I guess you have to provide the answer for this ... ... ... or will wait and see for the answer from other pollination biologists!

Biotic vectors could be different plants or animals and of course you have to consider the potential interactions

From my experience, the quick answer in most cases would be : no.

But of course there are many exceptions, and sometimes just having a look at the flower is enough to predict accurately which insect taxon will be the major vector responsible for the cross pollination of the focus plant species (many examples involving myophily).

The literature on this matter is abundant, just make a google search and you will find many articles. Here is in my opinion a key paper supporting the negative answer  :

http://aob.oxfordjournals.org/content/103/9/1471.full

Hope this answers your question.

The quick and dirty response is... yes, provided you know what pollinators are active in the region and you have previous evidence that they are active when the plant is in bloom and these animals retain physical dimensions that permits them to contact receptive stigmas and dehiscent anthers as they forage.  Remember, just because you see an animal foraging on a flower, more than once, is no reason to presume it is a primary or even secondary pollen vector.  We must also realize that the guild of pollinators can change over the full distribution of a plant species as many plants grow outside a pollinators time and space range (see attached).

We now understand that the syndromes described by Faegri and van der Pijl are insufficient to cover acts of pollination by an entire Order of insects.  The attractants and rewards associated with classic beetle-pollination (Cantharophily)  in magnoliids and aroids do NOT apply to the geophytic herbs of South Africa or the Middle East pollinated by scarab-type monkey beetles.  Likewise, with over 20,000 species of true bees floral characters vary considerably whether the dominant pollinators are large bees (>9 mms in length), medium or small.  Whether the bees have long proboscides or short.  Whether they can apply thoracic vibration to porose/porate anthers  and whether the bees collect liquid oils  or volatiles as rewards.  

Likewise, attractants and rewards associated with bird-pollination vary according to hemisphere as nectar consumption and foraging in hummingbirds found only in the Western Hemisphere differs from Old World systems dominated by perching birds (passerines) and parrots.  In some parts of the world (South Africa) pollination systems are so specialized that attractants and rewards for flowers pollinated by long-tongue flies may be subdivided by characters for flowers pollinated by nemestrinids vs. tabanids.

The real danger is presuming that anyone knows all the syndromes and can apply them to an entire flora where little research in pollination ecology has been done.  This produced a number of worthless papers from the late 70's - early 90's in which people went out, looked at flower colors and shapes and made lists of species and their presumed pollination syndromes.  One especially stupid paper came from South Africa in which the authors insisted that the flower shape and color invalidated the work of Herbert and Irene Baker because the nectar chemistry analyzed in the South African flowers didn't match their pollination syndromes based on flower color and shape.   Let's NOT go down that road again. 

"We must also realize that the guild of pollinators can change over the full distribution of a plant species...." 

Does this not contradict your "yes" answer ?

To me all your arguments support a quick and dirty "no", yet you answer "yes"... I'm totally confused here.  May I ask what you think of the article I mentioned above, where Ollerton et al. demonstrate that the answer is rather no ? I'm really interested in your answers, as I certainly don't have your experience.

I am in complete agreement with the Ollerton et al. paper but not for the same reasons as the authors.  The syndromes they tested are not discrete for two reasons.

1) Very different animals respond to the same cues and rewards.  Anthophilous birds and certain butterflies respond to the color, red.  Hummingbirds and large bees with long tongues prefer sucrose rich/dominant nectars while certain passerines can't digest sucrose.  Consequently, many flowers are pollinated by a spectrum of pollinators from different groups.  Giant hairy syrphid flies and wasps are both pollinators of Paeonia brownii, respond to the same attractants and rewards but don't disperse the same number of pollen grains and may not be active at the same time of the peony's flowering season.

2)  Syndromes look indistinct because pollination ecologists fail to understand that syndromes break up into smaller, discrete syndromes according to discrete regions with discrete plant and animal species.  If the pollination ecology of a broad and diverse flora has not been studied syndromes seem indistinct because viewers are unaware that syndromes for a monkey-beetle pollinated flower differ from pollination of a eumagnoliid-type flower.  See our book, "Darwin's Orchids; Then & Now" and read the chapter on pollination of the angraecoid orchids by Claire Micheneau.  It's easy to discriminate the classic characters of the sphinx-moth pollinated orchids but not easy at all to predict pollination by silvereye birds or cricket-like insects.   

If you do know the pollinators in your area and the literature on the pollination systems in your area then, yes, you can do a quick and dirty diagnosis on who is pollinating what but why bother?  There are a range of characters of flowers in temperate, eastern North America that make it likely they are bee-pollinated or hummingbird-pollinated.  Based on flower morphometrics you can even predict the physical sizes of the bees that will probably be the most efficient pollinators.  Based on a big body of literature, and past experience, I can pick out which species in the Australian flora are most probably pollinated by a range of perching birds and parrots.  Translation, guilds become distinct only after familiarity with the foraging habits of resident fauna, vs. pollen load analyses of the foragers, vs. itemizing the attractants and rewards of the pollinators.     

