西双版纳鸡嗉果榕内一种非传粉小蜂的性比调节

对西双版纳广泛分布的鸡嗉果榕（Ficus semicordata）雄树上寄生的一种非传粉榕小蜂Apocryptophagus sp.进行控制梯度放蜂实验,结合产卵行为、交配行为观察,定量研究了该种非传粉榕小蜂的性比率.结果表明：Apocryptophagus sp.雌蜂在传粉榕小蜂（Ceratosolen gravelyi）产卵后的第3天开始访问榕果,从果外完成产卵,产卵时间持续2d左右.发育成熟以后,其雄蜂几乎与传粉榕小蜂雄蜂同时羽化,雄蜂咬开寄生有其雌蜂的瘿花并进行交配,雌蜂交配后从瘿花内羽化出来离开榕果,去寻找新的处于接受期的榕果,而雄蜂一直留在其寄生的榕果内直至死亡.后代性比与局域配偶竞争理论预测一致：性比偏雌,随着在同一榕果产卵的繁殖雌蜂数量的增加,后代性比上升;同时,单个榕果内的后代数量也上升,而平均后代数量却显著下降.在个体水平上,当1头雌蜂在榕果上产卵时,后代性比与后代数量呈显著的负相关关系.     

母代雌蜂数、进果时间及非传粉小蜂对传粉榕小蜂后代数量及性比的影响

【目的】对性比的研究有助于我们理解自然界生物的选择压力及其所产生的原因和结果,榕树和榕小蜂之间的互惠共生关系以及生物学和生态学特性使其成为研究性比和局域配偶竞争模型（local mate competition）的理想材料。本研究旨在探明榕小蜂性比调节和进化机制。【方法】对分布于西双版纳地区的鸡嗉子榕Ficus semicordata进行了人工控制性放蜂实验。测定了母代雌蜂数量及其进果时间间隔、非传粉小蜂Sycoscapter trifemmensis数量对传粉榕小蜂Ceratosolen gravelyi后代数量（成蜂数量）和性比的影响,并分析了小蜂后代数量和性比的相关性。【结果】在榕果发育期一致的前提下,随着母代雌蜂数量的增加,每头雌蜂的平均后代数量明显下降(P<0.001),后代性比显著升高(P<0.001),后代数量和性比呈显著负相关(P<0.05);随着雌蜂进果间隔的延长,后代数量亦呈现下降趋势,且性比增大,放2头雌蜂和3头雌蜂的处理呈同样趋势,但差异均不显著(P=0.87; P=0.49),小蜂后代数量与性比无显著相关性(P=0.86)。此外,非传粉小蜂数量与传粉小蜂后代数量呈显著负相关(P<0.001),与传粉小蜂性比呈正相关(P<0.001),小蜂后代数量和性比同样呈现显著负相关(P<0.001)。【结论】本实验模拟了自然界中榕 蜂的相互作用,所得结果有助于我们理解自然状态下榕小蜂性比调节模式和机制,以及榕 蜂互利共生系统的进化机制。     

西双版纳鸡嗉果榕内一种非传粉小蜂的性比调节

对西双版纳广泛分布的鸡嗉果榕(Ficus semicordata)雄树上寄生的一种非传粉榕小蜂Apocryptophagus sp.进行控制梯度放蜂实验,结合产卵行为、交配行为观察,定量研究了该种非传粉榕小蜂的性比率.结果表明: Apocryptophagus sp.雌蜂在传粉榕小蜂(Ceratosolen gravelyi)产卵后的第3天开始访问榕果,从果外完成产卵,产卵时间持续2 d左右.发育成熟以后,其雄蜂几乎与传粉榕小蜂雄蜂同时羽化,雄蜂咬开寄生有其雌蜂的瘿花并进行交配,雌蜂交配后从瘿花内羽化出来离开榕果,去寻找新的处于接受期的榕果,而雄蜂一直留在其寄生的榕果内直至死亡.后代性比与局域配偶竞争理论预测一致：性比偏雌,随着在同一榕果产卵的繁殖雌蜂数量的增加,后代性比上升;同时,单个榕果内的后代数量也上升,而平均后代数量却显著下降.在个体水平上,当1头雌蜂在榕果上产卵时,后代性比与后代数量呈显著的负相关关系.     

