would bring two incidents come into truth: egg-laying and pollination. Firstly the C. fusciceps pollinates for the long-styled florets and makes them fertilized, which can complete the normally sexual reproduction of Ficus racemosa. Secondly the entering wasps oviposit in the ovules of short-styled florets that subsequently develop into gall flowers and produce fig wasps, hereby, they finish the mission of propagating off-springs and ensure the persistence of the fig wasp species, meanwhile, function as the media of fig pollinators. Our study was focused on the seasonal change of fruits of F. racemosa at the 2 sites in Xishuangbanna. We carried out two-year long consecutive dissection and observation on them, and collected the data on the quantity of gall flowers, seeds and abortive flowers inside the syconia of male phase, furthermore, compared the ratios of florets between the dry and rainy season two years round. The results were that the ratios of various florets varied in different season. F. racemosa produced the highest crop of seeds in Jan. and Nov. of dry season; next to it was in Sep. and Oct. of the end of rainy season; the lowest one was in Mar. of each year. The parasitic ratios of gall flowers shared no significant difference between the dry and rainy season, while the distinction among months was significantly different, and the highest parasitic ratio was in Jan. of dry season and May of early rainy season, the lowest one was in Mar. The abortive ratio of long- and short-styled female florets was highest when the temperature was lowest (Jan. to Feb.) and when the rainfall was most (Jul. to Aug.); the lowest abortive ratio was during the early phase of rainy (May) and dry season (Nov.). The floret abortion inside the syconium was mainly subject to the climate of low temperature and heavy rainfall. Nonpollinating fig wasps species include gall makers and inquilines; these have a great impact on the propagation of seeds of F. racemosa.