The point is that you must be familiar with the syndromes based on both the literature and have previous experience BEFORE you even consider an ecosystem by ecosystem diagnosis of pollination syndromes.  As syndromes overlap, and the geography of plant and animal species differ, this ultimately makes such predictions  very dirty when older reports show that certain plant species depend on a variable range of pollinators throughout their natural ranges.  Did you read the V. pedata paper?  The species we looked at in the midwest should be pollinated by both bees and Lepidoptera but the day-flying sphinx moths never showed up at either of our sites over two years.  Therefore, you can make pollinator predictions in an area if someone has already done the work determining which anthophilous animals are present and knows all presentations (cues and attractants) of the flowers but, let's be honest, that applies to only a few parts of the world.  My current field sites include the Chinese Himalayas between 3,000 -3,900 meters.  I can pick out the bumblebee and hawkmoth flowers but when you look at floral presentation in so many of the unstudied plant genera and a largely unstudied insect fauna you know that applying syndromes based on Western European and Eastern American species will probably result in over-generalizations.   I can look at them and predict insect-pollination but would never attempt to subdivide some as syrphid fly pollinated vs. small-bee pollinated.  Once we do field studies on enough of them then, yes, we should be able to recognize certain guilds based on phenology and modes of floral presentation.

I'm glad I asked for details, your answer is VERY interesting for a newcomer in the field of pollination research like me.

Of course I agree that it would be pointless to try and predict major pollinators of a plant species in a particular region without any knowledge of the flower-visiting fauna of this region.

I work in temperate areas, where only insects pollinate, and I think it's a lot more difficult to predict efficient pollinators than in regions where you just have to pick between bird, bat or insect... I am working at a much smaller scale.

Thanks again very much for the detailed and valuable answers. I am going to read your article in detail.

In this current trend for meta-analysis of everything ecologists are still attempting to identify plant guilds; pollination guilds, fruit dispersal guilds, masting guilds, arid sone guilds etc.  Unfortunately, guilds of flowering plants dependent on the same pollinator taxa become visible only after enough field and lab work is done to recognize certain floral characters, associated with certain vectors, in the first place.  Unfortunately, meta-analyzers want to put everything together before the hard work is done and pollination systems are identified species-by-species.  Once you realize that a certain suite of floral characters is associated with a certain group of pollinators you can, if you must, predict which plant species, flowering in the same habitat, with the same overlapping floral characters will probably have the same pollinators.  Drs. Faegri and van der Pijl both warned that their syndromes were being over-generalized by their detractors.  Their books emphasized that characters overlapped and the same pollinator was capable of pollinating a wide variety of floral forms (bowl, gullet, brush, etc.).

In an area in which insects are the only pollinators subdividing plant species into guilds becomes increasingly difficult for two reasons.

1) Insects in completely different Families and Orders are often attracted to the same visual/olfactory cues but disperse pollen and contact stigmas in the same flower at very different rates.

2) The actual degree of coadaptation between plant and insects in most species is not understood.  We can discriminate between big-bee and small bee flowers and, in some areas between short-tongue and long-tongue bee pollinators but, with the possible exception of Bombus (dominant buzz-pollinators in most of the northern hemisphere), it's very hard to discriminate between an andrenid-flower, megachilid-flower, colletid-flower etc.  

We understand very clearly from bee taxonomists that some species are specialists and forage almost exclusively for pollen on plants in narrow lineages (alfalfa bees, violet bees, cherry bees) but does that mean these bee species are the primary or specific pollinators of those flowers?  What if they've evolved as pollen and/or nectar thieves?  Does Andrea violae pollinate all the violet species it visits or does it pollinate some and rob others?  

In our lab we must often ask whether the dimensions of the prospective pollinator converge with the floral architecture of the plant.  This is especially important in food-mimic orchid species.  Please consider the following papers.

Bernhardt, P.  2000.  Convergent  evolution and adaptive radiation of beetle-pollinated angiosperms.  Plant. Systematics & Evolution. 222: 293-320.

Bermhardt, P., Meier, R. & Vance, N. 2013.  Pollination ecology and floral function of Brown’s peony (Paeonia brownii) in the Blue Mountains of northeastern Oregon.  Journal of Pollination Ecology.  1:  9 – 20.

Bernhardt, P., Edens-Meier, R., Westhus, E. & Vance, N. 2014. Bee-mediated pollen transfer in two populations of Cypripedium montanum Douglas ex Lindley. Journal of Pollination Ecology 13: 188-202..

