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有着更为复杂的相互关系。对叶榕一年结隐花果6～8,结果高峰期4～5次,其中雄性植株仅产生花粉和榕育榕小蜂,而雄性植株（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,雌蜂飞来熟榕果找寻雌株或雄株榕树上的幼嫩隐花果,一般需3～7min;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15～23h,在雄株榕树的隐花果内产卵时间为6～9h,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%。     

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%.     

西双版纳热带雨林对叶榕传粉生物学(英)

研究了西双版纳热带雨林地区雌雄异株植物对叶榕 (FicushispidaL .)的生物学、传粉物候学以及榕小蜂(CeratosolensolmsimarchaliMayr)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～ 6 7min ;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～ 2 3h ,在雄株榕树的隐花果内产卵时间为 6～ 9h。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 5 4 .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 ,     

聚果榕传粉榕小蜂传粉与产卵之间的权衡

【目的】榕树(Ficus)依赖专性榕小蜂(Agaonidae)传粉,同时为传粉榕小蜂提供繁衍后代的场所,两者形成动植物间经典的协同进化关系。在雌花期果内,榕小蜂需在有限的存活时间内完成传粉和产卵,而传粉榕小蜂如何在传粉与产卵之间进行权衡仍然是悬而未解的问题。本研究旨在明确传粉榕小蜂——一种栉颚榕小蜂Ceratosolen sp.在雌雄同株的聚果榕Ficus racemosa雌花期果内的行为活动及繁殖模式。【方法】借助测微尺测量聚果榕榕果雌花花柱长度与传粉榕小蜂(Ceratosolen sp.)产卵器长度,通过显微视频记录传粉榕小蜂在雌花期果内搜索、传粉及产卵行为;结合单果控制性引蜂试验,测定不同阶段榕小蜂个体大小、孕卵量、携粉量,以及雄花期最终繁殖的榕小蜂后代和榕果种子数量。【结果】聚果榕雌花花柱长度存在树间变异,榕小蜂产卵器长度比绝大多数的雌花花柱长,说明该小蜂可以产卵于大部分的雌花子房里。通常个体大的榕小蜂孕卵量更多,但个体大小与携粉量之间相关性不显著。观察发现,榕小蜂进入雌花期榕果内,前6 h集中产卵,可产下孕卵量的95%,平均搜索用时27 s,产卵用时46 s,此期间传粉行为少见,花粉筐中携带花粉量亦无明显变化;榕小蜂进果后6-24 h,主要执行传粉,其行为主动,连贯高效,单次传粉用时平均为2 s,最终可传完携粉量的80%。控制引蜂试验也证实榕小蜂进入榕果内前6 h主要执行产卵繁殖后代,之后6-24 h主要执行传粉以繁殖榕树种子。【结论】在雌雄同株的聚果榕雌花期榕果内,榕小蜂先产卵、后传粉。本研究首次展示了传粉榕小蜂在聚果榕雌花期榕果内的产卵和传粉行为,并获得与行为相匹配的产卵量和传粉繁殖量,反映了具主动传粉行为的榕小蜂在传粉和产卵之间存在时间和数量上的权衡。     

