Abstract

Pesticides use boosts agricultural yield by reducing crop losses. However, some pesticides are mutagens and active ingredients could produce different effects in different formulations. Wipe-out (WO) (Glyphosate 360 g/l), K-O Gard® (KOG) (Deltamethrin 10 g/l), Cutworm bait (CWB) (Sodium Fluosilicate, 100 g/kg), Snail ban (SB) (Metaldehyde, 30 g/kg and Carbaryl, 20 g/kg) and Coopex (CPX) (Permethrin 250 g/kg) were tested for cytotoxicity and genotoxicity using the onion (Allium cepa) test. Onion seeds were germinated and exposed (mg/l) to below EC₅₀ values of WO (78.1, 156.3, 312.5), KOG (156.3, 312.5, 625.0), CWB (78.1, 156.3, 312.5), SB (156.3, 312.5, 625.0), and CPX (312.5, 625.0, 1250.0) for 24 h. Root tips were cut, fixed, hydrolyzed in 1 N hydrochloric acid, stained, squashed and observed microscopically. Cytotoxicity and genotoxicity induction at each treatment was compared with the negative control using t-test. WO (78.1, 156.3, and 312.5), KOG (312.5, 625.0) and CWB (312.5) were cytotoxic, (P < 0.05). WO (78.1, 312.5), CWB (156.3, 312.5), SB (625.0) and CPX (1250.0) induced genotoxicity (P < 0.05), mostly, sticky chromosomes. The genotoxic pesticides have potential to cause adverse environmental and health effects, because most adverse effects by genotoxins result from genetic damage and genotoxicity of chemicals is likely to result from cell division abnormalities.

Key words: Allium cepa, agropesticides, Southern Africa, mitotic index, chromosome aberration.