Page 26 - 2005 DT 12 Issues

Crime and Punishment Even the queen herself may take on insect colonies. In a classic colony,
the role of policeman. The security cam- a queen may mate with as many as
eras showed that the queen tree wasp, 10 males, occasionally producing an
lassical social-insect colonies which can rove around the typically unfertilized egg, which will develop
have been considered models of small colonies, dispatched 49 percent only into a male. In that case, female
Caltruistic behavior, where each of the worker eggs that were destroyed, workers would be more closely related
individual evolves to serve a specific even though they were kin.. to their brothers or half-brothers than
purpose in service of the common good. The first such instances of punitive to any male offspring of their worker-
Individualism has no place in such a action were reported among honeybees sisters. When a worker disobeys the
structure. Kinship drives altruism and in 1989. Because honeybees closely rules and lays her own unfertilized
genetically driven altruism motivates follow colony rules, Francis L. W. male egg, some workers will seek out
cooperation over self–interest. Or Ratnieks of the University of Shef- and destroy these worker eggs to insure
does it? field in England, and colleague P. Kirk that only the queen’s sons survive. Kill-
Studies of wasps, bees and ants of Visscher, now at the University of ing off their nephews insures more of
various species by scientists from uni- California, Riverside, devised an ex- their own genes making it to the next
versities in Europe and the U.S. have periment where they, rather than colony generation.
revealed tactics calculated to punish workers, committed the crime. Dividing Workers of the saxon wasp tend to
individualism, regardless of kinship, a bee colony with a screen that allowed police co-workers eggs when the queen
through vigilante justice, according to the colony odor to flow freely through has had multiple mates, but not when
a recent article in Science News. the colony, they trapped the queen in the queen is singly-mated. In colonies
In a colony of tree wasps, nursemaids one half of the colony. In the queen- where the queen mates with only one
patrol the nest, feeding and tending the less half, workers began laying eggs as male, kinship usually dictates that
queen’s larvae. One wasp, however, they would if the queen were dead. The workers should bear most of the sons,
stops feeding and surreptitiously adopts researchers then because they would, on average, share
a crouching posi- harvested eggs more genes with their nephews than
tion, laying her from both halves with a brother. Yet in studies of 50 spe-
own egg in an of the colony to a cies of ants, bees and wasps by Robert
empty cell. This test colony. L. Hammond and Laurent Keller of the
crime against the A f t e r 2 4 University of Lausanne in Switzerland,
colony does not go hours, only 1 in 30 of 43 species with singly mated
unpunished. Not percent of the queens, the workers produced less than
only is the offend- t r a n s p l a n t e d 10 percent of the males. Kinship in these
ing egg killed, but worker eggs instances is only one biological driver
retribution may could be found, motivating intracolony violence.
fall on the self- yet 59 percent of Some insect colonies produce many
ish perpetrator, as © Richard Burkmar 2004 Tree wasp the introduced queens that are killed before they can
well. queen’s eggs had disrupt the colony by spreading their
In dozens of films taken with survived. The vigilantes focused pri- own genes, undermining the good of
infrared security cameras, biologist marily on destroying other workers’ the colony. Science News reported that
Tom Wenseleers of the Institute for eggs. in one experiment, researchers Ratnieks
Advanced Study in Berlin, Germany Since then, researchers have found and Wenseleers working together, put
found that justice was served, not by a similar behavior is 15 species, 5 of them several new queens into an established
special caste of investigators, but by a documented in 2004. colony. In four cases, a single worker
posse of vigilante workers. In the most Kinship among workers, typically caught a queen and quickly bit off her
dramatic episodes, the rogue worker sisters and half-sisters, and between head. Sometimes, several workers
is surrounded. “They’re grabbing queens and their offspring, had been grabbed a young queen by her legs,
on to her; they try to sting her.” says considered a determinant in police antennae and mandibles and dragged
Wenseleers. actions taken against rogues in social- her around the colony for perhaps an