Protocolo de análise toxicológica de inseticidas botânicos: efeitos da formulação microencapsulada do extrato etanólico de Annona muricata L. annonaceae em tilápia do Nilo

Abstract

Toxicological studies have become more and more frequent due to the growing concern about the effects on the environment and on non-target organisms. This increased attention is also related to the increased adoption of alternatives, such as the use of botanical insecticides in agriculture. This concern is accentuated by the absence of specific legislation that establishes parameters for the use of these products, which implies the lack of defined toxicological limits. In view of this, the objective was to evaluate possible toxic effects of the microencapsulated formulation of ethanolic extract of Annona muricata L (Annonaceae), a product with a patent already granted (BR102018008313-9), on fingerlings of Nile tilapia, Oreochromis niloticus (Linnaeus, 1758) (Cichiformes: Cichilidae). Acute and chronic toxicity tests were performed, with tilapia fingerlings approximately 30 days old with measuring on average between 1.5 and 3.0 cm, which were exposed to concentrations to increasing concentrations 0.125; 0.250; 0.500; 1.0 and 2.0 g/L of the formulation for 24 and 96 hours. As well as biochemical parameters with antioxidant enzymes. Based on the mortality results, the concentration values that kill 50% of the evaluated population (CL50), obtained by Probit analysis by SAS, resulting in 0.229 and 0.249 g/L in 24 and 96 hours, respectively. The enzymatic activity of superoxide dismutase (SOD) and glutathione S-transferase (GST) was quantified in the liver and gills and acetylcholinesterase (AChE) was quantified in the brain of O. niloticus. ANOVA statistical analysis showed differences only for SOD and GST activities in the liver. Despite that, when individuals were exposed to the two highest concentrations 1.0 and 2.0 g/L, they showed mortality rates of 93.33 and 100%, respectively, after 24 hours of exposure. Mortality likely stemmed from disturbance of the animal and alterations to its natural habitat. This is because the results of enzymatic activity and Acetyl analysis were positive when compared to the estimated LC50 value. Therefore, since toxicology is a weakness in the promotion of alternative products, more studies are needed in the area of natural products, such as extracts and oils.

Keywords: insecticides plants; microencapsulation; Oreochromis niloticus; ecotoxicology; oxidative stress.