毛乌素沙地固沙植物披针叶黄华主要传粉昆虫及其访花行为

披针叶黄华(Thermopsis lanceolata)是我国西部地区早春重要野生蜜源植物,也是一种重要的固沙植物,然而对其繁殖特性的研究甚少.本文在系统调查披针叶黄华的访花昆虫基础上,确定其主要传粉昆虫种类、访花行为、传粉过程以及日活动规律,以期揭示主要访花者行为对其有性繁殖的影响.作者在内蒙古毛乌素沙地设置1个10m×10 m的样方,于2010和2011年在披针叶黄华盛花期,采用目测、拍照和摄像等方式对传粉昆虫进行观测,记录样方内主要访花昆虫种类、数量、访花行为及日活动规律.研究表明,大和切叶蜂(Megachile japonica)和戎拟孔蜂(Hoplitis princeps)是披针叶黄华的主要传粉者,但两种昆虫的访花频率存在显著差异;晴天时,大和切叶蜂在19:00-13:00和16:00-18:00出现两个活动高峰,而戎拟孔蜂只在11:30-16:30出现1个活动高峰,两种蜂的访花活动高峰期存在互补关系.大和切叶蜂访花同时具有盗蜜行为,但其盗蜜行为对披针叶黄华的结籽率没有显著影响.根据种群数量、访花频率综合判断,大和切叶蜂是披针叶黄华优势传粉蜂.     

大叶铁线莲访花昆虫调查及盗蜜昆虫行为研究

大叶铁线莲Clematis heracleifolia DC. 的花朵大多下垂,需要传粉昆虫为其传粉,目前尚无关于其访花昆虫研究的报道。 通过2年的野外观察研究,共观察到27种昆虫访问大叶铁线莲。 发现有盗蜜行为的昆虫7种, 其中1种同时具有初级盗蜜和次级盗蜜行为,2种具有初级盗蜜行为,4种具有次级盗蜜行为;黄胸木蜂Xylocopa appendiculata Smith是主要的盗蜜昆虫,其盗蜜行为影响了其它昆虫的访花行为,对大叶铁线莲的传粉造成一定的影响。 在其余20种访花昆虫中,双带弄蝶Lobocla bifasciata (Bremer et Grey)、贡尺蛾Gonodontis aurata Prout、熊蜂Bombus sp.和姬蜂虻Systropus sp.是优势种; 而小青花金龟Oxycetonia jucunda Faldermann和日本条螽Ducetia japonica (Thunberg)访花频率最低,且访花目的只是取食花朵。 通过对大叶铁线莲访花昆虫的调查和盗蜜昆虫行为的研究,为大叶铁线莲的传粉生物学和保护提供参考依据。     

盗蜜对角蒿传粉者行为和生殖成功的影响

一些研究显示盗蜜对自交植物的结实和结籽没有显著影响。然而, 对于既有传粉者为其传粉实现异交又能通过自交实现生殖保障的兼性自交植物来说, 盗蜜对其生殖的影响还知之甚少。由于兼性自交植物可以自交, 盗蜜对其总体结实可能不会有显著影响, 但可能会通过影响传粉者行为而影响传粉者介导的结实。为了验证这一假说, 本研究以兼性自交的一年生角蒿(Invarvillea sinensis var. sinensis)为研究材料, 通过野外调查和控制实验, 探讨了盗蜜对传粉者介导的结实(传粉者行为)和总体结实率的影响。结果表明: 角蒿的盗蜜者和主要传粉者相同, 均为密林熊蜂(Bombus patagiatus)。熊蜂盗蜜频率平均为20.24% (范围为0-51.43%)。盗蜜对角蒿总体结实率、每果结籽数和每果种子重量没有显著影响。然而, 被盗蜜花的柱头闭合比率显著高于未被盗蜜花, 说明盗蜜影响传粉者的访花行为和传粉者介导的结实率。另外, 被盗蜜花的高度显著高于未被盗蜜花, 说明盗蜜者倾向于从较大较高的花上盗蜜。这些结果为全面认识盗蜜对植物生殖的影响提供了新的信息。     

