The fate and ecological risk of typical diamide insecticides in soil ecosystems under repeated application

Diamide insecticides are the third most widely used class of pesticides worldwide. However, the long-term impacts of repeated diamide applications on soil ecosystems remain unclear. This study investigated chlorantraniliprole (CLP) and cyantraniliprole (CYP) effects on soil ecosystems through simulated repeated exposures. Results showed both exhibited slow degradation in the soil, with repeated applications extending their persistence, particularly for CLP. Both significantly inhibited soil alkaline nitrogen and organic matter accumulation, while reducing urease and sucrase activities, with CLP exerting stronger inhibitory effects. Metagenomic analysis indicated that CLP and CYP notably reduced soil microbial diversity. Additionally, the two insecticides altered the soil microbial community structure and inhibited carbon-nitrogen metabolic pathways. Further analysis revealed that CLP treatment significantly decreased the relative abundances of Mesorhizobium and Marmoricola, whereas CYP treatment primarily reduced Clostridium_sensu_stricto_1. All of these genera exhibited significant positive correlations with key metabolic pathways in soil carbon and nitrogen cycling. Notably, the relative abundance of Sphingomonas increased significantly following CLP and CYP treatments, demonstrating potential degradation capabilities. Overall, both CLP and CYP posed ecological risks to soil ecosystems, with CLP exhibiting more severe impacts. These findings revealed the need for strengthened scientific management in actual production.