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。     

钝叶榕(Ficus curtipes)非传粉小蜂交配行为

榕树及其传粉榕小蜂繁殖上相互依存,被认为是生物界中协同进化时间最悠久,相互关系最密切的一对生物;在大多数榕树种类的隐头花序内,除了传粉榕小蜂外,还共存着多种非传粉小蜂,它们的繁殖行为直接影响着榕树和传粉榕小蜂的繁殖和互惠稳定。钝叶榕(Ficus curtipes Corner),是一种雌雄同株的绞杀性榕树。研究在西双版纳热带植物园里共收集钝叶榕100个隐头果内的榕小蜂,获得9493号标本;其中,包括1种传粉小蜂和5种非传粉小蜂,钝叶榕传粉小蜂Eupristina sp.占总数的4466%,杨氏榕树金小蜂Diaziella yangi 占46.13%,而其它4种非传粉小蜂（Lipothymus sp., Sycobia sp., Philotrypesis sp.和Sycoscopter sp.）仅占9.20%。前3种榕小蜂雌蜂进到果腔产卵,其余3种在果外产卵。观测23个钝叶榕榕果出蜂情况发现,6种榕小蜂在钝叶榕隐头花序内遵循严格的羽化出蜂顺序,首先是Sycobia sp.,次之是Lipothymus sp.,再次之是杨氏榕树金小蜂,最后是钝叶榕传粉小蜂、Philotrypesis sp.和Sycoscopter sp.。5种非传粉小蜂的交配场所与雄蜂翅型无关,雄蜂有翅型的杨氏榕树金小蜂大部分交配在果内完成,而且它们的雄蜂为争夺交配机会存在激烈的打斗行为;雄蜂无翅型的Lipothymus sp.有部分雄蜂爬出隐头果,在果壁和附近的叶片背面交配;雄蜂有翅型的Sycobia sp.,其所有交配都发生在果外;Philotrypesis sp.和Sycoscopter sp. 雄蜂均无翅,它们的交配全发生在果内。局域配偶竞争使榕小蜂性比偏雌,杨氏榕树金小蜂雄蜂虽然有翅,但大部分交配发生在榕果内,这将影响其最佳的性比率。因此,依赖雄蜂翅型并不能很好地预测榕小蜂的交配场所和性比率。     

钝叶榕(Ficus curtipes)非传粉小蜂交配行为

榕树及其传粉榕小蜂繁殖上相互依存,被认为是生物界中协同进化时间最悠久,相互关系最密切的一对生物;在大多数榕树种类的隐头花序内,除了传粉榕小蜂外,还共存着多种非传粉小蜂,它们的繁殖行为直接影响着榕树和传粉榕小蜂的繁殖和互惠稳定.钝叶榕(Ficus curtipes Corner),是一种雌雄同株的绞杀性榕树.研究在西双版纳热带植物园里共收集钝叶榕100个隐头果内的榕小蜂,获得9493号标本;其中,包括1种传粉小蜂和5种非传粉小蜂,钝叶榕传粉小蜂Eupristina sp.占总数的44.66%,杨氏榕树金小蜂Diaziella yangi 占46.13%,而其它4种非传粉小蜂(Lipothymus sp., Sycobia sp., Philotrypesis sp.和Sycoscopter sp.)仅占9.20%.前3种榕小蜂雌蜂进到果腔产卵,其余3种在果外产卵.观测23个钝叶榕榕果出蜂情况发现,6种榕小蜂在钝叶榕隐头花序内遵循严格的羽化出蜂顺序,首先是Sycobia sp.,次之是Lipothymus sp.,再次之是杨氏榕树金小蜂,最后是钝叶榕传粉小蜂、Philotrypesis sp.和Sycoscopter sp..5种非传粉小蜂的交配场所与雄蜂翅型无关,雄蜂有翅型的杨氏榕树金小蜂大部分交配在果内完成,而且它们的雄蜂为争夺交配机会存在激烈的打斗行为;雄蜂无翅型的Lipothymus sp.有部分雄蜂爬出隐头果,在果壁和附近的叶片背面交配;雄蜂有翅型的Sycobia sp.,其所有交配都发生在果外;Philotrypesis sp.和Sycoscopter sp. 雄蜂均无翅,它们的交配全发生在果内.局域配偶竞争使榕小蜂性比偏雌,杨氏榕树金小蜂雄蜂虽然有翅,但大部分交配发生在榕果内,这将影响其最佳的性比率.因此,依赖雄蜂翅型并不能很好地预测榕小蜂的交配场所和性比率.     