海切叶蜂的筑巢和访花行为

【目的】研究毛乌素沙地重要野生传粉昆虫海切叶蜂Megachile maritima的筑巢和访花行为对保护其栖息环境具有重要意义。【方法】采用目测及拍照等方法对海切叶蜂的整个筑巢过程进行了连续观测;以2 m×2 m 样方的方式观测海切叶蜂的访花频率、单花停留时间及日活动规律等访花行为,其中日活动规律每天连续观测,共观测7天。【结果】海切叶蜂在沙土中筑巢,每巢只有一个巢室,其筑巢过程为：寻找合适的筑巢地点,挖巢,构建巢室,采集蜂粮,产卵,封住巢室,筑完一个巢。它连续筑完一个巢大约需要9 h。海切叶蜂构建一个巢室需要切取26～29片叶子,为每巢室采集蜂粮11～12次,每巢室内产卵1粒;在塔落岩黄芪和细叶益母草上的平均访花频率分别为（13.23±6.49）朵/min和（16.72±4.84）朵/min,平均单花停留时间分别为（3.08±2.48）s和（2.49±1.31）s。晴天,海切叶蜂在12:00～14:00期间活动较活跃。【结论】海切叶蜂不同个体之间的筑巢行为相似。该蜂在塔落岩黄芪和细叶益母草上的访花过程、访花频率及单花停留时间具有显著的差异。     

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 (Alpiniablepharocalyx) 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 (Tamiopsswinhoei) 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。     

塔落岩黄芪主要传粉蜂的传粉效率研究

塔落岩黄芪 (Hedysarum laeve)是毛乌素沙地重要豆科植物, 在我国西部生态系统恢复与重建中起着重要作用, 但其自交率非常低, 必须依靠传粉昆虫授粉才能结实。野生传粉蜂是其主要传粉者。为了明确塔落岩黄芪的主要传粉蜂组成及优势传粉蜂的传粉效率, 2004–2006年, 我们设置了4个2 m×2 m样方观测访花昆虫的组成并对主要传粉蜂的访花频率、花粉移出率和柱头花粉沉降数目及单花停留时间进行了观测。结果表明白脸条蜂(Anthophora albifronella)、海切叶蜂(Megachile maritima)和散熊蜂(Bombus sporsdicus)是塔落岩黄芪的主要传粉蜂, 其中白脸条蜂在数量和访花频率上占有明显优势, 但其花粉移出率比海切叶蜂和散熊蜂的低, 3种蜂的柱头花粉沉降数目没有显著区别。通过对这3种蜂的花粉移出率、柱头花粉沉降数目和访花频率综合分析后, 我们认为白脸条蜂是塔落岩黄芪最有效的传粉蜂。     

盗蜜行为在植物繁殖生态学中的意义

在动植物的相互关系中,盗蜜行为被认为是一种不同于普通传粉者的非正常访花行为。动物之所以要采取这种特殊的觅食策略,有假说认为是由访花者的口器和植物的花部形态不匹配造成的,也有认为是盗蜜行为提高了觅食效率从而使盗蜜者受益。在盗蜜现象中,盗蜜者和宿主植物之间的关系是复杂的。盗蜜对宿主植物的影响尤其是对其繁殖适合度的影响归纳起来有正面、负面以及中性3类。与此同时,盗蜜者的种类, 性别及其掠食行为差异不仅与生境因素密切相关,而且会对宿主植物的繁殖成功产生直接或间接的影响。另外,盗蜜者的存在无疑对其它正常传粉者的访花行为也产生一定的影响,从而间接地影响宿主植物的繁殖成功, 而植物在花部形态上也出现了对盗蜜现象的适应性进化。作者认为, 盗蜜是短嘴蜂对长管型花最有效的一种掠食策略, 它不仅增加了盗蜜者对资源的利用能力, 而且由于盗蜜对宿主植物繁殖成功的不同的影响使其具有调节盗蜜者和宿主之间种群动态的作用, 两者的彼此适应是一种协同进化的结果。     

