西双版纳聚果榕隐头果内小蜂群落结构及种间关系

聚果榕Ficus racemosa Linn.是雌雄同株榕树，它是西双版纳热带雨林生态系统中的一个常见种群。聚果榕必须依靠聚果榕小蜂Ceratosolen fusciceps Mayr传粉才能获得有性繁殖，而聚果榕小蜂又必须依靠聚果榕隐头果内短柱花繁衍后代，两者间形成了种间专一的互惠共生体系。同时，在其隐头果内还存在一个复杂的非传粉小蜂功能群，它们主要是榕树种子和传粉榕小蜂的寄生者。在云南省西双版纳自治州勐腊县勐仑镇选取了5个样地，对聚果榕单果内小蜂群落组成和种间相互关系进行研究。在不同时间段采集聚果榕单果242个，共收集小蜂366660头。聚果榕隐头果内有6种小蜂，隶属小蜂总科Chalcidoidae中的榕小蜂科Agaonidae、长尾小蜂科Caliimomidae、金小蜂科Pteromalidae，其中榕小蜂科中的C．fusciceps是聚果榕唯一的传粉者。金小蜂科中的Apocryta westwoodi Grandi和Apocryta sp.两个种是榕小蜂的寄生者，它们的寄生是传粉榕小蜂的种群数量减少因素之一。长尾小蜂科中Platyneura agraensis Joseph，Platyneura mayri Rasplus和Platyneura testacea Motschulsky3个种是寄生榕树种子或与榕小蜂争夺食物(瘿花)资源的小蜂类群，它们的出现与发生，致使聚果榕正在发育成种子的长柱小花形成瘿花，同时一部分种类把卵寄生在已被榕小蜂产卵的短柱小花子房中与榕小蜂争夺食物资源，致使榕小蜂食物资源的匮乏而死亡，对传粉小蜂种群有明显的影响。传粉小蜂从花托口钻入隐头果内，在隐头果内的长柱小花传粉和短柱小花子房中产卵，5种非传粉小蜂从隐头果外部把产卵器刺穿果肉把卵产在小花子房上。通过对5块样地隐头果内小蜂群落的综合分析发现，传粉榕小蜂为优势种群，而Apocryta sp.种的数量最少。在传粉及非传粉小蜂自然群体中各种类性比明显具有偏雌现象。小蜂群落表现异常的是聚果榕孤立株的样地，该样地传粉小蜂个体数量明显下降，非传粉小蜂个体数量则增加，各小蜂种群之间竞争激烈，出现C．fusciceps和P．mayri两个优势种。

The community structure and the interspecific relationship of the fig wasps in syconia of Ficus racemosa L. in Xishuangbanna, China

The fig is considered to be the pre-eminent group of keystone plant resources in the ecosystem of tropical rainforest. Each species of Ficus is exclusively pollinated by a unique fig-pollinating wasp to complete its sexual reproduction, and the pollinator only depends on the ovaries of short-styled florets inside host inflorescence to foster its offspring. Ficus and their species-specific pollinator wasps (Agaonidae) form a remarkable plant-insect obligate mutualism. Besides fig-pollinating wasp in conspecific syconia, there also exist several functional groups of non-pollinating wasps. They are gall makers that attack syconia from the exterior, gall makers that enter syconia as do the pollinators, and parasitoids that attack other fig wasp larva. Ficus racemosa Linn. is monoecious, which is an important plant owing to their heavy fruit production all year round to support a broad spectrum of vertebrate frugivores during times of food scarcity in the ecosystem of Xishuangbanna tropical rainforest. The study was carried out in the 5 selected sites, located in Menglun town, Mengla country, Xishuangbanna Autonomous State. Inside single syconium of F. racemosa, the composing species were collected and the interspecific relationship were analyzed. The analyzing result showed: 242 sampled figs of single syconium had been collected in different seasons and got 366660 fig wasps. All fig wasps were classified into 6 species. They belonged to Agaonidae, Caliimomidae and Pteromalidae of Chalcidoidea respectively, among which only Ceratosolen fusciceps Mary of Agaonidae pollinated for F. racemosa, Apocrypta westwoodia Grandi and Apocrypta sp. of Pteromalidae were the parasites of fig-pollinating wasps. They directly ate C. fusciceps and when the number of these two species increased, the population of fig-pollinating fig wasps would obviously decrease. The Platyneura agraensis Joseph, Platyneura mayri Rasplus and Platyneura testacea Motschulsky of Caliimomidae were the parasites of fig seeds or the parasites of pollinators. They could result in the ovaries of the long-styled florets, which had been destined to produce seeds, turning into galls. Meanwhile, some might lay eggs into the ovaries of short-styled florets, which had contained the larva of fig-pollinating wasps, thus the pollinators would die for lacking of space and food resources. Several species of non-pollinating fig wasp oviposited from the outside of the figs using a long ovipositor after fig-pollinating fig wasps entered syconium to pollinating and ovipositing. By comparing the community structure of fig wasps, the appearing frequency of fig-pollinating wasps was the highest, its important index reached up to 0.721(female) and 0.653 (male). while the appearing frequency of Apocrypta sp. was the lowest. Even there were no Apocrypta sp in some syconia. All pollinating and non-pollination fig wasps took on female-biased sex ratios. The community character showed abnormalities in the site of a lone tree. The species diversity index and even index were the highest in this site, and both C. fusciceps and P. mayri were dominant species.