聚果榕传粉榕小蜂传粉与产卵之间的权衡

【目的】榕树(Ficus)依赖专性榕小蜂(Agaonidae)传粉,同时为传粉榕小蜂提供繁衍后代的场所,两者形成动植物间经典的协同进化关系。在雌花期果内,榕小蜂需在有限的存活时间内完成传粉和产卵,而传粉榕小蜂如何在传粉与产卵之间进行权衡仍然是悬而未解的问题。本研究旨在明确传粉榕小蜂——一种栉颚榕小蜂Ceratosolen sp.在雌雄同株的聚果榕Ficus racemosa雌花期果内的行为活动及繁殖模式。【方法】借助测微尺测量聚果榕榕果雌花花柱长度与传粉榕小蜂(Ceratosolen sp.)产卵器长度,通过显微视频记录传粉榕小蜂在雌花期果内搜索、传粉及产卵行为;结合单果控制性引蜂试验,测定不同阶段榕小蜂个体大小、孕卵量、携粉量,以及雄花期最终繁殖的榕小蜂后代和榕果种子数量。【结果】聚果榕雌花花柱长度存在树间变异,榕小蜂产卵器长度比绝大多数的雌花花柱长,说明该小蜂可以产卵于大部分的雌花子房里。通常个体大的榕小蜂孕卵量更多,但个体大小与携粉量之间相关性不显著。观察发现,榕小蜂进入雌花期榕果内,前6 h集中产卵,可产下孕卵量的95%,平均搜索用时27 s,产卵用时46 s,此期间传粉行为少见,花粉筐中携带花粉量亦无明显变化;榕小蜂进果后6-24 h,主要执行传粉,其行为主动,连贯高效,单次传粉用时平均为2 s,最终可传完携粉量的80%。控制引蜂试验也证实榕小蜂进入榕果内前6 h主要执行产卵繁殖后代,之后6-24 h主要执行传粉以繁殖榕树种子。【结论】在雌雄同株的聚果榕雌花期榕果内,榕小蜂先产卵、后传粉。本研究首次展示了传粉榕小蜂在聚果榕雌花期榕果内的产卵和传粉行为,并获得与行为相匹配的产卵量和传粉繁殖量,反映了具主动传粉行为的榕小蜂在传粉和产卵之间存在时间和数量上的权衡。     

比较钝叶榕的三种传粉者及其传粉效率

钝叶榕 (Ficus curtipes)是雌雄同株,它除了依赖钝叶榕传粉榕小蜂Eupristina sp.传粉外,另外两种进入果内繁殖的杨氏榕树金小蜂Diaziella yangi 和Lipothymus sp.金小蜂也能有效地为它传粉,这3种小蜂同时产卵于雌花的子房内,在榕果内繁殖后代.通过控制性放蜂试验,比较研究钝叶榕3种传粉者的传粉效率,结果表明:自然状态下,3种小蜂在绝大多数榕果里只各进1头.在控制性放蜂试验中,3种小蜂的传粉效率均随着放入雌蜂数量的增加而增加,两种金小蜂的传粉效率有时比钝叶榕传粉榕小蜂的传粉效率还高.当钝叶榕传粉榕小蜂分别与两种金小蜂同时放入榕果内传粉时,其生产的种子数量居于或者是接近两种小蜂单独传粉时形成的种子数量,传粉效率没有显著增加.在比较3种小蜂单种分别放1头和2头的传粉效率时,增加单果放蜂数量,钝叶榕传粉榕小蜂和Lipothymus sp. 的平均传粉效率降低,但杨氏榕树金小蜂的平均传粉效率是增加的.对3种不同属传粉小蜂传粉效率的比较,可为研究榕-蜂互惠系统的互惠的起源提供依据.     

钝叶榕果实内繁殖的两种榕小蜂与寄主榕树间的协同进化

 榕树(Ficus)及其传粉榕小蜂(Agaonidae)构成了高度专一的互惠共生体系。榕树的果实(以下简称榕果)内也寄生着一些非传粉小蜂。 绝大多数非传粉小蜂在榕果外把产卵器刺入果壁产卵到果腔内, 只有极少数种类能够进入果腔内产卵。在西双版纳地区, 钝叶榕(Ficus curtipes)上的杨氏榕树金小蜂(Diaziella yangi)类似于传粉者钝叶榕小蜂(Eupristina sp.), 它也是进入榕果内产卵繁殖后代的, 这就为比 较研究榕果内产卵小蜂与寄主榕树间的关系提供了材料。该文从形态学、行为学和生态学角度比较研究了这两种进入榕果内产卵的小蜂与寄主 钝叶榕之间的作用关系, 研究结果显示: 1)杨氏榕树金小蜂与钝叶榕小蜂的雌蜂头部形状存在趋同进化; 2)两种小蜂的产卵器的平均长度都比 雌花花柱长, 因而能把卵产在子房里; 3)钝叶榕小蜂从瘿花出来需要3~5 h, 交配需要17~19 min, 杨氏榕树金小蜂从瘿花出来只需18~20 min, 交配时间为20~30 s; 4)在自然群落中, 大约90%的雌花期榕果里都只进一只杨氏榕树金小蜂和一只钝叶榕小蜂, 杨氏榕树金小蜂能通过传粉来 增加榕树种子数量, 但对钝叶榕小蜂种群的繁衍造成了极显著的负面影响; 5)两种小蜂于同一时期进入榕果内繁殖, 子代同期成熟羽化, 发育 期与榕树雄花的发育期同步。研究表明: 进入榕果内繁殖的两种小蜂与寄主榕树之间存在着协同进化关系, 杨氏榕树金小蜂为榕树有效地传粉, 这可能是一个由寄生者向互惠方向进化的实例。     

