Clastrogenic Instrict of Sodium Bispyribac and Pinoxaden Herbicides on <I>Drosophila melanogaster</I>

Abstract

The present research is attributed to evaluate the genotoxic potential of two herbicides namely Sodium Bispyribac and Pinoxaden, at sublethal level, LC 20 using larval salivary gland polytene chromosomes of Drosophila melanogaster. Standardization of exposure concentration was achieved by exposing second instars larvae of Drosophila to serial dilution concentration of the selected herbicides, for continuum of 24 hours. Thereafter, on the basic of observed mortality in treated and control groups, exact value of LC 20 was calculated by applying probit analysis and the corresponding values are 4.4 pl/ml for Sodium Bispyribac and 7.1pl/ml for Pinaxoden. Subsequently, exposure of standarized concentration was provided to second instar larvae, by mixing specified concentration in culture medium and, simultaneously negative control were also maintained. Third instar larvae were sacrificed for temporary squash preparation of polytene chromosomes and chromosomal complement were scrutinized for various types of structural chromosomal abnormities, in herbicide exposure group and natural population. Procured data indicated that the selected herbicides affected the structural integrity of polytene chromosomes, by inducing intrachromosomal, interchromosomal and telomeric fusions, paracentric inversions, inversion complexes, intrachromosomal and interchromosomal ectopic pairings due to induced homozygocity, chromatid breaks, chromosomal translocations and homologous chromosomal asynapses with respective value with respective number 45.66 ± 6.65 and 21 ± 3.60 in Sodium Bispyribac treated individuals and control, whereas in Pinoxaden treated and controls value 48.64 ± 8.6 and 25.32 ± 3.66 in control group. Subsequently, analysis of procured data, indicated that selected herbicides induced statistical significant genotoxicity in treated individuals in comparison to control groups (p<0.05).