Cannibalistic moths help scientists understand how extreme self-sufficiency is growing

Scientists have discovered a way to stop cannibalistic moths from eating their sisters from themselves. You just have to have a place to get to know each other.

Indian flour moth, or pantry lion (Plodia interpunctella), is usually a wild vegetable, clinging to flour, grains, rice, and other packaged foods like a young caterpillar. However, if there is not enough nutrition around, or if there are too many moths in the brood, these larvae can turn on each other at times, feasting on both strangers and relatives.

That’s some brutal survival behavior, but a new study shows that this moth mind isn’t eating sexually for the species. Under more friendly conditions, these insects can be very neighborly.

When researchers directly treated an area of ​​five moths, they found that a tighter condition led to significantly fewer cannabalism in just ten generations.

“Families that were very cannibalistic didn’t do as well in that system,” says biologist Volker Rudolf from Rice University.

“Less cannibalistic families had significantly lower mortality and produced more offspring.”

The findings support a previously unproven theory behind the evolution of social behavior. A team of researchers – including Rudolf and the first author of the moth study, Mike Boots, a biologist at the University of California, Berkeley – suggested that when animals interact more, the level of cannibalism increases. going down. That’s because the chance to happen and eat your friends is statistically more likely in a more dense browser, and ultimately, that would be a disadvantage.

In short, the closer a family unit is, the more likely they are to kill each other.

The new microevolutionary test puts this theory to the test.

In the early stages of the life of this particular moth, caterpillars live and grow in their food, so the authors decided to limit the ability of the larvae to spread by forming five different foods of equal nutrition. In practice, this meant that some situations made it easier for caterpillars to move in, while other environments were sharper and led to less movement and more interaction between individuals.

0324 CANNIBAL fig lg 620x620 1 (Rudolf University / Rice)

Above: The sealed fields where moths were raised either contained sticky food (top) or food that was easier to move through (bottom).

After 10 generations, researchers compared the level of cannibalism in each group. In cases where dispersal was limited by seizures, the self-governing behavior of cannibalism decreased significantly over time.

“Because they lay eggs in collections, they are more likely to stay in those small family groups in the sticky foods that limit how fast they can move,” Rudolf says.

“It led to more local interaction, which, in our system, meant more interaction with sisters. That is exactly what we think was driving this shift in cannibalism. . “

In this case, the cost of cannibalism seems to outweigh the benefits. Eating another moth may reduce competition and provide nutrition, but in limited areas a caterpillar is more likely to eat its brother. Destructive affiliation can weaken the continuity of the shared genes if it happens enough.

Over time, these moths with more cooperative perspiration were those that survived in more sticky material.

It is not known whether this finding is for other species, but the authors say their results imply a “great potential” for nature to choose against self-made behavior.

Natural selection is often defined as a force that is completely self-sufficient, but this does not necessarily mean that there are no benefits to cooperative behavior under certain conditions. Some signs of this have already been seen in yeast and bacteria when their spatial structure is altered. There is also evidence that parasites are less aggressive than their hosts when spread opportunities are limited.

A similar situation could occur even between people.

“In societies or cultures that live in large family groups among close relatives, for example, you might expect more abusive behavior, on average, than in societies or cultures where people are more isolated from their families and more likely to be surrounded by strangers because they have to move frequently for jobs or other purposes, “Rudolf explained.

For decades, evolutionary biologists have been fascinated by unhealthy behaviors and their rise in the animal kingdom. But extreme forms of self-behavior have not been overlooked.

Rudolf has spent decades trying to change that, and his new research on moths just shows how important cannibalism can be in the dynamic evolution of animals and their interactions and behavior. .

It is worth finding out more.

The study was published in Ecology Letters.

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