木瓜榕传粉生物学

 木瓜榕（Ficus auriculata Lour.）是雌雄异株植物,它只有通过大果榕小蜂（Ceratosolen emarginatus Mayr）传粉才能获得有性繁殖,大果榕小蜂也仅在木瓜榕雄果内产卵才得以繁衍后代。经两年来的实验和研究结果表明：木瓜榕繁殖能力在不同季节随进蜂量的多少而变化,雌树在4月和11月出现的两次结果高峰期与进蜂量最多的时期相遇;同时雄树与雌树在11月挂果高峰期重叠,导致该期进入雄果产卵的雌蜂量减少,进蜂量高峰推迟到部分雄果成熟、只有稀少接受果的3月下旬和4月上旬。木瓜榕在与大果榕小蜂互惠共生的进化历程中,逐渐完善了自身保证远交的繁殖机制,它们在不同程度上受到雌雄异熟、雌雄异株和短花柱雌花不亲和3种机制的共同作用。温湿度对大果榕小蜂访果行为有明显的影响,在温湿度变化缓和的早晚,有利于榕小蜂出行,雌蜂访果最为频繁。大果榕小蜂活动最佳的温湿度是：温度20～24 ℃之间、湿度85%～93%之间;温度高于29 ℃、湿度低于58% 或风雨天均不利于该蜂出行活动。榕小蜂日活动高峰的出现先后在不同季节略有差异,高温高湿的夏季榕小蜂活动出现早,7∶40达高峰;秋季榕小蜂活动推迟,高峰出现在11∶00;干凉的冬季最晚,13∶00才到达高峰。通过人工套袋、放蜂传粉试验,平均进8头的隐头果传粉效率最高,单果平均种子数量为11 247粒,结实率50.8%,未受精的败育花8 207朵;平均进蜂4头以下或10头以上的隐头果,由于花粉量不足或者雌蜂争夺资源的损伤使种子量下降,平均结实率分别达37.2% 和44.4%;放蜂试验结果与大量调查自然界中每果进蜂量和结实率的结果一致。     

同种榕小蜂在木瓜榕两种地理型上的繁殖及传粉特征

榕树与其传粉榕小蜂的共生关系常被认为是专一性的,但该系统中有些榕小蜂可在不同种榕树或者同种榕树的不同亚种、变种和地理型上产卵和传粉。探讨榕小蜂在不同寄主中的繁殖和传粉特征,有利于理解非专性榕蜂系统形成的过程及稳定机制。本研究中,作者分别对比分析了传粉榕小蜂Ceratosolen emarginatus在木瓜榕(Ficus auriculata)的两种地理型auriculata-form和oligodon-form上的产卵和传粉特征。结果显示,进蜂量为1,2,3只时,相同寄主上的榕小蜂后代和种子数量均随进蜂量的增加而增加,且平均单只繁殖雌蜂的后代及种子数量均无差异。这可能是由于进蜂量较低时,两寄主可被利用的繁殖资源较充足,榕小蜂间不存在干扰竞争,可最大化地利用雌花资源。另一方面,进蜂量相同时,同一寄主上产生的种子数量明显多于榕小蜂后代数量,说明榕树的繁殖利益更占优势。榕小蜂在auriculata-form上产生的后代总量和平均单只雌蜂后代数量与oligodon-form均无差异,但后者产生的种子数量明显多于前者,说明当繁殖资源充足时寄主不影响榕小蜂的繁殖,然而寄主差异影响种子产生,即auriculata-form和oligodon-form的繁殖能力已发生分化。     

