Galactose, glucose, and sucrose mediate the host acceptance of Hyphantria cunea (Lepidoptera: Erebidae) larvae

Hyphantria cunea (Drury) is an invasive polyphagous pest, yet the chemical basis of its larval host acceptance is unclear. Here, we integrated behavioral assays and non-targeted metabolomics to identify key phagostimulants influencing larval host acceptance of H. cunea. Our results exhibited the highest level of acceptance toward Camptotheca acuminata Decne. compared with Populus deltoides W.Bartram ex Marshall, Prunus serrulata Lindl, Taxodium distichum (L.) Rich, and Camphora officinarum Nees, which was significantly correlated with leaf soluble sugar content. Through two-choice assays, we identified galactose, sucrose, and glucose as key phagostimulants that induce feeding acceptance, with effective thresholds of 10, 1, and 10 mM, respectively. In addition, ablation of sensilla styloconica in maxillary galea led to the reduction of larval perception for sucrose and glucose by 19.3% and 14.1%, indicating gustatory mechanism involved in perception for these 2 sugars, while galactose-induced phagostimulatory effect is mediated by other pathways. Our findings establish that these specific sugars serve as critical gustatory cues driving larval host acceptance of H. cunea, laying the groundwork for understanding its rapid host adaptation.