Green synthesis of zinc oxide nanoparticles from Sargassum ilicifolium to enhance tomato resistance against Tuta absoluta.

This study evaluated the effects of ZnO and green-synthesized ZnO nanoparticles (ZnO-NPs) from Sargassum ilicifolium extract on the biochemical interactions between tomato leaves and the destructive pest Tuta absoluta. The average size and stability of ZnO-NPs were characterized using DLS, X-RD, and FE-SEM. Peaks in the FT-IR spectrum of the extract of the algae and ZnO-NPs, indicated the presence of carboxyl groups, amines, alkynes and alcohols. Treated tomato leaves exhibited increased total chlorophyll and anthocyanin contents, particularly at 100 and 50 ppm, compared to the control. A significant increase in total flavonoid content was observed at 100 ppm, while total phenolic content was also enhanced at 50 ppm. In T. absoluta larvae, exposure to 50 and 100 ppm ZnO-NPs led to a reduction in α-amylase, total protease, total protein, and TAG levels, alongside increased catalase activity. Additionally, GPD and ALT activities decreased at 50 ppm compared to the control. Lactate, MDA, and the RSSR/RSH increased at 100 ppm. Furthermore, ZnO-NPs at 50 and 100 ppm elevated larval aldolase activity, while AST and γ-GT activities declined. These findings indicate that ZnO-NPs enhance tomato defense mechanisms and mitigate larval damage, supporting their potential use in integrated pest management strategies against T. absoluta.