The impact of dinotefuran application at different concentrations on soil microbial communities in vineyards

Soil microbiomes are essential for grapevine health and vineyard sustainability. Grape phylloxera poses a serious threat to the grape industry, although dinotefuran effectively controls this pest, the concentration-dependent effects of this insecticide on vineyard soil microbial communities remain unclear. Using high-throughput sequencing, this study examined the structural and functional responses of soil bacterial and fungal communities to varying concentrations of dinotefuran. Our results revealed that both 10 and 20% dinotefuran treatments significantly altered bacterial community structure without affecting bacterial alpha diversity. Fungal communities were more sensitive, showing significant structural changes, and significantly reduced alpha diversity (particularly richness) under the 20% treatment. In bacterial communities, high-concentration treatment reduced key soil health and nutrient cycling (e.g., <i>Kaistobacter</i>, <i>Solibacter</i>), and biocontrol (e.g., <i>Streptomyces</i>) group. The 10% treatment retained bacteria with potential ecological remediation (e.g., <i>Nocardioides</i>), whereas the relative abundance of potential stress-adapted bacteria (e.g., <i>Arthrobacter</i>) significantly increased. For fungi, high-concentration treatment reduced beneficial phosphate-solubilizing (e.g., <i>Mortierella</i>) and biocontrol (e.g., <i>Trichoderma</i>) fungi, while potential pathogenic fungal groups exhibited significantly higher relative abundances. Functionally, high-concentration insecticide treatment suppressed beneficial bacterial functions, including secondary metabolite synthesis, lipid metabolism, and microbial group behavior, while also reducing fundamental metabolic and genetic information processing activities. This treatment additionally increased the abundance of pathogenic and saprotrophic fungi, and decreased symbiotic fungi, with the relative abundances of plant pathogens showing a significant increasing under high doses. In contrast, low-concentration treatment enhanced bacterial detoxification pathways, whereas high-concentration treatment activated stress-response functions. These findings elucidate the dose-dependent responses of microorganisms to insecticides, and underscore the critical importance of rational pesticide application in maintaining soil ecological balance and vineyard sustainability.