短柄五加开花及传粉生物学研究

本文对短柄五加（Ｅｌｅｕｔｈｅｒｏｃｏｃｃｕｓｂｒａｃｈｙｐｕｓ）的花期物候、开花式样、访花昆虫种类、访花行为及访花频率进行了观察,对花粉活力、柱头可授性、花粉胚珠比以及传粉效果和繁育系统做了检测。初步结果表明,短柄五加以根茎进行无性繁殖,１个居群为１个无性系。虽自交亲和,但昆虫的访花活动可显著提高座果率。昆虫传粉主要在无性系内异花间进行,属于广义的自花传粉。传粉者为多种不同的昆虫,包括马蜂和胡蜂在内的蜂类、蝇类和甲虫。其花期物候、花粉活力、柱头可授期和蜜汁分泌期等特征使其能够适应环境,从而获得较高的座果率。平均座果率为６５％,饱满种子率为４５．５％。自然条件下未发现实生苗,广义的自花传粉导致的种子质量低下可能是其原因,也是限制短柄五加分布范围的重要因素。     

干热河谷麻疯树访花昆虫及主要传粉昆虫

膏桐为一种重要的油料作物,其种子可以提炼生物柴油,生物柴油在我国将成长为有一定规模的产业。为了增加膏桐结籽率,提高其产量,给膏桐规模化栽培方面提供传粉生物学的科学依据,于2006年对云南元江坝区半栽培膏桐(Jatropha curcas L.)居群的访花昆虫及主要传粉昆虫种类进行调查。膏桐开花示样醒目,具花香与蜜腺,花形态没有特化,这些特征使得它提供的酬物适合于不同的昆虫采食,其访花昆虫种类较丰富,共有35种访花昆虫,分属5目20科。综合访花昆虫的传粉数量,及传粉质量包括访花行为、访花频率与日活动规律等确定主要传粉昆虫,确定大头金蝇Chrysomya(Compsomyia)megacephala Fabricius、中华蜜蜂Apiscerana Fabricius、迁粉蝶(淡色型)Catopsilia pomona f.Crocale为该居群的主要传粉昆虫。3种传粉昆虫具有不同的访花习性和日活动规律。雌雄迁粉蝶日活动规律相似。访花者的组成受气象因素、开花示样及生境条件的影响。最后,探讨膏桐与访花昆虫的关系,以及主要传粉者的组成随时空变异而改变的规律。     

宁夏枸杞的花粉呈现式样及交配系统研究北大核心CSCD

被子植物的花回馈、雌雄蕊时空分离特征和花粉呈现式样等花部特征及传粉者效率会影响雄性适合度和有性繁殖过程。宁夏枸杞(Lycium barbarum)是中国宁夏、新疆、内蒙等干旱和半干旱地区分布的特有种。该研究对新疆喀什地区宁夏枸杞自然种群的花部综合征、花粉呈现式样、花回馈、传粉者行为与交配方式的关系进行观察及统计分析,以探讨其花粉逐步呈现的适应性及其在提高雌雄繁殖过程中的意义。结果表明:(1)宁夏枸杞的单花寿命为(4.07±0.15) d,而雄性持续时间(0.07±0.01 d)比雌性持续时间短(4±0.01 d);花寿命内雌蕊长度比雄蕊长,属柱头探出式异位类型;花粉呈现式样为不完全逐步呈现。(2)花寿命不同阶段花回馈间存在显著差异。(3)意大利蜜蜂(Apis mellifera)、熊蜂(Bombus sp.)、食蚜蝇(Syrphidae sp.)是宁夏枸杞在自然居群的主要访花者,其中熊蜂和食蚜蝇是主要传粉者,但传粉者效率低,属于高移出低沉积类型。(4)宁夏枸杞的花粉胚珠比(2 448.11±448.32)及授粉实验结果均表现出兼性异交特征;自发自交及人工自花授粉花的座果率及结籽率很低,属于自交不亲和类型;自然传粉花的座果率及结籽率比人工去雄异花低,存在其较高的花粉限制(40.71%)。研究发现,宁夏枸杞花部综合征表现出雌雄异位和花粉不完全逐步呈现式样,这是避免雌雄功能及雄蕊各花药间的干扰、减少花粉同步移出及保障其雄性适合度的有效途径,但自然居群的传粉者种类限制、传粉效率低以及自交不亲性是导致宁夏枸杞花粉限制及降低雌性繁殖成功的主要原因。     