洛阳地区黄胸木蜂采访丹参的访花行为研究

在洛阳地区丹参Salvia miltiorrhiza的盛花期5月上中旬,采用目测、拍照、测量等方法记录丹参花的基本特征、黄胸木蜂Xylocopa appendiculata的访花行为、丹参被盗蜜后盗蜜口的大小和盗蜜率。在洛阳地区,黄胸木蜂是丹参的主要访花者,在对丹参进行访花时,多盗取花蜜。黄胸木蜂访花时,其单花停留时间平均为3.81±0.28 s,两花间隔时间的平均值为3.64±1.94 s,访花频率的平均值为每分钟采访的花朵数为6±0.98朵,访花朵数为6时,访花频率最大。黄胸木蜂在丹参上的盗蜜口的大小的平均值为0.304±0.046 cm,盗蜜率平均为37%±12%。黄胸木蜂对丹参的盗蜜现象普遍存在,且重复盗蜜,有的一朵花上可能有多个盗蜜口,其盗蜜行为对丹参繁殖适合度的影响还有待进一步研究。本文对黄胸木蜂采访丹参的访花行为进行研究,旨在为进一步开发和利用木蜂资源奠定基础。     

洛阳地区黄胸木蜂访花植物种类及访花行为

【目的】明确黄胸木蜂Xylocopa appendiculata的访花植物种类和访花行为, 为进一步开发和利用木蜂资源奠定基础。【方法】 2009-2011年连续3年, 在洛阳地区黄胸木蜂的活动期3-10月, 采用目测、 拍照等方法记录其访花植物及访花行为, 记录和统计访花植物的生物学特征; 测量访花植物种类被盗蜜后盗蜜口的大小。【结果】在洛阳地区黄胸木蜂访花植物种类为27科52种, 主要的访花植物有25种。采访的植物种类中, 忍冬科和豆科植物最多, 分别为9种和8种, 占采访植物种类的17.31%和15.38%; 其中黄胸木蜂盗蜜的植物有16种, 占其采访植物种类的30.77%。在采访的植物种类中, 黄胸木蜂喜欢采访中等花型、 两侧对称的紫色、 黄色和白色花。在不同植物上, 黄胸木蜂的盗蜜口大小和访花频率不同, 黄胸木蜂在臭牡丹上的盗蜜口最大, 为9.43±1.91 mm, 蝟实上的盗蜜口最小, 为3.46±0.98 mm; 在紫薇上的访花速度最快, 访花频率为25.71±2.36朵/min; 在蜀葵上的单花停留时间和访花间隔时间均最长, 单花停留时间5.89±3.34 s, 访花间隔时间为2.63±2.04 s。【结论】在洛阳地区黄胸木蜂访花植物种类多、 访花时间长。对于不同的植物种类, 黄胸木蜂的访花行为和访花频率有差异。     

双斑切叶蜂的筑巢习性

【目的】明确双斑切叶蜂Megachile leachella在沙地上的筑巢环境及筑巢特点,旨在当地利用人工巢管诱引其筑巢。【方法】采用目测和拍照等方法对双斑切叶蜂的整个筑巢过程进行了连续观察; 采用挖掘、测量方法对双斑切叶蜂巢内结构进行了观测;在室内对蜂茧在土中和指形管中的羽化情况进行了初步观测。【结果】双斑切叶蜂一般在废弃的泥墙或者沙地上蚂蚁等废弃的巢穴中筑巢,有时候它也在沙地上挖掘新巢筑巢。双斑切叶蜂用叶片构建巢室,一巢多室,各巢室首尾相接排列在巢中,筑完巢后用叶片将巢口封住。双斑切叶蜂构建一个巢室需要切取11～14片叶子,为每巢室采集蜂粮6～9次,每巢室内产卵1粒;在内蒙古毛乌素沙地,该蜂一年2代,第1代在6月中下旬羽化,第2代大约在7月下旬至8月上旬羽化,主要寄生性天敌有尖腹蜂Coelioxy sp.、青蜂Chrysis sp.。双斑切叶蜂能在指形管中羽化。【结论】双斑切叶蜂不同个体之间的筑巢行为相似,雌蜂可以用人工巢管进行诱集和驯化。     

Effects of nectar robbing on pollinator behavior and plant reproductive success of Pitcairnia angustifolia (Bromeliaceae)

