Climate warming and host plant species influence the potential voltinism of the invasive fall webworm Hyphantria cunea in China

BACKGROUND: Climate warming and host plants are key drivers of development, voltinism and outbreak risk of insect pests. This study evaluated the combined effects of temperature and host plant on the potential number of annual generations of the fall webworm, Hyphantria cunea, in China. RESULTS: Developmental durations were determined at constant temperatures of 15, 20, 25, 30, and 35 °C using green ash (Fraxinus pennsylvanica) and Beijing poplar (Populus × beijingensis). Theoretical voltinism under current climatic conditions and warming scenarios of +1.5 °C and + 2 °C was predicted based on estimated lower developmental threshold, thermal constant, and temperature data from China (2010-2020). Hyphantria cunea was unable to complete a generation at 35 °C. Thermal constants were estimated as 707.29 ± 17.17 degree-days on F. pennsylvanica and 647.41 ± 17.02 degree-days on P. × beijingensis. Under current climatic conditions, most regions in China could support two to five generations per year, with slightly higher voltinism on Beijing poplar than on green ash. Climate warming is projected to increase voltinism overall, particularly in southern and low-latitudinal regions. CONCLUSION: Rising temperatures may increase the number of generations and the outbreak risk of H. cunea. Additionally, host plant differences may further modify voltinism by affecting developmental rates. These findings provide a quantitative basis for predicting population dynamics and developing region-specific management strategies under climate change.