Residual dynamics of thiamethoxam and tebufenozide insecticides and their differential temporal effects on soil microbial communities

BACKGROUND Pesticide residues alter soil microbial communities by interacting with abiotic and biotic soil components. This study investigated the residual dynamics of two insecticides, Thiamethoxam (Thi) and Tebufenozide (Teb), in apple orchard soils, as well as their effects on soil microbial communities after 1 day (1d) and 14 days (14d) exposures. RESULTS Both insecticides degraded following the first‐order kinetic equation, with significant reductions in residual concentrations after 14d exposure. Thi treatment increased the feature number and richness of bacterial communities after 1d exposure and then returned to baseline levels after 14d exposure, while the feature number and richness of fungal communities decreased significantly after both 1d and 14d exposure. Furthermore, the pathways enriched in soil microbial communities showed a similar pattern to the diversity of soil microbial communities after 1d and 14d Thi exposure. However, Teb treatment had less effects on bacterial and fungal communities after 1d and 14d exposure. The pathways enriched in bacterial communities increased transiently after 1d Teb exposure and then declined to baselines after 14d Teb exposure. Meanwhile, the pathways enriched in fungal communities were the highest after 14d Teb exposure. Among TOP 20 soil microbial taxa, Thi and Teb treatments exerted stronger effects on fungal communities than on bacterial communities. Fungal components, potentially involved in the pesticide degradation, showed a transient decline after 1d Thi exposure but a sustained rise from 1d to 14d Teb exposure. CONCLUSION Two insecticides had different effects on soil microbial communities, depending on the insecticide type and exposure duration.