To Bee or Not to Bee: The caste system is alive and well in honeybee society.

To Bee or Not to Bee: The caste system is alive and well in honeybee society. A female embryo fed on “royal jelly” emerges as a Queen, specialized to lay eggs, while other females are sterile workers. All workers begin as nurses, tending to the eggs.  After a few weeks some nurses switch to become foragers leaving the hive to search for nectar. They are genetically identical, so what determines caste? The answer lies in epigenetics.

Epigenetics is the bees knees! It is the chemical modification of DNA over and above the underlying genetic code. DNA is wrapped tightly around histone proteins, like beads on a chain. (a) Relaxed DNA has chemically modified histones (green dots). This makes it open for business, inviting transcription factors (TF) to get to work transcribing a gene. (b) DNA methyltransferase (DNMT) adds methyl groups (grey triangles) to CpG dinucleotides. (c) This triggers different chemical modifications (red) to the core histone, to condense and inactivate the DNA structure. Genes are silenced when transcription factors cannot bind to them. So, is the division of bee labor decided by these chemical tags? Not to belabor this, but in short, yes.

Tag Teams: Johns Hopkins molecular biologist Andy Feinberg teamed up with bee expert Gro Amdam (Arizona State Univ, Tempe) to show for the first time, epigenetic changes associated with behavior. Age matched workers and foragers have 155 differences in DNA methylation, mostly associated with genes that regulate other genes. Better yet, these changes are reversible. Using hive trickery, researchers introduced foragers to a new hive. This induced about half of them to revert back to worker bees. Remarkably, DNA methylation tags reverted as well. This may help decipher complex behavioral changes in humans.


REF: Herb et al. (2012) Reversible switching between epigenetic states in honeybee behavioral subcastes. Nature Neuroscience DOI: 10.1038/nn.3218

Image: Modified from Strietholt et al. (2008)

For #scienceeveryday when it’s not ScienceSunday .

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50 Responses to To Bee or Not to Bee: The caste system is alive and well in honeybee society.

  1. Todd Settimo says:

    You always have the most fascinating and informative posts. So nice to end the week a little more enlightened than I started it.

  2. A local beekeeper told me when his back pain got bad he would grab a bee and have it sting his lower back for relief.  I mentioned it to one of my doctors and he looked at me in amazement, having just returned from a convention where one of the topics was bee stings and pain relief. 

  3. Rajini Rao says:

    Thank you, Todd Settimo 🙂

    Linda Hedrick , I will look into the chemical basis for this! At my last conference, there was a talk on pain receptors (such as capsaicin receptor) that are targets of snake and spider venom. If the pain pathways are overly activated, they desensitize or numb down, causing relief. That’s why there are capsaicin creams used to treat sore muscles. Thanks for that tidbit of info 🙂

  4. Interesting…a chiropractor once, not having found a basis for the pain in my knee, suggesting rubbing tabasco on it (for the capsaicin).  It worked!  I’ve had my husband try it with similar success.

  5. Rajini Rao says:

    Exactly, there is scientific basis to your homespun treatment Linda Hedrick !

    The scientist who discovered the first capsaicin receptor, Mike Caterina, is a colleague and friend.

  6. Thank him for me, Rajini Rao!  And thanks for all you do to educate us!

  7. I need a bee to sting me in the back. Does it have to sting where the pain is…. If so, how does one get a focused sting?

  8. La Vergne Lestermeringolo Thatch.  I believe it has to be where the pain is.  The beekeeper I mentioned had been working with bees for decades and knew how to “catch” them.  He would hold them by the wings and aim their stingers where he wanted.  Probably shouldn’t try this at home!   😉

  9. Rajini Rao says:

    Google tells me that there is an American Apitherapy Society that specializes in bee venom therapy, La Vergne Lestermeringolo Thatch . I don’t know anything about it, though.

  10. Generally, they actually take the bees individually and place them directly on the skin at the site where they want the sting, with the bees held in tweezers.

    Here’s NatGeo discussing it:

    Bee Therapy

  11. Rajini Rao says:

    Thanks for the link, Howard C. Shaw III . I searched the scientific literature and there is progress in understanding bee venom components (for example, they have a serine protease that triggers an immune response).

    It should be possible to use purified venom components for pain relief, or treatment of disease, instead of bees. That would be more controlled and less dangerous, and it should be possible to evaluate their efficacy more systematically this way.

  12. And also not involve killing the bees, as is currently required.

  13. Rajini Rao says:

    Yeah, that’s what I thought too. I wonder why a bee dies after a sting? Is it physically damaging? Perhaps our G+ bug expert Chris Mallory knows 🙂

  14. Something about it pulls out the abdomen or something…

  15. Yes, when a bee stings, the stinger remains in the wound, because it is barbed, unlike the smooth stings of wasps. When the bee attempts to fly away, or is flicked away by the stung animal, the stinger remains behind, tearing out part of the insides.

  16. Rajini Rao says:

    Everyone else just gets Marmite on their toast, Peter Lindelauf 🙂

  17. Rajini Rao says:

    Marmalade, I like marmalade ..

    Alan’s Psychedelic Breakfast.

    (Trying to find a link, help me out Feisal Kamil )

  18. Or when the confused young citrus blossom (thinking itself a chicken) remarked to the tree upon seeing last year’s crop on the ground:

    “Look at the Orange Marmalade!”

  19. Rajini Rao says:

    Groan, I’m so confused William McGarvey . Can’t we simplify it?

  20. Rajini Rao Let’s try this:

    A young Florida chicken was surprised by something oddly spherical and bright in color in its parents’ nest, so it asked:

    “Is that an Orange Marmalade?”

