Insecticidal Activity Research Articles

Chitin nanocrystal Pickering emulsions for sustainable release pesticide microencapsulation with superior leaf adhesion and enhanced safety

Traditional pesticides often exhibit high non-target toxicity, poor stability, short persistence, and susceptibility to wash-off by rain. Pesticide microencapsulation represents a significant advancement in formulation strategies, addressing safety and sustainability concerns associated with conventional pesticides. This study explores the utilization of biodegradable chitin nanocrystals (ChNCs), prepared via acid hydrolysis, for the development of pesticide microcapsules. Specifically, ChNCs were employed to emulsify molten pesticides, followed by interfacial polymerization to fabricate pesticide-loaded microcapsules. Using molten emulsification and Pickering emulsion templates offer a simple and solvent-free approach for microcapsule preparation, eliminating the need for conventional surfactants. The microcapsules displayed a size distribution ranging from hundreds of nanometers to several micrometers, which could be tuned by adjusting the ChNCs content. These microcapsules demonstrated remarkable properties, including a high pesticide loading capacity (reaching 78.7% for lambda-cyhalothrin), excellent storage stability, and enzyme-responsive release behavior. Furthermore, the abundant positive charges enhanced the interaction between the microcapsules and leaf surfaces, leading to improved pesticide retention. Microencapsulation reduces acute insecticidal activity of pesticides due to the slow-release effect; however, field experiments provide compelling evidence that microcapsule formulations significantly prolong pesticide efficacy compared to conventional formulations. Additionally, microencapsulation significantly improved the safety of pesticides, with the LC50 increasing from 0.0116 mg/L to 3.75 mg/L. Overall, this study introduces a promising method for pesticide microencapsulation using ChNCs Pickering emulsion, highlighting its potential advantages and providing valuable insights for the development of environmentally friendly and novel pesticide formulations.

Synergistic Phytochemical and Nanotechnological Exploration of Melia azedarach With Silver Nitrate: Elucidating Multifaceted Antimicrobial, Antioxidant, Antidiabetic, and Insecticidal Potentials.

Plants are a rich source of bioactive compounds with significant pharmaceutical and health applications. This study explores the phytochemical, therapeutic, and phytotoxic properties of Melia azedarach by analyzing extracts from its bark, flowers, leaves, and fruits using six solvents: ethanol, methanol, acetone, hexane, chloroform, and distilled water. Twenty-one phytochemical tests were conducted, revealing significantly positive results for various tests. However, the ethanolic and methanolic flower extracts yielded no significant results in other tests. The highest total phenolic content was found in the chloroform extract of the leaves (96 ± 0.01 mg/100 g), and the highest antioxidant activity was observed in the ethanolic and hexane leaf extracts, with a 98% DPPH scavenging rate. Antibacterial testing showed significant efficacy against Serratia marcescens, Bacillus subtilis, Kluyvera spp., and Pseudomonas spp., with p values < 0.0001. The fruit chloroform extract demonstrated the highest alpha-amylase inhibition (93 ± 0.05), while the ethanolic leaf extract had the greatest tumor inhibition (85.6 ± 0.5). Insecticidal assays revealed that the acetone bark extract had the highest control values (56% and 57%). Due to their higher reducing potential, the leaves were used to biosynthesize silver nanoparticles (AgNPs), characterized by UV-Vis spectroscopy, EDX, and SEM, revealing an average particle size of 20-30 nm and spherical morphology. The AgNPs exhibited excellent antibacterial, antioxidant, antidiabetic, and insecticidal activities. These findings highlight the potential of M. azedarach and its AgNPs for developing novel therapeutic agents.

The herbicidal activity and mechanism of Talaromyces purpureogenus CY-1 metabolites.

