Insecticidal Activity Research Articles

The Underrepresented Quinolinone Alkaloids in Genera Penicillium and Aspergillus: Structure, Biology, and Biosynthetic Machinery.

Quinolone alkaloids are N-heterocycles with extensive structural diversity, mainly derived from in fungi from anthranilic acid and amino acids as precursors with a wide range of biological activities as antifungal, antimicrobial, anti-inflammatory, and insecticidal activities. The quinolone basic skeleton comprised of either 2-quinolones or 4-quinolones generated more than one hundred compounds. Several reviews discussed quinolones; particularly, the fluoroquinolones, yet few studies tackled natural quinolones. Many of these quinolones were not assayed for their antimicrobial potential despite their unique stereospecificity, which can supersede synthetic quinolones if their discovery is coupled with OMICS techniques, biochemical and molecular strategies as heterologous expression to maximize their yield. Herein, we conducted a comprehensive review of the quinolone's family in Aspergillus and Penicillium species, the exclusive producers of quinolones whether they are soil, endophytic or marine derived highlighting their isolation, chemical structures, pharmacological effects, structure activity relationships if any, and biosynthetic machinery. We believe that our initiative will pave the way for further development of natural quinolones as future antimicrobial agents.

Anticancer, antimicrobial, insecticidal and molecular docking of sarcotrocheliol and cholesterol from the marine soft coral Sarcophyton Trocheliophorum.

The anticancer, antimicrobial, and insecticidal activities of sarcotrocheliol (1) and cholesterol (2) obtained from the soft coral Sarcophyton trocheliophorum (S. trocheliophorum) were intensively studied. According to this study, both compounds 1 and 2 showed potential cytotoxicity towards the human colorectal carcinomaHCT-116 (IC50 10.4, 11.8µg/mL) and human liver carcinoma HepG2 cell lines (IC50 8.8, 12.0µg/mL), respectively. Compounds 1 and 2 were evaluated as potential inhibitors of caspase-3, a member of the cysteine protease family, which is considered a key enzyme in inducing cell apoptosis. Results showed that compounds 1 and 2 have induced apoptosis via up-regulation of caspase-3. Sarcotrocheliol (1) displayed antimicrobial activity against P. aeruginosa (15mm), B. subtilis (15mm), M. luteus (14mm) and C. albicans (15mm), with a MIC of 1.5µg/mL against the reported test microorganisms. On the other hand, cholesterol (2) showed less activity towards P. aeruginosa (10mm), B. subtilis (14mm), S. aureus (12mm) and C. albicans (10mm) with MICs of 3.0, 1.5, 1.5 and 3.0µg/mL against the tested microorganisms, respectively. Larvicidal activity revealed that compounds 1 and 2 induced remarkable toxicity against the third instar larvae of the mosquito, Culex pipiens even at concentration of 2 ppm. Adulticidal activity data showed that tested compounds are distinctly potent toxicants against the housefly, Musca domestica adult females. Overall, compound 2induced much more insecticidal activity than 1, and M. domestica adult females were more sensitive to tested compounds than C. pipiens larvae. Computationally, Density Functional Theory (DFT) analyses revealed that compound 2 had a higher dipole moment and lower band gap energy when compared to compound 1. So, compounds 2 is chemically more reactive and less stable than compound 1. According to the molecular docking study against PDB IDs: 3KJF, 5UHF and 1ACJ, compounds 1 and 2 demonstrated their activity mode as anticancer, antimicrobial, and insecticidal agents. The compounds exerted many interactions and showed high binding to the proteins, recognizing their potential as drug candidates with broad bioactivities.

Evaluation of the strategy for insecticidal crystal encapsulation with cell wall in industrial processes.