西双版纳鸡嗉果榕小蜂繁殖和传粉行为

鸡嗉果榕 Ficus semicordata Buch.-Ham.ex J. E. Sm.是西双版纳地区常见的榕属植物,它是热带雨林生态系统中的一类先锋树种,当热带雨林被破坏后,它最先在林缘、沟谷和路边迅速生长起来,是热带和亚热带地区森林生态系统恢复初期一类重要物种。在西双版纳通过不同样地定树、定期生态学观察和室内剖查不同生长时期的鸡嗉果榕隐头果的方法,对榕小蜂繁殖和传粉行为进行了研究,结果表明,鸡嗉果榕雌雄异株,在西双版纳一年结2～3次隐头果,雌株隐头果内小花由榕小蜂传粉后产生种子。雄株则产生雄花和中性小花,中性小花专门供给传粉小蜂产卵繁殖后代。鸡嗉果榕小蜂Ceratosolen gravelyi Grandi是鸡嗉果榕唯一的传粉昆虫。传粉小蜂的雄蜂比雌蜂早羽化30～90 min,一部分雄虫羽化后,在虫瘿上爬动寻找雌蜂寄生的瘿花,一找到雌蜂寄生的瘿花,就咬破虫瘿的一个小口,把生殖器伸进瘿花与雌蜂交配,一部分雄蜂则在果肉上咬出蜂口。雌蜂交配后,顶大交配孔出蜂爬到雄花区采集花粉,然后,飞出寻找鸡嗉果榕雌花期的嫩隐头果传粉和繁殖后代。到鸡嗉果榕雌株传粉的小蜂能飞翔300～500 m,进果腔传粉行为长达5～27 h,传完粉3～5 h在果腔内死亡。到雄株上繁殖的小蜂一般飞翔在20～100 m左右近距离寻找嫩隐头果,进果腔产卵,每只小蜂在无干扰的情况下可产400多粒卵。除传粉榕小蜂外,在鸡嗉果榕雄株隐头果上还有4种植食、造瘿和复寄生等非传粉小蜂,它们对传粉小蜂的种群繁衍影响很大,常使传粉小蜂的种群数量降低25～70%。每个隐头果内进传粉小蜂量多少对鸡嗉果榕和榕小蜂繁殖有关,最佳进蜂量为3只,高或低于最佳进蜂量对鸡嗉果榕树和它的传粉小蜂繁殖均不利。     

Finding hidden females in a crowd: Mate recognition in fig wasps

Multi-species mating aggregations are crowded environments within which mate recognition must occur. Mating aggregations of fig wasps can consist of thousands of individuals of many species that attain sexual maturity simultaneously and mate in the same microenvironment, i.e, in syntopy, within the close confines of an enclosed globular inflorescence called a syconium – a system that has many signalling constraints such as darkness and crowding. All wasps develop within individual galled flowers. Since mating mostly occurs when females are still confined within their galls, male wasps have the additional burden of detecting conspecific females that are “hidden” behind barriers consisting of gall walls. In Ficus racemosa, we investigated signals used by pollinating fig wasp males to differentiate conspecific females from females of other syntopic fig wasp species. Male Ceratosolen fusciceps could detect conspecific females using cues from galls containing females, empty galls, as well as cues from gall volatiles and gall surface hydrocarbons.In many figs, syconia are pollinated by single foundress wasps, leading to high levels of wasp inbreeding due to sibmating. In F. racemosa, as most syconia contain many foundresses, we expected male pollinators to prefer non-sib females to female siblings to reduce inbreeding. We used galls containing females from non-natal figs as a proxy for non-sibs and those from natal figs as a proxy for sibling females. We found that males preferred galls of female pollinators from natal figs. However, males were undecided when given a choice between galls containing non-pollinator females from natal syconia and pollinator females from non-natal syconia, suggesting olfactory imprinting by the natal syconial environment.     

A switch from mutualist to exploiter is reflected in smaller egg loads and increased larval mortalities in a ‘cheater’ fig wasp

The interaction between the hundreds of Ficus species and their specific pollinating fig wasps (Agaonidae) presents a striking example of mutualism. Foundress fig wasps pollinate fig flowers, but also lay their eggs in (and gall) some of them. Only two cases of cheating fig wasps (that fail to pollinate) have been reported, from two continents, suggesting that there is a cost to abandoning pollination. Reasons for the rarity of cheating are a major question in fig biology, because persistence of the mutualism depends on fig wasps continuing to pollinate. A cost in terms of reduced reproductive success among cheaters could be one explanation. Here we compare the behavior and reproduction of an undescribed Eupristina sp., a cheater that coexists with the pollinator Eupristina altissima on Ficus altissima in southern China. Adult females of both species fought with conspecifics when they were seeking entry through the ostiole into receptive figs, but there was no fighting with heterospecifics. Despite a similar body size, female pollinators contained more eggs than female cheaters. Pollinators and cheaters produced similar number of galls, and although almost twice as many flowers were galled in figs entered by two compared to one foundress, larval mortality was greatly increased when two foundresses were present. Larval mortality was also significantly higher for cheaters compared to pollinators, independent of the number of foundresses. Ovules galled by the cheater were thus significantly less likely to result in adult offspring, suggesting that there are significant costs associated with abandoning the mutualism.     

