Community Research and Development Information Service - CORDIS

How queen social insects choose their mates

In social insects sexual competition between males is not part of normal colony life, but completed under female control before she starts a colony.
How queen social insects choose their mates
Colonies of some social insects such as ants, bees and wasps contain a female 'queen' who is inseminated by multiple males. This results in sexual conflict, with males competing to have their sperm stored by the queen before she initiates a colony.

We expect that the sperm of multiple males compete within the female reproductive tract and that seminal fluid may kill other males' sperm. However, as queens never re-mate after founding a colony their fitness only benefits from sperm culling before storage, but not from sperm-wars continuing after storage.

The EU-funded CONFLICTS (The post-copulatory interplay between females and ejaculates in social insects) initiative used honeybees and leafcutter ants as models to find out whether and how queen social insects make these discriminating choices at the molecular level.

Part of the answer lies in the secretions of a special organ of queens, the spermatheca or sperm pouch. Here, she stores sperm for up to several years (honeybees) or two decades (ants) to fertilise eggs throughout life.

CONFLICTS showed that females secrete a substance into the spermatheca that preserves the sperm and stops rival sperm from killing each other. To determine how these secretions interact with sperm, scientists identified the proteins in female secretions of artificially inseminated leafcutter ant queens.

Scientists also looked at proteins in male seminal fluid before and after exposure to female secretions. They found that female secretions disable seminal fluid enzymes known as proteases that would otherwise kill the sperm of other males.

In addition, they discovered that females overproduce specific proteins when their sperm storage organ secretions come into contact with male ejaculates. This suggests that these proteins help to maintain the stored sperm in top condition during the queen’s life.

CONFLICTS answered important questions about sexual selection that are relevant to all sexually reproducing organisms, including insects, birds and mammals.

Related information

Keywords

Sexual competition, social insects, honeybees, leafcutter ants, spermatheca
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