福州大叶榕隐头果内的小蜂群落结构与多样性

对福州2个样地10株大叶榕果内小蜂群落组成和物种多样性进行研究。全年在两个样地267个隐头果内共收集到小蜂13458只。发现大叶榕隐头果内有7种小蜂,隶属小蜂总科Chalcidoidae中的榕小蜂科Agaonidae、金小蜂科Pteromalidae的隐针榕小蜂亚科Epichrysomallinae、锥尾榕小蜂亚科Otitesellinae和延腹榕小蜂亚科Sycoryctinae;广肩小蜂科Eurytomidae、刻腹小蜂科Ormyridae、姬小蜂科Eulophidae,其中榕小蜂科的Platyscapa coronata是大叶榕唯一的传粉者,传粉方式为主动传粉;非传粉榕小蜂的雄性多型现象普遍。传粉与非传粉小蜂的性比明显具有偏雌现象。传粉小蜂性比为0.19±0.07,非传粉小蜂中Camarothorax bismasculinus小蜂性比为0.36±0.10;Walkerella sp.小蜂性比为0.36±0.22,Sycoscapter sp.小蜂性比为0.31±0.22,Sycophila sp.小蜂性比为0.35±0.13。雄性多型现象可能是导致非传粉小蜂性比提高的原因之一。根据各种榕小蜂发生数量及连续性,可将大叶榕隐头果中的榕小蜂分为常见种和偶见种,Platyscapa coronata、Camarothorax bismasculinus、Walkerella sp.、Sycoscapter sp.和Sycophila sp.为常见种,Omyrus sp.和Aprostocetus sp.为偶见种。偶见种的存在对常见种的数量几乎没有影响,偶见种利用的是榕果内未饱和的一部分资源,也可能是榕果为偶见种的发生预留了空间和资源。首次发现姬小蜂科的昆虫寄生在榕果内,且有一定的种群数量,为姬小蜂科昆虫分类及其生物学、生态学特性研究提供了基础资料。在大叶榕小蜂群落结构中,传粉小蜂和非传粉小蜂的种类和数量呈现明显的季节性。冬-春季(12-翌年5月)榕果内小蜂的种类和数量较多,传粉榕小蜂是优势种,其重要值达到0.42,榕果种子结实率高;夏-秋季(6-11月间)小蜂种类和数量略少,Camarothorax bismasculinus和Sycophila sp.是优势种,其重要值分别为0.56和0.28,而传粉小蜂的重要值仅为0.025,此期大叶榕榕果中几乎找不到传粉小蜂,榕果结实率极低,对大叶榕的繁殖利益有较大的负面影响。雨水和高温等不良气候,可能是导致夏-秋季雄花期榕果内的传粉小蜂数量骤减的主要原因。两个实验样地的小蜂群落结构组成没有明显差异,年变化趋势相似。研究结果为城市绿化和热带雨林生物多样性保护提供科学依据。     

