Frances Xu wrote to me:
Someone asked me why evolution lets a bee die after it stings. I don’t seem to have a good theory. I have a bad one: it shows that bees are of a crazy type, so people are more afraid of them. Just wonder if you have any thoughts on this.
There are two ways to phrase the question. First, why would a bee sacrifice its life to sting me. Second, why would Nature design the bee so that it dies after it stings? The answer to the second question is that after stinging the bee’s life is not worth living. The answer to the first is that it wasn’t worth much before either.
The queen honeybee uses sperm stored from her maiden flight to fertilize and lay eggs. Time seems to be the only binding constraint on how many bees she can bring to life. There is no opportunity cost because her capacity is essentially unlimited. This means that the marginal bee has close to zero net marginal value for the colony.
The marginal bee’s value at birth incorporates the value of stinging together with the value of all of the other services it contributes to the colony. When the bee loses its stinger it loses its ability to sting and its value to the colony drops a discrete amount. Now its value to the colony is negative. The cost in terms of demand on colony resources for survival outweighs the benefits.
At this point it is optimal for the colony that the bee should die.
Now if the bee were genetically identical to the colony then its interests would align perfectly and it would therefore also be in the bee’s interest to die. In fact the bee is genetically identical only to a component of the colony: those other bees produced from the sperm of the same drone. (Roughly 15 drones mate with the queen.) Since the bee’s contribution to the colony is presumably shared by all bees, this means in fact that the bee has even less incentive to go on living.
The final variable is whether the bee could expect someday to mate with a new queen and get his genes into a new colony. That prospect would give the bee reason to live. But worker bees are sterile.
Drones are not. And drones don’t die when they sting. (update: drones don’t have stingers.)
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April 7, 2010 at 3:03 am
Frances
Why not some reusable weapons: such as a beak or a horn, instead of a sting? (After all, a replacement would take some nutrition/time to grow and the old one could have done other tasks such as feeding drones and building honeycombs.)
After more reading, I realize that the question itself might be a misconception. (Sorry!) According to http://en.wikipedia.org/wiki/Bee_sting, it might be that bees are not supposed to die when stinging most enemies, but only when the attacked has elastic skin, such as mammals. Probably mammals are not very natural enemies anyway.
I do see one benefit of an automatically suicidal attacker: since they are dying anyway, they will pick the most painful spot of a victim and sting in a way with no consideration for making it easy to escape. This incentive can work if the society also imposes a death penalty on one that evades attacking and comes back alive.
June 28, 2010 at 6:08 pm
Ashley
Acually a bee dies after stinging something because its butt breaks off and the just die off.
September 9, 2010 at 7:43 pm
jeff
ashley:
you are describing the mechanism which kills the bee. this is the usual answer you get when you ask why a bee dies after it stings you. but this is like saying that penguins don’t fly because they have underdeveloped wings.
the deep question is why is it evolutionarily advantageous that honeybees’ stingers do not cleanly detach after they sting. this is the question i am addressing.
April 7, 2010 at 9:22 am
Ben
I wonder if people would find it as peculiar if there was some giant bee with a thousand stingers and it did not die when it lost one stinger when it stung something. I would argue that even though bees are separate organisms, the genetic interests of the DNA worker bees contain is the same as the genetic interests of the DNA the stingers on the giant bee contain.
All the sterile worker bees exist for the same exact genetic interests of helping the fertile queen they came from do its job of reproducing. All the thousand stingers on a giant bee are working for the same exact genetic interests of helping the reproductive organs in the giant bee do their job. Most importantly, neither the stingers on the giant bee, nor the sterile worker bees can pass on the DNA they contain, they can only help other DNA very similar to theirs be passed on.
So it should be no more surprising that a worker bee might give it’s “life” for the benefit of the queen than if a stinger on a giant bee would give it’s “life” for the benefit of the giant bee’s reproductive organs. The fact that a sterile worker bee is a separate organism and the stinger on the giant bee is not makes no difference in a genetic interests model.
April 7, 2010 at 11:20 am
ron
Some relatives of honey bees and certainly more distant wasps do have reusable stingers that inject venom and also don’t cause suicide with a single use. So it is not a necessity.
the sort of pedestrian answer would be that the worker bees die because their death does not affect the survival of the hive and the queen, who does reproduction enough. It may have been an accidental mutation that caused the sting to be fatal to the bee, but that mutation has carried through all the colonies because it does not affect the colony survival and reproduction. i.e. ‘no selection pressure against the mutation’.
Probably the more interesting question you are asking is whether there is positive selection to this aspect of the bee’s sting. probably there is. speculating you could say that this may co-evolve with less aggressive bees. honeybees have valuable food and aggressive bees may actually endanger the hive by stinging anything that comes by.
