Table_4_Neonicotinoid Seed Treatments Have Significant Non-target Effects on Phyllosphere and Soil Bacterial Communities.XLSX

The phyllosphere and soil are dynamic habitats for microbial communities. Non-pathogenic microbiota, including leaf and soil beneficial bacteria, plays a crucial role in plant growth and health, as well as in soil fertility and organic matter production. In sustainable agriculture, it is important to understand the composition of these bacterial communities, their changes in response to disturbances, and their resilience to agricultural practices. Widespread pesticide application may have had non-target impacts on these beneficial microorganisms. Neonicotinoids are a family of systemic insecticides being vastly used to control soil and foliar pests in recent decades. A few studies have demonstrated the long-term and non-target effects of neonicotinoids on agroecosystem microbiota, but the generality of these findings remains unclear. In this study, we used 16S rRNA gene amplicon sequencing to characterize the effects of neonicotinoid seed treatment on soil and phyllosphere bacterial community diversity, composition and temporal dynamics in a 3-year soybean/corn rotation in Quebec, Canada. We found that habitat, host species and time are stronger drivers of variation in bacterial composition than neonicotinoid application. They, respectively, explained 37.3, 3.2, and 2.9% of the community variation. However, neonicotinoids did have an impact on bacterial community structure, especially on the taxonomic composition of soil communities (2.6%) and over time (2.4%). They also caused a decrease in soil alpha diversity in the middle of the growing season. While the neonicotinoid treatment favored some bacterial genera known as neonicotinoid biodegraders, there was a decline in the relative abundance of some potentially beneficial soil bacteria in response to the pesticide application. Some of these bacteria, such as the plant growth-promoting rhizobacteria and the bacteria involved in the nitrogen cycle, are vital for plant growth and improve soil fertility. Overall, our results indicate that neonicotinoids have non-target effects on phyllosphere and soil bacterial communities in a soybean-corn agroecosystem. Exploring the interactions among bacteria and other organisms, as well as the bacterial functional responses to the pesticide treatment, may enhance our understanding of these non-target effects and help us adapt agricultural practices to control these impacts.

叶面和土壤是微生物群落动态的栖息地。非致病微生物群，包括叶片和土壤中的有益细菌，在植物的生长与健康、土壤肥力和有机物质生产中发挥着至关重要的作用。在可持续农业中，理解这些细菌群落的组成、它们对干扰的响应变化及其对农业实践的适应性至关重要。广泛使用的农药可能对这些有益微生物产生了非靶标影响。吡虫啉是一类广泛用于控制土壤和叶面害虫的系统性杀虫剂。一些研究表明，吡虫啉对农业生态系统微生物群落的长期和非靶标效应，但其普遍性尚不明确。在本研究中，我们利用16S rRNA基因扩增子测序技术，对加拿大魁北克省3年大豆/玉米轮作中，吡虫啉种子处理对土壤和叶面细菌群落多样性、组成和时空动态的影响进行了表征。我们发现，栖息地、宿主物种和时间比吡虫啉的应用更能驱动细菌组成的变异，它们分别解释了群落变异的37.3%、3.2%和2.9%。然而，吡虫啉确实对细菌群落结构产生了影响，尤其是在土壤群落（2.6%）和随时间的变化（2.4%）的物种组成上。它们还导致生长季节中期土壤α多样性的下降。尽管吡虫啉处理有利于已知为吡虫啉生物降解菌的一些细菌属，但农药应用导致一些潜在有益土壤细菌的相对丰度下降。其中一些细菌，如植物促生长根瘤菌和参与氮循环的细菌，对植物生长和土壤肥力的提高至关重要。总体而言，我们的结果表明，吡虫啉对大豆-玉米农业生态系统中的叶面和土壤细菌群落产生了非靶标效应。探究细菌与其他生物之间的相互作用，以及细菌对农药处理的机能响应，可能有助于加深我们对这些非靶标效应的理解，并有助于调整农业实践以控制这些影响。