细叶榕榕小蜂群落结构及动态变化

细叶榕为桑科榕属植物,雌雄异株,广泛分布于印度-澳大利亚(Asia-Australasia)榕树植物分布中心区,它既是热带雨林的主要树种,也是庭院和行道绿化的常见树种。通过全年定时、定点、定株观察与采集,对福州2个样地19株细叶榕隐头果内小蜂群落结构及其动态进行研究。全年在两个样地530个隐头果内共收集到小蜂26318只。发现细叶榕隐头果内有17种小蜂,隶属小蜂总科Chalcidoidae中的榕小蜂科(Agaonidae)、隐针榕小蜂亚科(Epichrysomallinae)、金小蜂科(Pteromalidae)、广肩小蜂科(Eurytomidae)和刻腹小蜂科(Ormyridae),其中榕小蜂科的Eupristina verticillata是细叶榕唯一的传粉者,传粉方式为主动传粉,其性比为0.16,具明显偏雌现象;非传粉小蜂中,有翅雄蜂的榕小蜂(Odontofroggatia galili,O.quinifuniculus,O.corneri,Sycophila sp.1,Sycophila sp.2,Meselatus bicolor)的性比(0.46—0.55)较高,无翅雄蜂的榕小蜂(P.taiwanensis,Sycoscaptergajimaru,W.microcarpae)的性比(0.31—0.37)较低,而既具有翅雄蜂又具无翅雄蜂的非传粉榕小蜂(P.okinavensis)性比(0.47)居中。榕小蜂的性比可能与其交配行为策略有关。在细叶榕小蜂群落结构中,传粉小蜂E.verticillata的重要值占绝对优势,非传粉小蜂O.galili和Sycophila sp.2的重要值仅次于传粉小蜂。根据榕小蜂发生数量及连续性,可将细叶榕隐头果中的榕小蜂分为常见种和偶见种,E.verticillata、Odontofroggatia galili、Walkerella microcarpae、Sycophila sp.1、Sycophila sp.2和Philotrypesis okinavensis为常见种,其余11个种为偶见种。传粉小蜂和非传粉小蜂的种类和数量呈现明显的季节性变化。2月至6月期间,每月出现的榕小蜂种类较少,仅3—4种,单果内平均有传粉小蜂48.88只,非传粉小蜂13.64只;7月至翌年1月间,每月出现的榕小蜂种类较多,达6—13种,单果内平均有传粉小蜂24.38只,非传粉小蜂18.89只,表明,7月—翌年1月单果内传粉小蜂数量比较于2—6月极显著降低(P<0.001),而单果内非传粉小蜂数量极显著提高(P=0.001),同时种类也显著增加。雄花期榕小蜂的种类与数量取决于雌花期产卵榕小蜂的种类与数量,而雨量、气温以及雌花期花序果数量对产卵小蜂的数量,以及小蜂产卵行为都可能产生影响。本研究结果可为城市绿化和热带雨林生物多样性保护提供科学依据。     

高榕榕果内Eupristina属两种榕小蜂的遗传进化关系

对生长在福州地区的高榕进行长期追踪观察,发现高榕榕果内仅生活着Eupristina altissima和Eupristina sp.榕小蜂,前者为高榕的传粉小蜂,后者无传粉行为,两者雌蜂之间在体色、触角、花粉袋和花粉刷等部位存在细微的差异,而两者雄蜂之间无形态差异。通过克隆福建地区5个样地的高榕榕果内收集到的E. altissima和Eupristina sp.榕小蜂,以及细叶榕的传粉小蜂Eupristina verticillata(外群)的Cytb及COI基因,并进行碱基组成及遗传距离分析,用邻接法构建系统发育树,分析两榕小蜂群体之间的遗传进化关系,结果显示:(1)榕小蜂COI及Cytb序列碱基组成中A+T的含量(Cytb序列中A+T=75.3%,COI序列中A+T=75.5%)显著高于G+C,符合膜翅目昆虫线粒体基因碱基组成特征。(2)对两群体小蜂进行遗传距离分析显示,Cytb序列中E. altissima和Eupristina sp. 群体内各样本之间的平均遗传距离分别为0.0092和0.0030,而E. altissima与Eupristina sp. 群体间的平均距离为0.1588;COI序列中E. altissima 与Eupristina sp. 群体内各样本之间的平均遗传距离分别为0.0065和0.0205,而二者群体间的平均遗传距离为0.1043,表明两者群体间的遗传距离明显大于各自群体内各样本间的遗传距离。统计GenBank中下载的6个属34种榕小蜂Cytb序列的种间遗传距离为0.0811-0.1723,6个属28种榕小蜂COI序列的种间遗传距离为0.0939-0.1986。由此认为E. altissima和Eupristina sp.之间的遗传距离差异已经达到了种间水平,即E. altissima与Eupristina sp.为两个不同的种。(3)在形态上,两种小蜂的雌蜂之间有微小差异,而二者雄蜂之间无差异,但Cytb与COI序列分析结果一致表明:E. altissima与Eupristina sp.雄蜂之间,以及二者雌蜂之间的遗传距离均差异显著,表明形态变异滞后于基因变异。雌蜂在表型上进化快于雄蜂,可能是由于雌蜂羽化后从榕果出飞,受到外界环境因素的影响较大,且两种雌蜂在传粉功能上存在差异,故二者之间的形态差异较大,而雄蜂寿命短,又终生生活在黑暗封闭、环境变化相对恒定的榕果内,两种雄蜂在行为上不存在差异,故二者表型变异较为缓慢。E. altissima和Eupristina sp.小蜂对宿主的专一性不强,在榕-蜂协同进化过程中,可能发生过宿主转移事件。     

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.     

