Spiders Love Sweet Smell of Blood Perfume

By Susan Milius, Science News

This takes the pre-kiss breath mint into new territory. Certain jumping spiders prefer partners that have recently dined on blood-fed mosquitoes.

Engorged-mosquito breath proves attractive to both males and females among Evarcha culicivora jumping spiders, says spider biologist Fiona Cross of the University of Canterbury in Christchurch, New Zealand. She and her colleagues tested the preferences of both spider sexes by timing how long they lingered in a stream of air wafting over potential mates that had different dining histories.

This species, native to East Africa, is the only animal known to feed on vertebrate blood indirectly, Cross explains. The spiders don’t do the blood sucking themselves but seek out mosquitoes that have bitten vertebrates.

E. culicivora will eat non-bloody prey too, so Cross and her colleagues offered lab spiders whiffs of potential mates that had been fed various meals such as male mosquitoes (which don’t draw blood) and sugar-fed female mosquitoes. Spiders showed less interest in these alternatives than in the indirect blood feeders.

The mosquito allure wasn’t the pull of delicious blood alone, the researchers found. Same-sex spiders didn’t attract more attention even after eating a romantic blood-carrier dinner.

Cross presents a hypothetical human version of spider dating in which eating chocolates changes human body odor. But “it would only be the people who ate the chocolates with particular centers who smelled particularly attractive,” she says.

A spider’s food odors may give clues to its potential quality as a mate, the researchers suggest. One question the allure of blood perfume raises is whether an indirect blood diet enhances spider egg or sperm production, they say. Cross and her colleagues describe their results online October 26 in Proceedings of the National Academy of Sciences.