Evaluation of environmental safety and biological efficacy of ectoparasiticide in tambaqui (Colossoma macropomum)

Author(s)

Isabella Alves Brunetti

• Document type: Master's Dissertation
• Press: Jaboticabal. 2021-01-05.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Ciências Agrárias e Veterinárias. Jaboticabal
• Defense date: 2020-11-11
• Advisor: Maria José Tavares Ranzani Paiva

Abstract

The objective of this study was to evaluate the acute toxicity (LC50 / EC50) of azametiphos for the macrophytes Lemna minor and Azolla caroliniana, for the mollusk Pomacea canaliculata and for the zebrafish fish (Danio rerio); evaluate the acute and chronic toxicity of tambaqui (Colossoma macropomum), perform histopathological analysis in tambaqui after chronic exposure and histopathological and hematological tests after treatment simulation and recovery. Acute toxicity tests were performed with Azolla caroliniana, Lemna minor, Pomacea canaliculata, Danio rerio and Colossoma macropomum all in accordance with ABNT and OECD standards. For chronic toxicity tests, fish were exposed to sublethal concentrations of insecticides for seven days, and organ samples (gills, liver, brain and kidney) were collected for histological evaluation. For the treatment simulation test, the fish were exposed to azametiphos for seven days and after 21 days of recovery, at both times, hematological variables and histopathological changes in the environment (C. macropomum) were evaluated. Azametiphos is slightly toxic to A. caroliniana, moderately toxic to L. minor, C. macropomum and very toxic to P. canaliculata and D. rerio. The chronic sublethal exposure of tambaqui to the insecticide revealed histological changes in gills and liver. After seven days of treatment simulation, the fish showed an increase in total leukocytes, monocytes, lymphocytes and neutrophils. After 21 days of recovery, the fish showed an increase in VCM, HCM and CHCM in relation to the 7 days of treatment. In the histopathological analysis (gill, brain, liver and kidney) at the end of 7 days of treatment, all samples showed changes in relation to the control. After 21 days of recovery, histological analysis showed that the nervous and hepatic tissue showed 100% recovery of cells in all concentrations tested. In the gills, only in the concentrations 0.042 and 0.21 mg L-1 did the gill lamellae recover and the changes in the renal tissue were not recovered. Thus, the presence of azametiphos in aquatic environments can compromise the survival of non-target organisms and impair the functioning of exposed fish organs. The simulation of treatment and recovery with azametiphos demonstrated histopathological changes and does not cause significant hematological changes in tambaqui, with recovery of branchial, nervous, hepatic and blood tissues, in low concentrations. (AU)

• FAPESP's process: 18/16504-1 - Evaluation of environmental safety and biological efficacy of ectoparasiticide in tambaqui (Colossoma macropomum)
• Grantee: Isabella Alves Brunetti
• Support Opportunities: Scholarships in Brazil - Master