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。     

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。     

钝叶榕榕果内榕小蜂的产卵顺序及其群落结构

通过对钝叶榕榕小蜂行为的观察以及榕果内各类小花的统计,研究了钝叶榕12种榕小蜂的产卵行为和群落结构.结果表明：钝叶榕中除了传粉榕小蜂Eupristina sp.进入果腔产卵以外,还有2种非传粉榕小蜂（杨氏榕树金小蜂和Lipothymus sp.）与传粉榕小蜂在同一时期进入果腔产卵,其他9种非传粉榕小蜂（Walkerella sp.、Micranisa sp.、Sycophilomorpha sp.、Philotrypesis sp.、Sycosapter sp.、Sycobia sp.、Ficomila sp.、Ormyrus sp.和Sycophila sp.）在果外产卵;在钝叶榕榕小蜂群落中,传粉榕小蜂占整个群落总数的62.11%,是该群落的优势种,杨氏榕树金小蜂和Lipothymus sp.分别占整个群落总数的27.19%和4.71%,其他9种非传粉榕小蜂占5.99%.钝叶榕中的非传粉榕小蜂通过各自产卵时序和幼虫食性分化的繁殖策略来分配榕果中的资源,以实现自身繁殖.非传粉榕小蜂与传粉榕小蜂的数量变化呈显著负相关,但非传粉榕小蜂与榕果内的种子没有相关性.     

福州大叶榕隐头果内榕小蜂的分类

通过对福州两个样地大叶榕雄花期隐头果进行定时、定点采集,观察与鉴定,从546个花序果内共收集到榕小蜂33641头,隶属于小蜂总科中的7个科(亚科)7个属的11个种,其中传粉小蜂为榕小蜂科的Platyscapa coronata,其余10种非传粉小蜂分别隶属于隐针榕小蜂亚科Epichrysomallinae,金小蜂科Pteromalidae的锥尾榕小蜂亚科Otitesellinae和延腹榕小蜂亚科Sycoryctinae,广肩小蜂科Eurytomidae,刻腹小蜂科Ormyridae和姬小蜂科Eulophidae。传粉小蜂和非传粉小蜂的种类和数量呈现明显的季节性。冬-春季(12-翌年5月)榕果内小蜂的种类和数量较多,传粉榕小蜂是优势种;夏-秋季(6-11月间)小蜂种类和数量略少,Camarothorax bismasculinus和Sycophila sp.1是优势种。在非传粉小蜂中,Camarothorax、Sycophila、Otitesella、Sycoscapter等4个属的榕小蜂为常见种,而Ormyrus和Aprostocetus等2个属的榕小蜂为偶见种。根据小蜂的形态特征制定大叶榕隐头果中榕小蜂种类检索表,本实验为榕小蜂分类、榕-蜂协同进化研究,以及非传粉小蜂对榕-蜂共生体系的影响等研究提供科学依据。     

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.     

Relative investment in egg load and poison sac in fig wasps: Implications for physiological mechanisms underlying seed and wasp production in figs