  21. Rajini Rao says:

    That’s more a-peeling, William McGarvey . The other version threw me for a fruit loop.

    Peter Lindelauf , that was beeyutiful. Hive you any more?

  22. Fred Gandt says:

    Wow. That’s extremely complex. It’s beautiful.

    My thoughts are currently swirling around the philosophical questions the understanding raises. The whole “nature vs nurture” question gets really twisted for a start.

    If I understand what I just read even close to correctly; bees (and thus most likely most other complex life forms) are like living Swiss army knives. I am so crap at making sentences.

    Bee do biochemistry thing. Me go wow!

  23. Fred Gandt says:

    Mark Bruce Free Will and Sim-hype? Is it just me or does this seem helpful?

  24. Rajini Rao says:

    Fred Gandt , you are absolutely right…epigenetics adds nurture to nature. These modifications of DNA can be stable and inherited. They are affected by nutritional status for example..there are documented cases of maternal stress or famine altering gene expression in offspring.

  25. Fred Gandt says:

    What intrigues me is that the genes dictate that the creature can recreate itself and be recreated dependant on need by changing the way its genes suggest how its built……..

    I am not expressing what I’m thinking. I seem to have a serious mental deficiency.

    Cause and effect.

    Intelligent design.

    Biochemical intelligence?

    Is complexity enough to determine [something]?

    What is deeper than anyone can look?

    The machine is built to rebuild itself. Very clever.

    Going to sulk.

  26. Rajini Rao says:

    No need to sulk, your instincts are correct.

    All biological systems have built-in regulatory systems. Some are feed back, some feed forward. They start simple and then get more elaborate as bells and whistles are added on. As you can imagine, all this keeps us very busy 🙂

    Interesting that regulatory circuits can be mathematically modeled, so that the underlying principles can be breathtakingly elegant. Glad you appreciate it, I sure do!

  27. Fred Gandt says:

    I think it’s awesome, and I’m grateful to you for sharing it 🙂

    I’m sulking over my own frustrations with my inability to communicate clearly what I am thinking (a lot of the time).

    I need Swiss army genes that rebuild me a better “make words for saying things” cortex.

    I suppose I could try dancing instead. It works for bees after all!

  28. And so, these bees have TWO lifes within ONE and will they be able, with a little boost, switch from one to the other… COOL!!

  29. Rajini Rao says:

    Yes, that is right Fadia Lekouaghet 🙂

  30. Viet Le says:

    Rajini Rao I don’t have access to the paper right now, anything revealed re: the trigger for epigenetic change?

  31. Rajini Rao says:

    Hi Viet Le , the genes that were differentially methylated were involved in gene modification, themselves! They included histone deacetylases, phosphotransferases and methyltransferases. One of them was involved in dendrite morphogenesis, and could have played a role in brain remodeling during the nurse to forager transition.

    Actually, I don’t know what the earliest events are in triggering the change. I’ll have to ask Andy Feinberg.

  32. Hum the song of epi’s and api’s to keep the hives forever ‘appy.

    Have you tried marmalade (grapefruit marmalade, that is) on Colby cheese on toast Rajini Rao?  _Warning:_ it is addictive. Apply gobs of marmalade to a slab of cheese on buttered or unbuttered toast. Drool for a time, then EAT! 🙂

  33. Rajini Rao says:

    +100 for your ‘appy snippet of epis on Apis 🙂

    I love marmalade on buttered toast, Nobilangelo Ceramalus , I should try it with cheese sometime. IMO, marmalade in the US is a bit too sweet, lacking that bitter edge that makes it so unique. 

  34. Rahul Joshi says:

    Loved reading this. Very educational Rajini Rao !

  35. Viet Le says:

    Rajini Rao I’ll have a read of the paper when I am on campus tomorrow. 

  36. Rajini Rao says:

    Mark Bruce , while I don’t know the specifics in this case, I suspect that the initial signals are chemical, such as pheromones. For example, ethyl oleate acts as a forager pheromone to slow the maturation of nursers and keep the ratio of foragers to nursers at an optimum. These chemical signals must be translated into some early responses..key genes that are master regulators of the transition. These, in turn, must kick off a developmental cascade that includes the epigenetic changes reported in this paper. Finally, there has to be a mechanism to turn off the process once the changes have taken place. 

    If I pick up anything on the specific signals in the case of honeybee social behavior, I’ll come back to update!

  37. Rajini Rao says:

    Sure, let me know if you want me to email it to you, Viet Le . 

  38. Rajini Rao says:

    Thanks, Andy…it was sweet of you to stop by!  

  39. You’re pollen my leg, Andy Feinberg — stop me before I drone on and on and on and…..

  40. Rajini Rao says:

    We must beehive ourselves, William McGarvey , or we may become social outcastes. I’d rather bee the queen 🙂

  41. Interesting. I would like to read the article. Is there direct evidence that DNA methylation determines worker/forager identity? 

  42. “To Bee or Not to Bee”…….. interesting post there Rajini Rao 

  43. well that sounds like a hell of a lot like me I could sure give a good DNA code very strong proteins

  44. Rajini Rao says:

    Here is a great video narrated by the one and only Neil deGrasse Tyson explaining epigenetics. A great share via Fred Gandt and Chris Robinson (thanks, guys).

    Epigenetics in NOVA SCIENCE

  45. Excellent.  Thanks for bringing the link in, Rajini Rao .

  46. Rajini Rao says:

    Neil deGrasse Tyson does so much for science. I had not realized that he spoke on topics outside astronomy, William McGarvey . I thought the video was really well made.

  47. That’s PBS, Nova, and — of course — Tyson for you…

  48. Rajini Rao says:

    A beeyoutiful trifecta 🙂

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