Beyond mortality: A fungicide mixture alters physiology and causes impaired behavior in zebrafish

Pesticides have been widely used to ensure high productivity in monoculture systems. However, due to pathogen resistance and the need to improve the safety and sustainability of these substances, new compounds have emerged on the market. One example is pesticide mixtures, which aim to provide a broader spectrum of functionality within a single product. The azoxystrobin- and tebuconazole-based fungicide (ATBF) is a commercial premix fungicide containing two active ingredients. Nevertheless, studies investigating the effects of such mixtures on non-target organisms remain a significant gap in literature. Therefore, the main goal of this study was to investigate the toxicological effects of this fungicide mixture on the physiology and behavior of zebrafish. Developmental exposure (3-120 h post-fertilization [hpf]) to environmentally relevant concentrations was evaluated through assessments of survival, hatching, spontaneous movement, heart rate, and behavior (shoaling and antipredator response). Exposure to ATBF impaired survival, reduced spontaneous movement, altered heart rate, and affected shoaling behavior in zebrafish larvae. These findings highlight the importance of research on pesticide mixtures, as these products may exert additive or synergistic effects on aquatic fauna.