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

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.