Edens-Meier, R.E., Joseph, M., Arduser, M., Westhus, E. & Bernhardt, P. 2011. The pollination biology of an annual endemic herb, Physaria filiformis (Brassicaceae), in the Missouri Ozarks following controlled burns. The Journal of The Torrey Botanical Society 138: 287-297.

Edens-Meier, R., Arduser, M., Westhus, E. & Bernhardt, 2011. Pollination ecology of Cypripedium reginae Walter (Orchidaceae): Size Matters. Telopea 13: 327-340.

Zong-Xin, R., Hong, W., Bernhardt, P., Camilo. G. & De-Zhu, L. 2014. Which food mimic floral traits and environmental factors influence fecundity in a rare orchid, Calanthe yaoshanensis? Botanical Journal of the Linnaean Society 176:4210433.

Thanks to everybody for your support to clarify my question.

Thanks again for sharing your experience and the references.

I really like the interpretation of Peter Bernhardt  and fan of his work. Currently, the trend is everything global analysis as above detail mentioned by Peter Bernhardt , without understandings the local ecology. We have a couple of papers from Nepal Himalaya 1500-4400m, under construction that shows that even the different guild of pollinators are active in the area, all of them are not  flower visitor and pollinator. So it's complex and understanding them at the local level is better for the first instant instead utilizing the work done in Europe or America in your local context.

Generally a syndrome should be indicator of a pollination mechanism, but it is important to distinguish between the flowers with biotic pollination which are generalist fro  the specialists flowers (lixe many orchids which must be pollinated by one species of hymenopterans). To distinguish the biotic from the abiotic pollen vectors you must analyze iz the flowers have the perianth reduced. the stamens and stigmas are exposed to the wind and the floration occurs before the leaves develop. Among the flowers pollinated by the waer as a vector, we can diferentiate the epihidrophylous (pollen moves through th water surface till reach the conspecific stigmas, ej.: Elodea) from the hifihydrophyllous (the pollination occurs within the water as occur in Zoostera marina in which the pollen, expulsed from the anthers, swim to reach the conspecific stigmas). Between the flowers with biotic pollination you can see ornitophilous ones, melitophylous, quiropterophyls, cantarophyls, pollinated by mammalian, marsupiales, etc., and other without specialization. for mor information you should read Faegri & Van der Pijl (1979), "Principles of pollination ecology", this is a master piece since the XIX century. Good luck

It is hard to avoid using syndromes in broad surveys, but except in extreme cases (e.g. where the pollinator is an extremely long-tongued moth, fly or bee) the literature suggests that they are not reliable, even for biotic vs abiotic vectors. I think there has been work on Plantago and/or Salix that looks at the balance between wind and animal vectors. In tropical Asia, you tend to get Apis honeybees on most flowers, but close observations show they are often stealing or scavenging pollen without contacting the stigma. Butterflies can take nectar without touching the anthers or stigma.

Faegri & van der Pijl (1979) acknowledged syndromes but also acknowledged that syndromes overlapped.  The following link to a recent publication in Nature would have delighted them but it's unlikely it would have surprised them.  Yes, I know that Thalassia is  not Zostera but say, hello, to the intergradation of hydrophily and zoophily, Ms. Hoc.

http://www.nature.com/articles/ncomms12980

Once again, the need to do surveys and meta-analyses before syndromes are clearly defined according to region wastes time and misuses available resources.  I remember earlier attempts at putting lots of characters into a computer to determine phylogeny of the monocots by Dahlgren and Clifford in the late 1970's.  They based their survey on comparative anatomy/morphology derived from 19th and early 20th century studies.  The trouble with that was that a number of these studies were incorrect due to misidentified specimens, poor microscopy and using pressed instead of living specimens.  Their analyses of staminal nectaries is worthless on closer inspection (the strumae of Dianella do not secrete liquids, trust me).  

Spend enough time working on the pollination of enough species in the same lineage and phytogeographic region and I assure you that syndromes will become obvious.  Look at Goldblatt's and Manning's studies on the pollination of Iridaceae, over the last 25 years, in southern Africa, for example.  One should always read Faegri & van der Pijl before starting a career in pollination ecology but be prepared to be as flexible as these authors were.  There are always novel and extenuating circumstances since speciation in so many angiosperms appears pollinator driven. The orchid genera, Thelymitra and Cypripedium, have a very different and distinct floral morphology and are found in two very different parts of the world.  However, both syndromes are based on food mimicry, and both appear dependent on cross-pollination by generalist bees and some flower flies (see attached).

I refered to Faegri & Van der Pijl as the start point to the knowledge of this fied od knowledege. If you can and like should seed at my curriculum to understand that en each case that you study, the learned knowledge must be reinterpreted.