Studies have shown that Talaromyces can produce a large number of secondary metabolites in its metabolic process, many of which have good insecticidal, antibacterial, antitumor, antiviral and other biological activities. In order to explore the herbicidal activity and mechanism of Talaromyces purpureogenus CY-1, we determined the inhibitory effect of the fermentation broth of the CY-1 strain on weeds, identified the major active components, and further investigated the herbicidal mechanism. The results showed that CY-1, with IC50 values of 5.40 g/L and 4.39 g/L, respectively, exhibited good herbicidal activity against Xanthium sibiricum and Amaranthus lividus. Spraying CY-1 strain fermentation broth on redroot pigweed resulted in plant protection efficiencies and fresh weight protection efficiencies of 83.7% and 87%, respectively. The active component identified in the broth was 2-(3-hydroxybenzoyloxy) acrylic acid. Treatment of Amaranthus lividus with 2-(3-hydroxybenzoyloxy) acrylic acid resulted in trends of increasing superoxide dismutase activity, peroxidase activity, respiratory rate, cytochrome oxidase activity, and soluble protein content, followed by a decrease. Peroxidase activity, relative conductance and malondialdehyde content gradually increased, while acetyl lactate synthase and glutamine synthetase initially decreased and gradually returned to normal. The soluble sugar content showed a gradual decrease. The findings of the present study indicate that 2-(3-hydroxybenzoyloxy) acrylic acid can induce oxidative stress in plants, damaging plant cell walls, weakening respiratory activity, inhibiting protein synthesis and sugar metabolism, ultimately leading to weed wilting and death. © 2024 Society of Chemical Industry.

Discovery of Acaricidal, Insecticidal, and Fungicidal Candidates Inspired by Natural Ethyl Cinnamate Compounds Isolated from Polygonum orientale L.

As a continuation of our research on the pesticide development of Polygonum orientale L., the chemical constituents of the seeds of P. orientale were systematically investigated. Eleven natural compounds (PO-1 to PO-11) were isolated from the EtOAc extract of P. orientale. Notably, compound PO-9 and its dimeric compound PO-10 were first isolated from P. orientale and possessed excellent acaricidal activity against Tetranychus cinnabarinus. With PO-9 and PO-10 as the lead compounds, two series of cinnamate derivatives were further synthesized, and their acaricidal, insecticidal, and fungicidal activities were evaluated systematically. The insecticidal activity results showed that dimeric derivative NKY-70 displayed the highest acaricidal activity against T. cinnabarinus and insecticidal activities against Brevicoryne brassicae and Myzus persicae. Furthermore, most of these compounds showed excellent in vitro antifungal activity against plant fungi. Compound NKY-66 displayed the highest and broad spectrum of antifungal activity against 23 fungi, and the respective EC50 values were 0.09, 0.08, 0.12, 0.18, 0.12, and 0.09 mg/mL against Valsa mali, Fusarium oxysporum f. sp. cucumerinum, Fusarium graminearum, Magnaporthe oryzae, Colletotrichum capsici, and Phytophthora infestans, which were more potent than those of chlorothalonil and procymidone. Moreover, the in vivo fungicidal evaluation also demonstrated that compound NKY-66 could effectively control plant fungal diseases in the greenhouse and in the field, such as damping off, powdery mildew, and cucumber downy mildew. Therefore, these findings implied that the cinnamate derivative NKY-66 displayed superior in vitro and in vivo fungicidal activities and could be a potential candidate against plant fungal diseases.

Bacillus thuringiensis strains with high insecticidal activity against insect larvae of the orders Coleoptera and Lepidoptera

Abstract The concept of sustainable agricultural development is aimed at reducing the use of chemical pest control agents. Since the use of chemical pesticides poses a significant environmental threat, one of the possible solutions to overcome this problem is the study of biological approaches, in particular, the use of entomopathogenic microorganisms as biological pest control agents. Insecticidal activity of over 220 strains of Bacillus thuringiensis (Bt) and Lysinibacillus sphaericus from the collection of the Laboratory of Spore-Forming Microorganisms of the Microbial Depository Center of the Scientific and Production Center “Armbiotechnology” and 15 strains isolated from samples of dead insects (imago) of representatives of various genera of the Coleoptera order was studied. The pathogenic effect of the strains was assessed in relation to the insect species Tenebrio molitor, Zophobas morio, Leptinotarsa decemlineata Say and Pieris brassicae, belonging to the Coleoptera and Lepidoptera orders. Among the test objects, the representative of Lepidoptera Pieris brassicae demonstrated the highest degree of sensitivity to B. thuringiensis strains up to 100%, with some Bt strains causing 60–100% mortality of Tenebrio molitor and Zophobas morio larvae of different ages. The larvae of the beetle Leptinotarsa decemlineata Say were also partially susceptible, presenting mortality levels of between 31 and 60%. The article is devoted to the study of Bt bacterial strains that have pronounced insecticidal activity against insect larvae of the orders Coleoptera and Lepidoptera.

