西双版纳热带雨林对叶榕传粉生物学

研究了西双版纳热带雨林地区雌雄异株植物对叶榕(Ficus hispida L.)的生物学、传粉物候学以及榕小蜂(Ceratosolen solmsi marchali Mayr)的传粉和繁殖行为.研究结果表明:雌雄异株的对叶榕与其他雌雄同株的榕属植物不同,它的种子形成与传粉者有着更为复杂的相互关系.对叶榕一年结隐花果6～8次,结果高峰期4～5次,其中雄性植株仅产生花粉和孕育榕小蜂,而雌性植株(无雄蕊)则需榕小蜂带花粉进入隐花果内,进行传粉授精,使之发育成种子.对叶榕的成熟花粉不能从花药开裂处自行散发出来,必须由榕小蜂采集才能散落.榕小蜂雌蜂羽化、交配后,找到雄花区,用足、触角、口器在推动中采集花粉.雌蜂飞出熟榕果找寻雌株或雄株榕树上的幼嫩隐花果,一般需3～67 min;一部分雌蜂在雄株中寻找幼嫩的隐花果,进去产卵繁殖,另一部分雌蜂则寻找雌株雌花期嫩隐花果进去传粉.雌蜂在雌株榕树的隐花果内传粉时间为15～23 h,在雄株榕树的隐花果内产卵时间为6～9 h.对叶榕小蜂在雌株上进入单个隐花果的数量多少关系到雌花结实率;观察表明,每个隐花果最佳进蜂数为2头;榕小蜂传粉后榕树成熟种子形成率在54.1%～82.5%之间,平均为73.8%;而在雄株上雌蜂进蜂数量则关系到榕小蜂在隐花果内的产卵率,每个隐花果最佳进蜂数为3～4头,产卵率在72.3%～93.8%之间,平均为84.4%.

Pollination Biology of Ficus hispida in the Tropical Rainforests of Xishuangbanna,China

Ficus hispida L. (Moraceae) is a remarkable species in the ecosystem of tropical rainforests in Xishuangbanna, China. The figs and fig pollination wasps (Chalcidoidae: Agaonidae) are highly co evolved mutualists that depend completely on each other for propagating descendants. Pollination of all fig species is do ne by fig wasps; their unique symbiotic associates, the fig wasps, cannot develop in anywhere except in the fig syconia. The present paper reports on the biology and flowering phenology of F. hispida, as well as the propagation character and pollination behavior of the fig wasps (Ceratosolen solmsi marchali Mayr) based on our observations in the rainforests of Xishuangbanna, southern Yunnan of China. F. hispida is a dioecious tree that annually blossoms and bears fruits 6-8 times, with four to five fruit bearing peaks. The male trees produce pollen and provide fig wasps with reproductive havens, while the female trees produce fig seeds after pollination by the female wasps. Pollen of F. hispida cannot escape from the dehiscent anthers until they are disturbed by fig wasps. The female wasps open the anthers and collect pollen with their antennal scrapes, mandibles and legs, and then carry pollen to the female receptive syconia where fertilization takes place. Meanwhile, some of the female wasps lay eggs in the male receptive syconia. It takes about 3-67 min to search for the receptive syconia for pollination, and 15-23 h to enter the female receptive syconia. The number of female wasps entering a syconium has close relation with the impregnation and seed bearing rate of female flowers, as well as the oviposition and reproduction rate of the fig wasps themselves. F. hispida is endowed with a relatively high level of seed bearing (54.1%-82.5%, average 73.8 % ). The wasp oviposition rate on the male flowers is between 72.3% and 93.8% with a mean of 84.4%.