Fig pollinating wasps and most non-pollinator wasps apply secretions from their poison sacs into oviposited flowers that appear necessary to the formation of the galls that their developing offspring consume. Thus, both eggs and poison sac secretions appear to be essential for wasp reproduction, but the relative investment in each is unknown. We measured relative investment in poison sac and egg production in pollinating and non-pollinating wasps associated with seven species of monoecious Panamanian figs representing both active and passive pollination syndromes. We then collected similar data for four fig hosts in China, where some wasp species in the genus Eupristina have lost the ability to pollinate (“cheaters”). All wasps examined possessed large poison sacs, and we found a strong positive correlation between poison sac size and absolute egg production. In the Panamanian species, the relative poison sac to egg investment was highest in the externally ovipositing non-pollinator wasps, followed by active pollinators, then by passive pollinators. Further, pollinator wasps of fig species with demonstrated host sanctions against “cheating” wasps showed higher investment in the poison sac than wasps of species without sanctions. In the Chinese samples, relative investment in the poison sac was indistinguishable between pollinators and “cheaters” associated with the same fig species. We suggest that higher relative investment in poison sac across fig wasp species reflects higher relative difficulty in initiating formation of galls and subsequently obtaining resources from the fig. We discuss the implications for the stability of the fig–wasp mutualism, and for the ability of non-pollinators to exploit this mutualism.     

榕小蜂的产卵模式及其对子代性比的影响

于2007年4月—2007年7月在中国科学院西双版纳热带植物园,通过干预控制榕小蜂产卵的方法研究了聚果榕的传粉榕小蜂Ceratosolen fusciceps和非传粉小蜂Platyneura mayri及垂叶榕的非传粉小蜂Acophila sp.1和Wakerella benjamini等的产卵顺序。对传粉榕小蜂,在完成放蜂后不同间隔时间向榕果内注入乙醚杀死小蜂;对非传粉榕小蜂,在放蜂后不同间隔时间将其从纱网袋内全部放出,从而控制了各种榕小蜂的产卵时间。到榕果成熟后,收集了榕果内的小蜂,并分析比较各种榕小蜂在不同产卵时间下的子代性比。结果表明：Ceratosolen fusciceps、P. mayri和Acophila sp.1在产卵的最初时间内倾向于产下更多的雄性后代,而随后的时间内则产下更多的雌性伴随少量的雄性后代,这样的产卵顺序导致子代性比随着母代产卵时间的延长而下降,榕小蜂后代雌性比例显著高于雄性。同时,子代榕小蜂数量随母代产卵时间的延长而增加,这在一定程度上解释了单头繁殖雌蜂的子代性比随子代数量的增加而减少的现象。而Wakerella benjamini在产卵顺序上是随机的,在其开始产卵后的不同时间段内子代性比都接近于50%。这一结果表明榕小蜂的产卵顺序与母代产卵时间的长短对子代性比有极为重要的影响。     

Quantitative tests of interaction between pollinating and non-pollinating fig wasps on dioecious Ficus hispida

Abstract.  1. The interaction between Ficus species and their pollinating wasps (Agaonidae) represents a striking example of a mutualism. Figs also shelter numerous non-pollinating chalcids that exploit the fig–pollinator mutualism.
2. Previous studies showed a weak negative correlation between numbers of pollinating and non-pollinating adults emerging from the same fruit. Little is known about the patterns and intensities of interactions between fig wasps. In the Xishuangbanna tropical rainforests of China, the dioecious Ficus hispida L. is pollinated by Ceratosolen solmsi marchali Mayr and is also exploited by the non-pollinators Philotrypesis pilosa Mayr, Philotrypesis sp., and Apocrypta bakeri Joseph. Here, the interaction of pollinator and non-pollinators on F. hispida is studied quantitatively.
3. The exact time of oviposition was determined for each species of fig wasp. Based on observational and experimental work it is suggested that (i) the relationship between pollinator and non-pollinators is a positive one, and that the genus Philotrypesis appears to have no significant impact on the pollinator population, whereas Apocrypta has a significant effect on both Philotrypesis and Ceratosolen ; (ii) gall numbers do not always increase with increasing number of foundresses, but developmental mortality of larvae correlates positively with the number of foundresses; and (iii) there is a positive correlation between non-pollinator numbers and their rates of parasitism, but the three species of non-pollinators differed in their rates of parasitism and show different effects on pollinator production.
4. The rates of parasitism when combined with the coexistent percentage and developmental mortality, underpin the way non-pollinating fig wasps successfully exploit and coexist stably in a fig–pollinator mutualism.     