Bacillus thuringiensis (Bt) can produce insecticidal crystal proteins during sporulation, and these are the basis of the most successful microbial insecticides in use today. However, the susceptibility of insecticidal crystal proteins to inactivation by ultraviolet (UV) radiation from sunlight causes damage to the insecticidal crystals and subsequent loss of toxicity. The deletion of the mclX gene, an unknown functional gene, can make the insecticidal crystal proteins become encapsulated by the cell wall which provides some protection against UV radiation. This study evaluates the potential of this innovative strategy during the industrial process of commercial strain KN11. Gene mclX was deleted from a commercial Bt strain KN11 successfully, and the mutant strain was cultured under different conditions, including laboratory and industrial fermentation conditions. The mother cells of the mclX mutant strain remained nonlysed after industrial processes. The deletion of mclX had no adverse effects on the production of Cry1Ac protein and no impact on the insecticidal activity. Most noteworthy, the ΔmclX mutant had improved UV resistance and insecticidal activity compared to the wild-type KN11 strain. This finding suggests that commercial strains can be genetically modified to encapsulate insecticidal crystal in Bt products using the mclX mutation strategy. This study evaluated the ability of commercial strains lacking the mclX gene to encapsulate crystals giving resistance to UV radiation. © 2024 Society of Chemical Industry.

Evaluating the insecticidal potential of alkaloids for the management of Thrips palmi: in vivo and in silico perspectives.

Insecticidal potential of seven commonly available alkaloids against melon thrips (Thrips palmi Karny) was investigated through in vivo experiments and the bioactivity was explained via in silico approaches. In vivo screening showed highest mortality of T. plami larvae for reserpine (43%), closely followed by tropinone (41%) after 24h of incubation. After 48h, tropinone surpassed reserpine with 83% mortality, indicating its prolonged insecticidal activity. A detailed bioassay of tropinone revealed its LC50 values as 1187.9 and 686.9µg mL-1 after 24 and 48h, respectively. While studying the molecular interactions between the alkaloids and four physiologically important target proteins of T. palmi, tropinone demonstrated the highest ligand efficiency and lowest predicted inhibitory constant, particularly when forming complexes with CathB protein. However, binding energy calculations of the docked complexes showed most favorable binding of reserpine with CathB. To clear the ambiguity, considering both binding energy and ligand efficiency as the evaluation parameters, a molecular dynamics study was carried out, which predicted higher stability of CathB-tropinone complex than CathB-reserpine complex in terms of the total energy of the system. These in silico findings aligned well with the in vivo results, confirming tropinone as a promising candidate for effective thrips management programs.

Synthesis and Fungicidal Activity Evaluation of Novel Triazole Thione/Thioether Derivatives Containing a Pyridylpyrazole Moiety.

Compounds containing N-pyridylpyrazole motif have aroused interest and brought about research hotspots due to their highly-efficient insecticidal activity. The fungicidal potential of N-pyridylpyrazole derivatives has gradually been disclosedin recent years. To discover new agrochemicals with poly-heterocyclic features, a series of novel triazole thione/thioether derivatives containing pyridylpyrazole motif (8-11) wassynthesized.The new compounds were identified by melting point, 1H NMR, 13C NMR, 19F NMR, HRMS,and elemental analysis. The bioassaysshowed that most of the pyridylpyrazole-containing triazole thione Mannich bases possessed favorable in vitrofungicidal activitytoward pathogenic fungi, such as Magnaporthe oryzae, Sclerotinia sclerotiorum, Botrytis cinerea andFusarium verticillioides, and were comparable with those of the contrast compounds Aand triadimefon. Some of them exhibited moderate to good in vivofungicidal activityagainst S. sclerotiorumat 0.2 mg/mL(e.g. 8fcontrol efficacy: 60.9±3.2%).The SEM observation displayed that 8f might cause disruptionof cell membrane and wall of S. sclerotiorum.Compounds 8a, 8c, 8f-8h, 8pand 9bcan serve as promising new fungicidal agents to make further structural optimization.The findings in this article provide useful clue and guidance for the design and development of new poly-heterocyclic agrochemicals.

Investigation on chemical composition and insecticidal activity against Anopheles gambiae of essential oil obtained by co-distillation of Cymbopogon citratus and Hyptis suaveolens from Western Burkina Faso.

