Past experience of pheromones induces dominant courtship behavior in fruit flies


Past experience of pheromones induces dominant courtship
behavior in fruit flies
October 11, 2005
By investigating the interplay between pheromone signaling and
behavior in fruit flies, researchers have begun to understand how
an adult fly's earlier experience as a young individual can
influence its behavior towards other flies as an adult.

In
particular, the researchers found that pheromone signals in the
context of experience with adult flies can influence how young
flies will behave once they reach maturity.
The work is reported by Jean-Francois Ferveur and colleagues at
the Universite de Bourgogne, France, and the University of
Manchester, United Kingdom.
When an adult male fruit fly encounters a young male fly, he
will actively court the younger individual, sometimes becoming
aggressive. These young males that have encountered older flies
will go on to similarly dominate other adult males that had
encountered only young flies-something in the early experience of
the "dominant" flies makes them more aggressive.

In the new work,
researchers investigated exactly what it is about past experience
of these flies that influences adult behavior. Clues caused the
researchers to suspect that a key role was played by a chemical
signal-a pheromone-carried by adult males during the early
encounter.
To prove this, the researches used mutant flies that lack the
normal adult pheromones, and they covered these pheromone-defective
flies with a variety of other smells. The researchers were able to
demonstrate that a male shows courtship dominance behavior over
young males if he has been exposed to the smell of normal adult
males during a critical period in his life-the first 24 hours.

In
fact, an encounter with a single adult male was sufficient to make
males exhibit dominance behavior when they reached adulthood. The
researchers found that, intriguingly, it was not enough for young
males to smell these pheromones-the pheromones had to be carried by
active adult males. The effect was so strong that males carried on
exhibiting courtship dominance behavior until they were five days
old.
The authors of the study note that similar findings have been
reported in mice and hamsters, suggesting that dominance behavior
may often be affected by chemical signals.

In future studies, the
researchers hope to take the next step in understanding how
dominance behavior develops and thereby to identify which parts of
the fly's brain are involved in processing dominance-inducing
signals.
Cell Press

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