Acute cadmium toxicity and its effects on enzyme activities in Helicoverpa armigera (Hubner) embryonic cell cultures

Heavy metals are a group of heterogeneous elements with diverse functions and chemical properties, the environmental pollution of which has become a major global concern due to their persistence and toxicity. Cadmium (Cd), a non-essential heavy metal, is known for its high toxicity even at low concentrations and its tendency to bioaccumulate in the tissues of plants and animals. In this study, the toxic effects of Cd on Helicoverpa armigera (Hübner) embryonic cell cultures were investigated using TC-100 culture medium. Embryonic cells were exposed to Cd at concentrations of 97.7, 152.5, 205.4, 303.2, and 400.8 μmol/L for 24 hours. Lethal concentration values (LC₁₀, LC₃₀, and LC₅₀) were determined as 43.516, 105.910, and 196.100 μmol/L, respectively. To further explore the sublethal and lethal effects of Cd, enzymatic responses were analyzed at LC₃₀ and LC₅₀ exposure levels after 24 h. Antioxidant enzymes, including peroxidase (POX), superoxide dismutase (SOD), catalase (CAT), and glucose-6-phosphate dehydrogenase (GPDH), were significantly enhanced in Cd-treated cells compared to controls. Additionally, the activities of detoxification enzymes such as glutathione S-transferase (GST) and cytochrome P450 monooxygenase (P450) were notably increased. In contrast, general esterase activity, assessed using α- and β-naphthyl acetate substrates, was markedly reduced following Cd exposure. These findings suggest that Cd, even at sublethal concentrations, disrupts cellular homeostasis and alters key enzymatic defense mechanisms in embryonic cells of H. armigera. This study highlights the toxicological risks posed by Cd contamination in ecosystems and its potential threat to insect development at the cellular level