A gustatory receptor mediates sucrose detection to enhance moth reproductive fitness.

The mutualism between pollinators and flowering plants is a fundamental interaction in ecosystems, mediated by nectar rewards. Sucrose, a major component of floral nectar, is a key driver of pollinator foraging, yet the sensory mechanisms underlying sucrose detection are poorly defined. Here we demonstrate that the pollinator Mythimna separata exhibits a strong sex-independent preference for sucrose, which directly enhances reproductive fitness. We identify MsepGR5, a gustatory receptor expressed in antennal sensilla chaetica, as a key receptor mediating sucrose detection. Crucially, genetic ablation of MsepGR5 completely abolishes both sucrose-evoked neural responses and feeding behavior. Our findings uncover a dedicated gustatory pathway for sucrose detection and establish its critical role in reproductive success in M. separata.