Avaliação dos efeitos adversos da exposição ao agrotóxico metomil nos estágios iniciais de desenvolvimento do zebrafish (Danio rerio)

Abstract

Pesticides are primarily defined as chemical, physical, or biological substances that act in the control of living organisms considered harmful to agriculture, domestic animals and human. Currently, Brazil is one of the largest food producers and exporters in the world and (consequently), the largest consumer of pesticides worldwide. As a large producer, Brazil has substantial areas of land destined for this purpose. Agricultural management for mass food production include the use of such substances, raising environmental risks concerns on natural resources and biota that may become contaminated with these xenobiotics. In this sense, use of model organisms to assess risks in vivo is essential and a main characteristic of ecotoxicology field. In this work, lethal and sublethal effect of the carbamate insecticide methomyl commercial formulation exposure in zebrafish embryos and larvae. The 96h-LC50 was determine and then, sublethal concentration ranges specified. Sublethal exposures were analyzed in terms of survival; hatching; spontaneous tail coiling (STC); heart rate; morphology; locomotor behavior and acetylcholinesterase (AChE) activity and ache gene expression. Methomyl exposure affected almost all morphological parameters, resulting in larvae with smaller body and eyes size and swimming bladder inflation failure. Behavioral parameters also presented significant changes: shorter traveled distance, speed, maximum acceleration; greater latency to enter the periphery, less frequency of change between zones, higher absolute turn angles and meanders. In addition, AChE activity decreased in a concentration-dependent manner, while no changes in ache gene expression were observed. Together, results corroborate that the (neuro)toxic effect of methomyl, and its potential to alter essential biological parameters for the survival of non-target organisms, even in sublethal concentrations.