Ten-year dynamics of seven major maize pests and recent insecticide resistance status of Ostrinia furnacalis in Henan Province, China

Maize ( Zea mays L.) is not only a major food and feed crop but also a key industrial biomass source for the production of starch, bioethanol, and other bio-based materials. Ensuring its stable production is therefore critical for maintaining reliable raw material supplies for the bioeconomy. However, in Henan Province, one of China’s primary maize-producing regions, frequent pest outbreaks driven by the overlap between maize growth stages and pest occurrence pose serious threats to sustainable maize-based biomass production. This study monitored the occurrence of major maize pests from 2015 to 2024, with annual affected areas ranging from 1.75 to 2.86 million ha for Ostrinia furnacalis , 1.22–1.73 million ha for Helicoverpa armigera , 264–800 Kha for Mythimna separata , 260–697 Kha for Spodoptera exigua , 237–742 Kha for thrips, 60–782 Kha for aphids, and 22–79 Kha for Athetis lepigone . O. furnacalis was the most destructive, particularly during silking and grain-filling stages, while S. exigua showed an increase in prevalence, and thrips, aphids, and A. lepigone declined in abundance. Susceptibility baselines for second-instar O. furnacalis larvae to six insecticides (emamectin benzoate, broflanilide, chlorantraniliprole, indoxacarb, lambda-cyhalothrin, and chlorfenapyr) were established using diet-overlay bioassays with the laboratory strain Of-KY, yielding median lethal concentration (LC 50 ) values of 0.0034, 0.017, 0.034, 0.32, 1.27, and 2.08 mg/L, respectively. Resistance ratios in seven field populations collected from 2023 and 2024 compared to the laboratory strain Of-KY were below 3, indicating sustained susceptibility. However, LC 50 variation among all populations/strains for emamectin benzoate (8.57-fold), broflanilide (7.31-fold), and lambda-cyhalothrin (5.04-fold) indicates elevated variability in susceptibility, warranting continued resistance monitoring. This study provides critical insights into maize pest dynamics and O. furnacalis resistance status of Henan Province, China, offering practical guidance for effective pest management strategies, especially against O. furnacalis . • Decadal dynamics (2015–2024) of seven major maize pests were characterised. • Ostrinia furnacalis remained the dominant maize pest. • Baseline susceptibilities of O. furnacalis to six insecticides were established. • ≥ 5-fold susceptibility variation was detected for emamectin benzoate, broflanilide, and lambda-cyhalothrin.