A bridegroom in red: function of body coloration of male giant wood spider Nephila pilipes

Prey attraction hypothesis had been tested on many orb web spider species in recent years, and the results show that conspicuous coloration of spiders may attract insects to the webs. However, all of these studies focus on female spiders rather than males. After reaching maturity, male spiders behave differently from females, so the body coloration of male spiders probably functions in ways different from that of female spiders . Male Nephila pilipes is conspicuous orange-red color and it seldom build its own web after reaching maturity but lives on female’s web waiting for copulating with female. I hypothesize that the conspicuous coloration of male N. pilipes may attract insects to female’s web and then increase the web site tenacity of female to increase male’s opportunity of mating. I manipulated the coloration of male N. pilipes and monitored the webs with male spiders by video cameras day and night and I also recorded the number of days a female stayed in a particular web site. In order to confirm if the attraction effect was caused by coloration instead of other factors, I made spider dummies resembling male N. pilipes in appearance and color. Results showed that the conspicuous coloration of male N. pilipes attracted insects to female’s web during day time, and similar results was found in dummy experiment. However, the prey attraction effect did not increase the web site tenacity of female spiders. Results of my study demonstrate the attraction function of body coloration of male N. pilipes. More researches are needed to realize the factors facilitating the evolution of conspicuous body colors in male N. pilipes.