Expression and evolutionary divergence of the non-conventional olfactory receptor in four species of fig wasp associated with one species of fig

Background  

The interactions of fig wasps and their host figs provide a model for investigating co-evolution. Fig wasps have specialized morphological characters and lifestyles thought to be adaptations to living in the fig's syconium. Although these aspects of natural history are well documented, the genetic mechanism(s) underlying these changes remain(s) unknown. Fig wasp olfaction is the key to host-specificity. The Or83b gene class, an unusual member of olfactory receptor family, plays a critical role in enabling the function of conventional olfactory receptors. Four Or83b orthologous genes from one pollinator (PFW) (Ceratosolen solmsi) and three non-pollinator fig wasps (NPFWs) (Apocrypta bakeri, Philotrypesis pilosa and Philotrypesis sp.) associated with one species of fig (Ficus hispida) can be used to better understand the molecular mechanism underlying the fig wasp's adaptation to its host. We made a comparison of spatial tissue-specific expression patterns and substitution rates of one orthologous gene in these fig wasps and sought evidence for selection pressures.     

Figs,pollinators, and parasites: A longitudinal study of the effects of nematode infection on fig wasp fitness

Mutualisms are interactions between two species in which the fitnesses of both symbionts benefit from the relationship. Although examples of mutualism are ubiquitous in nature, the ecology, evolution, and stability of mutualism has rarely been studied in the broader, multi-species community context in which they occur. The pollination mutualism between figs and fig wasps provides an excellent model system for investigating interactions between obligate mutualists and antagonists. Compared to the community of non-pollinating fig wasps that develop within fig inflorescences at the expense of fig seeds and pollinators, consequences of interactions between female pollinating wasps and their host-specialist nematode parasites is much less well understood. Here we focus on a tri-partite system comprised of a fig (Ficus petiolaris), pollinating wasp (Pegoscapus sp.), and nematode (Parasitodiplogaster sp.), investigating geographical variation in the incidence of attack and mechanisms through which nematodes may limit the fitness of their wasp hosts at successive life history stages. Observational data reveals that nematodes are ubiquitous across their host range in Baja California, Mexico; that the incidence of nematode infection varies across seasons within- and between locations, and that infected pollinators are sometimes associated with fitness declines through reduced offspring production. We find that moderate levels of infection (1–9 juvenile nematodes per host) are well tolerated by pollinator wasps whereas higher infection levels (≥10 nematodes per host) are correlated with a significant reduction in wasp lifespan and dispersal success. This overexploitation, however, is estimated to occur in only 2.8% of wasps in each generation. The result that nematode infection appears to be largely benign – and the unexpected finding that nematodes frequently infect non-pollinating wasps – highlight gaps in our knowledge of pollinator-Parasitodiplogaster interactions and suggest previously unappreciated ways in which this nematode may influence fig and pollinator fitness, mutualism persistence, and non-pollinator community dynamics.     

Seasonal change in the structure of fig-wasp community and its implication for conservation

Figs (Moraceae) and their pollinating wasps (Agaonidae) constitute a famous reciprocal mutualism in which figs provide some female flowers for the development of fig wasp offspring while the fig wasps pollinate fig flowers. However, figs also host many non-pollinating wasps which are either parasitoids or resource competitors of pollinators, and bring no benefit for figs and are detrimental to fig’ fitness. Our data onFicus racemosa in Xishuangbanna showed that the numbers of non-pollinators and the mature syconia without pollinator wasps increase in rainy season, especially in the highly fragmented forest. This might be because of the longer developing time of the syconia and thereby longer oviposition time to non-pollinators in the dry season. The galled flower and the viable seed percentages in dry seasons are also larger than in rainy seasons in both primary forest and fragmented forest, and the development of non-pollinators is mainly at the expense of pollinator wasps. Our results showed that there exists a discriminative seasonal impact of non-pollinators and fragmentation effects on population size of fig’s pollinators. This implies that fig/fig wasp mutualism is more fragile in dry season, and that the critical population size and breeding units of figs in seasonal area might be larger than previously estimated without considering the seasonal change of pollinator population.