Nectar robbers may have direct and indirect effects on plant reproductive success but the presence of nectar robbing is not proof of negative fitness effects. We combined census data and field experiments to disentangle the complex effects of nectar robbing on nectar production rates, pollinator behavior, pollen export, and female reproductive success of Pitcairnia angustifolia. Under natural conditions flowers were visited by four different animal species including a robber‐like pollinator and a secondary robber. Natural levels of nectar robbing ranged from 40 to 100%. Natural variation in nectar robbing was not associated with fruit set in any year whereas seed set was weakly positively associated for 1 year only. Artificial nectar robbing did not increase nectar production or concentration, did not affect the behavior of long‐billed hummingbirds, and when faced with artificially robbed flowers, these visitors behaved as secondary nectar robbers. The number of stigmas within a patch that received pollen dye analogs and the average distance traveled by these analogs were not significantly different between robbing treatments (robbed flowers versus unrobbed flowers), but the maximum distance traveled by these pollen analogs was higher when nectar robbing was not prevented. Overall, the proportion of robbed flowers on an inflorescence had a neutral effect to a weak positive effect on the reproduction of individual plants (i.e. positive association between nectar robbing and fruit set in 2002) even when it clearly changed the behavior of its most efficient pollinator potentially increasing the frequency of nectar robbing within a plant.     

沙地毛足蜂筑巢生物学研究

【目的】调查毛乌素沙地的一种群居独栖性野生毛足蜂Dasypoda hirtipes Panzer的巢穴结构及其日活动规律。【方法】采用目测和拍照等方法对沙地毛足蜂的整个筑巢过程进行了连续观测;采用挖掘、测量方法对毛足蜂巢内结构进行了观测。【结果】2008和2009年共挖掘巢穴22个,巢口直径为6.32～10.35 mm,巢穴具有多分枝的支道,一般有4～16个分支道,主道的深度为84～112 cm,巢室分布在主道周围的支道里面,每个支道里面仅有1个巢室,巢室深度为22～54 cm。巢室内壁无蜡层,较光滑,巢室内的花粉球底部有3个均匀大小的用来支撑花粉球的突起。对雌性成蜂日活动行为的观察结果显示,雌性个体一天内采集粉蜜的次数在6～8次,最后一次一般不携带花粉归巢。【结论】在内蒙古毛乌素沙地,该蜂一年1代,日活动时间与菊科植物抱茎苦荬菜Ixeris sonchifolia花序中的单花期相对应,主要的蜜源植物为菊科植物和蒺藜属植物。     

Nectar robbers deter legitimate pollinators by mutilating flowers

Nectar robbing – harvesting nectar illegitimately – can have a variety of outcomes for plant sexual reproduction and for the pollinator community. Nectar robbers can damage flowers while robbing nectar, which could affect the behavior of subsequent flower visitors and, consequently, plant reproduction. However, only nectar manipulation by nectar robbers has so far received attention. We found a short-tongued bee, Hoplonomia sp. (Halictidae), mutilating the conspicuous lower petal of the zygomorphic flowers of Leucas aspera (Lamiaceae) while robbing nectar. We hypothesized that the mutilation of the conspicuous lower petal deters legitimate pollinators on L. aspera flowers, which, in turn, might affect plant reproduction. We first assessed the proportion of naturally-robbed flowers in plant populations for three years to confirm that it was not a purely local phenomenon due to a few individual bees. We then studied diversity, community and visitation characteristics of pollinators, nectar dynamics and fruit set in unrobbed and robbed open flowers in naturally-robbed populations. The proportion of robbed flowers varied significantly across sites and years. Robbing did not affect nectar dynamics in flowers, but it did alter flower morphology, so much so that it reduced pollinator visitation and altered the pollinator community on robbed flowers. However, the maternal function of plant reproduction was not affected by nectar robbing. This study for the first time shows that a nectar robber can have an ecologically significant impact on floral morphology.     

