Botanical Oils Isolated from Simmondsia chinensis and Rosmarinus officinalis Cultivated in Northern Egypt: Chemical Composition and Insecticidal Activity against Sitophilus oryzae (L.) and Tribolium castaneum (Herbst)

The rice weevil, Sitophilus oryzae (L.), and the red flour beetle, Tribolium castaneum (Herbst), are key stored-product pests in Egypt and worldwide. The extensive use of synthetic insecticides has led to adverse effects on the environment, human health, and pest resistance. As a result, environmentally friendly pest management alternatives are desperately required. The botanical oils of jojoba, Simmondsia chinensis (L.), and rosemary, Rosmarinus officinalis L. plants growing in Egypt were extracted, identified by gas chromatography/mass spectrometry (GC–MS), and evaluated for their insecticidal activity against S. oryzae and T. castaneum. The main constituents identified in BOs were carvyl acetate (20.73%) and retinol (16.75%) for S. chinensis and camphor (15.57%), coumarin (15.19%), verbenone (14.82%), and 1,8-cineole (6.76%) for R. officinalis. The S. chinensis and R. officinalis BOs caused significant contact toxicities against S. oryzae and T. castaneum adults, providing LC₅₀ values of 24.37, 68.47, and 11.58, 141.8 ppm at 3 days after treatment (DAT), respectively. S. chinensis oil exhibited significant fumigation toxicity against both insects; however, it was more effective against S. oryzae (LC₅₀ = 29.52 ppm/L air) than against T. castaneum (LC₅₀ = 113.47 ppm/L air) at 3 DAT. Although the essential oil (EO) of R. officinalis significantly showed fumigation toxicity for S. oryzae (LC₅₀ = 256.1 and 0.028 ppm/L air at 1 and 3 DAT, respectively), it was not effective against T. castaneum. These BOs could be beneficial for establishing IPM programs for suppressing S. oryzae and T. castaneum.     

Identification of insecticidal constituents of the essential oils of Dahlia pinnata Cav. against Sitophilus zeamais and Sitophilus oryzae

The aim of this research was to determine the chemical composition of the essential oils of Dahlia pinnata, their insecticidal activity against Sitophilus zeamais and Sitophilusoryzae and to isolate insecticidal constituents. Based on bioactivity-guided fractionation, active constituents were isolated and identified as d-limonene, 4-terpineol and α-terpineol. Essential oils and active compounds tested exhibited contact toxicity, with LD₅₀ values ranging from 132.48 to 828.79 μg/cm² against S. zeamais and S. oryzae. Essential oils possessed fumigant toxicity against S. zeamais and S. oryzae with LC₅₀ from 14.10 to 73.46 mg/L. d-Limonene (LC₅₀ = 4.55 and 7.92 mg/L) showed stronger fumigant toxicity against target insects. 4-Terpineol (88 ± 8%) and d-limonene (87 ± 5%) showed the strongest repellency against S. zeamais and S. oryzae, respectively. The results indicate that essential oils and insecticidal constituents have potential for development into natural fumigants, insecticides or repellents for control of the stored-product insect pests.     

Insecticidal effect of <Emphasis Type="Italic">Mentha pulegium</Emphasis> L. and <Emphasis Type="Italic">Mentha suaveolens</Emphasis> Ehrh. hydrosols against a pest of citrus, <Emphasis Type="Italic">Toxoptera aurantii</Emphasis> (Aphididae)

Essential oils proved their efficiency as natural insecticides to fight many pests of stored products and crops whereas the hydrosols have not been evaluated yet. The objective of this work is to assess the insecticidal effect of hydrosols extracted from Mentha suaveolens Ehrh. and Mentha pulegium L. toward an insect pest of citrus, Toxoptera aurantii (Homoptera, Aphididae). The extraction of hydrosols was carried out by hydro-distillation using Clevenger apparatus and then the chemical composition was identified by gas chromatography coupled with mass spectrometry. The chemical composition of two hydrosols revealed the abundance of hydrophilic and oxygenated compounds as piperitenone oxide and carvacrol. Different concentrations of each hydrosol were separately diluted in distilled water and applied topically to aphids. The results of this investigation have shown a high insecticidal effect, and the M. suaveolens hydrosol is more effective against citrus pests than that of M. pulegium L. Consequently, these natural compounds can be used in the management of aphids on citrus.     

