"Aggressive virgin flies" attack successful competitors

It is traditionally believed that in sexual competition in animals, aggression predominates in males.

Researchers from the Champalimaud Center for the UnknownPortugal decided to check whether the females are really as “pacifists” as it seems from the outside. In a paper published in the journal Current Biology, they reported the discovery of a previously unknown form of aggressive sexual competition in female fruit flies.

To test their hypothesis, the researchersplaced two virgin females and one male in one chamber. At first, the male alternately courted both females. At that stage, there were no problems: the females calmly “accepted signs of attention” and did not quarrel with each other. But as soon as the male chose one of them and began to copulate, the second attacked the pair. During the attack, she hit them with her head and pushed. At the same time, most blows fell on the back of the female, where mating took place.

This is curious because when the situationthe opposite is when two males are in the same chamber with one female, both vigorously courting the female at the same time. But once mating occurs, the "losing" male does not attack. Instead, he continues to court, despite the fact that the female is busy with other things.

Maria Luisa Vasconcelos, Head of Research

Aggressive behavior during mating. Video: Miguel Gaspar et al., Current Biology

In further experiments, scientists testedseveral different behaviors. For example, they introduced a new female when the couple had already mated, or placed along with the "virgin" a female who had recently had intercourse. It turned out that in both of these cases, the females did not show aggression and did not pay attention to the couple at all.

The researchers found that the decisive factor inmating was smell: aggressive behavior was observed in "virgin" females only in the presence of food. At the same time, if the receptor, which is responsible for the perception of odors, is blocked, aggression was sharply reduced. Researchers believe that mating in an environment with food is a signal that there is enough food around and the pregnancy will be successful.

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