THE secret of a female fruit fly鈥檚 fidelity lies in a protein in the male
fly鈥檚 semen, biologists reported last week.
A female Drosophila melanogaster that has mated keeps the male鈥檚
sperm inside storage vessels around her oviduct. While she lays hundreds of
eggs, she shuns other males for up to 10 days.
How a female knows she holds enough sperm to keep laying fertilised eggs has
been a mystery. Now Deborah Neubaum and Mariana Wolfner of Cornell University in
Ithaca, New York, claim it is all down to a protein in fly semen that sticks to
sperm and acts as a 鈥済lue鈥� to hold it inside the storage organs.
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When the team mated females with males that lack the protein but have
otherwise normal sperm, they produced only a tenth of the usual number of
offspring, and were out looking for new mates within two days of mating.