Unravelling the Impact of Next-Generation Pesticide and Abiotic Factors: Multi-Model Insights into Population Structure of benthic oligochaete at Environmentally Relevant Exposures

The ecological consequences of next-generation pesticides, such as emamectin benzoate (EMB), in aquatic systems under varying environmental conditions remain poorly understood, particularly for non-target benthic organisms like Tubifex tubifex . A full factorial composite toxicity analysis approach (FCTA) was developed with EMB ( 0.01 ∼ 0.5 mg/L ) under diverse pH ( 6 ∼ 8 ), organic matter ( 0.5 ∼ 2.5 % ), temperature ( 15 ∼ 30°C ), hardness ( 50 ∼ 250 mg/L ), and light intensity ( 300 ∼ 1800 lux ) based on field-relevant concentrations from five sampling sites to identify significant effects and interactions (e.g., EMB, EMB:Temperature) on response variables (juvenile mortality, adult mortality, individual cocoon production, metabolic rate, autotomy % and relative weight loss). Effect modification scores revealed more than additive interactions, notably EMB:pH and EMB:Hardness:Temperature, influencing mortality and stress responses. Structural equation modeling (SEM) integrated these findings into a causal framework and producing latent variables (e.g. population decline risk), achieving good fit ( CFI = 0.925, RMSEA = 0.052, χ 2 (30) =35.214, p = 0.234 ). Bayesian network (BN) analysis extended the SEM results into a probabilistic model, enabling scenario-based predictions under three climate change scenarios: global warming, freshwater acidification, and their combined effects. Our findings underscore the synergistic effects of next-generation pesticides and abiotic stressors, informing targeted conservation strategies for aquatic ecosystems. Our integrative approach-combining FCTA, SEM, and BN-pioneers the assessment of interactive effects between next-generation pesticides and environmental factors on freshwater macroinvertebrates, providing critical insights for developing targeted conservation strategies to mitigate impacts on aquatic ecosystems.