BURNABY, British Columbia, July 13 (UPI) -- Black widows are deadly -- and destructive. New research suggests male specimens sabotage the webs of females after mating, an attempt to ward off sexual competitors.
Black widows spin messy webs which they use to communicate via vibrations and pheromones. By destroying a female's web, male spiders diminish their one-time mate's ability to attract more males.
According to new research on the phenomenon, the females don't mind the home-wrecking, as it allows them to avoid harassment from males and focus on motherhood.
"The silk pheromones that female black widows produce are like scent-based personal ads," Catherine Scott, a researcher at Canada's Simon Fraser University and lead author of a new paper on the subject, said in a press release.
"One whiff of the pheromone can tell a male about the age, mating history and even hunger level of the female," Scott explained. "These complex chemical messages are just one part of the spiders' communication system, and web reduction is a fascinating behavior that allows a male to interfere with a female's message."
Scott and her colleagues conducted a series of lab experiments during which females are allowed to construct webs inside a glass case. Males were then allowed to visit as they pleased, as researcher observed their behavior.
Intact webs attracted three times as many spiders over the course of several hours than did webs that had already been partially sabotaged by destructive males.
Whatever the males are doing during web reduction is much more effective than simply reducing the amount of silk by half," said Scott. "One possibility is that the female pheromone is concentrated in certain areas of the web, and males are bundling up those specific sections with silk, which stops the pheromone from being released."
Scott thinks the males could also be adding their own pheromones to confuse would-be rivals. She hopes to investigate the possibility in future experiments.
"By reducing the web, the male is not only reducing his chances of competing with other males, he might also be doing the female a favor," Scott added. "Web reduction may be giving her the opportunity to rebuild her web without pheromones and get on with reproduction, rather than wasting time and energy chasing away a parade of redundant male suitors."