Worldwide, the developing industry of cucumbers (Cucumis sativus L.) grown in greenhouses is threatened by damage from sucking pests, especially aphi

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, G₆PD 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.

In this study, the effect of 20 barley cultivars were evaluated on the life table parameters and digestive enzymatic activity of the lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae) under laboratory conditions (28 ± 1°C, 60 ± 5% RH, and a photoperiod of 16:8 (L:D) h). Among barley cultivars tested developmental time of R. dominica immature stages was longest on cultivar Bahman (61.00) and shortest on Mahoor (46.60 d). The lowest realized fecundities were recorded for insects reared on cultivar Bahman (217.60); and the highest ones were observed for insects reared on Sahra (348.05 eggs/female). The net reproductive rate (R₀) was significantly affected by various barley cultivars being lowest on cultivar Bahman (53.98) and highest on Mahoor (146.79 offspring/female). Records for intrinsic rates of increase (r_m) were lowest on cultivar Dasht (0.043) and the highest on Mahoor (0.066 day⁻¹). The highest levels of amylolytic and proteolytic activity were recorded on cultivars Mahoor and EBYT-92-10, respectively. By contrast, the insects reared on cultivars Dasht had the lowest levels of α-amylase and general protease activity. Correlation analyses showed that high correlations existed between the immature period, adult longevity, fecundity, and life table parameters on one side and protein content and particle size index on the other. The results of our experiments showed that cultivar Mahoor was a relatively susceptible and cultivars Bahman and Dasht were relatively resistant to R. dominica which could be useful in the development of IPM programs for this pest in store.