Body size in a pollinating fig wasp and implications for stability in a fig‐pollinator mutualism

The fig–fig pollinator association is a classic case of an obligate mutualism. Fig‐pollinating wasps often have to fly long distances from their natal syconia to a receptive syconium and then must enter the narrow ostiole of the syconium to reproduce. Large wasps are expected to have a greater chance of reaching a receptive syconium. In this study, we tested this hypothesis and then examined whether the ostiole selectively prevented larger pollinators from entering the syconial cavity. In Xishuangbanna, China, Ceratosolen solmsi marchali Mayr (Hymenoptera: Agaonidae) pollinates the dioecious syconia of Ficus hispida L. (Moraceae). The body size of newly emerged wasps and wasps arriving at receptive syconia were compared. Wasps arriving at receptive syconia were significantly larger than newly emerged wasps. We also compared the size of wasps trapped in the ostiole with those in the cavity. Wasps trapped in the ostiole were significantly larger than those in the syconial cavity. Thus, in the case of F. hispida, large wasps were more likely to reach receptive syconia, but the ostiole limited maximum fig wasp size. This indicates that the ostiole, as a selective filter to pollinators, stabilizes pollinator size. Hence, it helps to maintain stability in the fig–fig pollinator mutualism.     

对叶榕隐头果内佩妃延腹小蜂属两种非传粉榕小蜂的繁殖特点

2005年8-11月,在西双版纳热带植物园对寄生对叶榕的佩妃延腹小蜂的产卵行为进行了观察,并解剖雄花前期的隐头果观察小蜂利用瘿花资源情况;对不同年份（2003、2004、2005）,不同批次的隐头果内榕小蜂数量进行了统计。结果表明： 对叶榕Ficus hispida隐头果内寄生的佩妃延腹小蜂属Philotrypesis的两种榕小蜂——短尾佩妃延腹小蜂P. pilosa和长尾佩妃延腹小蜂Philotrypesis sp.,都是在果外利用长的产卵器刺穿隐头果果壁将卵产于果中雌花子房内。它们不能为寄主榕树传粉,为非传粉小蜂。短尾佩妃延腹小蜂的产卵时间与传粉榕小蜂接近,几乎与传粉榕小蜂同时到达隐头果产卵,该时期隐头果可供其产卵2天;而长尾佩妃延腹小蜂的产卵时间较晚,在传粉榕小蜂产卵后的第6天开始到果外产卵,并可持续产卵约一周时间。对叶榕雄花期雄果中的瘿花子房由于花梗长度不同而明显分为3层：果壁层（具短花梗）,中间层和果腔层（具长花梗）。短尾佩妃延腹小蜂和长尾佩妃延腹小蜂在紧靠果壁的子房果壁层中分布最多,而很少存在于果腔层的瘿花子房内。在自然情况下,短尾佩妃延腹小蜂和长尾佩妃延腹小蜂寄生榕果的比率因季节和植株个体不同而变化。但无论是对榕果的寄生比率还是单果内寄生的数量,长尾佩妃延腹小蜂一般均比短尾佩妃延腹小蜂高,这可能与长尾佩妃延腹小蜂群体在隐头果上产卵时间比后者更长有关系。     