露蕊乌头(毛茛科)不同海拔居群的传粉生态学

对青藏高原东北部两个不同海拔地点（互助,2460m和海北,3200m）的露蕊乌头Aconitum gymnandrum的传粉生态学进行了比较研究。研究结果表明高海拔居群的单花花期、雄性期持续时间、雌性期持续时间比低海拔长。露蕊乌头不存在无融合生殖现象,尽管高度自交亲和,但产生种子必须依赖传粉媒介。熊蜂是露蕊乌头的主要传粉昆虫,两个居群均存在传粉限制。熊蜂取食花蜜为主,在同一个花序上的访问顺序以由下向上为主,但在互助居群和海北居群有3．9％和2．7％的访花是由上向下进行的。统计发现有37．7％和29．3％的访问行为发生在同一植株内;因此,同株异花传粉造成的自交在露蕊乌头中仍然不能避免。低海拔居群的熊蜂种类和访花频率均高于高海拔居群,但自然状态下两个居群的结实率并没有显著差异。高海拔露蕊乌头居群可能具有较长的柱头持续时间,从而补偿了由于访花频率低带来的结实率降低。     

柴黄姜的传粉生物学特性

对产自湖北武当山的柴黄姜（Dioscorea nipponica subsp．rosthornii Prain et Burkill）的花部特征和访花昆虫种类及访花行为、访花频率和携粉量进行了研究，并对柴黄姜的传粉方式、结实和种子萌发状况进行了检测。结果表明，柴黄姜具有虫媒花的典型花部特征，共观测到访花昆虫4目34种，其中传粉昆虫6种，隧蜂属（Halictus sp．）和地蜂属（Andrena sp．）的2种昆虫是柴黄姜的主要传粉昆虫。访花昆虫对雄株的访花高峰时段为11：00至14：00，对雌花没有明显的访花高峰时段。在自然条件下，柴黄姜的座果率为18．86％，结实率为7．12％，种子萌发率为64．76％。在武当山，柴黄姜种群扩展仍以有性繁殖为主，无性繁殖为重要补充。     

珍稀濒危植物单性木兰传粉生态学研究

野外定位观测了单性木兰的花期物候、访花昆虫种类、访花频率、访花行为和同花期植物种类,并对其花粉散播距离和繁育系统进行了检测,旨在探讨制约单性木兰传粉过程的某些因素,为单性木兰的保护生物学提供科学依据。结果表明,单性木兰雄株和雌株在花期物候上存在差异,雌株在结实上存在明显的大小年现象。单性木兰以虫媒传粉为主,雄株访花昆虫30种,雌株访花昆虫仅14种,雌株和雄株共有的访花昆虫仅6种。单性木兰同花期植物共17种,其访花昆虫种类大部分与单性木兰的访花昆虫种类相同。蜂类和蝶类均非单性木兰的传粉者,其结实率低的原因不仅与访花昆虫种类少和访花频率少有关,更与其缺乏有效的传粉昆虫有关。     

云南草蔻花蜜分泌格局与访花动物行为及其对果实和种子产量的影响

 依靠动物传粉的植物,其繁殖成功(胚珠受精与花粉散布)很大程度上取决于访花动物的种类和拜访行为,而访花动物的种类和行为又受植物提供给传粉者的回报,主要是花蜜分泌格局的影响。通过对姜科山姜属植物云南草蔻(Alpinia blepharocalyx)花蜜分泌量及糖分含量的测定,拜访动物种类、传粉昆虫拜访频率及停留时间的调查,主要盗蜜者花松鼠（Tamiops swinhoei）的盗蜜行为观察,植物的结实率以及结籽量的分析等,探讨花蜜分泌与传粉昆虫的关系以及盗蜜对果实及种子生产的影响。研究表明：云南草蔻的两种花型花蜜的分泌量在一天的单花开花过程中呈现相反的格局,花柱上举型花下午的花蜜分泌量高于上午,而花柱下垂型花则上午略高于下午;两种花型花蜜的糖分浓度都随着开花时间而下降;共有17种访花动物拜访云南草蔻的花,其中8种具有传粉作用;传粉昆虫的停留时间随拜访频率的不断增加而缩短;被盗蜜植株与未被盗蜜植株的结实率差异不显著而结籽量差异显著。     

