Reproductive status modulates colour preference and multimodal cue integration in host plant location by butterflies

Butterflies utilize visual, odour and tactile cues, individually or in combination, to navigate their surroundings and make decisions. The effectiveness of these cues varies based on distance and context. Colour is a crucial visual cue across multiple behavioural contexts, including when searching for oviposition sites. We investigated the multimodal integration of information and its modulation of colour preference in the common emigrant butterfly, Catopsilia pomona. Specifically, we tested their preference towards green colour in different scenarios including during the phase in which they are expected to prioritize finding host plants for oviposition. We offered virgin and mated females and males a choice of four colours including green. We show that mated females prefer green but only in the presence of the odour of their preferred host plant. Virgin females and males, irrespective of mating status, preferred colours other than green. Our results suggest that host plant odour and colour are both salient cues for butterflies, and butterflies use them synergistically to find leaves to oviposit on. The sex-specific preference towards green, and the finding that green is preferred only under some contexts, highlights the adaptive plasticity of colour preferences in butterflies.