Cytogenetic effects of three commercially formulated pesticides on somatic and germ cells of Allium cepa

Cytological effects of Endosri-ES (endosulfan), Nuvan-NU (dichlorvos), and Kvistin-KS (carbendazim) were evaluated on mitotic and meiotic cells of Allium cepa. Test concentrations were chosen by calculating EC50 values of formulated ES, NU, and KS, which turned to be 60, 200, and 500 ppm (parts per million), respectively. Cytological studies were undertaken on root meristem cells of A. cepa using EC50, 1/2 x EC50, and 2 x EC50 of these pesticides for 24 and 48 h. Similarly, a meiotic study was conducted by applying the pesticides at the aforesaid concentrations from seedling to bud stage. A set of onion bulbs exposed to tap water was run parallel for negative control and maleic hydrazide (112.09 ppm) as positive control. During the study period, mitotic index (MI) decreased at all the pesticide concentrations compared to the negative control. Among various chromosomal aberrations, chromatin bridges, breaks, stickiness, laggard, vagrant chromosomes, fragments, C-mitosis, multipolarity, ring chromosome as well as micronuclei were observed in mitotic preparations. In contrast, meiotic aberrations revealed comparatively less frequency of chromosomal aberrations and the most frequent were lagging chromosome, stray bivalents, secondary association, chromatin bridge, disturbed anaphase, and stickiness. Comparative analysis of the pesticides showed that NU was highly toxic to plant cells than KS, while as ES showed intermediate effects between the two. Further, our study revealed that all the three pesticides produce genotoxic effects which can cause health risks to the human populations.