Tactile active sensing in an insect-plant pollinator

The interaction between insects and the flowers they pollinate has driven the evolutionary diversity of both insects and flowering plants, two groups with the most numerous species on Earth. Insects use vision and olfaction to localize host plants, but we know relatively little about how they find the tiny nectary opening in the flower, which can be well beyond their visual resolution. Especially when vision is limited, touch becomes crucial in successful insect–plant pollination interactions. Here, we studied the remarkable feeding behavior of crepuscular hawkmoths Manduca sexta, which use their long, actively controlled, proboscis to expertly explore flower-like surfaces. Using machine vision and 3D-printed artificial flower-like feeders, we revealed a novel behavior that shows moths actively probe surfaces, sweeping their proboscis from the feeder edge to its center repeatedly until they locate the nectary opening. Moreover, naive moths rapidly learn to exploit these flowers, and they adopt a tactile search strategy to more directly locate the nectary opening in as few as three to five consecutive visits. Our results highlight the proboscis as a unique active sensory structure and emphasize the central role of touch in nectar foraging insect–plant pollinator interactions.

昆虫与其传粉花卉之间的互作，驱动了地球上物种丰度最高的两个类群——昆虫与显花植物的演化多样性。昆虫依靠视觉与嗅觉定位寄主植物，但我们对它们如何定位花卉中尺寸远超其视觉分辨率的极小蜜腺开口却所知有限。尤其在视觉受限的场景下，触觉在昆虫-植物传粉互作的成功完成中发挥着决定性作用。本研究以晨昏性烟草天蛾（Manduca sexta）为研究对象，剖析其非凡的取食行为：这类天蛾借助细长且可主动操控的喙（proboscis），精准探索仿花表面。研究团队借助机器视觉（machine vision）与3D打印的人工仿花喂食器，揭示了一种全新的行为模式：天蛾会主动探查表面，反复将喙从喂食器边缘扫向中心，直至定位到蜜腺开口。此外，无经验的天蛾可快速学会利用这类花卉，并在仅3至5次连续造访后，便会采用触觉搜索策略以更直接地定位蜜腺开口。本研究结果凸显了喙作为一种独特的主动感觉结构的特性，并强调了触觉在花蜜觅食型昆虫-植物传粉者互作中的核心地位。