Yellow, black pattern helps orb weaver spiders trap prey

Feb. 11 (UPI) -- The color yellow and coloration patterns featuring yellow and black are common among orb weaver spiders that build their webs in lighter environs. However, orb weaver species that live in dark environs, like caves, rarely evolve yellow coloration.

Now, scientists know why.

Tests featuring cardboard cut-out models of the golden orb-weaver, Nephila pilipes, showed the color yellow and black-and-yellow patterns are quite effective at luring prey.

There are more than 45,000 species of spider in the world, and 12,500 species, 28 percent, are orb weavers. Orb weavers build big nests and camp out in the middle of them, waiting for prey to become entwined in their threads.

Most studies of the evolution of coloration don't consider the influence of prey on predators. Usually, it's the other way around.

"Our research addresses a surprisingly neglected topic in visual communication," Po Peng, zoologist at the University of Melbourne, told UPI in an email. "Typically, studies of this topic focus on how specific receivers shape sexual signals, or how predators shape the protective coloration of prey -- warning signals and camouflage."

For the new study, Peng and his colleagues replaced real orb weaver spiders in the wild with differently colored spider models. Scientists captured hours and hours of model-prey interactions in a variety of light conditions.

"We reviewed the videos and recorded attraction events, which were defined as events where either the prey flew toward or physically contacted the model spiders, or the prey were intercepted by the webs," Peng said.

The natural yellow and black colored models proved most effective at attracting prey.

Researchers found yellow coloration works to attract prey both during the day and at night. Previous studies have shown many insects can perceive the color yellow in dim lighting.

Scientists suspect insects are attracted to yellow because of its association with flowers.

"Chromatic properties of various floral parts play important roles in the signalling efficacy of flowers to pollinators , where yellow centers or yellow pollen are common attributes of flowers," Peng said. "Because nectar could represent food resources for insects, the inner parts of many flowers resemble the color of pollen."

Researchers published their study of orb weaver coloration this week in the journal Functional Ecology.