to keep the bees addicted! It is no wonder why citrus blossoms are always abuzz with bees. Citrus keeps them addicted.... And caffeine might be present in other flower nectar as well.


Something new I learned today:

Where Bees Get Their Buzz: Caffeine-Laced Nectar
By JAMES GORMAN
Published: March 7, 2013

Nothing kicks the brain in gear like a jolt of caffeine. For bees, that is.

And they don’t need to stand in line for a triple soy latte. A new study shows that the naturally caffeine-laced nectar of some plants enhances the learning process for bees, so that they are more likely to return to those flowers.

“The plant is using this as a drug to change a pollinator’s behavior for its own benefit,” said Geraldine Wright, a honeybee brain specialist at Newcastle University in England, who, with her colleagues, reported those findings in Science on Thursday.

The research, other scientists said, not only casts a new light on the ancient evolutionary interaction between plants and pollinators, but is an intriguing confirmation of deep similarities in brain chemistry across the animal kingdom.

Plants are known to go to great lengths to attract pollinators. They produce all sorts of chemicals that affect animal behavior: sugar in nectar, memorable fragrances, even substances in fruit than can act like laxatives in the service of quick seed dispersal.

Lars Chittka, who studies bee behavior at Queen Mary, University of London, and wrote a commentary on the research in the same issue of Science, said that in the marketplace of plants seeking pollinators, the plants “want their customers to remain faithful,” thus the sugary nectar and distinctive scents.

“The trick here,” said Dr. Chittka, who was not involved in the research, “is actually to influence the memorability of the signal using a psychoactive drug. And that’s a new trick in the book for plants.”


Complete article:
http://www.nytimes.com/2013/03/08/science/plants-use-caffeine-to-lure-bees-scientists-find.html

Very interesting. The article mentions that citrus leaves have toxic levels of caffeine, but many sites online list lemon leaf tea as being caffeine free???
Also makes me wonder about what the plants are uptaking from coffee grounds. Maybe caffeine isn't the alkaloid from coffee that helps citrus fend off insects?

Very cool paper, got me thinking about caffeinated "citrus tea". So I went digging around in the literature. The upshot is I do not believe that it would be practical. The open flowers have the most caffeine, but this still lower than the caffeine content of coffee beans.

Greg, I'm not sure where that comment about the citrus leaves having toxic levels of caffeine came from. I did not see any reference to it while skimming over the original research article (published in Science magazine)

However, I did uncover the first research paper to discover the presence of caffeine in citrus tissues (from 1985): J. Agric. Food Chem. 1985, 33, 1163-1165.

Below are some interesting excerpts from the paper:



For reference coffee beans are somewhere between 2 and 3% caffeine by weight. The caffeine content of citrus flowers is only fractions of a percent by weight (according to the above excerpt).

The young citrus leaves were found to have even smaller amounts of caffeine and mature leaves did not have any.

Overall, very cool info. Had no idea that any part of the citrus tree would have caffeine and they use it to "drug" honey bees!

JoeReal, thanks for posting this!

Jeepers, Joe, where the heck have you been!?! Very interesting article, thanks for sharing.

About midway down in the link from Joe:

"Several varieties of coffee and citrus plants have toxic concentrations of caffeine in leaves and other tissues, but low concentrations, similar to that in weak coffee, in the nectar itself. The toxic concentrations help plants fend off predators."

Maybe most citrus don't and it's just a few varieties? Wonder which ones? Maybe they have very healthy foliage.

Greg,
I think I figured it out. I believe that the author of the NY times article is just not being very precise. I see this quite often when reading science focused articles in the news. I am pretty sure that the statement regarding toxic levels of caffeine in the leaves of citrus just applies to insects/bees etc... The 6ug/g of caffeine found new leaves of Valencia orange trees could very well fit into this "toxic to insects and other pests" range.

One could also reason that the new tender growth would need more protection against insects/pests, explaining why caffeine was found in these leaves, but not mature leaves.

I would assume that most citrus would follow something similar to the above pattern (caffeine in new growth, flowers, and nectar, but not in mature leaves, etc...). If there are major differences between varieties, I wonder if it would be possible to correlate this to the susceptibility of these different citrus cultivars to specific pests?

It is a very interesting subject...

I wonder if I could brew a tea from citrus flowers for a little caffeine boost for myself?


If so, this would be yet another reason to grow citrus.

I wonder if anyone has tested honey made from citrus nectar? Just curious if the caffeine stays or if the bees somehow process it out. If it stays does it become more concentrated like the sugars do?

A little searching brought this up:

"Orange Blossom honey contains caffeine which is a unique characteristic, although the amount is less than 4mg/Kg of honey, much less than decaffeinated coffee."
http://www.honeytraveler.com/single-flower-honey/orange-blossom-honey/

So appearantly it isn't concentrated in the honey.