ORIGINAL ABSTRACT

Wild populations of Caiman latirostris in South America are potentially exposed to complex mixtures of pesticides used in agricultural practices. These contaminants can disrupt physiological processes, including reproductive success and breeding performance. This study evaluated the effects of 60-day sub-chronic exposure in caiman yearlings to four commercial pesticide formulations: glyphosate (GLY; 2%), 2,4-dichlorophenoxyacetic acid (2,4-D; 0.12%), imidacloprid (IMI; 0.2%), chlorantraniliprole (CAP; 0.03%), and mixtures: M1 (GLY 1% + 2,4-D 0.06%), M2 (IMI 0.1% + CAP 0.015%), and M3 (M1 + M2) compared to a negative control (NC) group. Blood samples were collected after exposure to analyze the frequency of micronuclei (FMN), lipoperoxidation levels, hematological and biochemical parameters, as well as body condition (BC). Our outcomes revealed significant disruptions across key physiological systems, including genotoxicity, higher lipoperoxidation, immune cell alterations, shifts in metabolites (triglycerides, albumin, total protein, glucose, cholesterol, lactate dehydrogenase) and hepatic enzyme activities (glutamate pyruvate and glutamate oxaloacetate transaminases), alongside impairment in BC in mixtures compared to NC and their respective individual components. The Integrated Biomarker Response index further revealed that mixtures, particularly M2 and M3, elicited the most complex and amplified physiological disruptions. These findings suggest that agrochemical mixtures compromise the capacity of this species to respond to adverse environmental conditions, potentially reducing fitness and reproductive performance, thereby threatening the viability of wild populations. Our study highlights the value of biomarker-based assessments for understanding pesticide impacts on wildlife, recognizing the organism as an integrated system that may exhibit distinct responses to contaminant mixtures.