Sequential multimodal sensory integration drives foraging decisions in leaf-cutting ants: Volatiles, contact cues and phytochemistry

Identifying the sensory cues that enable insects to find host plants, and understanding the neurobiology underlying their selection, provide solid foundations for developing state-of-the-art pest management strategies. Our work was aimed at identifying the main sensory cues attracting the leaf-cutting ant Acromyrmex ambiguus to alternative host plants in commercial willow plantations in the Lower Delta of the Parana River (Argentina), with a focus on native plant species. Eight plant species were selected and evaluated as potential hosts under field and laboratory conditions, allowing the establishment of a robust hierarchy of preference based on individual and collective behaviour. As a result, Senna corymbosa emerged as the most preferred species, whereas Blepharocalyx salicifolius was the least preferred. Video analyses of ant foraging in controlled indoor nests revealed a sequential decision-making process underlying plant preference and consumption. This included an initial approach driven by olfactory cues, followed by a second step involving contact-dependent cues that elicited leaf-cutting and carrying the leaf fragments to the nest. Volatile compounds and leaf cuticular components potentially involved in plant preference were identified. In addition, physicochemical analysis of both plant species - including total sugars, organic matter, polyphenols, leaf hardness, total proteins and lignin- revealed differences, particularly in polyphenol content, which may contribute to preference patterns. These findings provide insights into the sensory ecology of host preference and inform management strategies based on the reintroduction of native plants as alternative resources in willow plantations, potentially reducing pesticide use and promoting environmental sustainability.