Evaluation of Genotoxic and Cytotoxic Effects of a Botanical Insecticide on Root Meristematic Cells of Allium cepa

Cytogenetic and genotoxic effects of a commercial formulation of a botanical insecticide (Neemarin 10000 ppm) containing azadirachtin as an active ingredient was investigated on ischolar_main meristem cells of onion, Allium cepa. Different test concentrations (0.25, 0.5, 1.0, 2.5, 5.0 mg/l) were selected after determining the EC₅₀ value (2.58 mg/l) of the insecticide on Allium ischolar_main growth length. The ischolar_mains of Allium cepa were exposed to these concentrations, for 12 and 24 hours respectively and mitotic index (MI) and micronucleus (MN) frequency in ischolar_main meristem cell were determined in both control and test groups. The insecticide showed a depressive action on mitosis in ischolar_main meristem cell of Allium cepa, which was indicated by the decrease in MI with increasing concentrations and time of exposure. Significant induction in formation of micronucleus was found in ischolar_main meristem cell of Allium cepa exposed to different concentrations of the insecticide in comparison to the control. The pronounced MN frequency of 2.57 was observed at 2.5 mg/l concentration of the insecticide after 24 hrs of incubation. Thereafter, at the elevated concentrations of the insecticide, there was steady decrease in MN frequency that might be due to the greater physiological damage of the cells by the higher concentration of insecticide.