Spodoptera frugiperda, the fall armyworm (FAW), is a highly invasive polyphagous insect pest that is considered a source of severe economic losses to agricultural production. Currently, the majority of chemical insecticides pose tremendous threats to humans and animals besides insect resistance. Thus, there is an urgent need to develop new pest management strategies with more specificity, efficiency, and sustainability. Chitin-degrading enzymes, including chitinases, are promising agents which may contribute to FAW control. Chitinase-producing microorganisms are reported normally in bacteria and fungi. In the present study, Serratia marcescens was successfully isolated and identified from the larvae of Spodoptera frugiperda. The bacterial strain NRC408 displayed the highest chitinase enzyme activity of 250 units per milligram of protein. Subsequently, the chitinase gene was cloned and heterologously expressed in E. coli BL21 (DE3). Recombinant chitinase B was overproduced to 2.5-fold, driven by the T7 expression system. Recombinant chitinase B was evaluated for its efficacy as an insecticidal bioagent against S. frugiperda larvae, which induced significant alteration in subsequent developmental stages and conspicuous malformations. Additionally, our study highlights that in silico analyses of the anticipated protein encoded by the chitinase gene (ChiB) offered improved predictions for enzyme binding and catalytic activity. The effectiveness of (ChiB) against S. frugiperda was evaluated in laboratory and controlled field conditions. The results indicated significant mortality, disturbed development, different induced malformations, and a reduction in larval populations. Thus, the current study consequently recommends chitinase B for the first time to control FAW.

Background: In Egypt, risk assessment of pesticides usage and pesticides misuse to protect plants and increase productivity connected with health hazards and pollution problems have been of public interest. Around the world three million acute poisoning cases from pesticide exposure annually report. Aim of study was to investigate the histopathological alterations, biochemical and genotoxicity adverse effects of synthetic insecticides Diazinon (organophosphorus) and alpha cypermethrin (pyrethroid) which are using for agricultural and public health applications on male albino rats. Methods: Twenty one albino rats were detached into control and two experimental groups. The experimental groups were treated with Diazinon (DIZ) and Alpha-cypermethrin (α-CYP) at sub-lethal dose (1/10 LD₅₀ 36.51 and 1.4 mg/kg body weight, respectively) by oral treatment for consecutively 28-days. The male albino rats in control treatment were put in similar surrounding conditions and treated with 5 ml /Kg tap water. Albino rats were killed after completing exposure of 28-days, liver and brain samples were dissected out for processing and sectioning examinations. Results: The obtained results revealed that both tested insecticides induced oxidative damage as appearance by a significant raise in malondialdehyde (MDA) indicating lipid peroxidation and deoxyribonucleic acid (DNA) damage indicating genotoxicity in the liver and brain. Besides, increase in GSH level and decline in enzymatic antioxidants (GST, CAT, SOD) activities were observed in liver. Marked increase was noticed in GSH levels and GST activity in brain whereas CAT and SOD antioxidant enzymes activity were significantly reduced. Histopathological studies in brain and liver revealed multiplied focal hepatic necrosis, hydropic degeneration of the hepatocytes and portal infiltration inflammatory cells in the liver. Necrosis of neurons, neuronophagia, focal gliosis and cellular oedema, congestion of cerebral blood vessel were noticed in the brain of exposed rats. Conclusion: The histopathological examination of brain and liver tissues and oxidative damage biomarkers showed adverse effects of DIZ or α-CYP insecticides at the tested dose (1/10 LD₅₀).

Fungal infection and pests attack arevery serious problems that facing grapes growers in Egypt. Fungicide azoxystrobin, (Azostar® 25%SC), insecticide lufenuron, (Cymax® 5%EC) and acaricide fenpyroximate (Ortus super® 5%EC) are the most common pesticides used to control such pests (downy mildew, grape fruit worm Eudemis botrana and red spider mite, respectively) in Egypt. The present study was carried out to assess persistence Vs. degradation behavior of the mentioned pesticides when sprayed on foliage of grape plants under field conditions during fruiting stage at the recommended and double the recommended rates of application during the season of 2017 in Adam village, El-Nobaria district, El-Behaira Governorate, Egypt. Fruit samples were collected randomly, two hours (initial time) and 1, 3, 7, 14 and 21 days after application. Samples of treated and untreated (control) grape fruits were prepared, extracted, cleaned-up by QuEChERS analytical method before quantification by high performance liquid chromatography with diode array detector (HPLC-DAD) and gas chromatography extended by electron capture detector (GC). The corresponding values for dissipation of the mentioned pesticides initial deposits, degradation percentages of residues, Residual Lifetime 50% (RL50), Residual Lifetime 90% (RL90) and pre-harvest intervals (PHIs) of the tested pesticides were determined. Results revealed that grape fruits remained higher initial amounts by (2.93 and 3.97), (0.82 and 1.14) and (1.74 and 1.94) mg kg-1 azoxystrobin, lufenuron and fenpyroximate for both doses, respectively. As for RL50, RL90 andPHIs, values showed (3.22, 1.73, 1.85 days) and (9.71, 4.22 and 6.31 days) and (5, 6.89, 4.05 days) when the recommended doses were applied and also, (3.80, 10.4 and 6.85 days) and (1.91, 5.02 and 7.12 days) and (2.58, 6.09 and 5.24 days) at the double recommended rates of application, in/on grape, respectively. In general, azoxystrobin, lufenuron and fenpyroximate residue in/on grape fruits had low persistence. In addition, the grape fruits could be consumed safely after 5, 6.89, 4.05 days, respectively from treating by the recommended rate of azoxystrobin, lufenuron and fenpyroximate when compared by the Maximum Residue Limits (MRLs) of the Codex Alimentarius Commission or the European Union (2, 0.01 and 0.01 mg kg-1), respectively.