非传粉小蜂对榕-蜂共生系统的影响

榕-蜂共生系统是桑科榕属(Ficus)植物与传粉榕小蜂专一互惠形成的生态学关系。但是,也有一些非传粉的小蜂出现在这个系统中,对榕-蜂共生系统可能产生较大的影响。西双版纳的聚果榕(Ficus racemosa)树上主要有5种非传粉小蜂,分别在榕果发育的不同阶段从果外向果内产卵。在传粉榕小蜂进果之前的花前期,Platyneura testace、Apocrypta sp.和P. mayri这3种非传粉小蜂先后到果外产卵繁殖后代,对榕-蜂共生系统造成显著影响,尤其是影响传粉榕小蜂的繁殖。在传粉榕小蜂进果之后的间花期,P. mayri、A. westwoodi和P. agraensis这3种非传粉小蜂相继到果外产卵,它们虽然能减少种子形成和传粉榕小蜂繁殖的数量,但最终没有对榕-蜂共生系统造成显著的影响。造瘿类的P. mayri可在花前期和间花期产卵繁殖,在花前期产卵时它主要是影响传粉榕小蜂的繁殖,而在间花期产卵时它则更多地是影响种子的生产。     

高榕雌花期传粉榕小蜂和欺骗性小蜂的繁殖特点

榕树及其专一性传粉榕小蜂组成了动植物界最为经典的协同进化关系,传粉榕小蜂演化出欺骗性是非常罕见的。在雌雄同株的高榕隐头果内,共存着一种传粉榕小蜂Eupristina altissima和一种欺骗性的小蜂Eupristina sp.,两种小蜂在雌花期进入隐头果内繁殖,但有不同的繁殖特点。对比研究了两种小蜂从成虫羽化到产卵和传粉这个阶段的雌蜂个体大小、孕卵量及繁殖差异,结果表明:羽化期两种雌蜂的平均个体小,经飞行小个体的雌蜂易死亡,大个体雌蜂到达接受树,但通过苞片通道,一些个体较大的传粉榕小蜂被夹死导致进入果腔的雌蜂相对小,而欺骗性小蜂易通过苞片以至进入果腔的雌蜂个体较大。两种未产卵雌蜂均表现为个体大者孕卵量较多,但两种雌蜂的平均孕卵量没有差异。即使有充足雌花资源产卵,两种雌蜂均未产完所有卵,产卵后两种雌蜂卵巢中的卵量均显著减少,遗留下的卵量两种小蜂间没有差异。传粉榕小蜂只有部分个体传完所携带花粉,并表现为传粉越成功的雌蜂,产卵越多。存在种内竞争时,两种小蜂的产卵量均减少,传粉榕小蜂的传粉效率也降低。在种间竞争背景下,欺骗性小蜂产卵更成功,传粉榕小蜂的产卵和传粉量均受到极大抑制。研究结果说明雌花期隐头果内传粉榕小蜂只适量利用雌花资源产卵繁殖后代,更有效地传粉繁殖榕树种子,这可能是维持榕-蜂互惠系统稳定共存的重要机制之一;欺骗者稳定存在需降低与传粉者的直接竞争,而欺骗者和传粉者分散在不同果内,甚至是不同的树上繁殖是理想的繁殖策略。     

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。     

小叶榕隐头果内加利里金小蜂的发生规律

小叶榕Ficus microcarpa是一种广泛分布于亚洲热带和亚热带地区的雌雄同株榕树,在它的隐头果中,除了专一性传粉的榕小蜂外,还寄生着多种非传粉小蜂,这些非传粉小蜂在榕果发育的不同时期来到果外产卵,对榕树和传粉榕小蜂繁衍后代产生不同的影响。加利里金小蜂Odontofroggatia galili是寄生于小叶榕雌花子房里的主要非传粉小蜂。本文在2012~2013年对该种小蜂的发生规律进行了研究,结果表明:该种小蜂雌雄蜂有翅,雄蜂二型,个体大小有显著差异。加利里金小蜂在榕果的雌花前期产卵,能独立造瘿;在西双版纳地区,干热季和雨季从卵发育到成虫羽化需31~38 d,雾凉季则长达58~72 d。成虫在榕果雄花期羽化出蜂,大多数雄蜂在苞片口等待羽化出果的雌蜂交配,雌雄蜂通常仅交配一次;为争夺交配机会,雄蜂间存在激烈打斗,且个体大者获交配机会多。成虫期雌蜂寿命2 d,雄蜂寿命仅1 d。小叶榕40%的树上隐头果内有加利里金小蜂寄生,但不同地区寄生率和单果内加利里金小蜂雌雄蜂数量树间均存在显著差异。在原生地西双版纳地区加利里金小蜂种群小,传粉榕小蜂种群占主导地位;而在引入地昆明地区,加利里金小蜂发生频率高,种群显著较大;随着纬度北移和海拔升高,在榕果内罕见有传粉榕小蜂传粉和繁殖,而加利里金小蜂种群则不断升高。说明小叶榕在海拔较高和纬度偏北地区栽种,不适宜传粉榕小蜂繁殖,而非传粉的加利里金小蜂则较为适应,获得成功繁殖及种群扩张。     