Bioinsecticides based on neem (Azadirachta indica) and rue (Ruta graveolens) against Agrotis ipsilon

Agrotis ipsilon is an important pest of several crops, where it causes damage to various parts of the plant such as stems, roots, leaves and tubers. Due to the growing demand for controlling these pests, there is a constant need for new products as the organisms acquire resistance after continuous contact. And this also generates a demand for bioinsecticides, which normally pose a lower health risk and are less harmful to the environment. Among the plants commonly used as insecticides are neem and rue, which have already been studied for several pests, although never together. This work aimed to determine the insecticidal activity of a natural insecticide derived from a mixture of neem and rue, commonly used in the region of Senhor do Bonfim-BA against A. ipsilon. Four different solutions were prepared, containing a) 20 neem leaves, 10 rue leaves and 5 A. ipsilon caterpillars, b) 20 neem leaves and 10 rue leaves, c) 20 neem leaves and d) 10 rue leaves. Water was tested as control. In the tests carried out, both the mixture popularly used in the region, containing neem, rue, and A. ipsilon caterpillars, as well as the solution containing only neem and rue had good results, killing all caterpillars in 72 hours. Isolated plant extracts did not obtain good results, only delaying the formation of pupae for neem extracts. Therefore, the mixture of Neem and Rue showed good insecticidal potential against A. ipsilon, with much higher activity than its isolated components.

Antioxidant cysteine and methionine derivatives show trachea disruption in insects.

To prevent the deterioration of the global environment, the reduction of chemical pesticide use and the development of eco-friendly pest control technologies are urgent issues. Our recent study revealed that the production of reactive oxygen species (ROS) by dual oxidase (Duox) plays a pivotal role in stabilizing the tracheal network by intermediating the tyrosine cross-linking of proteins that constitute trachea. Notably, the formation of dityrosine bonds by ROS can be inhibited by the intake of an antioxidant cysteine derivative N-acetyl-L-cysteine (NAC), which can suppress insect respiration. In this study, we screened for the derivatives showing insecticidal activity and tracheal formation inhibition. As a result of investigating the soybean pest bug Riptortus pedestris, cysteine and methionine derivatives showed respiratory formation inhibition and high insecticidal activity. In particular, NAC had a slow-acting insecticidal effect, while L-cysteine methyl ester (L-CME) showed relatively fast-acting insecticidal activity. Furthermore, the insecticidal activity of these derivatives was also detected in Drosophila, mealworms, cockroaches, termites, and plant bugs. Our results suggest that some antioxidant compounds have specific tracheal inhibitory activity in different insect species and they may be used as novel pest control agents upon further characterization.

New CYP154C4 from Streptomyces cavourensis YBQ59 performs regio- and stereo- selective 3β-hydroxlation of nootkatone

Nootkatone, a sesquiterpenoid widely used in the food and cosmetics industries, exhibits diverse biological activities and pharmaceutical prospects. Modification of nootkatone to create new derivatives with desirable activities has attracted significant attention. For this purpose, cytochrome P450 monooxygenases (P450 or CYP) are attractive candidates due to their ability to perform regio- and stereoselective hydroxylation at allylic C–H bonds. In this study, CYP154C4 from Streptomyces cavourensis YBQ59 was cloned and expressed in Escherichia coli. By screening 64 candidate substrates, this P450 was found to catalyze the regio- and stereoselective hydroxylation of nootkatone, yielding a single product, 3β-hydroxynootkatone. Using a whole-cell E. coli system expressing CYP154C4, supported by the heterologous redox partners YkuN from Bacillus subtilis and FdR from E. coli, 3β-hydroxynootkatone was produced on a preparative scale. The structure of this compound was determined by 1H NMR, 13C NMR, NOESY, HMBC, and HSQC. The kinetics of product formation were analyzed using HPLC, and the Km and Kcat values were calculated. Furthermore, structural insights into the selective hydroxylation of nootkatone were elucidated by molecular docking. 3β-Hydroxynootkatone, recently synthesized semi-synthetically from nootkatone, has been reported to exhibit a higher insecticidal activity than its parent compound. Additionally, the functionalization of nootkatone with N-acyl-2-aminothiazole at the C3 and C2 positions, yielding an α-glucosidase inhibitor, has also been previously described. Therefore, 3β-hydroxynootkatone has great potential for further research and for synthesizing new derivatives with valuable biological activities for agricultural and medicinal applications.

