It is known that bees leave olfactory footprints on the flowers, which indicate that the flowers just have been visited. The bees oviously learn the association between the nectar refilling duration and the strength or compostion of the footprints and avoid to land on flowers that have been visited recently. . See the publications of Thomas Eltz and coworkers:

Wilms, J. & Eltz, T., 2008. Foraging scent marks of bumblebees: footprint cues rather than pheromone signals. Naturwissenschaften 95: 149-153.

Witjes, S. & Eltz, T., 2007. Influence of scent deposits on flower choice: experiments in an artificial flower array with bumblebees. Apidologie 38: 12-18.

Eltz T., 2006. Tracing pollinator footprints on natural flowers. Journal of Chemical Ecology 32: 907-915

thank You very much, I'll try to find these articles in the net.

You will find the articles on the homepage of Thomas Eltz at the Ruhr-Univesitaet Bochum.

OK, thank You.

Dear Anastasiya,

Indeed, there are exist plants, flowers of which require multiple visits to the formation of normal germ - for example, the flowers of apple trees. In contrast, in plants such as alfalfa, pollination occurs only after the first visit of bee. In the future, these flowers quickly wilt and seeds are formed.

With regard to olfactory footprints that left by bee after a visit on the flower, they are species-specific and does not affect the visit of flower by other species of bees. Such leaving of smell marks are commonly observed in bumblebees, and it is associated with the theory of optimal foraging (see: Radchenko V.G., Pesenko Yu.A. 1994. Biology of bees (Hymenoptera, Apoidea). S-Petersburg: Zoological Institute of the RAS. 350 p. DOI: 10.13140/2.1.3938.6242

https://www.researchgate.net/publication/264556842_Biology_of_bees_Hymenoptera_Apoidea

With best wishes,

Vladimir G. Radchenko

Book Biology of bees (Hymenoptera, Apoidea)

I disagree with Vladimir,

as fas as I know the scent marks are species-specific, but not actively deposited on the flower; thus olfactory footprint is a good definition. Bees have to learn the meaning of the scent marks just many other features of the flower and they also learn that scent marks left by other species are associated with emptied flowers.

See: Gawleta, N., Zimmermann, Y. & Eltz, T., 2005. Repellent foraging scent recognition across bee families. Apidologie, 36:330.

Dear Klaus,

Such scent marks relate primarily to the presence of nectar. Therefore, they are relevant for the bumblebees that make the honey reserves. But they are less relevant for the solitary species of bees, which are mainly collected only pollen.

Best,

Vladimir

Dear Klaus,

The case with the Anthidium manicatum (which is given in the article: Gawleta, Zimmermann, Eltz, 2005) is special, because, firstly, this species also stores a considerable amount of nectar (food has a form of porridge). Secondly, the males of this species have a controlled area, which they are marks with scent and kill (damaged the wings) not only other species of bees and wasps but also other flying insects. Therefore, they can precisely respond to other scents.

Kind regards,

Vladimir

However Eltz and coworkers showed that Anthidium manicutum females are repelled by the scent marks of Bombus terrestris and of conspecifics, and on the other hand that Bombus terrestris workers are repelled by the scent marks of Anthidium manicatum females and of conspecifics. Similar studie show that this is not exceptional: Tomoyuki Yokoi , Dave Goulson and Kenji Fujisaki (2007) The use of heterospecific scent marks by the sweat bee Halictus aerarius, Naturwissenschaften 94:1021-1024.

Dear Klaus,

Incidentally, Halictus aerarius is not a solitary bee. This is eusocial species, which has workers that widely use the scents. Although olfactory marks are also used by subsocial bees from the genus Xylocopa.

In general, the question related to the marking of flowers by bees is much more complicated.

For example, in experiments with Bombus voznesenskii, conducted by Cameron (1981) on artificial flowers, opposite result was obtained. Foraging individuals of this species, in contrast, were marked the flowers, which reward them with nectar. Later the foragers examined only marked flowers, although they could no contain nectar.

It should also be taken into account that many of the experiments were made not entirely correct. Although, of course, in some cases, we can say for sure that there are obviously repellent marks. But I am not sure that such marks are directly related to the mechanism of single-pollination (it was the primary question!).

Cameron S.A. Chemical signals in bumble bee foraging. Behav. Ecol. a. Sociobiol. 1981. Vol.9, N 4. P.257260.

Best regards,

Vladimir

The bees do not actively mark the flowers rather than passiely leaving olfactory footprints. They have to learn the maening of the marks. If you use permanently rewarding artificial flowers, they will learn that a scent marks means rewars; if use use natural flowers, they will learn that a scent marks means emptied flower, and if you use once rewarding artificial flower, they will treat them like natural ones.

There are many species of flowering plants, which have large reserves of pollen and each flower produces nectar for a long time. As a result, these flowers are constantly repeatedly visited by bees. Many years ago, my colleagues and I carried out the calculation of reserves of pollen and nectar at some cruciferous plants (see Pesenko, Radchenko, Kaygorodova, 1980). Simultaneously we calculated the number of visits per each flower.

At plants that are pollinated only once, there are many other mechanisms to prevent re-pollination. However, these mechanisms usually do not relate to the behavior of bees such as leaving the marks, which are necessary for bees to reduce their own energy expenditures that is especially important for species with a large body size.

Pesenko, Yu.A., Radchenko V.G., Kaygorodova M.S. Ecology of pollination in Strigosella grandiflora and Erysimum badghysi (Brassicaceae) by bees (Hymenoptera, Apoidea) in Badkhyz: estimation of the pressure of competitive relationships. Entomological Review, 1980, 59(4):58–73.

https://www.researchgate.net/publication/268279604_Ecology_of_pollination_in_Strigosella_grandiflora_and_Erysimum_badghysi_Brassicaceae_by_bees_Hymenoptera_Apoidea_in_Badkhyz_estimation_of_the_pressure_of_competitive_relationships

Article Ecology of pollination in Strigosella grandiflora and Erysim...