Spatial distribution patterns of three fig wasps on Ficus semicordata: How non-pollinators affect pollinator’s sex ratio

Sex ratio theory is one of the most productive fields in research on evolutionary biology. Pollinating fig wasps, due to their particular natural life history, are considered to be a valuable model for the study of sex ratio evolution. A great deal of research concerning the factors that affect pollinator fig wasp (Agaonidae) progeny sex ratio has been done, and at present three main factors (haplodiploidy, local mate competition and inbreeding) are found to be important at the population level. However, there still exists variation between empirical data and model predictions. Another factor to which little thought has been given before is the effect of non-pollinating fig wasps (NPFWs) which parasitize in the larvae gall of pollinator thus kill pollinators and exploit the fig/fig pollinator mutualistic systems. In this study, we focus on why and how non-pollinating fig wasps distort pollinator fig wasp’s original sex ratio. Through controlling the number of ovipositing foundresses inside a fig, combined with the observation of ovipositing behavior and sequence, we studied three species of wasp in the figs of a dioecious fig Ficus semicordata including the pollinator Ceratosolen gravely and NPFWs Platyneura cunia, Sycoscapter trifemmensis in tropical area of Xishuangbanna from September to December 2009. First, we observed the timing of oviposition of all fig wasps utilizing F. semicordata and found differences when compared to previous studies. Such as P. cunia is the fourth rather then the secondary fig wasps to oviposit on the syconia approximately 10 days after the pollinator. S. trifemmensis oviposits much earlier than previously thought, 14–32 days after the pollinators. We examined the spatial location of male and female progeny of the pollinator. We found foundresses of pollinator prefer to use innermost ovules first. Only at high offspring numbers were the outer ovules used. More male pollinator offspring were developed near the fig cavity, while female pollinator offspring were more evenly distributed among ovule layers. As pollinator offspring numbers increased, this phenomenon became more pronounced. This pattern of segregation of male larvae gall in inner ovules and female larvae gall in outer ovules suggests that female offspring might be more vulnerable to attack by parasitic wasps that oviposit from outside the syconium. Experiments later demonstrated that NPFWs are restricted by their ovipositor length and they prefer to or can only lay their eggs into ovules near the fig wall. Then we examined the spatial location of NPFWs and compared this with the spatial location of male/female progeny of pollinator. NPFWs had a high probability of parasitizing female pollinator larvae. Thus, NPFWs have a substantial effect on the sex ratio of the pollinator, as parasitism risk decreases towards the center of the syconium, where inner ovules provide enemy-free space for most of male pollinator offspring. Partial correlation analyse shows that sex ratio of pollinator progeny has a positive relationship with the number of NPFWs. We suggest that the resulting gradient in offspring viability between male and female contributes to selection on pollinators’ for a less femalebiased sex ratio. When the affect of NPFWs was excluded, the pollinator sex ratio was not in good agreement with local mate competition theory, although it was still female-biased. In addition, the average number of offspring per foundress decreased with increasing foundress number, but pollinator sex ratio was positively related to brood size. Thus, pollinator females do not appear to adjust their sex ratio to foundress density directly, but use brood size and foundress density simultaneously as cues to assess potential LMC.     

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。     

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。     

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.     

鸡嗉果榕榕小蜂产卵时序与种群数量分析

榕树与传粉榕小蜂的互惠共生体系被多种非传粉榕小蜂利用。在同一个榕果中,具有较高种群密度的传粉榕小蜂和多种非传粉榕小蜂生存在一起并相互作用。通过野外观察和采样分析的方法,对鸡嗉果榕内5种榕小蜂（传粉榕小蜂Ceratosolen gravelyi;非传粉榕小蜂Apocrypta sp., Philotrypesis dunia, Platyneura cunia和Sycoscaptertr ifemmensis）的产卵行为进行了研究。结果证明,鸡嗉果榕内生活的各种榕小蜂通过比较严格的产卵时序在榕果内产卵以占领不同的生态位,这反映了这些榕小蜂各自的生物学特性。自然种群数量分析表明,单个非传粉榕小蜂物种的种群数量几乎不与传粉榕小蜂种群数量呈负相关,而所有非传粉榕小蜂物种的种群个体总量与传粉榕小蜂的种群个体数呈正相关,这可能是多个物种共存于单个榕果内的进化适应。     

