SCARY, hairy and large they may be, but there’s one exotic spider that has no
difficulty attracting a mate. Its secret? Perfume.
Female wandering spiders (Cupiennius salei) from Costa Rica use
pheromones to lure mates, and if many other spiders share the trick, the
chemicals could be used to trap nuisance spiders or attract pest-eating
species to farmland. This is only the second type of spider which has been found
to use pheromones, and it’s a first for a large hunting species.
Chemists in Germany found that the female spiders leave scented silk
draglines behind wherever they go. When males pick up the scent, they respond by
drumming rapidly on plant leaves or stems with pedipalps, small finger-like
appendages on the spiders’ faces.
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If the vibrations reach the female, she returns the signal. “The male and
female find each other through these drumming vibrations,” says Stefan Schulz
from the Technical University of Braunschweig, who identified the spider
pheromone.
To find it, Schulz enlisted the help of Harald Tichy, a tropical spider
expert from the Institute for Zoology at the University of Vienna in Austria.
“We sent the female spiders to sleep with carbon dioxide, and strapped them down
with tape,” says Schulz. The pair then used a machine to draw silk from the
spider onto a reel.
By chemically analysing male and female draglines, Schulz identified the
chemical components unique to female silk. He painstakingly daubed each female
extract in turn onto male silk, and eventually he found a chemical which made
the males react as if they’d found a female. The substance turned out to be one
not found before in nature, dimethyl citrate, which Schulz has provisionally
named “cupilure”.
In 1993 Schulz isolated the only other spider pheromone, from the tiny money
spider (Linyphia triangularis). But no one knows if all spiders make
pheromones: “That’s an open question,” he says.
John Pickett, an expert in pheromone chemistry at the Institute for Arable
Crops Research in Rothamsted, Hertfordshire, believes that spider pheromones
deserve further study. “The success of this work demonstrates the possibility of
controlling spider behaviour,” he says.
“We could either bring them into crops from natural surroundings to attack
pests, or culture them and control them more effectively,” says Pickett. “And if
people are plagued by noxious or nuisance spiders, they could be lured into
traps outside the house or into a non-killing box indoors from which they could
be freed alive,” he says.
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More at:
Angewandte Chemie (vol 39, p 4339)