Pollinators shift to nectar robbers when florivory occurs,with effects on reproductive success in Iris bulleyana (Iridaceae)

• Studies have indicated that florivory and nectar robbing may reduce reproductive success of host plants. However, whether and how these effects might interact when plants are simultaneously attacked by both florivores and nectar robbers still needs further investigation.
• We used Iris bulleyana to detect the interactions among florivory, nectar robbing and pollination, and moreover, their effects on plant reproductive success. Field investigations and hand‐pollination treatments were conducted on two experimental plots from a natural population, in which Experimental plot was protected from florivores and Control plot was not manipulated.
• The flower calyx was bitten by sawflies to consume the nectary, and three bumblebee species were pollinators. In addition, the short‐tongued pollinator, Bombus friseanus, was the only robber when there was a hole made by a sawfly. The bumblebee had significantly shortened flower handling time when robbing, as compared to legitimate visits. Pollinator visitation and seed production decreased significantly in damaged flowers. However, seed production per flower after supplementary hand‐pollination did not differ significantly between damaged and undamaged flowers. Compared to the Experimental plot, bumblebees visited fewer flowers per plant in a foraging bout in the Control plot.
• The flowers damaged by florivory allowed B. friseanus to shift to a nectar robber. Florivory and nectar robbing collectively decreased plant reproductive success by consuming nectar resources, which may reduce attractiveness to pollinators of the damaged flowers. However, the changes in pollinator behaviour might be beneficial to the plant by reducing the risk of geitonogamous mating.

     

Foraging strategy predicts foraging economy in a facultative secondary nectar robber

In mutualistic interactions, the decision whether to cooperate or cheat depends on the relative costs and benefits of each strategy. In pollination mutualisms, secondary nectar robbing is a facultative behavior employed by a diverse array of nectar‐feeding organisms, and is thought to be a form of cheating. Primary robbers create holes in floral tissue through which they feed on nectar, whereas secondary robbers, which often lack chewing mouthparts, feed on nectar through existing holes. Because primary robbers make nectar more readily available to secondary robbers, primary robbers facilitate the behaviors of secondary robbers. However, the net effect of facilitation on secondary robber fitness has not been empirically tested: it is unknown whether the benefit secondary robbers receive is strong enough to overcome the cost of competing with primary robbers for a shared resource. We conducted foraging experiments using the bumble bee Bombus bifarius, which can alternatively forage ‘legitimately’ (from the floral opening) or secondary‐rob. We measured the relative foraging efficiencies (handling time per flower, flowers visited per minute, proportion of foraging bout spent consuming nectar) of these alternative behaviors, and tested whether the frequency of primary robbing and nectar standing crop in primary‐robbed flowers of Linaria vulgaris (Plantaginaceae) affected foraging efficiency. Surprisingly, there was no effect of primary robbing frequency on the foraging efficiency of secondary‐robbing B. bifarius. Instead, foraging strategy was a major predictor of foraging efficiency, with legitimate foraging being significantly more efficient than secondary robbing. Legitimate foraging was the more common strategy used by B. bifarius in our study; however, it is rarely used by B. bifarius foraging on L. vulgaris in nature, despite indications that it is more efficient. Our results suggest the need for deeper investigations into why bees adopt secondary robbing as a foraging strategy, specifically, the environmental contexts that promote the behavior.     

Effects of nectar robbing on nectar dynamics and bumblebee foraging strategies in Linaria vulgaris (Scrophulariaceae)

Differences in morphology among bumblebee species sharing a nectar resource may lead to variation in foraging behaviour and efficiency. Less efficient bumblebees might opportunistically switch foraging strategies from legitimate visitation to secondary robbing when hole-biting primary robbers are present. We observed various aspects of pollination and nectar robbing ecology of Linaria vulgaris in the Colorado Rocky Mountains, with emphasis on the role of bumblebee proboscis length. Bees can extract nectar from a nectar spur legitimately, by entering the front of the flower, or illegitimately, by biting or reusing holes in the spur. Although L. vulgaris flowers are apparently adapted for pollination by long-tongued bees, short-tongued bees visited them legitimately for trace amounts of nectar but switched to secondary robbing in the presence of primary robbers. Longer-tongued bees removed more nectar in less time than did shorter-tongued bees, and were less likely to switch to secondary robbing even when ∼100% of flowers had been pierced. As the proportion of robbed flowers in the population increased, the relative number of legitimate visits decreased while the relative number of robbing visits increased. Robbing decreased nectar standing crop and increased the proportion of empty flowers per inflorescence. Despite these potentially detrimental effects of robbers, differences in inflorescence use among robbers and pollinators, and the placement of holes made by primary robbers, may mitigate negative effects of nectar robbing in L. vulgaris . We discuss some of the reasons that L. vulgaris pollination ecology and growth form might temper the potentially negative effect of nectar robbing.     

