Investigation of the toxic effects of a carbamate insecticide methiocarb in Allium cepa L.

In this study, the toxic effects of Methiocarb insecticide were investigated in Allium cepa L. test material. Physiological effects were investigated with germination percentage, root length measurement and weight gain parameters; Cytogenetic effects were analyzed with micronucleus (MN), chromosomal damage and mitotic index (MI). For this aim, A. cepa L. bulbs were divided into four (4) groups, one (control) and three (3) applications; the bulbs in the control group were tap water; the bulbs in the application group were treated with 2.5 mg L-1, 5.0 mg L-1 ve 7.5 mg L-1 doses of Methiocarb for 72 hours. In conclusion, Methiocarb administration caused a decrease in physiological parameters compared to the control group. In bulbs exposed to a dose of 7.5 mg L-1 of Methiocarb, the germination percentage decreased by 64%, root length by 29% and weight gain by 21% compared to the control group. Methiocarb administration caused an increase in the number of MN and chromosomal damage and a decrease in MI. The number of MN in the root cells exposed to 7.5 mg L-1 of Methiocarb was increased 172-times compared to the control group and the MI value decreased by 1.69-times. Methiocarb administration has promoted chromosomal damage such as fragment, sticky chromosome, bridge, unequal distribution of chromatin and vagrant chromosome in root tip cells. As a result, Methiocarb caused toxic effects, and A. cepa L. test material was found to be a useful bio-indicator for monitoring these effects.