Fly sex peptide flips behavior

Researchers have identified a molecular switch that triggers behavioral changes in female insects after mating, a new study in Nature reports. The finding reveals a direct biochemical connection between a peptide in male seminal fluid and female neuronal activity and behavior.

"[This] is a crucial step if we are to understand the evolution and maintenance of certain insect behaviors," Marie Herberstein of Macquarie University, who did not participate in the work, told The Scientist.

Many animals dramatically change their behavioral patterns at distinct times in their lives. In most species, this occurs during the transition from juvenile to adult, when breeding becomes a priority, but the changes can also take place later. One such later change in insects is a marked flip in female behavior just after she mates. It can be as mundane as the female being no longer interested in breeding or as striking as her needing to drink blood.

Researchers have hypothesized that a peptide in male seminal fluid might be modulating the activity of neurons that control post-breeding behavior -- perhaps an evolutionary mechanism to keep the female from mating with second male, which might remove the first male's sperm from her spermatophore. Barry Dickson of the Institute of Molecular Pathology in Vienna, Austria, and collaborators validated this idea by identifying the gene responsible for post-breeding behavior in Drosophila melanogaster.

The team screened the fruit fly genome to find genes that act in neurons to control egg laying. They identified about 100 genes, but one in particular, CG16752, caught their attention because it belonged to a family of receptors known to function as peptide receptors. Using RNA interference, they found that females in which the gene was knocked down laid fewer eggs after a sexual encounter and were attracted to males 48 hours after mating. (Control females reject males for a longer period after mating.) The results linked the gene to neurons controlling post-breeding behavior

"This gives us a first step in understanding how a peptide from a male can induce a change in female behavior by interacting with her neurons," Brigitte Dauwalder at the University of Houston said. Further study of this phenomenon, she said, will bring better understanding of how peptides govern the behaviors generated by the nervous system.

And because the gene is conserved broadly amongst insects, the same mechanism is likely at play in many species. "It should be possible to interfere with this receptor chemically in agricultural pests or disease vectors like the mosquito, effectively creating a birth control pill," Dickson told The Scientist.

Matt Kaplan
mail@the-scientist.com


Links within this article:

N. Yapici et. al., "A receptor that mediates the post-mating switch in Drosophila reproductive behaviour," Nature, published online December 9, 2008.
http://www.nature.com

A. Rinaldi, "Drosophila's sex peptide," The Scientist, July 22, 2003.
http://www.thescientist.com/article/display/21480/

Marie Herberstein
http://www.bio.mq.edu.au/behaviouralecology/Marie%20page/Mariella%20page.html

B.I. Arthur et al, "Sexual behaviour in Drosophila is irreversibly programmed during a critical period," Curr. Biol. 8:1187-90, 1998.
http://www.the-scientist.com/pubmed/9799737"

D. Kvitsiani, and D.J. Dickson, "Shared neural circuitry for female and male sexual
behaviours in Drosophila," Curr. Biol. 16:R355-6, 2006.
http://www.the-scientist.com/pubmed/16713940
Barry Dickson
http://www.imp.ac.at/research/barry-dickson/

Brigitte Dauwalder
http://www.bchs.uh.edu/ra_prof.php?155622-961-5=bdauwald