Evaluation of the mutagenic potential of chlorpyrifos (CPF) using polytene chromosomes of Anopheles mosquito

Diverse cytogenetic tests are employed for short term screening of suspect environmental mutagens by using insects and mammals as models. In the present paper the polytene chromosomes of a mosquito Anopheles maculatus were used to evaluate the mutagenic potential of a widely used organophosphate pesticide chlorpyrifos-o, o-diethyl-o-(3, 5, 6-trichloro-2-pyridyl) phosphothioate]. The results are based on the frequency of various structural aberrations encountered in the polytene chromosomes of the larvae treated with LC20 of chlorpyrifos (CPF). These aberrations were dominated by inversions, stickiness of the chromosomes, heterochromatinization of the bands and lack of polyteny. The frequency of various aberrations was highest in the left arm of chromosome number 2L followed by 2R, 3L, 3R, and X-chromosomes i.e. 2.10 +/- 0.44, 1.84 +/- 0.44, 1.57 +/- 0.54, 1.31 +/- 0.50, and 0.22 +/- 0.27 respectively. The susceptibility of different chromosomal arms to this pesticide was 2L > 2R > 3L > 3R > X and the regions prone to these aberrations have been marked on the polytene chromosome map of Anopheles maculatus.