Solanum nigrum extract and solasonine affected hemolymph metabolites and ultrastructure of the fat body and the midgut in Galleria mellonella

Glycoalkaloids, secondary metabolites abundant in plants belonging to the Solanaceae family, may affect the physiology of insect pests. This paper presents original results dealing with the influence of a crude extract obtained from Solanum nigrum unripe berries and its main constituent solasonine on the physiology of Galleria mellonella (Lepidoptera). Both extract and solasonine applied in the nourishment changed the level of hemolymph metabolites such as sugars, polyols and proline, and ultrastructure of the fat body and the midgut cells. The extract and solasonine, tested in the same concentration found in the extract, decreased the proline level, while mannitol was under the limit of detection in the hemolymph. The extract increased the erythritol level in the hemolymph compared to control, enlarged the intracellular space in fat body cells, decreased cytoplasm and lipid droplets electron density. In the midgut, vacuolized areas of cytoplasm ap-peared with vast reticulum systems. Solasonine, tested with three concentrations, caused the decrease of cytoplasm electron density in both fat body and midgut cells. Obtained results high-lighted the disturbance of the midgut and the fat body due to glycoalkaloids and the potential role of hemolymph ingredients in its detoxification.