Size effect of ZIF-8 based nanocarrier pesticide delivery system on targeted release and insecticidal activity.

Traditional chemical pesticides are easily lost by surface runoff and only small quantities reach the target, thus causing serious environmental pollution. In this work, dinotefuran@zeolitic imidazolate framework-8@polydopamine@zein (DNF@ZIF-8@PDA@zein), was constructed to deliver DNF with pH and enzyme double response of release, thereby achieving targeted release and efficient long-term pest control. DNF@ZIF-8@PDA@zein was synthesized with three hydrated diameters (249.73 ± 9.99 nm, 142.94 ± 5.63 nm and 75.16 ± 4.66 nm, respectively). The release of DNF from DNF@ZIF-8@PDA@zein after 28 h was significantly higher at pH 5.0 (89.22 ± 7.18%) compared to that at pH 8 (81.8 ± 6.11%). Protease-assisted release of DNF was notably higher than that without protease (pH 5: 89.22 ± 5.55% versus 27.19 ± 3.22%; pH 8: 81.8 ± 6.11% versus 25.39 ± 3.87%). The stimuli-responsive release of DNF from DNF@ZIF-8@PDA@zein increased with decreased particle size due to increased pore size, reduced binding forces (i.e., weaker π-π stacking, hydrogen bonding, and Zn-N covalent bonding), and the shortening of diffusion path, leading to faster disintegration and drug release. Additionally, the anti-photolysis ability of DNF@ZIF-8@PDA@zein was 3.2 times that of pure DNF. The insecticidal activity improved with smaller nanoparticles due to higher drug release rate and greater inhibition of detoxification enzyme activity by more zinc ion (Zn2+) dissolution. The pH and enzyme dual-responsive release as well as insecticidal activity of DNF@ZIF-8@PDA@zein increase with decreased nanoparticle size, showing effective pest management in long-term and potential application prospects in sustainable agriculture. © 2024 Society of Chemical Industry.

Novel Insecticidal Benzo[4,5]imidazo[1,2-b]pyrazole Derivatives Identified through Ring-Closure Scaffold Hopping on Fipronil.

A series of innovative benzo[4,5]imidazo[1,2-b]pyrazole scaffold containing compounds were rationally designed through a ring-closure scaffold hopping strategy and synthetized with an intermediate derivatization approach. Physicochemical properties analysis indicated the potential pesticide-likeness of the target compounds. The optimal target compound A14 showed relatively good insecticidal activity against P. xylostella, with an LC50 value of 37.58 mg/L, and demonstrated lower acute fish toxicity compared to fipronil. Docking binding mode analysis demonstrated that compound A14 bound to GABAR through a H-bond between the amide group and the residue of 6'Thr. The differences in binding modes between benzo[4,5]imidazo[1,2-b]pyrazole target compounds and fipronil may be a key factor for the reduced insecticidal activities. The elucidated binding mode and SAR profile lay a foundation for the further structural optimization of insecticidal benzo[4,5]imidazo[1,2-b]pyrazole derivatives.

Target Discovery of Dhilirane-Type Meroterpenoids by Biosynthesis Guidance and Tailoring Enzyme Catalysis.

Dhilirane-type meroterpenoids (DMs) featuring a 6/6/6/5/5 ring system represent a rare group of fungal meroterpenoids. To date, merely 11 DMs have been isolated or derived, leaving their chemical diversity predominantly unexplored. Herein, we leverage an understanding of biosynthesis to develop a workflow for discovery of DMs by genome mining, metabolite analysis, and tailoring enzyme catalysis. Twenty-three new DMs, including seven unprecedented scaffolds, were consequently identified. An α-ketoglutarate (α-KG)-dependent oxygenase DhiD was found to catalyze the stereodivergent ring contraction of dhilirolide D to form the dhilirane skeleton; while the cytochrome P450 DhiH reshaped the structural diversity by establishing diverse C-C bonds and oxidation. Crystallographic and mutagenesis experiments provide a molecular basis for the DhiD reaction and its stereodivergent products. Notably, DhiD exhibits substrate-controlled catalytic versatility in the chemical expansion of DMs through ring contraction, hydroxylation, dehydrogenation, epoxidation, isomerization, epimerization, and α-ketol cleavage. Bioassay results demonstrated that the obtained meroterpenoids exhibited anti-inflammatory and insecticidal activities. Our work provides insight into nature's arsenal for DM biosynthesis and the functional versatility of α-KG-dependent oxygenase and P450, which can be applied for target discovery and diversification of DM-type natural products.

