Association of Different Host Diets with the Nutritional Composition of the Fall Webworm, Hyphantria cunea Drury (Lepidoptera: Erebidae)

Different host plants influence the nutritional and metabolic profiles of the fall webworm (Hyphantria cunea), a globally invasive pest. This study investigated the proximate composition, free amino acid and lipid profiles of its pupae from larvae reared on three distinct diets (Robinia pseudoacacia, Morus alba and Armeniaca sibirica). The results showed that pupal weight and size varied significantly with host plant. The pupae contained 64.94 ± 1.57% crude protein and 30.82 ± 0.53% crude fat (dry mass basis), with high levels of magnesium and calcium. A total of 82 free amino acids and their metabolites were identified, including all essential and non-essential amino acids. In addition, 1026 lipids were detected, with triacylglycerols as the predominant class. Notably, the levels of linoleic and α-linolenic acid were highest in the pupae fed on R. pseudoacacia. Among the three diet groups, the lipid species TG (16:0_16:2_20:5) was identified as a characteristic differential metabolite. These findings show that host-plant-induced nutritional variation reflects metabolic plasticity, which underlies the dietary adaptability and invasion success of this polyphagous pest and also suggestsits potential use as a feed ingredient.