Do carnivorous plants exploit prey perceptual bias? A case study in Drosera finlaysonii with yellow-green traps

Abstract

Perceptual biases—disproportionate sensory responses to specific stimuli—are widespread in animals and can be exploited by predators to attract prey. However, this mechanism has not been rigorously tested in carnivorous plants. We investigated whether the yellow-green traps of Drosera finlaysonii (Droseraceae) exploit hemipterans’ preference for yellow to yellow-green stimuli that strongly activate green relative to blue photoreceptors. Using multispectral imaging, we quantified trap brightness and modelled the green-to-blue photoreceptor activation ratio (G/B ratio) of hemipteran prey. We characterized the taxonomic composition of prey captured by D. finlaysonii and deployed adhesive models differing in brightness and G/B ratio. We then compared arthropod assemblages between plants and models, and taxon-specific capture numbers among models. D. finlaysonii traps were brighter and had higher G/B ratios than sympatric graminoid leaves. Hemiptera were a major prey component, although their relative abundance varied between years. Yellow models, with the highest G/B ratio, captured more hemipterans than other colour models. However, arthropod assemblages captured by D. finlaysonii differed from those captured by yellow models, with proportionally more dipterans and fewer hemipterans. Thus, a high G/B ratio may contribute to hemipteran attraction and capture but cannot alone explain the overall prey assemblage in D. finlaysonii.