Abstract The fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is a globally significant agricultural pest capable of devastating cereal crops and other economically important plants. The present study investigates the in vitro inhibitory effects of copper(II) sulfate (CuSO₄), ethylenediaminetetraacetic acid (EDTA), and sodium chloride (NaCl) on key carbohydrate-digesting enzymes in the fourth instar of S. frugiperda, with a particular emphasis on invertase. Enzyme activity profiling revealed that invertase dominates carbohydrate metabolism in adults, while trehalase and amylase are more active in larvae. CuSO₄ exhibited the strongest inhibition, completely suppressing invertase, trehalase, and amylase activity at 0.5 M (P < 0.01), with significant dose-dependent suppression evident even at 0.01 M. EDTA exerted significant but less potent inhibition, reducing enzyme activities by approximately 24–38% at 0.5 M (P < 0.01). NaCl showed negligible inhibitory effects across all tested concentrations (0.1–2.0 M; P > 0.05 at ≤ 0.1 M for amylase). Notably, CuSO₄ inhibition was rapid, requiring less than two minutes to achieve near-complete suppression at 25 °C, and was significantly influenced by temperature. The strong inhibitory effect of CuSO₄ suggests that it disrupts key metabolic pathways in S. frugiperda, likely through protein denaturation and metal ion interference. These findings highlight the potential of CuSO₄ as a biochemical disruptor that could be further explored as a novel pest control strategy. Future research should focus on in vivo assessments of CuSO₄ toxicity, its interactions with insect physiological processes, and its potential integration into sustainable pest management programs.
Abstract Background The predatory mite Neoseiulus californicus (McGregor) is extensively used in biological control programs, yet quantitative comparisons of its efficacy against different pest species remain limited. This study systematically quantified and compared the functional and numerical responses of N. californicus to two economically significant pests: the two-spotted spider mite, Tetranychus urticae Koch and western flower thrips, Frankliniella occidentalis (Pergande), across egg and first-instar larvae under controlled laboratory conditions. Results N. californicus exhibited a Type II functional response to all prey stages (R² = 0.955–0.994). Attack rates were 1.2–1.7 times higher for T. urticae (0.72–0.76 day⁻¹) than F. occidentalis (0.45–0.59 day⁻¹). The most pronounced difference was handling time: 7.6–9.3× times shorter for spider mites (3.7–3.9 min.) than thrips (29.5–34.7 min.), resulting in maximum predation rates of 370–385 vs. 41–49 prey day⁻¹. At operational densities (15–30 prey/arena), predation efficiency was 72.4% for spider mites vs. 53.5% for thrips. Oviposition rates were 1.39× times higher on T. urticae (2.50 ± 0.27 eggs female⁻¹ day⁻¹) than F. occidentalis (1.80 ± 0.22 eggs/ female/ day). An integrated performance index was 2.89× times higher for spider mites, with optimal predator deployment densities at 18.7 and 22.3 prey per arena for T. urticae and F. occidentalis, respectively. Conclusion N. californicus demonstrates greater predatory and reproductive performance against T. urticae compared to F. occidentalis, driven by more efficient prey handling and enhanced reproductive output under laboratory conditions. These results suggest predator: prey ratios of 1:6–1:10 as a theoretical baseline for spider mite management. These ratios represent a theoretical starting point for hypothesis generation; field validation is required before operational application. For thrips control, N. californicus should be integrated with complementary approaches. These laboratory-derived parameters provide a quantitative foundation for designing future field studies and informing the development of release strategies.
Strawberries are highly perishable fruits due to moisture loss, intense metabolic activity, and microbial contamination, leading to rapid quality deterioration during storage. In this study, mango seed extract (MSE), a natural antioxidant source, was loaded with chitosan (CS) and carboxymethyl chitosan (CCS) nanoparticles to develop edible coatings for postharvest quality enhancement. Nanoparticles were characterized by dynamic light scattering (DLS) to determine particle size and zeta potential, revealing stable formulations with average sizes of 68.1 nm (CS LM) and 91.3 nm (CCS LM). Antioxidant capacity was assessed using ABTS and DPPH radical scavenging assays, where CCS LM exhibited superior activity (> 92%, p < 0.05) compared to free MSE and CS LM. Antimicrobial properties were evaluated by microbial inhibition tests against Staphylococcus aureus, Escherichia coli, and Candida albicans, showing significant inhibition rates at 800 µg/mL. Storage performance was assessed over 21 days at 2 °C by monitoring weight loss, firmness, color preservation, pH, titratable acidity, and microbial counts. Results demonstrated that CCS LM-coated strawberries had minimal weight loss (5.7%, p < 0.05), retained firmness, and showed reduced bacterial (1.2 log₁₀ CFU/g) and fungal counts (1.3 log₁₀ CFU/g) compared to uncoated fruits. These findings suggest that MSE-loaded CCS nanoparticles, through their antioxidant and antimicrobial functions, offer a promising sustainable strategy to improve the postharvest quality and storage performance of strawberries.