两种生境下野慈姑繁殖差异及其机制

植物的生长环境不但可直接作用于其可利用资源的多寡及其繁殖分配,而且可通过影响植物所在的群落以及传粉者的组成或行为而间接的导致繁殖差异。然而,直接与间接作用的方向或强度很少被同时关注,从而限制了从机制上理解环境对植物繁殖的影响。选取野慈姑(Sagittaria trifolia L.)为研究材料,将相同基因型组成的植株分别种植在光照差异明显的两个同质园(林荫区与日照区),于盛花期对野慈姑的开花数量、昆虫访花进行了观察,确定其主要访花昆虫、记录访花行为以及野慈姑的繁殖产出水平。研究表明,日照区野慈姑每天开放的花朵和植株数量显著高于林荫区。两个区域内野慈姑的主要访花者有四大类:蚜蝇类、蜂类、蝶类和蝇类;其中林荫区的主要传粉昆虫为蚜蝇类,而日照区为蜂类。日照区昆虫单位时间内的访花频率、昆虫每回合访问的雄花数、总花数和花序数均显著高于林荫区。日照区野慈姑的座果率显著高于林荫区,而单果种子数量与种子面积与林荫区相当。总体而言,日照区野慈姑的繁殖产出达到了林荫区的三倍以上,这是环境的直接作用与环境介导的传粉作用在同一方向上叠加的结果,且前者占主导地位。在关注植物、物理环境和生物因子三者之间互作的前提下,量化每个繁殖阶段的水平,特别是传粉昆虫在不同生境下的表现,阐述了环境异质性导致植物繁殖差异的根本原因。     

信息素促进凹唇壁蜂访花提高苹果座果率和果实品质

【目的】凹唇壁蜂Osmia excavata Alfken是我国北方早春重要的果树传粉昆虫之一,但是其访花活动容易受到早春低温等不良天气的影响。为应对低温等不良天气,研究信息素(蜜蜂活动增强剂)对凹唇壁蜂活动规律、苹果树花朵座果率以及果实产量的影响具有重要意义。【方法】测定苹果树在释放信息素与不释放信息素的条件下,凹唇壁蜂的访花活动规律、花朵座果率及果实产量等数据。【结果】苹果对凹唇壁蜂授粉的依赖程度为0.95。释放信息素区域的凹唇壁蜂访花效率是对照的1.34倍,显著提高苹果的座果率,增加程度为12%;增加平均单果重3.53 g;显著提高0.15 mg/100 g的维生素C含量。【结论】在低温等不良环境条件下,可以通过释放信息素等人工管理措施,提高授粉昆虫对作物的访花效率,进而改善作物品质,提高作物产量,减少损失。     

紫花苜蓿的传粉昆虫种类及其访花行为

紫花苜蓿(Medicago sativa)属典型的异花授粉植物,其种子生产主要依靠蜜蜂等传粉昆虫.本文对河西地区张掖实验站紫花苜蓿传粉昆虫种类及其访花行为进行了调查.结果表明:苜蓿访花昆虫共计22种,分别属于4个目,11个科,根据弹花效率初步确定鳞地蜂、黑颚条蜂、净切叶蜂、细切叶蜂和紫木蜂为河西地区主要传粉昆虫;主要传粉昆虫的日活动规律出现单峰型和双峰型2种,净切叶蜂、细切叶蜂和紫木蜂属于前者,只在11:30-15:30出现一个活动高峰,而鳞地蜂与黑颚条蜂则为双峰型,在9:30-11:30和16:30-18:30分别出现访花高峰,不同的传粉昆虫之间存在互补关系;主要传粉昆虫的弹花频率和小花停留时间存在显著差异,且访花行为与野生蜂体型紧密相关.     

