Spider's perfume fatal for moths.

Spider's perfume fatal for moths

For certain male moths, bolas spiderscan be the ultimate cold shower. New results of field studies confirm that the bolas spider first attracts a male moth by emitting odors reminiscent of the sex pheromones released by female moths. As the moth is drawn to what it thinks is the flame of passion, the spider flicks its sticky, bolas-like webbing--a silken strand with a drop of glue at the end-- and reels in the moth for a decidedly nonsexual meal.

Scientists have suspected that bolasspiders can release chemicals similar to female moth pheromones because the spiders capture and eat only male moths. Now researchers have the first chemical evidence that this is actually the case.

In the May 22 SCIENCE, Mark K. Stoweof Harvard University and James H. Tumlinson and Robert R. Heath of the U.S. Department of Agriculture in Gainesville, Fla., report that they have identified three compounds released by bolas spiders, and the compounds are identical to the chemical constituents of some moth sex pheromones. According to Stowe, other examples of chemical mimicry in nature include orchids, which use pheromone-like odors to entice pollinating bees and wasps. But spiders are the only known example of a predator using such odors to lure prey. And unlike the moths, the orchid-seekers, he says, "live to tell the tale.'

The researchersfound that the composition and ratio of different compounds in the "perfumes' collected from groups of spiders changed with time. This may mean that different spiders emit different blends of chemicals, or, as Stowe suspects, that individual spiders are able to change their blends. In future studies they plan to monitor spiders individually.

Stowe and his colleagues hope thatthese and other studies will provide new insights to the ecology and evolution of the insect world and help agricultural scientists to develop better ways to control pests. For example, moth pheromones are used to attract and monitor moths so that insecticides can be applied more judiciously, according to Stowe. Farmers can also permeate a field with pheromone-like odors so that male moths can't find and mate with females. An advantage of exploiting the smells of nature, he says, is that insects are less likely to develop a resistance to compounds they've been responding to for a long time.

Scientists, he says, "are only nowbeginning to appreciate and understand nature's chemical library involving organisms that mimic odors.'