Modulation of the antioxidant system by glycoalkaloids in the beetle Tenebrio molitor L.

Various factors may affect the antioxidative system in insects, including xenobiotics. Glycoalkaloids (GAs) are plant secondary metabolites produced mainly by the Solanaceae family (nightshades), such as the food crop tomato Solanum lycopersicum L. These compounds exhibit a wide range of biological activities and have attracted increasing interest in the context of potential insecticide properties. Therefore, the aim of the presented study was to analyze the effects of GAs (solanine, chaconine, tomatine, and extracts of tomato leaves) on lipid peroxidation; the expression levels of genes encoding manganese superoxide dismutase (MnSOD), catalase (CAT), and heat shock protein 70 (HSP70); and the enzymatic activity of SOD and CAT in Tenebrio molitor larvae. This species is amodel organism for toxicological and ecophysiological studies and is also a pest of grain storage. The reported changes depend on the GA concentration, incubation time, and type of insect tissue. We observed that the tested GAs affected MnSOD expression levels, increased SOD activity in the fat body, and reduced enzyme activity in the gut. The results showed that CAT expression was upregulated in the fat body and that the enzymatic activity of CAT in the gut was greater in the treated group than in the control group. Moreover, GAs affected HSP70 expression and malondialdehyde levels in both tested tissues. This research contributes to our knowledge about the effects of GAs on the antioxidative system of T. molitor beetles. As efficient antioxidative system functioning is necessary for survival, the tested components may be targets of potential bioinsecticides.