Factors affecting the difference in foraging success in three co-existing Cyclosa Spiders



Species-specific differences in prey-capture success of co-existing web-building spiders are derived from complex factors: various web parameters, web placement, and the spider's response to prey. By examining these, this study revealed prey-capture modes of three species of web-building spiders of the genus Cyclosa living in the same habitat. Cyclosa octotuberculata and C. argenteoalba showed a greater prey capture rate than C. sedeculata, though size compositions of prey were similar in all species. Cyclosa octotuberculata spins thick silk with large adhesive droplets, which may contribute to the higher stopping and retention abilities of the web. Cyclosa argenteoalba constructs webs at open sites where prey is abundant, and has webs of dense mesh size, which may result in the high stopping ability of webs. In C. sedeculata, the web is less effective for stopping and retaining prey, probably owing to the thin silk with a small amount of sticky material, and the response to prey is not rapid. It seems that the former two species achieve a similar level of foraging success by using different sets of foraging traits and the third species has the disadvantage in most aspects of foraging.