April 9, 2010 at 5:27 pm
Lawrence
I heard that ants leave the colony and die alone when they get sick.
September 29, 2010 at 4:39 pm
youwishyouwereme
“And drones don’t die when they sting.”
Drone Bees don’t have stingers.
November 4, 2010 at 3:24 am
ben
iiiiiiiiiiiiiiiii
January 19, 2011 at 4:40 pm
Bzzzz
I think that economists should write about economy and not about biology (in particular those who think that if two bees were born from the sperm from the same drone then they’re genetically identical. Never heard of crossing-over? Moreover, of course, each sperm/egg is genetically different).
March 4, 2011 at 5:07 pm
buzz
A tiny prick that lasts 2 seconds, rolls over and acts dead?
Sounds like husband
March 18, 2011 at 9:29 pm
russel1200
Honeybee stings hurt like blazes. They drive their stingers in pretty deep, and the barb makes it hard to get them out. It is a more effective attack.
Yellow jackets can do multiple stings, but they are just sharp stings. Not fun, but not nearly as bad.
Possibly the energy and effort to regrow a stinger is not as great as that to simply to birth a new neutered sister; particularly if you take into account the cost of having a bunch of stingless workers around.
March 25, 2011 at 10:34 am
walt
I came to exactly the same conclusion re the argentine ants invading my home: the colony has no use for a worker that does not find food. They wander until they starve or until they find food to bring back and signal the others.
April 4, 2011 at 10:39 pm
The Wife
Our 4 year old son asked me the same question today. He asked a very good follow up question. If other bees see the bee die (after stinging a person), then the other bees won’t sting you because they don’t want to die right?
April 10, 2011 at 6:42 pm
Meh
Some things just can’t be explained by evolution.
June 17, 2011 at 2:19 am
Marianne
The honeybee is unique with its barbed stinger. The other types of bees, wasps, and hornets have smooth stingers for multiple reentry.
Perhaps it’s a genetic mutation that helps feed the birds?
July 18, 2011 at 7:08 pm
Jose Espín
If we agree that a kamikaze bee attack is more painful than any other type of attack that does not involve losing the sting, then we have to explain why bees do not re-grow their stings.
The reason might be that kamikaze bees would be in bad shape after a succesful attack (even if they could survive without a sting and grow a new one). If this is the case, then it is cheaper for the colony to “build” a new bee, rather than “repay” the old one.
October 18, 2011 at 2:59 pm
andrew O'daye
bees dont really matter they sting and they die thats all no one cares we onle need the honey thats all
January 19, 2012 at 11:41 pm
Legend
@andrew bit harsh. but also true.
June 18, 2012 at 11:52 pm
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June 19, 2012 at 1:43 am
Miraj Patel
I am not an expert on bees, but the question “Does the bee know it is going to die before it stings?” is relevant here.
Beyond that, and perhaps more importantly, a lot of people here are mischaracterizing evolution and how it works. It is not a sentient process, but one driven by chance.
There are a lot of potential explanations here (again I am not an expert on bees so some of mine might well be proven wrong already) including that only stingers that also kill the bee upon stinging have evolved (stingers without killing the bee may not have been an option in those particular species if the mutation has not evolved) or that past environments favored the killing of bees that stung something for whatever reason. Or it could simply be that it is a bad trait that has lived on because the bees that carried it survived. Might sound silly, but it is all chance and if the groups of bees that had that trait lived on and reproduced as an aggregate, then that trait should (and does) still exist today even if it was always harmful to the individual and the aggregate.
June 19, 2012 at 5:27 am
foosion
Evolution questions should be analyzed from the point of view of the gene (what is most likely to cause the gene to continue) rather than the individual or the species. If some attribute increases the chance of the gene continuing to the next generation, it will be more likely to survive, if not, it won’t. The interests of the individual or species are irrelevant except to the extent they increase the chances of the gene surviving.
June 19, 2012 at 5:36 am
foosion
For example, a barbed stinger may be more effective and a queen whose children do more to protect the colony has a greater chance of having her genes survive, so the death of a child is not important to continuation of the gene. A side effect of a barbed stinger would be it coming out and harming the bee, but the gene pool goes on. Add in the genetic uniformity of bees and this can make sense.
Maybe bees stinging mammals (as opposed to other bees) is so unusual that it’s an irrelevant oddity with no significance in the grand scheme.
November 18, 2012 at 5:43 am
tikkie
Actually it’s only certain species of bees that sting. These species have their ‘stingers’ attached to their abdomen. If the try to fly off after stinging something, they end up ripping off a part of their abdomen which makes them die.