Reproductive system and fitness of Vriesea friburgensis,a self‐sterile bromeliad species

Reproductive biology and plant fertility are directly related to many aspects of plant evolution and conservation biology. Vriesea friburgensis is an epiphytic and terrestrial bromeliad endemic to the Brazilian Atlantic rainforest. Hand‐pollination experiments were used to examine the reproductive system in a wild population of V. friburgensis. Plant fertility was assigned considering flower production, fruit and seed set, seed germination, and pollen viability. Self‐sterility observed from spontaneous selfing and manual self‐pollination treatments may be the consequence of late‐acting self‐incompatibility. Hand‐pollination results indicated no pollen limitation in the population studied. Floral biology features such as a few daily open flowers, nectar production, and sugar concentration corroborate hummingbirds as effective pollinators, although bees were also documented as pollinators. Components of fitness such as high flower, fruit, and seed production together with high seed and pollen viability indicate that this wild population is viable. From a conservation point of view, we highlight that this self‐sterile species depends on pollinator services to maintain its population fitness and viability through cross‐pollination. Currently, pollinators are not limited in this population of V. friburgensis. Conversely, the maintenance and continuous conservation of this community is essential for preserving this plant–pollinator mutualism.     

Effects of season and population size on pollination and reproductive output in a Mediterranean shrub

• Pollinator guilds may change throughout extended flowering periods, affecting plant reproductive output, especially in seasonal climates. We hypothesised a seasonal shift in pollinator guild and an autumn reduction in pollinator abundance, especially in small and sparse populations.
• We recorded pollinator identity, abundance and behaviour in relation to flower density from plant to population throughout the extended flowering of Ononis tridentata. We evaluated female reproductive output by recording pollination success and pre‐dispersal seed predation in eight populations of contrasting size and density. Offspring quality was also characterised through seed weight and germination.
• A diverse guild of insects visited O. tridentata in spring, while only Apis mellifera was observed in autumn. Visitation frequency did not vary seasonally, but the number of flowers per foraging bout was lower, and seeds were heavier and had a higher germination rate in autumn. Plant and neighbourhood flowering display were not related to pollinator visitation frequency or behaviour. However, the rate of fertilised ovules, seed set and autumn flowering display size were positively related to population density.
• The maintenance of pollination in autumn enhances the reproductive performance of O. tridentata due to higher quality of autumn seed, and to a large reduction in seed predator pressure. We also suggest that observed changes in pollinator behaviour could be one of the processes behind seasonal variation in seed performance, since geitonogamous crosses were less likely to occur in autumn.

     

Pollinators and Reproductive Success of the Wild Cucurbit Cucurbita maxima ssp. andreana (Cucurbitaceae)

Abstract: We studied the reproductive success and pollinators of Cucurbita maxima ssp. andreana in different disturbed habitats where it grows naturally. Data were obtained from three populations. One grew within a soybean crop, the other within a corn crop, and the third in an abandoned crop field. Cucurbita maxima ssp. andreana is an annual vine with a flowering period from December to April. Male flowers appear first, thereafter female and male flowers appear together. Flower lifetime (9 h) was similar in male and female flowers. The pollinator guild was comparable for the three populations but some differences in the frequency of the insect species were observed. Native bees were the main pollinators in the population in the abandoned field, while beetles pollinated the populations in crop fields. These differences were not linked with the pre-emergent reproductive success, fruit and seed set, or fruit quality. This is a self-compatible plant. Fruit and seed set and fruit traits (total mass, width and length of fruits, number of seeds per fruit, and seed mass) did not show significant differences between hand-cross and hand-self pollinated flowers. This wild cucurbit is a generalist with respect to pollinator guild, and flower visitors seem to be highly efficient in pollen transference. Cucurbita maxima ssp. andreana is well adapted to disturbed habitats because plants ripened fruits successfully, regardless of the group of insects visiting flowers.     

Effects of patch size and density on flower visitation and seed set of wild plants: a pan-European approach