Chemical Composition and Evaluation of Insecticidal Activity of Calendula incana subsp. maritima and Laserpitium siler subsp. siculum Essential Oils against Stored Products Pests

The problems of the environment and human health related to the use of synthetic and broad-spectrum insecticides have increasingly motivated scientific research on different alternatives and among these, the use of green systems, such as essential oils, have been explored. Several species of the Apiaceae and Asteraceae families, aromatic herbs rich in secondary bioactive metabolites, are used in the industrial field for pharmaceutical, cosmetic, and food purposes. Different essential oils extracted from some species of these families have shown acute toxicity and attractive and/or repellent effects towards different insects. In our work, we investigated the toxic potential of Calendula incana subsp. maritima and Laserpitium siler subsp. siculum essential oils against four insect species, Sitophilus oryzae, Lasioderma serricorne, Necrobia rufipes, and Rhyzoperta dominica, which are common pests of stored products. The composition of both oils, extracted by hydrodistillation from the aerial parts of the two plants, was evaluated by GC×GC-MS. Calendula incana subsp. maritima essential oil was rich in oxygenated sesquiterpenoids, such as cubebol (35.39%), 4-epi-cubebol (22.99%), and cubenol (12.77%), while the Laserpitium siler subsp. siculum essential oil was composed mainly of monoterpene hydrocarbons, such as β-phellandrene (42.16%), limonene (23.87%), and β-terpinene (11.80%). The toxicity Petri dish bioassays indicated that C. maritima oil killed a mean of 65.50% of S. oryzae and 44.00% of R. dominica adults, indicating a higher biocidal activity in comparison with L. siculum oil, while toward the other species, no significant differences in mortality were recorded. Calendula maritima oil could be, then, considered a promising candidate for further tests as an alternative biocide toward S. oryzae and R. dominica. The possibility that the relatively high content of oxygenated sesquiterpenoids in C. maritima essential oil determines its higher biocidal activity is discussed.     

Insecticidal and Enzyme Inhibition Activities of Leaf/Bark Extracts,Fractions, Seed Oil and Isolated Compounds from Triadica sebifera (L.) Small against Aphis craccivora Koch

Aphid, Aphis craccivora Koch (Hemiptera: Aphididae), is a major sap-sucking insect pest of leguminous crops and also transmits plant viruses, leading to economic yield loss. Indiscriminate and repeated use of insecticides for control of aphid leads to the development of resistance, and is harmful to the environment, non-target organisms, etc. Plant-based extracts/seed oils (SO) are the best alternatives to insecticides. Insecticidal activities of Triadica sebifera have not been reported against A. craccivora and other insect pests to date. In the current study, the main objective was to study the insecticidal activities of leaf/bark extracts/fractions, seed oil, isolated compounds, and their combinations against A. craccivora. Results showed that, among the extracts, ethanolic bark extract 80% (LC₅₀ = 5115.98 mg/L) was more effective against A. craccivora. Among fractions, the n-hexane fraction of leaves (LC₅₀ = 425.73 mg/L) and the ethyl acetate fraction of bark (LC₅₀ = 813.45 mg/L) were promising. Among compounds, gallic acid was the most effective (LC₅₀ = 1303.68 mg/L) compared to shikimic acid and quercetin. SO (LC₅₀ = 850.94 mg/L) was superior compared to extracts/fractions/compounds. All the combinations showed toxicity and synergistic activity. Leaf/bark extracts and SO significantly inhibited the AChE and GST activity in A. craccivora. Based on field bio-efficacy, the leaf extract/SO or their combinations can be recommended for the control of aphids.     

