Pleasure Chemical Is Secret Key to Locust Swarms  Published
February 02, 2009  | Associated Press  A chemical that affects
people's moods also can transform easygoing desert locusts into
terrifying swarms that ravage the countryside, scientists
report.  "Here we have a solitary and lonely creature, the
desert locust. But just give them a little serotonin, and they
go and join a gang," observed Malcolm Burrows of the University
of Cambridge in England.  The brain chemical serotonin has been
linked to mood in people. It plays a role in sexual desire,
appetite, sleep, memory and learning, too.  Under certain
conditions, locusts triple the amount of serotonin in their
systems, changing the insects from loners to pack animals,
Burrows and his co-authors report in Friday's edition of the
journal Science.  These packs can be devastating. They affect 20
percent of the Earth's land. Last year a swarm nearly four miles
long plagued Australia. They also occur in Africa and Asia and
have affected the western U.S.  • Clic