Niche differentiation of two sorghum aphid species: Host leaf ontogeny drives divergent feeding behavior and fitness

BACKGROUND: Aphids are major pests threatening sorghum production, and their population dynamics and feeding behavior are profoundly influenced by host developmental stages and leaf traits. To clarify niche differentiation between Rhopalosiphum maidis and Melanaphis sacchari on sorghum, we combined life table and electrical penetration graph (EPG) techniques to compare their fitness and feeding behaviors across different sorghum leaf niches. RESULTS: The life table experiment included four leaf treatments designed to compare aphid feeding niches: Heart Leaves at Seedling Stage (HL-SS), Old Leaves at Seedling Stage (OL-SS), Heart Leaves at Jointing Stage (HL-JS), and Old Leaves at Jointing Stage (OL-JS), whereas the EPG experiment focused on leaf age effects with two treatments: heart leaf (HL) and old leaf (OL). Results consistently demonstrated distinct niche adaptations between the two aphid species. Rhopalosiphum maidis exhibited optimal fitness only on HL, characterized by the longest lifespan (25.62 days), highest fecundity (F = 51.8 nymphs), and extended reproductive period (15.3 days), while EPG recordings revealed the least mechanical resistance during probing (Total duration of F = 0.33 min), allowing localization of suitable feeding sites. However, it performed poorly on OL. In contrast, M. sacchari showed superior adaptation on OL but the lowest fitness on HL. CONCLUSION: By integrating population performance and feeding behavior, this study reveals that leaf age and plant phenology jointly drive aphid niche differentiation on sorghum. These findings inform sorghum aphid-resistant breeding by emphasizing stage- and leaf-specific resistance evaluation, and support precision aphid management targeting key leaf niches across sorghum developmental stages. © 2026 Society of Chemical Industry.