Study Finds Male Black Widow Spiders Prefer Well-Fed Virgins

Posted on April 23, 2014

University of Toronto Scarborough have found that male black widow spiders prefer to mate with well-fed virgins. The study, authored by UTSC post-doc Emily MacLeod and Maydianne Andrade, a professor in UTSC's Department of Biological Sciences, found in both controlled field studies and the wild that males overwhelmingly chose to mate with well-fed, unmated females. The researchers also determined that male black widows can tell whether a potential mate is well-fed and unmated by pheromones released by the females. A female black widow is pictured above.

MacLeod says in a release, "This near unanimous preference by males for well-fed mates using only phermonal cues has not been documented in any other spider species. These are not visual or auditory cues they are picking up but smells they are sensing, often from far away."

One reason for the well-fed preference is that a hungry female might try to eat them. Males of the Latrodectus Hesperus black widow species are much smaller than the female, so they are vulnerable if the female is hungry. The researchers note that if the female is hungry her drive to feed will be greater than her drive to reproduce. Another reason for the well-fed preference is that mating with a fatter female may result in more offspring.

Andrade says, "It's important to remember that when a female eats a lot of prey, she's less likely to eat a potential mate."

The research was published here in the journal Animal Behaviour.

SPIDERS