Wednesday, September 24, 2008

Wasps Remember Past Rivals

It is hard not to remember a person you’ve previously fought with. Paper wasps (Polistes fuscatus) aren’t too bad compared to humans when it comes to remembering prior social interactions with particular individuals. A comb nest, which usually houses hundreds of wasps, is also the stage of intense fights among nest founding queens eager to establish relative dominance ranks. But these wasp queens recognize individuals they’ve fought with previously and save themselves the trouble of fighting again.

Elizabeth Tibbetts and Michael Sheehan of the University of Michigan, Ann Arbor tested whether wasps remember their former rivals. 50 unrelated wasp queens were tested in four different encounters over eight days. Initially, wasps encountered a new social partner and naturally fought against each other. But after 24 hours, the wasps were removed to separate cages, and the same wasps interacted again 7 days later. This time, instead of fighting, they mostly kept to themselves. To make sure that the lack of hostility was not due to waning motivation over time, Tibbetts and Sheehan introduced the wasps to new play dates on the days before and after the reunion, and fighting ensued.

It is surprising that creatures with such tiny brains can have such good social memories. Tibbetts had previously found that paper wasps appear to use facial patterns to distinguish among their nestmates.

Social insects, including the wasps, were once thought to have simple, undifferentiated relationships. Yet the wasps’ robust social memories are an essential component of complex relationships. The fact that even these small-brained invertebrates can form cognition-based social relationships means that perhaps it doesn’t take a big brain to process basic social cognition.

Update 09/29/08:

Each colony of paper wasps has a number of queens, who fight each other and end up ranked from top queen to all-around loser queen. So there exists a social hierarchy.

The queens can found nests alone or in groups. The survival of nest that starts off with only one foundress is low that an individual queen has more chance of being reproductively successful by working with a group of queens and fighting for dominance of the resulting nest. The nest then fades into functional haplometrosis as one of the original foundresses becomes dominant. But after the mating season is over, the subordinate queens usually leave to form their own nests. Therefore fighting usually takes place among the queens only.

The researchers only did the experiment in which the wasps were separated for 7 days, and it demonstrated the most robust social memory shown in an insect. No research has been done on how long it will take for the wasp’s memory to fade.

It has been suggested that wasps use variable visual features for individual recognition, and examples of some facial patterns are shown in the original article. But again, we don’t really know how they remember the patterns.

Overall, this is only preliminary research and MUCH more study, such as the mechanism behind all this, still needs to be done.

Posted by Hanbing Guo (2)


At 11:04 AM, Blogger PWH said...

Isn't it true that a single hive has only one queen, and therefore after one fight between two queens, the loser leaves and starts her own hive? Also is there any follow up data suggesting that after time the weaker (maybe also the younger) queen will wait some time get stronger and more experienced and then come back to the original hive to try to fight the original queen? Or did this paper not discuss this possibility?

-Joe Alonzo

At 3:18 PM, Blogger PWH said...

How can wasps remember those? I did not think they had ability for that. Where does this ability come from? Is it genetic component? Can you explain a little bit more detail about the experiment. That will be great.

So Jin Lee

At 5:06 PM, Blogger PWH said...

Thank you for posting a very interesting article. I was just wondering if paper wasp conflicts occur solely between females, or are males ever involved?

-Benjamin Spozio

At 7:50 PM, Blogger Dan said...

It's surprising that a wasp's memory is that good. The experiment states that they were separated for only 7 days. I wonder how long a wasp can go before forgetting a past rival.

~Dan Hong

At 10:33 PM, Blogger PWH said...

I am amazed that these paper wasps have the ability to remember their past rivals. You mentioned that Tibbetts found that the wasps use facial patterns to distinguish between each other. Could you go into more detail? As in how do they do that and what type of patterns are there that they can distinguish between hundreds of wasps? Also, in the study the wasps that previously fought were put together after 7 days and did not fight again. Is there a certain amount of time that must pass till they fight again or will they always remember and therefore never fight each other again?

-Tara Quist

At 2:26 PM, Blogger PWH said...

I am always surprised at how little neurons it takes to complete a task. I would like to know more about the wasps' social structure. How many queens are there per nest, or is the social structure similar to bees?

Jimmy Sullivan

At 2:41 PM, Blogger PWH said...

This comment has been removed by the author.

At 2:42 PM, Blogger PWH said...

I did not know that there were multiple queens per nest. How do these wasps recognize others that they have fought? Is it a social cue or some signal given to one of there senses? You had said that they only fight once and don't bother to fight each other again. Does this cause a hierarchy among the wasps?

Rob Lubenow

At 3:56 PM, Blogger PWH said...

it is interesting to see that these insects have the ability to recognize the individuals they have encountered before, is this wired into their short memory or are these wasps able to recognize the individual they have fought with after a very long time?

-Hessom Minaei

At 6:59 PM, Blogger PWH said...

Isn't that amazing? Even the smallest creatures are so complex. Do you know whether or not there is a specific part of their brain linked to memory? Or is the research just based on the investigators observation?

-Michele Copeland (2)

At 8:55 PM, Anonymous Anonymous said...

Interesting article, I wonder if the researchers waited longer than a week if the wasp would fight again. Also, i wonder what cues remind the wasp that they already faught and not to fight again? Could it be apperance, or maybe smell?

Alex Pavidapha

At 9:20 PM, Blogger PWH said...

I think that brain size is not completely related to complexity. I would think that brain size is proportional to body size and therefore it is possible that animals and small insects who have the same proportion of brain to body size as humans would be more similar in complexity. Obviously no animal is able to advance in technology like humans have, but they certainly aren't dumb. I like your article because it opens up so many other questions. I would also be interested in more details about the experiment and whether they have tried expanding the testing of wasp memories for longer than a week.

Ashley Maillet

At 9:46 PM, Blogger PWH said...

I found the topic of paper wasps intriguing. As mentioned above, this does open the doors for many many questions about the details of these fights. I wonder if once these queen wasps fight, is one killed, or is it simply injured enough to retreat. Also, where would the loser retreat, does the wasp have to leave the comb?

Ahmed Sandakli

At 11:25 PM, Anonymous Anonymous said...

Good article, but my biggest question is how are they able to do it? What allows them to remember the facial patterns?

Tazneena Ishaque

At 12:06 AM, Blogger PWH said...

I am confused about how the wasp remembers their rivals. How do scientist know they recognize each other? Is it because the previously fought and will not fight again because they have already determined who was the superior wasp? I would like to know more about this article. Good work.

Carlos A. Varela

At 11:12 AM, Anonymous Anonymous said...

This was a very interesting article, I know that bees are able to remember the way to gardens and flowers to pollenate but I did not expect wasps to remember other individuals. I would liek to know more about the way they recognize eachother, its mentioned that they used facial patterns but could they be using other senses?

posted by Erica Damon

At 12:28 PM, Anonymous Anonymous said...

I wonder if the wasps can remember other members of the hive and not just the ones that they fought with. There might not be a need to remember other members so maybe it's only when the two wasps fight that something happens in the brain that allows the wasp to remember the facial patterns of the enemy. I would also be interested in the time period, if there was one, that the wasps can remember the face. If the wasps can remember the face for it's lifetime then that would be impressive because it would be able to remember all of the faces of the wasps it has ever fought with. That seems like it could be a lot of information. On the other hand, their lifespan might be short enough that it wouldn't matter.

Rachel Carboni


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