1.  Habitat fragmentation can affect pollinator and plant population structure in terms of species composition, abundance, area covered and density of flowering plants. This, in turn, may affect pollinator visitation frequency, pollen deposition, seed set and plant fitness.
2.  A reduction in the quantity of flower visits can be coupled with a reduction in the quality of pollination service and hence the plants' overall reproductive success and long-term survival. Understanding the relationship between plant population size and/or isolation and pollination limitation is of fundamental importance for plant conservation.
3.  We examined flower visitation and seed set of 10 different plant species from five European countries to investigate the general effects of plant populations size and density, both within (patch level) and between populations (population level), on seed set and pollination limitation.
4.  We found evidence that the effects of area and density of flowering plant assemblages were generally more pronounced at the patch level than at the population level. We also found that patch and population level together influenced flower visitation and seed set, and the latter increased with increasing patch area and density, but this effect was only apparent in small populations.
5.   Synthesis. By using an extensive pan-European data set on flower visitation and seed set we have identified a general pattern in the interplay between the attractiveness of flowering plant patches for pollinators and density dependence of flower visitation, and also a strong plant species-specific response to habitat fragmentation effects. This can guide efforts to conserve plant–pollinator interactions, ecosystem functioning and plant fitness in fragmented habitats.     

Florivory indirectly decreases the plant reproductive output through changes in pollinator attraction

Species often interact indirectly with each other via their traits. There is increasing appreciation of trait‐mediated indirect effects linking multiple interactions. Flowers interact with both pollinators and floral herbivores, and the flower‐pollinator interaction may be modified by indirect effects of floral herbivores (i.e., florivores) on flower traits such as flower size attracting pollinators. To explore whether flower size affects the flower‐pollinator interaction, we used Eurya japonica flowers. We examined whether artificial florivory decreased fruit and seed production, and also whether flower size affected florivory and the number of floral visitors. The petal removal treatment (i.e., artificial florivory) showed approximately 50% reduction in both fruit and seed set in natural pollination but not in artificial pollination. Furthermore, flower size increased the number of floral visitors, although it did not affect the frequency of florivory. Our results demonstrate that petal removal indirectly decreased 75% of female reproductive output via decreased flower visits by pollinators and that flower size mediated indirect interactions between florivory and floral visitors.     

Unpaved roads disrupt the effect of herbivores and pollinators on the reproduction of a dominant shrub

Anthropogenic linear developments, such as trails and firebreaks, also called soft linear developments (SLD), can influence animal behavior, altering the ecological interactions in which animals are involved. For example, SLD can affect the behavior of pollinators and herbivores, but little is known about the combined effect of these three elements on plant reproduction.We evaluated the combined effect of SLD, insect pollinators and herbivores (ungulates) on three reproductive output variables (fruit set, seed set, and seed mass) of a Mediterranean shrub (Halimium halimifolium). We considered two different habitats (SLD verges vs. adjacent scrublands), two scenarios of herbivory (with and without ungulates), and three scenarios of pollinator activity (without pollinators, with manual pollination and with natural pollination).SLD had contrasting effects on H. halimifolium reproduction. In the absence of herbivores, overall fruit set was lower in the verges of SLD than in adjacent scrublands, probably due to lower flower pollination rates. Where herbivores were present, overall fruit set was similar between habitats, because ungulate browsing was lower in SLD verges than in adjacent scrublands. The quantity and weight of seeds per fruit was similar in both habitats, probably because all fertilized flowers received similar amounts of pollen.SLD can alter the interaction among pollinators, herbivores and plants, leading to changes in the reproductive performance of the latter. These changes can have strong negative impacts on endangered plants that rely on fruit and seed production to persist. However, SLD verges could be safe places for plants particularly sensitive to herbivory by ungulates.     

Fertility of Vriesea gigantea Gaud. (Bromeliaceae) in southern Brazil

Plant fertility is a central subject of many questions in plant evolutionary and conservation biology. Pollen availability, abiotic resources, and flowering pattern can limit fruit and seed production. Open pollination and pollen supplementation studies are used to estimate any pollen limitation in natural populations. To study the impact of these factors on the reproductive success of Vriesea gigantea, an epiphytic bromeliad in the Atlantic Rainforest in Brazil, its fertility in four natural populations in Itapu? State Park was assessed by considering plant and inflorescence size, flower production, fruit and seed set, flower and fruit set pattern, and seed viability and germination rate. Supplemental pollination in adult plants was used to determine whether fruit production in V. gigantea is limited by reception of pollen. The results showed that V. gigantea has a high production of flowers, fruits, and seeds. Seeds are highly viable in all populations, presenting an average germination rate of 94% (SE ± 3.5). Plants of V. gigantea from Itapu? State Park are highly fertile. The high proportion of fruit and seed set after manual hand pollination indicates that the species is self-compatible. Pollination treatments showed evidence of pollinator limitation in the Itapu? State Park population.     