Synthesis and Pesticidal Activities of Ester Derivatives of the Labdane Diterpenoid Andrographolide at the C-3 Position Containing the Isoxazoline Fragment and Their Toxicology Study against Tetranychus cinnabarinus Boisduval.

Due to the long-term overuse of chemical pesticides, serious resistance and negative problems on human health and the ecological environment have appeared. To develop plant-product-based pesticide candidates, a series of novel andrographolide ester derivatives containing the isoxazoline skeleton were prepared at the C-3 position. Their pesticidal activities were evaluated against three typical pests such as Mythimna separata Walker, Aphis citricola Van der Goot, and Tetranychus cinnabarinus Boisduval. Against M. separata, compounds Ik, IIf, IIg, and IIk showed 1.6-1.8 times insecticidal activity compared to that of andrographolide; against A. citricola, compounds 6, Ih, and IIh possessed 3.7-3.9-fold aphicidal activity compared to that of andrographolide; against T. cinnabarinus, compounds Ib, Ig, and IIk exhibited 7.4-9.1-fold promising acaricidal activity compared to that of andrographolide. It is worth mentioning that effects of IIk on morphological changes of the treated mite cuticle layer structures were observed by the scanning electron microscope imaging method. Compound IIk can be studied as a pesticidal lead for further structural modification.

Novel "Phenyl-Pyrazoline-Oxadiazole" Ternary Substructure Derivatives: Synthesis, Insecticidal Activities, and Structure-Activity Relationship Study.

In recent years, isoxazole insecticides or parasiticides targeting the γ-aminobutyric acid receptor, such as fluralaner or fluxametamide, featured a novel chemical structure and exhibited potent insecticidal activity with no-cross resistance. Thus, many research institutes have tried to modify the structures of these agents to find a new insecticide. Previously, the majority of researchers stuck to the "phenyl-isoxazole-phenyl" structure, making modifications only to other components. In this study, the "phenyl-isoxazole-phenyl" ternary motif was modified for the first time based on bioisosterism theory. A series of new derivatives carrying pyrazoline and 1,3,4-oxadiazole moieties were designed and synthesized to investigate their insecticidal activities against the diamondback moth (Plutella xylostella) and fall armyworm (Spodoptera frugiperda). Preliminary bioassay data showed that some of the target compounds exhibited good insecticidal activities against P. xylostella and S. frugiperda. Especially, compound A21 showed insecticidal activity against P. xylostella (LC50 = 1.2 μg/mL) better than commercial insecticide ethiprole (LC50 = 2.9 μg/mL) but worse than parasiticide fluralaner (LC50 = 0.5 μg/mL). Similarly, compound A21 exhibited insecticidal activity to S. frugiperda (LC50 = 13.2 μg/mL) better than commercial insecticide fipronil (LC50 = 78.8 μg/mL) but worse than fluralaner (LC50 = 0.7 μg/mL). Compound A21 could serve as a potential lead compound to control P. xylostella and S. frugiperda. The three-dimensional quantitative structure-activity relationship model revealed that the further introduction of an electron-donating group in the 2- or 3-site may increase the insecticidal activity of A21. Molecular dynamics simulations showed that the hydrogen bond of A21 and receptor was important for the binding receptor. This study has identified a new substructure called "phenyl-pyrroline-oxadiazole" instead of the previously known "phenyl-isoxazole-phenyl" substructure, offering a useful guide for the design of novel insecticide molecules.

