Toxicologia em Allium cepa (Amaryllidaceae) submetido a ensaio agudo com um inseticida utilizado no combate a dengue

Abstract

Aedes aegypti is the mosquito that transmits Dengue, Zika Virus and Chicungunya Fever. These diseases reach billions of people around the world and are mainly linked to the tropical regions. Despite important advances in the development of alternative measures for mosquito control, chemical insecticides still remain the main method of integrated control programs. In this way, the present work will evaluate the toxicology in the bioindicator Allium cepa (Amaryllidaceae) submitted to an acute test with the insecticide Malation, currently used in the control of the mosquito Aedes aegypti. Tests of genotoxicity, mutagenicity and cytotoxicity in meristematic cells of Allium cepa were performed according to the protocol established by Grant (1982) with adaptations. The insecticide Malation, with purity of 99.9%, of the brand Sigma- Aldrich (PESTENAL®), which has as active ingredient Malationa. This insecticide belongs to the chemical group of organophosphates and toxicological classification II (highly toxic). For the tests with Allium cepa, two concentrations of the insecticide Malation were prepared. The first concentration was 1.0 mg / mL, corresponding to a concentration greater than the indicated minimum of the active product for use in cultures. The second concentration was obtained from the first in a dilution in distilled water, in the proportion of 1:1, which resulted in the lower concentration: 0.5 mg / mL. The slides were analyzed under a light microscope, with a 40-fold objective, traversing the fields of observation so as not to repeat them. Chromosomal aberrations (genotoxicity), micronuclei frequency (mutagenicity) and mitotic index (cytotoxicity test) were evaluated for each treatment. Ten slides per treatment were analyzed and 1000 cells of each were counted, totaling 10,000 cells per treatment. Of the CAs found, the anaphase bridges had the highest incidence, and a significantly higher rate was observed at the concentration of 0.5 mg / mL, even when compared to the positive control. The treatment containing the 1.0 mg / mL concentration also showed a significant increase in the number of bridges compared to the negative control, and an equality, compared to the positive control. Our results suggest that DNA-induced aggressions, due to the lower concentrations tested for malathion, occurred because they induce a greater number of divisions, and have a higher permeability in the cells because they are in more diluted concentrations. Malation was shown to have cytotoxic effects under A. strain at the concentrations tested. The mutagenicity and genotoxicity tests performed in this work indicated that this insecticide has clastogenic properties on exposed organisms.