Cockroach scent as status symbol.

For birds, it may be bold plumage. For elk, a giant rack of antlers. For the drab cockroach, 2-methylthiazolidine and 4-ethyl-2-methoxyphenol are the signals of success.

The compounds are ingredients in the female-attracting sex pheromone of the cockroach (Nauphoeta cinerea). By manipulating the abundance of these compounds, entomologist Allen J. Moore of the University of Kentucky in Lexington and his colleagues also changed a male's status in relation to other males.

As the researchers increased the amount of the two compounds on filter paper glued to a roach's back the roach was more likely to display dominant behavior when paired with another male roach. Increasing the amount of a third ingredient--3-hydroxy-2-butanone--in the pheromone turned the test roach into a subordinate.

When all three ingredients were increased, there was no difference in status between the two males. "The compounds have individual, additive, and contrasting effects on status," the researchers report in the Sept. 4 Nature.

This dual function--on male competition and female attraction--may work evolutionarily to maintain the pheromone as an "honest" status signal, the researchers conclude. The competitive element assures the females that the appealing scent is a true reflection of male status.