Essential oils of Cymbopogon citratus and Hyptis suaveolens are known for their insecticidal properties, but remain ineffective against mosquitoes resistant to synthetic insecticides. In order to improve insecticidal properties of these plants, this study aimed to investigate the chemical composition and insecticidal activity against Anopheles gambiae mosquitoes of essential oil obtained by co-distillation of dry leaves of C. citratus and H. suaveolens. Essential oils were extracted by hydrodistillation from dry leaves of C. citratus and H. suaveolens, separately, then from the mixture of the dry leaves of the two plants in mass ratio 50/50. Each pure essential oil and the mixture obtained either by co-distillation or by combining pure essential oils in volume ratio 50/50 were then analysed by GC/MS. All essential oils and Deltamethrin 0.05% (positive control) were tested on two species of mosquitoes of the genus Anopheles gambiae according to the World Health Organization standard methods. Essential oil obtained by co-distillation mainly contained piperitone (40.80%), 1,8-cineole (24.64%), p-menth-4(8)-ene (13.20%), limonene (6.09%) and α-pinene (4.73%). However, the mixture of pure essential oils of these two plants mostly contained geranial (20.74%), neral (16.42%), 1,8-cineole (19.79%), sabinene (6.03%) and β-pinene (3.87%). The essential oil of C. citratus mainly contained geranial (41.49%), neral (32.83%), β-myrcene (13.66%) and geraniol (3.49%) while the major constituents of essential oil of H. suaveolens were 1,8-cineole (39.58%), sabinene (12.06%), β-pinene (7.73%), α-terpinolene (6.72%) and (E)-caryophyllene (7.49%). At the dose of 1%, all essential oils, except that of H. suaveolens, induced about 100% of mortality on the sensitive species of An. gambiae. However, on the resistant species at the same dose, the essential oil obtained by co-distillation induced the highest mortality (53.44%). The essential oils of C. citratus, H. suaveolens and the mixture of the two pure essential oils caused respectively 2.47, 15.28 and 18.33% of mortality. The synthetic insecticide caused 100 and 14.84% of mortality respectively on the sensitive and resistant species of An. gambiae. Essential oil obtained by co-distillation showed good insecticidal efficacy against a resistant species of An. gambiae and might constitute a new solution to fight against mosquitoes resistant to synthetic insecticides.

Chemical Composition, Biological Activity, and Application of Rosa damascena Essential Oil as an Antimicrobial Agent in Minimally Processed Eggplant Inoculated with Salmonella enterica

Rosa damascena is mostly grown for its usage in the food, medical, and perfume industries, while it is also used as an attractive plant in parks, gardens, and homes. The use of R. damascena essential oil may yield new results in relation to the antimicrobial activity of essential oils and their use mainly in extending the shelf life of foods. This study investigates the chemical composition and antimicrobial properties of Rosa damascena essential oil (RDEO) using gas chromatography–mass spectrometry (GC-MS) and various bioassays to explore its potential applications in food preservation and microorganism growth control. The GC-MS analysis revealed that RDEO is predominantly composed of phenylethyl alcohol (70%), which is known for its antimicrobial and aromatic properties. Additionally, other significant constituents were identified, including nerol, citronellol, and geraniol, which may contribute to the EOs overall bioactivity. The antimicrobial activity was assessed through the minimal inhibition concentration against five Candida yeast strains, four Gram-positive, and four Gram-negative bacteria, including biofilm-forming Salmonella enterica. Determination of minimum inhibitory concentrations (MIC) revealed the strongest effects of RDEO’s on Gram-negative species, with MIC50 values as low as 0.250 mg/mL for S. enterica. Moreover, an in situ assessment utilizing fruit and vegetable models demonstrated that the vapor phase of RDEO significantly suppressed microbial growth, with the most substantial reductions observed on kiwi and banana models. As a result of our study, the antimicrobial effect of RDEO on the microbiota of sous vide processed eggplant was detected, as well as an inhibitory effect on S. enterica during storage. The insecticidal activity against Megabruchidius dorsalis Fahreus, 1839, was also studied in this work and the best insecticidal activity was found at the highest concentrations. These results suggest that RDEO has the potential to serve as a natural antimicrobial agent in food preservation and safety applications, providing an alternative to synthetic preservatives.

Antimicrobial, Antifungal, and Insecticidal Activities of Scolymus Grandiflorus Essential Oil Rich in Davanoid Compounds

