BEHAVIORAL RESPONSES OF THE RIVULID FISH HYPSOLEBIAS FLAGELLATUS TO EXPOSURE TO THE PESTICIDES IMIDACLOPRID AND TEBUCONAZOLE

• Grant number: 25/22250-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: January 01, 2026
• End date: December 31, 2026
• Field of knowledge: Biological Sciences - Ecology - Applied Ecology
• Principal Investigator: Raquel Aparecida Moreira
• Grantee: Samantha Poleti Xavier
• Host Institution: Faculdade de Zootecnia e Engenharia de Alimentos (FZEA). Universidade de São Paulo (USP). Pirassununga , SP, Brazil
• Associated research grant: 22/12104-4 - Fate and impacts of microplastics and pesticides in aquatic and terrestrial matrices in agricultural contexts, AP.TEM

Abstract

The population decline of freshwater fish has intensified in recent decades, reflecting anthropogenic activities on aquatic ecosystems. It is known that currently, about one-quarter of the fish population is threatened with extinction, a situation that is closely related to pollution, habitat fragmentation, the introduction of invasive species, and the indiscriminate use of chemicals such as pesticides, which enter water bodies through surface runoff, profoundly altering the physiology and development of native species. In this context, the research will address whether behavioral responses, such as swimming (involving parameters such as maximum speed and distance traveled), escape capacity, aggression, and predation ability in rivulid fish - specifically in the species Hypsolebias flagellatus, typical of the Brazilian Cerrado - are altered when exposed to the insecticide Imidacloprid and the fungicide Tebuconazole, both separately and in combination (the two pesticides together). Both Imidacloprid and Tebuconazole are widely used and marketed in Brazil, but they have distinct functions, properties, and mechanisms of action. The former is used to control and eliminate insect pests in crops, while the latter affects fungi by causing the loss of cytoplasmic elements, leading to their death. Both chemicals are classified by the Ministry of Agriculture, Livestock, and Supply as highly toxic to the environment. The test organism chosen, H. flagellatus, belongs to the Rivulidae family and is native to the Neotropical region. It is commonly known as the "cloud fish" due to its unique life cycle. The fish lay their eggs on the substrate, which undergoes a period of diapause and only hatch when environmental conditions become favorable, typically during the rainy season. Because of this, the species is highly vulnerable to environmental changes. The methodology for the tests will include analyzing stress levels related to potential behavioral responses, divided into two processes: the first involves non-forced exposure to contaminants (evaluating escape capacity), and the second involves forced exposure (evaluating swimming, predation, and aggression). In both cases, the fish will be exposed to different sublethal concentrations of pesticides at environmentally relevant levels. Finally, it is worth highlighting that, in addition to being highly sensitive to ecosystem changes, some species of the Rivulidae family are at risk of extinction in certain regions due to the loss of their habitats and spatial distribution. Therefore, this research will contribute to a better understanding of the effects of chemical pollution from pesticides on such a unique species, which is still little studied in ecotoxicological research, potentially informing conservation actions for its preservation.