Insecticidal and Attractant Activities of Magnolia citrata Leaf Essential Oil against Two Major Pests from Diptera: Aedes aegypti (Culicidae) and Ceratitis capitata (Tephritidae)

In this study, Magnolia citrata Noot and Chalermglin (Magnoliaceae) essential oil (MCEO) was evaluated for insecticidal activity against the yellow fever mosquito Aedes aegypti and attractant activity for the Mediterranean fruit fly Ceratitis capitata. The leaves of Magnolia citrata (Giổi chanh) were collected from northwestern Vietnam, and the water-distilled MCEO was analyzed by gas-chromatography and mass spectrometry (GC-MS). The major constituents of MCEO were identified as linalool 19%, geranial 16%, citronellal 14%, neral 14%, and sabinene 12%. MCEO showed 100% mortality at 1 μg/μL against 1st instar larvae of Ae. aegypti (Orlando strain, ORL), and the oil exhibited 54% (ORL) and 68% (Puerto Rico strain) mortality at 5 μg/mosquito against Ae. aegypti adult females. Initial screens showed that MCEO had weak insecticidal activity compared to the positive control permethrin. In bioassays with sterile male C. capitata, MCEO exhibited moderately strong attraction, comparable to that observed with a positive control, Tetradenia riparia essential oil (TREO). Herein, the insecticidal and attractant activities of MCEO are reported for the first time.     

Heterologous expression of the avirulence gene ACE1 from the fungal rice pathogen Magnaporthe oryzae

The ACE1 and RAP1 genes from the avirulence signalling gene cluster of the rice blast fungus Magnaporthe oryzae were expressed in Aspergillus oryzae and M. oryzae itself. Expression of ACE1 alone produced a polyenyl pyrone (magnaporthepyrone), which is regioselectively epoxidised and hydrolysed to give different diols, 6 and 7, in the two host organisms. Analysis of the three introns present in ACE1 determined that A. oryzae does not process intron 2 correctly, while M. oryzae processes all introns correctly in both appressoria and mycelia. Co-expression of ACE1 and RAP1 in A. oryzae produced an amide 8 which is similar to the PKS-NRPS derived backbone of the cytochalasans. Biological testing on rice leaves showed that neither the diols 6 and 7, nor amide 8 was responsible for the observed ACE1 mediated avirulence, however, gene cluster analysis suggests that the true avirulence signalling compound may be a tyrosine-derived cytochalasan compound.     

Encapsulation of Eucalyptus largiflorens Essential Oil by Mesoporous Silicates for Effective Control of the Cowpea Weevil,Callosobruchus maculatus (Fabricius) (Coleoptera: Chrysomelidae)

Although the use of synthetic chemicals is the principal method for insect pest management, their widespread application has led to numerous side effects, including environmental pollution and threats to human and animal health. Plant essential oils have been introduced as promising natural substitutes for synthetic insecticides. However, high volatility and/or low durability are the main limiting factors for essential oil application for control of insect pests. Accordingly, along with an evaluation of the fumigant toxicity of Eucalyptus largiflorens essential oil against the cowpea weevil, Callosobruchus maculatus, essential oil was nanoencapsulated by two mesoporous silicates, MCM-41 and zeolite 3A, to enhance fumigant persistence and toxicity. The chemical profile of essential oil was also analyzed through gas chromatographic-mass spectrometry. E. largiflorens essential oil showed significant concentration-dependent toxicity against insect pests; a concentration of 5.16 μL/L resulted in 100% mortality after 48 h. The toxicity of essential oil could be attributed to the presence of various insecticidal terpenes, such as spathulenol (15.6%), cryptone (7.0%), and 1,8-cineole (5.8%). Fumigant persistence was increased from 6 days to 19 and 17 days for pure and capsulated essential oil with MCM-41 and Zeolite 3A, respectively. The insect mortality also increased from 99 insects in pure essential oil to 178 and 180 insects in MCM-41 and Zeolite 3A encapsulated formulations, respectively. Therefore, the encapsulation of E. largiflorens essential oil by MCM- 41 and Zeolite 3A is a beneficial method for enhancing its persistence and toxicity against C. maculatus.     