Dear colleagues, thank you very much for the comprehensive discussion!

Look at the markings of the petals - extremely delicate petals of Geranium macrorhyzum. The honey bees left them with their claws - I observed them fro hours. And I think these markings were not on purpouse - the bees just needed to hold on to something...and these did not prevent next visits as it is seen from the photo

Anastasia,

la re-formulation du question 1, que vous avez posez :

Est-ce possible, que Iris a été visité 1 fois et la fleur devienne repulsive?

Selon votre observation - c'est oui.

Vladimir vous a repondu : ce mécanisme s'appele la "seule pollinisation"!!!

D'ou uni- (only one) et multi (ou poly-) visites. 

Alors, si la re-pollinisation (cité plus haut pour les pommiers), mais  n'est pas décrit pour les Iris pourquois vous avez ajouter la supposition suivant:

I suppose it may occur in Orchidaceae or Asclepiadaceae families.

la plupart des plantes Angiospermae ont la dispertion de pollen par les monades, ainsi que les orchidées ont le pollen souvant agglomerer dans les tetrades, polyades, massules, pollinies, etc. (monade existe chez plus primitives, f.ex. Cypripedioideae ).

Je sais que vous avez telecharger mon article sur l'interaction entre pollinisateurs et orchidées, mais je ne suis pas sur, que vous avez eu le temps pour le lire.

Bien cordialement,

Marpha

Anastasiya

Prof. Lunau may be the "right" person to answer your question, but I understand that Florian Schiestl and Manfred Ayasse (Oecologia: 2001) have already demonstrated that some Ophrys (Orchidaceae) flowers after being pollinated start emitting some deterrent substances. So, it seems logic to suppose that these flowers may be visited only once, if pollinated during this sole visit.

Schiestl, Florian P., and Manfred Ayasse. "Post-pollination emission of a repellent compound in a sexually deceptive orchid: a new mechanism for maximising reproductive success?." Oecologia 126.4 (2001): 531-534.

Interestingly, Neiland & Wilcock (Protoplasma, 1995) demonstrated that the flowers of other Orchidoid orchids are able to "accept" more than a pollination event. With all the best wishes,

Alors, retournez chez les oeuvres de plus grande des spécialistes en mythologie sur les orchidées Charles Darwin

In Leguminosae with explosive mechanism of Pollination, like Medicago sativa, the visitors arrive only once, then the floral mechanism "desactivate" and can^not receive other visit because the landing place formed by the wings is not functional yet.

Dear Dr, Odinstova:

Sorry to come to this exchange of ideas so late but there's an important question to ask.  How how long does your Iris flower live if it is not visited by pollinators vs. how long does it live after it is visited for the first and only time?  Have you done any tests?  Based on simple observation I've noted that Iris flowers rarely live more than 24 hours so it may not be possible to quantify results.

In contrast, there is an expanding body of literature showing that some long-lived orchid flowers collapse within hours after their pollinia is removed OR after pollinia is deposited on receptive stigmas.  The pattern emerging suggests that some orchid species producing hard or waxy pollinia (most epidendroids) are more likely to collapse in 12-24 hours after their pollinia is removed.  This is most dramatic if you remove the entire pollinarium from the big flowers of Angraecum sesquipedale (but the people who own the plant won't like you much if you do).

The system may be reversed in some orchidoid orchids that make friable or sectile pollinia in which the pollinators may leave fragments of pollen of several pollinia on the same stigma.  In the case of our studies on two, Australian, Thelymitra (orchidoid) species, the flowers lived the usual floral life-span of 5 - 7 days after the pollinia was removed but closed the same afternoon and never reopened the day AFTER pollen was placed on the stigma (see attached).  I also noticed that if a phytophagous beetle entered the flower, chewed on the anther and release some pollen onto the stigma below the flower closed and never reopened.  

Ophrys is also an orchidoid genus so it also makes sectile or mealy pollinia.  Therefore,  it is not surprising to learn that the flowers emit molecules that the male insects dislike (see Dr. Singer's earlier entry above) following the act of pollination.  I must read that paper to see if the act of pollination in Ophrys is also associated with a rapid collapse of labellum turgidity and/or dissolution of the pigmentation pattern.  

Our lab has been studying pollination in native American Asclepias species for several years.  The first publication should appear early in 2017.  We have not noticed an association between the number of pollinator visits to an individual flower in 5 species under study, so far.  Bees (Xylocopa, Apis, Bombus) and large pollinating butterflies (Speyeria cybele) visit the same flowers over and over again on the same umbel no matter how many pollinia were removed after the first visits.  Butterflies are more cautious visitors and leave after visiting only a few of the flowers on an umbel but large bees visit all the flowers on one umbel and one frequently sees more than one bee on the same umbel over a 2-3 hour period.  However, the rate of pollinaria removal in our 5 species is always higher than the rate of pollinia deposition into a stigmatic slot.  

Dear Dr Bernhardt, thank you for the interest to my question. We observe Iris sibirica flowers with anthesis about 1,5 days. The main pollinators are bees, we have no experiments, only observations during a day. We suppose, bees are very skilled insects and they learn to know whether or not the flower is full of nectar. The flower can be empty because of anths and beetles visiting it. It was only my guess about Orchids and Asclepias flowers because they have strategy " all or nothing". And Iridaceae are close to Orchidaceae in their flower structure (from the viewpoint of morphologist).

The main discussion is: signals are released from the pollinated or nectarless (changed) flower  OR signals come from the visiting insects for another insect.

it is an interesting observation for this moment.