Cytogenotoxic and Molecular Assessment of Pyrethrins on Non-Target Allium cepa Roots

The pyrethrins, which form a part of naturally occurring insecticidal chemicals derived from chrysanthemum flowers, not only provide rapid knockdown of a broad spectrum of insect pests but are also widely used in integrated pest management due to a generally favorable safety profile, largely attributed to low mammalian toxicity. In this research, cytogenotoxic and apoptotic effects of pyrethrins in Allium cepa root meristem cells were evaluated using root growth inhibition, Allium ana-telophase, comet, flow cytometry, and RAPD-PCR assays. Pyrethrins treatment caused a marked suppression of root elongation, with root length decreasing from 2.84 ± 0.45 cm at low doses to 0.13 ± 0.09 cm at high concentrations. Exposure to pyrethrins resulted in the dose and time-dependent decrease in the mitotic index (MI), with increased chromosomal aberrations (CAs) in ana-telophase cells such as disturbed ana-telophase, lagging chromosomes, stickiness, and anaphase bridges. Additionally, micronuclei and c-metaphase were observed in other cells; DNA damage also increased with concentration, as shown by the comet assay. Flow cytometric SubG1 analysis revealed a pronounced dose- and time-dependent increase in apoptotic cell populations in A. cepa following pyrethrins exposure, with high concentrations inducing apoptosis levels above the positive control. Concentration- and time-dependent genomic instability, DNA polymorphism, and diminished genomic template stability percentage (GTS%) in A. cepa root meristem cells after exposure to pyrethrins were demonstrated by RAPD-PCR, indicating possible genotoxic effects on non-target plant species. These findings collectively demonstrate that pyrethrins induce cytogenotoxic and apoptotic effects in A. cepa roots under controlled experimental conditions. However, further field-based and ecotoxicological studies are needed to assess the environmental relevance of these effects.