天仙果与两种隐头花序小蜂的相互关系

天仙果（Ficus erecta var.beecheyana）花为单性花、雌、雄异株、分别形成雌、雄花序,雌花序着生雌花,雄花序着生雄花和瘿花。花序中生活着银纹榕小蜂（Blastophaga silverstriana）和榕长尾小蜂（Sycoscapter sp.）。前者是唯一能进入雄花序腔产卵或雌花序腔传粉的昆虫,是天仙果专一性共生的传粉者;后者不能进入花序,在花序外通过产卵器将卵产在瘿花子房中,是植食性的寄生者。自然状态下天仙果每个雄花序均被2种小蜂产卵,平均每个花序出飞银纹榕小蜂208.2只、榕长尾小蜂64.2只。人为封堵花序口,银纹榕小蜂无法进入花序产卵,平均每个花序出飞榕长尾小蜂165.6只,是自然状态下的2.5倍,显然,2种小蜂互为竞争对手,榕长尾小蜂是榕-榕小蜂共生体系的破坏者。     

Interference Competition and High Temperatures Reduce the Virulence of Fig Wasps and Stabilize a Fig-Wasp Mutualism

Fig trees are pollinated by fig wasps, which also oviposit in female flowers. The wasp larvae gall and eat developing seeds. Although fig trees benefit from allowing wasps to oviposit, because the wasp offspring disperse pollen, figs must prevent wasps from ovipositing in all flowers, or seed production would cease, and the mutualism would go extinct. In Ficus racemosa, we find that syconia (‘figs’) that have few foundresses (ovipositing wasps) are underexploited in the summer (few seeds, few galls, many empty ovules) and are overexploited in the winter (few seeds, many galls, few empty ovules). Conversely, syconia with many foundresses produce intermediate numbers of galls and seeds, regardless of season. We use experiments to explain these patterns, and thus, to explain how this mutualism is maintained. In the hot summer, wasps suffer short lifespans and therefore fail to oviposit in many flowers. In contrast, cooler temperatures in the winter permit longer wasp lifespans, which in turn allows most flowers to be exploited by the wasps. However, even in winter, only in syconia that happen to have few foundresses are most flowers turned into galls. In syconia with higher numbers of foundresses, interference competition reduces foundress lifespans, which reduces the proportion of flowers that are galled. We further show that syconia encourage the entry of multiple foundresses by delaying ostiole closure. Taken together, these factors allow fig trees to reduce galling in the wasp-benign winter and boost galling (and pollination) in the wasp-stressing summer. Interference competition has been shown to reduce virulence in pathogenic bacteria. Our results show that interference also maintains cooperation in a classic, cooperative symbiosis, thus linking theories of virulence and mutualism. More generally, our results reveal how frequency-dependent population regulation can occur in the fig-wasp mutualism, and how a host species can ‘set the rules of the game’ to ensure mutualistic behavior in its symbionts.     

雀榕及其传粉昆虫传粉生态研究

雀榕（Ficus virens)花是单性的,雌雄同株,每一个隐头花序里同时具有雌花和雄花,雌花有长柱花和短柱花（瘿花）的分化,但二者均能结实和形成虫瘿,在生理上仍未分离,在这些花序中生长着4种小蜂总科的昆虫,其中榕小蜂科的2个种是雀榕的传粉省,尤以雀榕小蜂（Blastophagea sp.)为雀榕的主要传粉者,是共生体系的真正的互惠共生伙伴,冠缝榕小蜂（B.coronata)则是次要的传粉者也是主要传粉者的竞争者,食榕小蜂（Sycophila sp.)和刻腹小蜂（Ormyrus sp.)是上述2种榕小蜂的寄生者,但是刻腹小蜂的雄蜂也能参与出飞孔开掘,首次报道了我国雌雄同株的榕属植物和传粉昆虫的季节性环境胁迫下的共生关系,并探讨了共生体系维持的对策。     

Foundress re-emergence and fig permeability in fig tree-wasp mutualisms

Some female pollinating fig wasps (foundresses) re-emerge from figs after oviposition/pollination. We investigated why this occurs in the mutualism between the gynodioecious Ficus montana and Liporrhopalum tentacularis. Re-emergence increased with foundress density in figs and some foundresses oviposited in two male figs, indicating that they re-emerge because of oviposition site limitation. Re-emergence was independent of fig diameter, indicating that permeability is not because of fig age at entry. Rather, as some foundresses also pollinate two female figs we suggest permeability is selected for because it increases pollinator production and/or efficiency (although, potentially opposing these hypotheses, we also found between-tree differences in permeability in male figs). In addition, we show that re-emergence is much more common than previously suspected, and more common from gynodioecious than monoecious fig species. We argue that our findings in F. montana could explain this pattern of incidence.