Immunotoxic effects of force-fed ethephon on model organism Galleria mellonella (Lepidoptera: Pyralidae)

Cytogenotoxic effects of a commercial formulation of ethephon (ETF) and a commercially formulated mixture of ethephon+cyclanilide (ETF+CYC), which are used as plant growth regulators (PGRs) in modern agriculture, were investigated by using the anaphase-telophase chromosome aberration (CA) assay in root meristem cells of Allium cepa L. A. cepa roots were treated with 25 (EC50/2), 50 (EC50), and 100 ppm (EC50×2) of ETF, and with the same concentrations of ETF+CYC, for 24, 48, and 72 h periods. Both compounds increased various types of aberrations in the organization and morphology of the chromosomes in test material. These aberrations were clastogenic (bridges and fragments), aneugenic (disturbed anaphase-telophase, C-mitosis, binucleated cells, vagrant chromosomes, and polyploidy), and sticky (stickiness). Commercial formulations of ETF and ETF+CYC significantly increased the percentage of total aberrations, and the percentage of abnormal cells at all concentrations (25, 50, and 100 ppm), and treatment times (24, 48, and 72 h) when compared with the negative control. However, the commercially formulated mixture of ETF+CYC increased the CA formation more than commercial formulation of ETF alone (except the 50 ppm concentration, for 72 h). In addition, ETF and ETF+CYC significantly decreased the mitotic index (MI) at all concentrations and treatment times compared to both the negative and respective positive control, methyl methanesulfonate. The results of this study indicate that in the tested experimental conditions, the commercial formulations of ETF and ETF+CYC are genotoxic and induce cytotoxic effects in the root meristem cells of A. cepa.