Background: This study explores the antimicrobial, antifungal, and insecticidal properties of Scolymus grandiflorus essential oil, examining its potential uses in the fields of pharmacology and agriculture. Materials and Methods: The essential oil obtained by hydrodistillation was studied by GC and GC/MS. The antibacterial capacity of the essential oil was determined against two Gram-positive and three Gram-negative bacterial species. The antifungal activity of the essential oil was investigated against two fungi responsible for many fruit and vegetable diseases. The insecticidal activity of essential oil was evaluated against larvae, pupae, and adult flies of Ceratitis capitata. Results: The GC and GC-MS analysis of the essential oil of the roots of S. grandiflorus revealed the predominant presence of davanoids, representing more than 80% of its chemical composition. The results of the disc diffusion test showed significant antimicrobial activity. The essential oil inhibited the growth of Salmonella typhi (25 mm), Staphylocoque aureus (18 mm), and Escherichia coli (17 mm), with inhibition diameters comparable to those of gentamicin. The essential oil significantly inhibited mycelial growth, with up to 98% inhibition for Fusarium solani and 73% for Alternaria alternata at 8 μL/mL. Insecticidal activity was most pronounced on adult flies, followed by pupae and finally larvae. Conclusion: Tests on the essential oils of S. grandiflorus revealed promising characteristics as insecticidal, antifungal, and antimicrobial agents. These results could be used in the development of new solutions to control pathogens responsible for plant diseases and mycotoxin-producing organisms.

Structure Characterization of Four New Sesquiterpene Pyridine Alkaloids from Tripterygium wilfordii Hook. f. and Anti-Inflammatory Activity Evaluations

Sesquiterpene pyridine alkaloids (SPAs), as a main class of components in Tripterygium wilfordii Hook. f., possess a variety of bioactivities, such as immunosuppressive, insecticidal, and anti-tumor activities. SPAs can be structurally classed into four subtypes: wilfordate-, evoninate-, iso-wilfordate-, and iso-evoninate types. Our previous study unveiled ten new wilfordate-type SPAs, named wilfordatine A–J, isolated from the roots of Tripterygium wilfordii Hook. f., several of which exhibited significant immunosuppressive activities. As an extension and augmentation of the previous findings, we have now isolated one new iso-wilfordate-type SPA, wilfordatine K (1), alongside three new iso-evoninate-type SPAs, wilfordatines L–N (3–5), and six known analogs. Their structures were characterized by the extensive use of 1D and 2D NMR spectroscopic analysis, as well as HRMS data. Interestingly, compounds 4 and 6 were found to exhibit potent inhibitory effects on the nuclear factor-kappa B (NF-κB) pathway in lipopolysaccharide (LPS)-induced HEK293/NF-κB-Luc cells, with IC50 values of 1.64 μM and 9.05 μM, respectively. Notably, these two compounds had no influence on the cell viability at a concentration of 100 μM. Consequently, they hold significant promise as potential anti-inflammatory candidates for further exploration and development.

Toxicity and residual activity of insecticides to Grapholita molesta (Lepidoptera: Tortricidae) in apple orchards: implications for insecticide resistance management.

Organophosphate (OP) insecticides have been used to control Grapholita molesta (Busck, 1916) in Brazil since 1990. However, the evolution of pest insecticide resistance and toxicological reassessments has led to the replacement of OPs with other chemical groups. This study evaluated the toxicity of the insecticides abamectin + cyantraniliprole (1.1 + 3.7g a.i./100L-1), acetamiprid + etofenproxi (9.1 + 16.5g a.i./100L-1), emamectin benzoate (0.5g a.i./100L-1), Sophora flavescens (Fabales: Fabaceae) (22.8g a.i./100L-1), phosmet (87.5g a.i./100L-1), and indoxacarb (11.2g a.i./100L-1) to eggs, larvae, and adults of G. molesta. Additionally, the residual activity of these insecticides in apple orchards was assessed, and the diagnostic concentration for resistance monitoring was estimated using LC99 values (Lethal Concentration that causes 99% mortality in a susceptible population). In larval studies, all insecticides resulted in mortality rates of more than 90%. The insecticide acetamiprid + etofenproxi reduced larval hatching by 99%. This insecticide with phosmet and Sophora flavescens caused over 80% adult mortality and had a 14-day residual activity in apple orchards. The estimated LC99 (μg.ml-1) for resistance monitoring were 1.75 (indoxacarb), 6.45 (metaflumizone), 9.10 (acetamiprid + etofenproxi), 9.67 (Sophora flavescens), 36.13 (phosmet), and 45.61 (abamectin + cyantraniliprole). The insecticides evaluated have high toxicity for G. molesta, being new tools for integrated pest management and for insecticide resistance management in apple orchards.

