Effects of insectide use, host plant resistance, and nitrogen fertilization on the density of Melanaphis sorghi and the production of grain sorghum

Authors: UYI, OSARIYEKEMWEN - University Of Georgia; Ni, Xinzhi; BUNTIN, DAVID - University Of Georgia; TOEWS, M - University Of Georgia

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/31/2025
Publication Date: 4/9/2025
Citation: Uyi, O., Ni, X., Buntin, D., Toews, M.D. 2025. Effects of insectide use, host plant resistance, and nitrogen fertilization on the density of Melanaphis sorghi and the production of grain sorghum. Scientific Reports. Article number 12139. https://doi.org/10.1038/s41598-025-96942-3.
DOI: https://doi.org/10.1038/s41598-025-96942-3

Interpretive Summary: The impact of the invasive sorghum aphid outbreak since 2013 in sorghum production across the southern US states has been devastating, because heavy aphid infestation could cause serious plant damage leading to 100% grain yield loss. Studies aiming to refine the integrated pest management strategies are crucial to improve management of this pest. The current study assessed the impact of nitrogen fertilization, insecticide application methods, and resistant cultivars on aphid density and grain sorghum yield. The two-year field study was conducted at Tifton, GA in 2022 and 2023. Relatively high sorghum aphid infestations were observed on plots with low and high nitrogen fertilization in both years, although 2023 aphid infestation was very low, and no foliar insecticide was applied. In 2022, a single foliar insecticide application immediately reduced aphid infestations below the economic threshold, and in-furrow insecticide application significantly suppressed aphid density throughout the season, as well as improved the grain yield. High nitrogen fertilization increased sorghum yield for both cultivars. The two-year field study showed that manipulating nitrogen fertilization, grain sorghum cultivars and in-furrow and foliar insecticide applications can suppress sorghum aphid population and improve grain yield in sorghum production.

Technical Abstract: Melanaphis sorghi is a serious economically damaging pest of sorghum, Sorghum bicolor (L.), across the southern USA. Therefore, developing, and refining technologies that provide effective control is key to the management of this pest. Here, the authors investigated the influence of nitrogen (N) fertilization, sorghum cultivar and insecticide applications on M. sorghi and grain sorghum yield at Tifton, Georgia (31.5120° N, 83.6434° W). Field trials with three insecticide treatments (untreated, flupyradifurone in-furrow at 117 g/ha, flupyradifurone in-furrow at 146 g/ha, and flupyradifurone foliar at 73 g/ha), three nitrogen fertilization rates (25, 50 and 100 kg/ha) and two sorghum cultivars (resistant: DKS37-07 and susceptible: DKS53-53) were conducted on grain sorghum in the spring/summer of 2022 and 2023. Low and high N fertilization supported higher aphid density and severity of infestation [cumulative insect days (CID)] on both the susceptible and resistant cultivars in both years. Aphid density and severity of infestation on the susceptible sorghum cultivar (DKS53-53) were 3.4- to 4.8-fold greater than on the resistant cultivar (DKS37-07) for both low and high N fertilization plots in 2022. While a single foliar and in-furrow insecticide application significantly reduced infestations below the economic threshold across all treatment combinations in 2022, aphid population was too low to warrant foliar application in 2023. Nitrogen fertilization was associated with improved yield as the high N fertilization plots preserved yield for both sorghum cultivars. Compared to untreated plots, in-furrow and foliar insecticide applications supported greater grain sorghum yield across all insecticide treatments only in 2022. The study suggests that manipulating N fertilization, sorghum cultivars and in-furrow (IF) and foliar insecticide application can help suppress aphid infestations and improve grain yield in sorghum production in southern USA.