Essential oil-loaded polymeric nanoparticles as a viable alternative to control storage grain insects -a review

The loss of stored grains is becoming a major issue globally because of insect infestation. The extensive usage of chemical insecticides for insect control has caused enormous harm to the worldwide ecology. Hence, it is essential to look for more environmentally sustainable solutions. Several essential oils (EOs) and bioactive chemicals have been adopted as natural insecticides due to their considerable insecticidal activity, diversified mechanism of action, and nontoxicity to other organisms. Meanwhile, despite their potential features, EOs have certain disadvantages, including being extremely volatile, less water-soluble, more rapidly degradable and the cost of production in some cases. Encapsulating EOs as nanoemulsions into polymers has recently been recognized as a potential technique for increasing their stability, selective release, and usefulness in various domains. These EOs and nanoemulsions displayed insect-deterrent behaviour by acting as fumigants, contact repellents, antifeedants, egg development deterrents, and larval agents, in addition to inhibiting chemical messengers such as acetylcholinesterase (AChE) and octopamine and transforming enzyme performance. This review article summarizes recent trends and innovations to define polymeric nano-formulated EOs as environment-friendly substitutes for harmful conventional insecticides. It also provides opportunities for more secure and profitable methods of controlling agricultural insects. Along with this, the insecticidal activity and mechanism of action for various essential oils and essential oil-loaded polymeric nanoparticles on various insects of stored grains are thoroughly discussed.

Synthesis of novel meta-diamide compounds containing pyrazole moiety and their insecticidal evaluation

Abstract A novel series of meta-diamide compounds incorporating a pyrazole moiety (2a–2v) were designed and synthesized based on cyproflanilide. Their structures were validated through 1H NMR, 13C NMR, and HRMS analyses. These compounds were evaluated for their insecticidal activity against Plutella xylostella, Mythimna separate, Tetranychus cinnabarinus, and Nilaparvata lugens. Most of the title compounds exhibited good activity against N. lugens at 400 mg/L. Compound 2k demonstrated potential for further optimization as an insecticidal lead, thereby extending the application of meta-diamide compounds in the field of sucking mouthparts.

Moringa olifera leave extracts yielded from irradiated and unirradiated seeds cause toxicity and induce dysregulation of enzymatic activities in fall armyworm, Spodoptera frugiperda (JE Smith, 1797) [Lepidoptera: Noctuidae]

The fall armyworm, Spodoptera frugiperda is the most distractive polyphagous noctuid pest in tropical and subtropical regions. The current study was designed to examine the insecticidal activity of the water extract of Moringa olifiera leaves cultivated from unirradiated and 40 Gy irradiated seeds. Also, the effect of the extract on some digestive enzymes activities was assayed. The results indicated that the extract produced from 40 Gy irradiated seeds was more effective than those of unirradiated one. As well as, leaves extract produced from cultivated irradiated and unirradiated seeds decrease lipase protease and amylase activities of 3rd instar larvae of S. frugiperda and the highest decrease was in larvae fed on leaves produced from irradiated cultivated seeds. Therefore, the water extract of M. olifiera leaves cultivated from 40 Gy irradiated seeds might be seen as an environmentally beneficial pest management method.

Improved Ensemble Model for Insecticide Recognition by Incorporating Insect Toxicity Data.

Pesticide molecules, such as insecticides, play a critical role in modern agricultural production. Traditional pesticide development methods are often inefficient and expensive, while data-driven artificial intelligence (AI) techniques have emerged as a useful tool to facilitate drug discovery. However, currently available commercial pesticide data is limited, which makes the trained models unsatisfactory in terms of performance and generalization. From a domain knowledge perspective, insect toxicity data were incorporated to improve the insecticide recognition of AI models. Compared to the models trained with the original data set, the new models performed better in the external validation, and their generalization was more desirable. In addition, by integrating different types of individual models, we obtained an ensemble model with better performance. Based on this, an online platform was developed to provide researchers with free access to insecticide screening (https://dpai.ccnu.edu.cn/InsectiVS/). Finally, two potential insecticide molecules with insecticidal activity against Plutella xylostella were successfully identified in a real-world scenario. In conclusion, this idea connects the fields of AI and agricultural chemistry and is expected to have wide application in pesticide research.

Combating Spodoptera frugiperda (Lepidoptera: Noctuidae) with Moringa-Synthesized Silica Nanoparticles and Its Combination with Some Insecticides.

The fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith), is a major agricultural pest known for developing resistance to insecticides. This study investigated a novel approach to manage FAW by silica nanoparticles (SiNPs) synthesized from eco-friendly leaf extract of Moringa oleifera Lam. (Moringaceae). This green synthesis method offers a sustainable and potentially safer alternative to traditional chemical processes. SiNP formation was confirmed by various techniques: UV-visible spectrophotometer, X-ray spectroscopy with energy-dispersive (EDX), scanning electron microscopy (SEM), and dynamic light scattering (DLS). The effectiveness of SiNPs alone and their combination with three common insecticides (emamectin benzoate, indoxacarb, and chlorpyrifos) were evaluated against third instar larvae of fall armyworm. While SiNPs after 24h by leaf dipping method recorded limited insecticidal activity (LC50 = 9947.59mg/L), it significantly enhanced the potency of all three insecticides. Combining SiNPs with emamectin benzoate resulted in the most dramatic increase in effectiveness compared to the insecticide alone with LC50 = 0.295mg/L and 0.42mg/L, respectively. This research suggests that moringa extract can be a valuable resource for the green synthesis of nanoparticles potentially useful in pest control. This approach could potentially reduce the amount of insecticide needed for effective pest control, leading to a more sustainable and environmentally friendly agricultural practice.

Thiacloprid-silica nano-delivery system enhances toxicity against Aphis gossypii and improves non-target biosafety

Nanotechnology aligns with the requirements of sustainable development of agriculture, and nano-pesticides offer a promising approach to controlling agricultural pests and increasing productivity. Non-target predators also play a crucial role in pest controls and enhancing the efficacy of pesticide on target organisms. Reducing the toxicity of pesticides to non-target organisms is key to of coordinating chemical control and biological control methods. Therefore, it is essential to assess the toxicity of nano-pesticides on non-target predators. In this study, a carbon dots-doped mesoporous silica nano-delivery system (Thi@CD-MSN) was successfully developed using CD-MSN as carrier material and thiacloprid (Thi) as a model pesticide. The results demonstrated that the synthesized Thi@CD-MSN exhibited a relatively high loading efficiency (33.58%). Laboratory bioassay experiments revealed that Thi@CD-MSN demonstrated effective insecticidal activity (LC50 = 21.67 mg/L) in controlling Aphis gossypii Glover. Besides, the acute toxicity of Thi@CD-MSN on Chrysoperla pallens larvae was significantly lower than that of Thi, as was its toxicity to 4T1 cells. These findings suggest that CD-MSN can serve as an ecological safety carrier for pesticide delivery, improving the effective utilization of Thi while reducing the risks to non-target predators. These results are essential for comprehending the effects of nano-pesticides on non-target predators, providing informative data for implementing biological and chemical control strategies. It strengthens the safety evaluation of nano-pesticides.

Evaluation of the insecticidal efficacy of four plants to protect stored Bambara groundnuts [Vigna subterranea (L.) Verdc. (Fabaceae)

Bambara groundnuts [Vigna subterranean] is one of the main legumes consumed in Northern Cameroon. However, stored nuts by farmers are quickly destroyed by pests leading to low yields. To overcome this constraint, the efficient control of stored grains from insect pests is dependent on synthetic insecticides. To reduce post-harvest losses of stored voandzou seeds, four botanicals insecticides have been developed and evaluated on the main pest. Plant powders prepared from Piper nigrum Linn. (Pipericaceae), Syzygium aromaticum (L.) Merr. &amp; L.M.Perry (Myrtaceae), Xylopia aethiopica Dunal (Annonaceae) and Phaseolus vulgaris L.( Fabaceae), at different doses were tested on Callosobruchus maculatus Fabricius under laboratory conditions. The rest of the study involved combining black bean powder with the three condiment species in different proportions. The analysis shows a highly significant difference (p &lt; 0.0001) between the mortality induced by formulations on day two of exposure with the lowest dose (0.5 g). These mortalities are 100%, 94.44 ± 3.79%, 72.5 ± 96 and 8.33 ± 4.77, respectively for S. aromaticum, P. nigrum, X. aethiopica and P. vulgaris powders. In relation to the formulation, the results show S. aromaticum powder induced 100% mortality compared with 94.44%, 72.59% and 8.33% respectively for P. nigrum, X. aethiopica and P. vulgaris plant powder at a dose of 5%. The results show that the natural substances used had a good insecticidal action against bruchid. The persistent compounds present in the studied spice plant powders are not toxic for human consumption at the concentrations used, but rather a beneficial effect. Key words: botanical insecticide, aromatic plants, powder, seeds, storage, insect pest.