Biennial Variation and Herbivory Affect Essential Oils of Ipomoea murucoides and Stomata Density of Neighbor Plants

Essential oils (EOs) are mixtures of volatile organic compounds that mediate plant interactions and are also appreciated for their biological properties in aromatic plants. However, the study of EOs in wild plants with biological activity has been neglected. Ipomoea murucoides is a wild species with allelopathic and insecticide activities; however, the climate factors associated with EOs and their role in intra- and interspecific interactions are still unknown. We investigated the effects of temperature, rain, and solar irradiance for two years on the EOs of I. murucoides and documented the effect of herbivory (without, <20%, >20%, and mechanical damage) on their composition. We evaluated the receptivity to possible infochemicals in conspecific and congeneric neighbors to I. murucoides plants exposed to methyl jasmonate (MeJA), herbivory by Ogdoecosta biannularis and without an elicitor. We measured the stomatal density and aperture in the second leaf generation of the neighbor plants. The year and herbivory >20% affected the composition of EOs. Nerolidol could be a biological marker for herbivory. We concluded that herbivory and rain irregularity contribute to EOs changing. The response in the stomatal density in plants not consumed by I. pauciflora but near I. murucoides under MeJA or herbivory gives evidence of interspecific plant–plant communication.

Functionalized carbohydrazide: Synthesis, insecticide evaluation, biological and histological studies of some new carbohydrazide derivatives against Spodoptera frugiperda

Fall armyworms, or Spodoptera frugiperda, are a major pest for numerous economically significant cultures. The majority of S. frugiperda control is still accomplished through the use of genetically modified plants and artificial chemicals, both of which have the potential to negatively impact no target animals. In order to further improve the insecticidal activity based on eco-friendly principles, we synthesized ten novel carbohydrazide derivatives and evaluated their insecticidal performance against S. frugiperda larvae in their second and fourth larval instars. A number of spectroscopic techniques, were used to verify the newly developed products' structural integrity. Target compound 10 was the most active, with an LC50 of 2.14 mg/L for 2nd instar larvae and 15.33 mg/L for 4th instar larvae. In addition, some biological and histological characteristics of the demonstration compounds were also investigated. This work provides new insights into the production of carbohydrazide compounds and further supports the anti-proliferation of S. frugiperda.

Antiplasmodial and Insecticidal Activities of Third-Generation Ivermectin Hybrids.

Preclinical and/or clinical studies have demonstrated the potential of Ivermectin (IVM) for malaria control. In order to improve its antiplasmodial activity and build on previous knowledge, we have designed a third generation of hybrid molecules in which selected pharmacophores were appended to the IVM macrolide, while retaining one or both sugar moieties at the C-13 position. Moreover, we synthesized IVM hybrids that contain structural features of potent IVM metabolites. The evaluation of the in vitro antiplasmodial activity of these compounds against Plasmodium berghei pre-erythrocytic stages and Plasmodium falciparum erythrocytic stages identified molecules that displayed enhanced activity against the latter when compared to IVM. Additionally, two IVM intermediates and one IVM hybrid retained the insecticidal activity of the parental molecule, clarifying the contribution of the sugar moieties to this feature. Altogether, these results provide key structure-activity relationships to guide the rational design of new generations of IVM hybrids.

Diversity of biological activities of crude venom extracted from five species of South China Sea anemones

Developing novel, efficient, and safe peptide drugs from sea anemones has aroused great interest in countries around the world today. Sea anemones contain complex protein and peptide toxins, which determine the diversity of their biological activities. In this study, a variety of activities were assessed for crude venom extracted from five species of South China Sea anemones, including hemolytic, enzyme inhibition, anticancer, insecticidal, analgesic and lethal activities. The most toxic sea anemone was found to be Heteractis magnifica, which has high lethal activity in mice with an LD50 of 11.0 mg/kg. The crude venom of H. magnifica also exhibited a range of the most potent activities, including hemolytic, trypsin inhibitory, cytotoxic activity against U251 and A549 cells, insecticidal and analgesic activities. In addition, the crude venom of Stichodactyla haddoni was the most effective inhibitor of pepsin, and the crude venom of Heteractis crispa was extremely strong toxicity to HepG2 cells. These findings are of great significance for exploring the potential and application of South China Sea anemone resources, and are expected to provide new directions and possibilities for the development of novel anticancer drugs, analgesics and biopesticides.

