Genotoxicity of Imidacloprid on the forensically important species Chrysomya albiceps (Wiedemann, 1819) (Diptera: Calliphoridae), evaluated by Comet assay

Abstract

The increasing use of chemical pesticides for crop protection has led to irreversible DNA damage in many animal species, particularly soil-dwelling insects. In this study, we tested a protocol of Comet Assay to detect DNA damage in the hemolymph cells of Chrysomya albiceps larvae (Diptera: Calliphoridae) exposed to the neonicotinoid Imidacloprid (IMI). Third-instar larvae were fed on freeze-dried liver substrate rehydrated with one of the following treatments: (i) distilled water (negative control), (ii) imidacloprid (IMI) (0.4980 and 0.9360 mM), and (iii) cyclophosphamide 3.83 mM (positive control). We estimated the Damage Index (DI) and the Damage Frequency (DF) in 300 cells per treatment. According to the shape of the comets, the damage in cells exposed to biocides was significantly higher than the negative control. The DF was also consistently higher in the cells of intoxicated insects. The Comet assay in the haemolymph cells of C. albiceps larvae proved to be effective for detecting DNA damage, providing new evidence for genotoxicity. The increasing use of chemical pesticides for crop protection has led to irreversible DNA damage in many animal species, particularly in soil-dwelling insects. Third-instar larvae were fed freeze-dried liver substrate rehydrated with one of the following treatments: (i) distilled water (negative control), (ii) Imidacloprid (IMI) at concentrations of 0.4980 mM and 0.9360 mM, and (iii) cyclophosphamide at 3.83 mM (positive control). We estimated the Damage Index (DI) and Damage Frequency (DF) in 300 cells per treatment. According to the shape of the comets, DNA damage in cells exposed to biocides was significantly higher than in the negative control. The DF was also consistently higher in the cells of intoxicated insects. The Comet Assay in the hemolymph cells of C. albiceps larvae proved effective for detecting DNA damage, providing new evidence of the genotoxic effects of IMI on a necrophagous insect species. We discuss the advantages and limitations of the protocol in the context of environmental forensic entomotoxicology.