Non-pollinating wasps distort the sex ratio of pollinating fig wasps

In fig wasps, mating occurs among the offspring of one or a few foundress mothers within the fig, from which the mated females disperse to found new broods. Under these conditions, males will compete with each other for mating, and such local mate competition can result in female-biased sex ratios. In addition to pollinating wasps, non-pollinating wasp species are also associated with figs and develop in flower ovaries or parasitize the larvae of primary galling wasps. While studying the fig wasp Pegoscapus tonduzi , which pollinates Ficus citrifolia in Brazil, we examined the influence of non-pollinating fig wasps on the sex ratio of species that pollinate F. citrifolia to determine whether the presence of non-pollinating wasps resulted in a distorted sex ratio. There was a positive relationship between the sex ratio of P. tonduzi and the number of non-pollinating wasps that was independent of the number of foundresses and brood size. In addition, the number of non-pollinating wasps correlated negatively with the number of pollinating females, but was not significantly related to the number of pollinating males. This finding suggested that non-pollinating wasps had a direct effect in distorting the sex ratio of P. tonduzi broods. Our results indicate that the secondary sex ratio may not precisely reflect the primary sex ratio when there is a high infestation of non-pollinating fig wasps.     

垂叶榕上16种榕小蜂的种群动态

传粉榕小蜂和榕树的互利共生是传粉昆虫与植物间协同进化的典范。在榕果(榕树的隐头状花序)内,还生活着多种非传粉榕小蜂。这些生活在密闭榕果内由传粉榕小蜂和非传粉榕小蜂组成的群落对研究群落生态学有很大价值。然而,对生存在单一榕树的榕果内的所有榕小蜂的种群动态了解很少,特别是缺少相对长期的连续数据。通过野外近3a观察和采样,研究了垂叶榕榕小蜂群落结构和榕小蜂的种群动态。共记录榕小蜂16种;各种榕小蜂根据发生规律可分为常见种和偶见种,Eupristina koningsbergeri,Philotrypesis sp.1,Philotrypesis sp.4,Philotrypesis sp.5,Sycoscapter sp.1,Walkerella benjamini,Walkerella sp.1,Sycophila sp.2,Sycobia sp.2为常见种;Sycobia sp.1,Acophila sp.1,Sycophila sp.1,Ormyrus sp.1等为偶见种。每种榕小蜂在单果上的数量随季节呈波动变化,季节对榕小蜂群落的多样性和均匀性无显著影响。除了传粉榕小蜂外,Sycoscapter sp.1也是优势种类之一。传粉榕小蜂的数量与非传粉榕小蜂总数间呈显著负相关。传粉榕小蜂与非传粉榕小蜂几乎都呈负相关,而与Walkerella sp.1在数量上呈显著正相关。Sycobia sp.2与Sycophila sp.2在同一瘿中出现,数量上呈显著正相关。但其它非传粉榕小蜂种类在数量上的相关性较为复杂,可能是造成各种榕小蜂数量波动的一个原因。     

Effects of time-dependent competition for oviposition sites on clutch sizes and offspring sex ratios in a fig wasp

Fig wasps have been known as one of the best-documented examples of female-biased sex ratio predicted from the local mate competition (LMC) theory. However, observed sex ratios appear more female-biased than predicted. Before a close match between theory and observation can be claimed, the number and sex ratio of offspring left by each foundress in a multi-foundress syconium need to be determined. We examined the clutch size and sex ratio of individual females of the pollinator fig wasp Blastophaga nipponica (Agaonidae) in experiments using a pair of fertile and sterile females in which sequence and time interval of entering syconia were manipulated. To determine the number and sex ratio of offspring left by each foundress in a multi-foundress syconium, we prepared sterilized females that could oviposit ordinarily but whose offspring could not develop at all, by irradiating the females with ⁶⁰Co gamma rays. Female fig wasps contributed different numbers and sex ratios of offspring to the total brood within a syconium, due to different entry times among them. The variation in clutch sizes with different entry times appeared to be caused by competition for oviposition sites, and sex ratios to be adjusted according to the clutch size.