Developing a Hazomalania voyronii Essential Oil Nanoemulsion for the Eco-Friendly Management of Tribolium confusum,Tribolium castaneum and Tenebrio molitor Larvae and Adults on Stored Wheat

Most insecticides commonly used in storage facilities are synthetic, an issue that generates concerns about food safety and public health. Therefore, the development of eco-friendly pest management tools is urgently needed. In the present study, a 6% (w/w) Hazomalania voyronii essential oil-based nanoemulsion (HvNE) was developed and evaluated for managing Tribolium confusum, T. castaneum, and Tenebrio molitor, as an eco-friendly wheat protectant. Larval and adult mortality was evaluated after 4, 8, and 16 h, and 1, 2, 3, 4, 5, 6, and 7 days, testing two HvNE concentrations (500 ppm and 1000 ppm). T. confusum and T. castaneum adults and T. molitor larvae were tolerant to both concentrations of the HvNE, reaching 13.0%, 18.7%, and 10.3% mortality, respectively, at 1000 ppm after 7 days of exposure. However, testing HvNE at 1000 ppm, the mortality of T. confusum and T. castaneum larvae and T. molitor adults 7 days post-exposure reached 92.1%, 97.4%, and 100.0%, respectively. Overall, the HvNE can be considered as an effective adulticide or larvicide, depending on the target species. Our results highlight the potential of H. voyronii essential oil for developing green nanoinsecticides to be used in real-world conditions against key stored-product pests.     

Antioxidant,Antimicrobial, and Insecticidal Properties of a Chemically Characterized Essential Oil from the Leaves of Dittrichia viscosa L.

Since some synthetic insecticides cause damage to human health, compounds in plants can be viable alternatives to conventional synthetic pesticides. Dittrichia viscosa L. is a perennial Mediterranean plant known to possess biological activities, including insecticidal properties. The chemical composition of an essential oil (EOD) from D. viscosa, as well as its antioxidant, antimicrobial, and insecticidal effects on the cowpea weevil (Callosobruchus maculatus) were determined. Forty-one volatile compounds were identified in EOD, which accounted for 97.5% of its constituents. Bornyl acetate (41%) was a major compound, followed by borneol (9.3%), α-amorphene (6.6%), and caryophyllene oxide (5.7%). EOD exhibited significant antioxidant activity in all tests performed, with an IC₅₀ of 1.30 ± 0.05 mg/mL in the DPPH test and an EC₅₀ equal to 36.0 ± 2.5 mg/mL in the FRAP assay. In the phosphor-molybdenum test, EOD results ranged from 39.81 ± 0.7 to 192.1 ± 0.8 mg AAE/g E. EOD was active on E. coli (9.5 ± 0.5 mm), S. aureus (31.0 ± 1.5 mm), C. albicans (20.4 ± 0.5 mm), and S. cerevisiae (28.0 ± 1.0 mm), with MICs ranging from 0.1 mg/mL to 3.3 mg/mL. We found that 1 µL of EOD caused 97.5 ± 5.0% insect mortality after 96 h in the inhalation test and 60.0 ± 8.3% in the ingestion assay. The median lethal concentration (LC₅₀) was 7.8 ± 0.3 μL EO/L, while the effective concentration in the ingestion test (LC₅₀) was 15.0 ± 2.1 μL EO/L. We found that 20 µL of EOD caused a reduction of more than 91% of C. maculatus laid eggs.     

Semisynthesis of new ethers from furyl-ring-based acylation derivatives of fraxinellone as insecticidal agents against Mythimna separata Walker in vivo

A series of new ethers from furyl-ring-based acylation derivatives were obtained by structural modification of fraxinellone. Among them, two compounds exhibited more potent insecticidal activity than toosendanin with the final mortality rates greater than 60%.     

Synthesis of New Spiro-Cyclopropanes Prepared by Non-Stabilized Diazoalkane Exhibiting an Extremely High Insecticidal Activity

The synthesis of new insecticidal gem-dimethyspiro-cyclopropanes derived from pyrrolidine-2,3-dione have been described, and their biological effect against different insect species has been evaluated. The presented results demonstrate the excellent insecticidal activity of cyclopropane 5c against Aedes aegypti and Musca domestica. Cyclopropane 5c showed the quickest knockdown and the best killing against Aedes aegypti and Musca domestica compared to trans-chrysanthemic acid and pyrethrin. The biological results of the high insecticidal activity were confirmed by the results of docking. This is evident in the binding affinity obtained for cyclopropane 5c, indicating good binding with an important active amino acid residue of the 5FT3 protein.     

