This review provides an in-depth examination of the intricate interactions between plant metabolites and the digestive and antioxidative enzymes in insects, highlighting their essential roles in shaping insect herbivory and adaptation strategies. Plants have evolved a diverse arsenal of secondary metabolites to defend against herbivorous insects, which, in response, have developed sophisticated adaptations to overcome these defenses and efficiently exploit plant resources. We outline the importance of digestive enzymes, such as proteases and amylases, which allow insects to break down complex plant compounds and access vital nutrients. Additionally, the review focuses on antioxidative enzymes in the insect midgut, including superoxide dismutase and catalase, which play a crucial role in mitigating oxidative stress generated during digestion and other metabolic processes. Synthesizing findings from various studies, this review also considers how environmental factors, such as heavy metal exposure and temperature changes, influence these enzymes’ activity levels. It highlights the dual function of antioxidative enzymes in detoxifying harmful plant-derived compounds while preserving cellular stability. The implications of these biochemical interactions for pest management are discussed, with an emphasis on the potential for developing biopesticides that target specific enzymatic pathways to disrupt insect feeding and growth. By elucidating the biochemical mechanisms that underlie plant-insect interactions, this review enhances our understanding of co-evolutionary dynamics and offers insights into sustainable agricultural practices that could leverage these interactions for effective pest control. Finally, the review proposes future research directions aimed at identifying novel plant metabolites with enzyme-modulating properties and exploring the ecological impacts of enzyme-targeted pest management approaches.

The increasing use of nanofertilizers in modern agriculture and their impact on crop yield and pest management require further research. In this study, the effects of nano-Fe, -Zn, and -Cu (which are synthesized based on nanochelating technology), and urea (N) fertilizers on the antioxidant activities of wheat plants (cv. Chamran), and the wheat green aphid Schizaphis graminum (Rondani) are investigated. The authors observed the highest levels of phenolics in non-infested nano-Zn-treated plants (26% higher compared with control). The highest H₂O₂ levels are in the infested and non-infested nano-Zn-treated and infested nano-Fe-treated plants (in infested nano-Zn and nano-Fe treated plants, 18% and non-infested nano-Zn-treated plants, 28% higher compared with control). The highest peroxidase (POX) activity is observed in the infested and non-infested N-treated and non-infested water-treated plants (almost 14%, 37%, and 46% higher than control, respectively). The lowest activity is in the infested plants’ nano-Zn and -Fe treatments (almost 7 and 5 folds lower compared to the control, respectively). The highest and lowest catalase (CAT) activity are in the infested N-treated plants (almost 42% higher than control) and water-treated plants, respectively. The infested nano-Zn, -Fe, -Cu and Hoagland-treated plants showed the highest superoxide dismutase (SOD) activity. Regarding the antioxidant enzyme activities of S. graminum, the highest POX activity is in the nano-Cu treatment (more than two folds higher compared with control); the highest CAT and SOD activities are in the nano-Cu and -Zn treatments. It can be concluded that the application of nanofertilizers caused increasing effects on the wheat plant’s antioxidant system and its resistance to S. graminum.

The use of nanofertilizers has both advantages and concerns. One benefit is that nano-fertilizers can enhance plant resistance against insect pests, making them a valuable strategy in integrated pest management (IPM). This study focused on the effect of wheat leaves treated with nano-chelated fertilizers and nitrogen (N) fertilizer on the wheat aphid (Schizaphis graminum Rondani), a harmful pest of wheat plants that transmits dangerous viruses. The nano-Cu treatment showed the longest pre-adult longevity. Additionally, the nano-Cu treatment resulted in the lowest adult longevity, fecundity, nymphoposition day number, intrinsic rate of population growth (r), finite rate of population increase (λ), and net reproductive rate (R₀) and gross reproductive rate (GRR). Also, nano-Cu treatment led to the highest amount of (T). The N treatment led to the highest levels of fecundity, nymphoposition days, r, λ, and R₀. Nano-Fe and nano-Zn demonstrated fewer negative effects on S. graminum life table parameters than nano-Cu. Our results indicate that N treatment yielded numerous advantageous effects on the wheat aphid while simultaneously impeding the efficacy of the aphid control program. Conversely, nano-Cu treatment exhibited a detrimental influence on various parameters of the aphid’s life table, resulting in a reduction in the pest’s fitness. Consequently, the integration of nano-Cu should be seriously considered as a viable option in the IPM of the wheat aphid.

In the current study, the inhibitory effect of extracts from Gramineae (wheat, barley, and corn) and Leguminosae (sophora, bean, and pea) seeds was studied on the digestive alpha-amylase activity in cotton bollworm (Helicoverpa armigera Hubner). The insect was bred on artificial food based on Vigna unguiculata in the greenhouse condition (26 ± 2 °C, 60 ± 10% (Relative Humidity), R.H., 16:8 (Light: Darkness), L: D). The extracts of wheat (95.2%), barley (84.6%), corn (73.8%), sophora (77%), Vigna unguiculata (52%), and pea (56.7%) significantly inhibited the alpha-amylase activity in H. armigera. Studying the impact of different fractions (obtained via deposition at various concentrations of ammonium sulfate salt) on the alpha-amylase enzyme activity demonstrated that in 0–30% fractions, wheat, barley, and sophora have the highest effect (95.26%, 94.65%, and 94.73%, respectively) compared to the other fractions. The inhibitory activities of 0–30% fractions of corn, bean, and pea were 83.3, 56.94, and 50.92%, respectively. In 30–50% fractions, the most effective ones were those of wheat and barley with the inhibitory activity of 79.7% and 82.9%, respectively. In addition, bean and pea fractions inhibited 25.2% and 27.5%, in that order. No significant inhibitory impact was detected in 50–70% or higher fractions. The investigation of the impact of pH values (i.e., 2, 4, 8, and 10) on the inhibition of the alpha-amylase enzyme activity introduced 8–10 as the optimum pH in H. armigera. Nanotechnology offers several ways to enhance plant-based pesticides, which are a solution for making plant extract usage more efficient. The exploration of plant-based pesticides, in conjunction with the incorporation of nanotechnology and other scientific fields, offers a wide range of prospects for further investigation.