An antagonist of the neurotransmitter tyramine inhibits the hyperactivating effect of eugenol in the blood-sucking bug, Triatoma infestans

Eugenol is a botanical monoterpene found in the essential oils of several aromatic plants. It has shown to have insecticidal activity, modify insect behavior, and its site of action is most probably in the octopaminergic system. The aim of the present study was to explore whether tyramine receptors are involved in the hyperactivity produced by eugenol in Triatoma infestans, one of the main vectors of Chagas disease. Topical application of tyramine and eugenol increased locomotor activity in third instar nymphs of T. infestans in a dose-dependent way. Yohimbine hydrochloride, a tyramine antagonist, did not modify nymph activity. However, nymphs pretreated with yohimbine and then with tyramine or eugenol showed the same locomotor activity as the controls. Therefore, yohimbine hydrochloride inhibited the hyperactivating effect of both tyramine and eugenol. These results suggest that tyramine receptors are involved in the effect of eugenol on the locomotor activity of T. infestans.

Whitefly‐Pathogenic Beauveria bassiana JEF‐507 as a Competitive Biopesticide, Chongchae‐Stop

ABSTRACTSilverleaf whitefly, Bemisia tabaci (Hemiptera: Aleyrodidae), is a destructive insect pest damaging to diverse crops by vectoring several plant pathogenic viruses, which consequently causes economic losses in crop production. As the resistance of whiteflies to chemical insecticides is increasing, this study aimed to investigate the potential of entomopathogenic fungi as an alternative. A total of 72 entomopathogenic fungal isolates, collected from soils using Tenebrio molitor larvae as an insect baiting method, were assessed for their virulence against 2nd nymphs of whitefly. Their virulence was assayed by dipping whitefly‐infested tomato leaves in fungal conidia suspensions at 1.0 × 107 conidia/mL. Among the tested isolates, two isolates of Beauveria bassiana JEF‐462 and JEF‐507 showed high virulence. In the assessment of virulence depending on conidia concentrations, the estimated LC50 values for JEF‐462 and JEF‐507 were similarly 8.7–14.0 × 107 conidia/mL. However, B. bassiana JEF‐507 showed higher conidial productivity and thermotolerance on most of tested 12 grain substrates than B. bassiana JEF‐462, and millet was the most suitable grain substrate. Additionally, siloxane as a surfactant was able to sufficiently exhibit the insecticidal activity of JEF‐507 against whitefly nymphs compared with other surfactants. In a pot‐based greenhouse trial, JEF‐507 showed higher control efficacy than chemical insecticides, dinotefuran and spinetoram. This work suggests that B. bassiana JEF‐507 could be competitively used as a biopesticide to control silverleaf whiteflies while overcoming current resistance issues. The JEF‐507 isolate has been registered in Korea, 2022 and successfully commercialised as the name of Chongchae‐Stop in this local market to control whitefly and thrips.

Identification and synthesis of a long-chain antimicrobial peptide from the venom of the Liocheles australasiae scorpion.

Scorpion venom contains linear peptides without disulfide bonds in addition to peptides with disulfide bonds. Many such linear peptides have an amphiphilic α-helical structure, often with antimicrobial activity and can be classified into three groups based on their molecular size. Among them, long-chain antimicrobial peptides consisting of more than 40 residues have not been thoroughly studied due to the difficulty of synthesizing them. We have previously reported a transcriptome analysis of the venom gland of Liocheles australasiae that revealed precursor sequences of long-chain antimicrobial peptides. In the study reported here, we identified the mature structure of one such long-chain antimicrobial peptide, LaCT1, which we synthesized using chemical ligation to confirm its structure and evaluate its biological activities. The result showed that LaCT1 exhibited significant antimicrobial activity. In addition, we identified its partial peptides consisting of an N- or C-terminal region, which may be generated by enzymatic cleavage in the venom. Among them, only the peptide containing the N-terminal half region was active. LaCT1 also not only showed insecticidal activity but also synergistically enhanced the effects of another insecticidal peptide identified in L. australasiae venom as well. These results provide insights into the role of antimicrobial peptides in scorpion venom.