Prospects for using proteinase inhibitors to protect transgenic plants against attack by herbivorous insects

Proteinase inhibitors which act on the digestive enzymes of insect herbivores are a basic mechanism of plant defence. Attempts to exploit this defence mechanism in plant genetic engineering have used over-expression of both endogenous and exogenous inhibitors. While significant protection against insect pests has been routinely achieved, the engineered plants do not show levels of resistance considered commercially viable. As a result of selective pressures, insect herbivores have developed multiple mechanisms of adaptation to overcome the defensive effects of plant proteinase inhibitors. Common polyphagous crop pests are well adapted to deal with a range of different inhibitors, which have only limited effects on fitness as a result. A range of strategies have been attempted to improve effectiveness of proteinase inhibitors as antimetabolites towards insects, including selection for inhibitory activity against insect digestive enzymes, mutagenesis for novel inhibitory activity, and engineering inhibitors with multiple functions. However, proteinase inhibitor genes have only been used in transgenic crops in combination with other insecticidal genes. In Chinese genetically engineered cotton varieties which express Bt toxins as an insecticidal protein against lepidopteran larvae, the CpTI (cowpea trypsin inhibitor) gene has been employed as a second transgene to improve protection. This gene combination represents the only commercial deployment of a proteinase inhibitor transgene to date, with Bt/CpTI cotton grown on over 0.5 million hectares in 2005. Future prospects for using proteinase inhibitor genes to enhance insect resistance in transgenic crops will require reassessment of their mechanisms of action, particularly in affecting processes other than digestion, as exemplified by effects on sap-feeding hemipteran pests.     

<em>N</em>-Substituted 5-Chloro-6-phenylpyridazin-3(2<em>H</em>)-ones: Synthesis, Insecticidal Activity Against <em>Plutella xylostella </em>(L.) and SAR Study

A series of N-substituted 5-chloro-6-phenylpyridazin-3(2H)-one derivatives were synthesized based on our previous work; all compounds were characterized by spectral data and tested for in vitro insecticidal activity against Plutella xylostella. The results showed that the synthesized pyridazin-3(2H)-one compounds possessed good insecticidal activities, especially the compounds 4b, 4d, and 4h which showed > 90% activity at 100 mg/L. The structure-activity relationships (SAR) for these compounds were also discussed.     

Optimization of Biodiesel Production Catalyzed by Fungus Cells Immobilized in Fibrous Supports

A circulating packed-bed bioreactor system using fibrous nonwoven fabric as the immobilization matrix was suitable for simultaneous cell growth and immobilization of Rhizopus oryzae fungus cells, which could be used for lipase-mediated production of biodiesel by methanolysis of soybean oil. Response surface methodology and 5-level-5-factor central composite rotatable design was proved to be a powerful tool for the optimization of methanolysis conditions catalyzed by immobilized R. oryzae whole cell biocatalyst. A quadratic polynomial regression model was used to analyze the relationship between the yield and the significant reaction parameters. The analysis confirmed that water content, molar ratio of methanol to oil, cell weight, and reaction time were the significant factors affecting the yield at a 95% confidence level (p?<?0.05). Under the optimum condition at 10.97% (w/w) water content, 0.64 molar ratio of methanol to oil, 2.25% (w/w) cell weight, and 23.3 h reaction time, the predicted value of yield was 72.6%. Validation experiments with yields of 70.77?±?2.46% verified the availability and the accuracy of the model.     

Isolation of phytosterols of Dalbergia ecastophyllum (L.) Taub. (Leguminosae) and modulation of antibiotic resistance by a possible membrane effect

Globally there are a larger number of strains of microorganisms resistant to multiple drugs mainly due to misuse and indiscriminate, resulting in increased morbidity, costs inherent benefits of health care, as well as mortality rates for infections. As a result of this a large number of researches have been conducted emphasizing the antimicrobial properties of plant products. In this study, the ethanol extract and hexane fraction of Dalbergia ecastophyllum (L.) Taub. (Leguminosae) have been used to evaluate the antibacterial and antifungal activity and for modulating the resistance of antimicrobials against bacterial strains of Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans and fungal strains of Candida krusei, Candida tropicalis. The antibacterial and modulatory activity was determined by microdilution. Inhibition of the growth of bacteria and fungi tested extract was ?1024. The activity was enhanced when aminoglycosides were associated with sub-inhibitory concentrations of the ethanol extract and hexane fraction of Dalbergia ecastophyllum. Therefore, it is suggested that the ethanol extract and hexane fraction of Dalbergia ecastophyllum (L.) Taub. (Leguminosae) can be used as a source of natural products with a view to changing the resistance of these microorganisms to antimicrobials.     

