Gross: cockroaches have individual personalities, study says

Chuck Bednar for redOrbit.com – @BednarChuck

Perhaps best known as a massive pest and the only creature able to survive a nuclear apocalypse (in popular theory, at least), cockroaches also apparently have individual personalities, according to new research published recently in the journal Proceedings of the Royal Society B.

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In fact, according to Reuters, the Belgium research team responsible for the study found that the cockroach even displays different character traits – they can be shy and timid, or brave and eager to explore their surroundings. The discovery could help explain why the insects are considered to be such great survivors and so able to adapt to even the most inhospitable environments.

The buggy experiment

The researchers reviewed the behavior of American cockroaches (Periplaneta americana) when they were exposed to light. Sixteen cockroaches were tested in a round arena located underneath a bright light at various times over a three-month span. In the arena’s center was a pair of round shelter areas that the dark-loving insects to go to in order to seek refuge from the light.

Once they were released, the bugs were left along for a period of three hours, during which time their locations were recorded by a camera and a tiny chip that had been placed on their backs. This system allowed the scientists to monitor their location using a computer to determine if the insects were hiding from the light or exploring their surroundings.

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The experiments were repeated multiple times, and the researchers found that some cockroaches would consistently spent more time in the shelter, while others regularly spent more time outside, according to The Washington Post. The insects “reacted the same way each time,” lead author Isaac Planas-Sitja, a PhD student at the Universite’ libre de Bruxelles, told the newspaper.

The purpose of the experiment, he explained, was to search for variances in group behavior and the way that the group of insects reached a decision. While roaches are known for their dislike of bright light, they also have an affinity for groups and protection, and all of those traits factored in to the decisions reached by each individual during the experiments, Planas-Sitja reported.

Instead of all of the roaches quickly seeking refuge in the shelters, the research showed that the amount of time it took for the group as a hole to do so varied, which Planas-Sitja attributed to the differences in individual personalities and behaviors. If one roach was quick to settle under one of the shelters, it might encourage others to do so as well, thus reducing the total amount of time required to achieve that end result, according to Reuters.

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While the researchers pointed out that the decision of one cockroach could influence the others around it as well, ultimately each insect was responsible for choosing whether or not it wanted to remain in the light. This separates these bugs from ants, termites and other insects, each of which acts according to an established social hierarchy.

Making decisions (and planning world domination)

“Cockroaches are a simple animal, but they can reach a complex decision. So with little information, with little interactions, only knowing if I have a partner here or not, only with this information, they can make complex decisions,” said Planas-Sitja. “We have a group of equal individuals that reach a choice, can have consensus decision making as we can see in sheep, bats, some monkey species, fish, birds, for example, or also humans in this case.”

However, what surprised Planas-Sitja and his colleagues the most was that, no matter what the personalities each of the cockroaches in the group exhibited, all of them wound up in the shelters by the end of the experiment – it just look some of them longer than others.

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“The fact, and we didn’t expect it, is that they always reach this consensus,” he said. “So we expected that some groups have more trouble than others to resist consensus or to choose a shelter, but at the end, no, they always finished aggregated. So it is something really inside the individuals or in the cockroaches. So that was amazing.”

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Source: http://www.redorbit.com/news/science/1113351159/gross-cockroaches-have-individual-personalities-study-says-031215/