Effects of nectar-robbing on plant reproduction and evolution

The relationship between plant and pollinator is considered as the mutualism because plant benefits from the pollinator’s transport of male gametes and pollinator benefits from plant’s reward. Nectar robbers are frequently described as cheaters in the plant-pollinator mutualism, because it is assumed that they obtain a reward (nectar) without providing a service (pollination). Nectar robbers are birds, insects, or other flower visitors that remove nectar from flowers through a hole pierced or bitten in the corolla. Nectar robbing represents a complex relationship between animals and plants. Whether plants benefit from the relationship is always a controversial issue in earlier studies. This paper is a review of the recent literatures on nectar robbing and attempts to acquire an expanded understanding of the ecological and evolutionary roles that robbers play. Understanding the effects of nectar robbers on the plants that they visited and other flower visitors is especially important when one considers the high rates of robbing that a plant population may experience and the high percentage of all flower visitors that nectar robbers make to some species. There are two standpoints in explaining why animals forage on flowers and steal nectar in an illegitimate behavior. One is that animals can only get food in illegitimate way because of the mismatch of the morphologies of animals’ mouthparts and floral structure. The other point of view argues that nectar robbing is a relatively more efficient, thus more energy-saving way for animals to get nectar from flowers. This is probably associated with the difficulty of changing attitudes that have been held for a long time. In the case of positive effect, the bodies of nectar robbers frequently touch the sex organs of plants during their visiting to the flowers and causing pollination. The neutral effect, nectar robbers’ behavior may destruct the corollas of flowers, but they neither touch the sex organs nor destroy the ovules. Their behavior does not affect the fruit sets or seed sets of the hosting plant. Besides the direct impacts on plants, nectar robbers may also have an indirect effect on the behavior of the legitimate pollinators. Under some circumstances, the change in pollinator behavior could result in improved reproductive fitness of plants through increased pollen flow and out-crossing. __________ Translated from Acta phytoecologiaca Sinica, 2006, 30(4): 695–702 [译自: 植物生态学报]     

Effects of nectar-robbing on plant reproduction and evolution

The relationship between plant and pollinator is considered as the mutualism because plant benefits from the pollinator's transport of male gametes and pollinator benefits from plant's reward.Nectar robbers are frequently described as cheaters in the plant-pollinator mutualism,because it is assumed that they obtain a reward (nectar) without providing a service (pollination).Nectar robbers are birds,insects,or other flower visitors that remove nectar from flowers through a hole pierced or bitten in the corolla.Nectar robbing represents a complex relationship between animals and plants.Whether plants benefit from the relationship is always a controversial issue in earlier studies.This paper is a review of the recent literatures on nectar robbing and attempts to acquire an expanded understanding of the ecological and evolutionary roles that robbers play.Understanding the effects of nectar robbers on the plants that they visited and other flower visitors is especially important when one considers the high rates of robbing that a plant population may experience and the high percentage of all flower visitors that nectar robbers make to some species.There are two standpoints in explaining why animals forage on flowers and steal nectar in an illegitimate behavior.One is that animals can only get food in illegitimate way because of the mismatch of the morphologies of animals'mouthparts and floral structure.The other point of view argues that nectar robbing is a relatively more efficient,thus more energy-saving way for animals to get nectar from flowers.This is probably associated with the difficulty of changing attitudes that have been held for a long time.In the case of positive effect,the bodies of nectar robbers frequently touch the sex organs of plants during their visiting to the flowers and causing pollination.The neutral effect,nectar robbers' behavior may destruct the corollas of flowers,but they neither touch the sex organs nor destroy the ovules.Their behavior does not affect the fruit sets or seed sets of the hosting plant.Besides the direct impacts on plants,nectar robbers may also have an indirect effect on the behavior of the legitimate pollinators.Under some circumstances,the change in pollinator behavior could result in improved reproductive fitness of plants through increased pollen flow and out-crossing.