Synthesis,bioactivity, action mode and 3D-QSAR of novel anthranilic diamide derivatives

Several newly synthesized anthranilic diamide derivatives were found to exhibit excellent bioactivity. The action mode test and 3D-QSAR analysis provided valuable information for evaluation and future design of anthranilic diamide insecticides.     

Secondary Metabolites of Purpureocillium lilacinum

Fungi can synthesize a wealth of secondary metabolites, which are widely used in the exploration of lead compounds of pharmaceutical or agricultural importance. Beauveria, Metarhizium, and Cordyceps are the most extensively studied fungi in which a large number of biologically active metabolites have been identified. However, relatively little attention has been paid to Purpureocillium lilacinum. P. lilacinum are soil-habituated fungi that are widely distributed in nature and are very important biocontrol fungi in agriculture, providing good biological control of plant parasitic nematodes and having a significant effect on Aphidoidea, Tetranychus cinnbarinus, and Aleyrodidae. At the same time, it produces secondary metabolites with various biological activities such as anticancer, antimicrobial, and insecticidal. This review attempts to provide a comprehensive overview of the secondary metabolites of P. lilacinum, with emphasis on the chemical diversity and biological activity of these secondary metabolites and the biosynthetic pathways, and gives new insight into the secondary metabolites of medical and entomogenous fungi, which is expected to provide a reference for the development of medicine and agrochemicals in the future.     

Design, synthesis, insecticidal evaluation and molecular docking studies of cis-nitenpyram analogues bearing diglycine esters

Based on the strategies of receptor structure-guided neonicotinoid design, a series of novel cis-nitenpyram analogues bearing diglycine esters were designed and synthesized. Preliminary bioassays indicated that the insecticidal spectra of the target compounds were expanded compared with our previous work, while all the target compounds presented excellent insecticidal activities against Nilaparvata lugens and Aphis medicagini at 100 mg/L. Among these analogues, 6b showed 100% mortality against Nilaparvata lugens (LC 50 = 0.163 mg/L) and 90% against Aphis medicagini at 4 mg/L. SARs suggested that the insecticidal potency of our designed cis-nitenpyram analogues was dual-controlled by the size and species of the ester groups. The molecular docking simulations revealed that the structural uniqueness of these analogues may lead to a unique molecular recognition and binding mode compared with the previously designed compounds. Introduction of the peptide bond gave rise to more significant hydrogen bonds between the nitenpyram analogues bonding with the amino acid residues of insect nAChRs. The docking results explained the SARs observed in vitro, and shed light on the novel insecticidal mechanism of these cis-nitenpyram analogues.     

Production of Microbial Cellulose by a Bacterium Isolated from Fruit

This study presents the production of bacterial cellulose (BC) by a bacterium isolated from a rotten fruit and its process optimization. Here, isolation and screening of potent cellulose producers were carried out from different natural sources, viz., soil, rotten fruits, and vegetables and vinegar. A total of 200 bacterial isolates were obtained, which were screened for cellulose production using Hestrin?CSchramm medium. A novel and potent cellulose-producing bacterium was newly isolated from a rotten fruit and identified as Gluconacetobacter sp. F6 through 16S ribosomal DNA sequencing and morphological, cultural, and biochemical characteristics. After optimization of culture conditions, including pH, temperature, agitation, carbon/nitrogen sources, and inducers, the BC production was greatly increased from 0.52 to 4.5?g/l (8.65-fold increase). The optimal culture medium contained 1% (w/v) glucose, 1.5% (w/v) yeast extract, 0.5% (w/v) peptone, 0.27% (w/v) disodium hydrogen phosphate, 0.115% (w/v) citric acid, and 0.4% (w/v) ethanol. BC produced was analyzed for the presence of cellulose fibrils by epiflourescent microscopy using Calcofluor white stain and scanning electron microscopy and confirmed by NMR. There are very scanty reports about the optimization of BC production by bacteria isolated from rotten fruits.