A trap and a lure: dual function of a nocturnal animal construction

Abstract

Animals that use deceptive visual signals to attract prey often employ colour mimicry or bioluminescence but less commonly self-excreted lures. The conspicuous web decorations and silks of some web-building spiders have been shown to visually lure prey in the daytime. However, it remains unknown whether spider webs can also lure prey at night with these self-produced silks. In this study, we tested this hypothesis by manipulating the coloration of the webs of Psechrus clavis and the presence of the web dwellers. We monitored the foraging performance of four treatment groups (spider present, normal web; spider present, blackened web; spider absent, normal web; spider absent, blackened web) and measured the reflectance spectra of spider body parts and web silks. We found that both spider body colour and web silk can lure insect prey at night. Lepidopteran insects comprised the majority of attracted prey. This study is the first to empirically demonstrate that animals can use self-produced substances to visually lure prey in a nocturnal environment and improve foraging success.