C-terminus processing in Tma12 is critical for its insecticidal activity

Tma12 is a fern-derived biopesticide (22 kDa) whose LPMO activity is associated with its insecticidal activity. The absence of the last 9 amino acids in the crystal structure of Tma12 suggested a possibility of its C-terminus processing. In this communication, we have shown the importance of protein C-terminus in the insecticidal activity. Additionally, we have also established the role of N-linked glycosylation in protein stability. Pichia produced (His)6 tagged Tma12 in two forms. The 30 kDa protein comprising 192 amino acid residues did not show insecticidal activity. Contrary, 24 kDa protein exhibited toxicity to whiteflies with an LC50 1.38 μg/ml. Absence of (His)6 tag in 24 kDa protein indicated processing at the C-terminus which was confirmed with deletion mutagenesis. Failure in expressing glycosylation defective mutant suggested the importance of glycans in the stability of Tma12. New findings together with earlier reports suggest that along with the N-terminal catalytic center, correct C-terminus is pivotal for anti-whitefly activity of Tma12.

Synthesis, Characterization, Insecticidal Activity and Antibacterial Evaluation of Some Heterocyclic Compounds Containing 1,2,3-Triazoles Moiety

A series of 1,2,3-triazole compounds having thymol or paracetamol moieties have been designed via employing ‘click’ chemistry with copper-catalyzed azide-alkyne cycloaddition reactions. Additionally, the insecticidal characterizations of many designed products were perceived with respect to second & fourth of Spodoptera littoralis instar larvae. Numerous insecticides are revealed as novelties. As a result, numerous triazole derivatives were designed chemically to assist as analogues a comprehensive class of insecticides. With LC50 value of 0.321 mg/L for second larvae instar and LC50=0.627 mg/L four instar larvae, components 10 display the highest insecticidal bioactivity. This article deliberates how to find novel compounds that could be employed as insecticidal components in the future. A few biological and biochemical properties of the compounds produced in a laboratory environment were also examined. This work also addresses the process of finding new compounds that could be used as insecticidal products in the future. Ultimately, the antibacterial effectiveness of each developed component contrary to both Gram-positive & Gram-negative bacteria was observed.

The toxicity, repellent, and biochemical effects of four wild plant extracts against Aphis gossypii Glover and Phenacoccus solenopsis Tinsley: HPLC analysis of phenolic compounds

The insecticidal and repellent activities of the four wild plant extracts: stinging nettle, Urtica dioica L., white henbane, Hyoscyamus albus L., camphorweeds, Pluchea dioscoridis L., and cocklebur, Xanthium strumarium L. were tested compared to the insecticide spirotetramat against the 3rd nymphal instar of Aphis gossypii Glover and adult females of Phenacoccus solenopsis Tinsley after 24 and 48 h of treatment. Their effects on acetylcholinesterase (AChE) and glutathione-S-transferase (GST) enzyme activities were also assessed to explore their possible mechanisms of action. The phenolic compounds of the plant extracts were investigated by high-performance liquid chromatography (HPLC) analysis. The most abundant compounds in the methanol extract from P. dioscoridis were gallic acid (14.45 µg/mL), and cinnamic acid (11.44 µg/mL); from U. dioica were caffeic acid (15.32 µg/mL) and syringic acid (13.47 µg/mL); from H. albus were syringic acid (7.12 µg/mL) and catechol (5.33 µg/mL); and from X. strumarium were p-coumaric acid (24.53 µg/mL) and pyrogallol (18.35 µg/mL). According to the LC50 values, the contact toxicity of U. dioica, H. albus, P. dioscoridis, and X. strumarium against A. gossypii was 40.3, 60.6, 56.2, and 32.3 mg/L, whereas, the contact toxicity against P. solenopsis was 56.4, 67.5, 64.3, and 36.2 mg/L, compared to the spirotetramat (17.2 and 24.5 mg/L), respectively, at 48 h of treatment. The highest repellency rates were observed with LC50 values for X. strumarium (63.2 and 60.3%), followed by U. dioica (46.2 and 43.5%), P. dioscoridis (45.3 and 42.8%), and H. albus extract (38.8 and 35.2%) compared to the spirotetramat (78.5 and 76.2%) against A. gossypii and P. solenopsis at 24 h, but decreased with time. The AChE and GST activities in pests were significantly inhibited, compared to control and spirotetramat, with dose and time-dependent effects. These findings indicate that tested wild extracts may be suggested as viable alternatives for aphids and mealybugs control.