The cotton leafworm, Spodoptera littoralis (Boisd.), is a devastating pest in Egyptian agriculture, where intensive pesticide use has accelerated the evolution of resistance. This study monitored the resistance levels of five field populations collected from major governorates (Al-Sharqia, Al-Gharbia, Menoufia, Beni-Suef, Fayoum) against seven biorational insecticides and six chitin synthesis inhibitors (CSIs). Additionally, the biochemical basis of resistance was investigated through enzyme assays and synergism tests. Results revealed high levels of resistance to spinosad, with resistance ratios (RRs) ranging from 3232-fold in the Al-Sharqia strain to 7371-fold in the Menoufia strain. Spinetoram and emamectin benzoate showed moderate resistance (RR 18.40-79.85 and 9.83-41.69, respectively), while Bacillus thuringiensis formulations exhibited variable efficacy (RR 16.06-72.24). In sharp contrast, all tested CSIs retained high efficacy, with most RRs <= 2.0; notably, chlorfluazuron and flufenoxuron displayed hypersensitivity in several populations, identifying them as critical rotation partners. Biochemical profiling indicated significant elevations in cytochrome P450s (up to 20-fold) and esterases (up to 16-fold) in resistant strains. Strong positive correlations were found between spinosad resistance and esterase (rs = 1.000) and CYP450 activity (rs = 0.829). However, synergism assays with piperonyl butoxide (PBO), triphenyl phosphate (TPP), and diethyl maleate (DEM) failed to significantly restore spinosad susceptibility (Synergism Ratios <= 1.21). Although detoxification enzymes were elevated, metabolic detoxification alone does not explain the high resistance levels. These findings suggest the involvement of additional mechanisms, potentially including target-site modification, which requires molecular confirmation. Cluster analysis identified Menoufia and Beni-Suef as high-risk hotspots. These findings highlight a critical crisis in spinosyns and support the immediate incorporation of CSIs into rotation schemes to manage resistance in S. littoralis.
PURPOSE:Rising temperatures resulting from climate change play a vital role in the development of crop phenological stages. Egyptian cotton (Gossypium barbadense L.) is an important industrial cash crop that requires optimal temperature for economic production. Extreme temperatures cause a sharp decline in cotton yield and quality via affecting plant growth and physiology. Sowing time is a fundamental practice for maximizing the crop's genetic potential by minimizing the deleterious impacts of abiotic stress, specifically during critical reproductive stages, thereby enhancing the key yield attributes that collectively construct the final economic yield. METHOD:To create discrepancies in environmental growth resources over crop life span, three cotton cultivars (super Giza 94, Extra Giza 96 and Super Giza 97) were sown at three sowing dates (25-April, 15-May and 25-May) during 2022 and 2023 seasons. The meteorological data were collected and accumulated growing degree days (AGDD) were computed. Growth and phenological traits and yield attributes were estimated. RESULTS:Findings exhibited that the lowest values of small boll shedding % and the highest values of earliness % were observed with Super Giza 94 when sown early on 25-April in both seasons. With sowing on 25-April, Super Giza 94 produced the maximum increases in all yield attributes. Super Giza 94 was the most efficient cultivar for exploiting the cumulative heat units under different sowing dates with a higher value at sowing on 25-April in both seasons. CONCLUSION:The proper choosing crop cultivar keeps one of the most serious decisions for cotton farmers, since it determines the ceiling of the potential return, upon which the other agricultural activities, such as sowing dates, can be tailored. Accordingly, the current work deduce that sowing Super Giza 94 cultivar on 25-april is regarded as a promising practice for efficient use of prevailing climatic factors, hence balanced vegetative growth with high cotton productivity.