Pollination ecology of a plant in its native and introduced areas

Entomophilous and obligate out-crossing non-native plants need to become well integrated in the resident plant–pollinator network to set seeds and become established. However, it is largely unknown how pollination patterns differ between native ranges and those where plants have been introduced.We compared the identity, abundance and visitation rates of pollinators, insect pollen loads, pollen deposition on stigmas, and fruit and seed sets of Hedysarum coronarium, an entomophilous short lived N-fixing perennial, in populations from native and introduced ranges in Spain (South of mainland Spain and Menorca Island, respectively).In both areas, Hedysarum was visited by a similar number of species, mainly hymenopterans; seven species were common between native and introduced areas. However, pollinator richness, abundance, and visits per flower were greater in the native than in the introduced range, as were fruit and seed sets. Hedysarum pollen loads on stigmas and on Apis mellifera, the most common pollinator, did not differ between areas. Lower abundance of pollinators might be causing lower visitation rates, and to some extent reducing Hedysarum fruit and seed sets in the introduced area.Our biogeographical approach shows that integration of a non-native plant in a resident pollinator network does not prevent pollen limitation in the introduced area. Therefore, despite being necessary, pollination mutualistic relationships might not be the key for non-native plant establishment success in the introduced area.     

Breeding system, flower visitors and seedling survival of two endangered species of Helianthemum (Cistaceae)

BACKGROUND AND AIMS: Helianthemum marifolium and H. caput-felis are two endangered plant species of the western Mediterranean. Several aspects of the reproduction of both species were examined to determine whether their rarity could be related to factors causing reproductive limitation. METHODS: The flowering and fruiting phenology of both species in two non-sympatric island populations (Mallorca, Balearic Islands, western Mediterranean) were compared. Hand-pollination experiments were conducted to determine their fruit and seed production under different pollen sources. The composition of the pollinator assemblage and the effect of temporal variation and sun exposure on reproductive output and seedling survival were also investigated. KEY RESULTS: Flowering periods were longer for H. marifolium than for H. caput-felis in the populations studied. Helianthemum marifolium is mostly an outbreeder, i.e. fruit and seed set was three-fold higher when pollen came from other plants. In H. caput-felis, neither fruit nor seed set was affected by pollination treatments. Flower visitors were more diverse for H. caput-felis than for H. marifolium. In both species, most floral visits were made by hymenopterans. The total number of pollinator visits varied significantly between years, decreasing more than two-fold from 2001 to 2002, in both species. In agreement with its outbreeder character, variation in reproductive output between years was also observed in H. marifolium. It showed a 50 % decrease in fruit set in 2002, a pollinator-poor year. Finally, seedling survival increased three- to six-fold from 2001 to 2002. A correlation between seedling size and survival had also been detected. CONCLUSIONS: Reproductive limitations were detected for neither species (i.e. fruit and seed set, pollination service and seedling survival on natural populations). Hence, the increasing rarity of these two species is probably a direct result of the destruction of their habitat.     

Pollination limitation to reproductive success in the Missouri evening primrose, Oenothera macrocarpa (Onagraceae)

Habitat fragmentation may result in plant populations that are less attractive to pollinators and thus susceptible to reduced reproductive output due to pollination limitation. Pollination limitation was investigated in three Missouri populations of Oenothera macrocarpa, a hawk-moth-pollinated, perennial herb. The populations represented extremes in size and habitat quality. Following supplemental pollination, mean fertilization success (proportion of ovules fertilized) across populations increased from 24.3 to 44.8% and mean seed set (proportion of ovules that matured into seed) increased from 14.7 to 27.9%. These increases were statistically significant in two of the three populations. Failure to achieve 100% fertilization and seed set following supplementation indicates that other factors, in addition to pollination, were limiting to female reproductive success. Fruit set was pollination limited in only one population. Fruits matured with as few as one seed, suggesting that fruit set was not resource limited. The degree of pollination limitation was greatest in the most disturbed population. The population located in the highest-quality habitat was not significantly pollination limited. This suggests that pollination limitation is occurring, at least in part, because of reduced pollinator activity in degraded habitats.