Insecticidal Activity Research Articles

Whole-Genome Sequencing of the Entomopathogenic Fungus Fusarium solani KMZW-1 and Its Efficacy Against Bactrocera dorsalis.

Fusarium solani KMZW-1 is recognized for its potential as a biocontrol agent against agricultural and forestry pests, particularly due to its compatibility with integrated pest management (IPM) strategies. This study aimed to investigate the complete genome of F. solani KMZW-1 and assess its pathogenicity against Bactrocera dorsalis. Whole-genome sequencing revealed a genome size of 47,239,278 bp, comprising 27 contigs, with a GC content of 51.16% and fungus identified as F. solani KMZW-1. The genome completeness was assessed as 97.93% using BUSCO analysis, the DFVF sequence identifier was Fusarium 0G092560.1, and AntiSMASH analysis identified 35 gene clusters associated with secondary metabolite biosynthesis, providing insights into the genetic basis of its pathogenic mechanisms and biocontrol potential. Comparative genomic analysis found 269 unique genes for F. solani KMZW-1, and collinearity analysis exhibited a high degree of synteny with Fusarium solani-melongenae. The pathogenicity of F. solani KMZW-1 was assessed using concentrations ranging from 1 × 104 to 1 × 1011 conidia/mL. Higher concentrations (1 × 1010 to 1 × 1011 conidia/mL) resulted in significantly increased cumulative mortality rates of B. dorsalis adults compared to the control group. Notably, the pathogenicity was higher in male adults than in females. Probit analysis yielded LC50 (50% lethal concentration) values of 5.662 for female and 4.486 for male B. dorsalis adults. In summary, F. solani, KMZW-1 exhibits strong insecticidal activity against B. dorsalis and shows potential as a biocontrol agent with IPM strategies. These findings provide robust genomic evidence supporting the use of F. solani KMZW-1 in managing against B. dorsalis populations.

Toxicity and deterrence of pyroligneous extracts on Liriomyza sativae (Diptera: Agromyzidae)

Liriomyza sativa is a cosmopolitan and polyphagous insect, a key pest of crops such as tomato and melon. The inadequacy of insecticide application techniques has developed resistant populations. The objective of this research was to evaluate the toxicity, insecticidal activity and deterrence of pyroligneous extracts on the leafminer fly. The experiments were carried out under laboratory conditions of 25 ± 2°C and humidity of 60 ± 10%. For the toxicity test, solutions were prepared in different concentrations by diluting them in distilled water. Leaf discs containing L. sativae larvae were immersed in the solutions. For insecticidal activity and deterrence tests, jack bean plants were subjected to application of treatments using an airbrush, spraying 6 mL of the solutions on each plant. All extracts showed significant mortality for the larvae, with emphasis on the pyroligneous extract of coffee straw at 350ºC. The extracts did not interfere with the other developmental stages of the leafminer fly. The pyroligneous extract from the commercial company Agttec and the coffee straw extract at 600ºC were classified as attractive and the coffee straw extract at 350ºC as detergent. It is concluded that pyroligneous extracts can be used in the management of L. sativae.

Comparative assessment of the nature of the combined action of insecticides: different methodical approaches

Introduction. Pesticide mixtures containing insecticide methomyl are commonly used in agriculture. However, the interaction of their active ingredients in a mixture has been insufficiently studied. The purpose of the study was to evaluate the nature of the combined action of a mixture of insecticides methomyl (carbamate) and bifenthrin (pyrethroid) using various methods: a classical model (orthogonal planning of the experiment using nonlinear variables); a generalized linear regression model for the binomial distribution (probit regression); and an isobologram. The study was conducted at the Federal Scientific Center of Hygiene named after F.F. Erisman of the Federal Service for Supervision in Protection of the Rights of Consumer and Man Wellbeing, according to the protocol approved by the local bioethical commission. Materials and methods. Ninety male outbred rats were administered 9 combined doses of the insecticides (combinations of LD16, LD33 and LD50 for the individual compounds, as devised from a preliminary study). Results. Impaired coordination, tremor of the limbs and head, turning into convulsions, rapid (shallow) breathing were observed in all groups. The data on mortality as used to construct 2 mathematical models, as well as to construct an isobologram. Limitations. The study was limited to studying the indicators of acute oral toxicity, without taking into account the possible repeated exposure. Conclusion. The models showed that the additive effect for the combination of methomyl and bifenthrin was only observed for combinations when the individual dose of bifenthrin was equal to or greater than 45 mg/kg b.w. (LD33) and the dose of methomyl was less than 30 mg/kg b.w., as all animals receiving a dose of 30 mg/kg b.w. of methomyl (LD50) in the mixture died. Therefore, the dose of methomyl dictated the toxic effect of the mixture, which should be accounted for in hygienic regulation of methomyl-containing formulations.

Insecticidal activity of silver nanoparticles synthesised from aqueous leaf extract of Eucalyptus tereticornis on horn flies

An insecticidal efficacy of silver nanoparticles (AgNps) synthesised from aqueous leaf extract of Eucalyptus tereticornis, was carried out against adults, larval and pupal stages of Haematobia flies. In in vitro adulticidal and larvicidal assays the mortality ranged between 30.0 to 67.0 and 5.0 to 75.0 per cent in treated groups after 24 hours at different concentrations, respectively. The inhibition of pupation ranged between 5.0 to 30.0 per cent after 24 hours by dipping method. The lethal concentration values were calculated for all the assays. The probit analysis revealed the significant (p<0.05) effect at different concentrations of AgNPs synthesised from aqueous leaf extract of E. tereticornis on adults, larvae and pupal mortality Keywords: Haematobia flies, silver nanoparticles, in vitro assays

Eco-friendly formulation preparation of fungal biopesticide Metarhizium anisopliae and its impact on the viability, insecticidal activity and pesticidal compatibility

Aim: The present investigation evaluated the effect of various formulations on the viability, pesticide compatibility and biocontrol potential of fungal biopesticidal agent Metarhizium anisopliae under laboratory conditions. Methodology: Soil isolate of M. anisopliae biomass was formulated with different oils like sunflower, groundnut, neem oil, water and diesel using green principles. Results: Sunflower oil recorded maximum viability among the formulations, revealing 91.4% formulation efficacy, followed by groundnut oil, which showed 87.2% efficacy. The viability of the fungal isolate was found to be low in diesel formulation, which showed 69.2% formulation efficacy. A compatibility study revealed that sunflower oil formulation showed high tolerance to all the tested pesticides. Sunflower oil formulation also showed a high rate of mortality against S. litura. Interpretation: The present study suggests using oil formulation as an effective carrier for the fungal biopesticide Metarhizium anisopliae with high compatibility and viability. Key words: Biopesticide, Fungal strains, Metarhizium anisopliae, Sunflower oil

Synthesis of Nodupetide Analogue: Substitution of β- to α-hydroxy Acid

Nodupetide, a cyclodepsipeptide with the potential as an antimicrobial agent, was isolated from the fermentation of the fungi Nodulisporium sp strain IFB-A163. It possessed antibacterial activity against Pseudomonas aeruginosa and revealed an insecticidal activity. In our effort to synthesized nodupeptide, the preparation of the (3S,4S)-3-hydroxy-4-methylhexanoic acid (HMHA) as one of the nodupetide residue was found to be challenging, where it is not commercially available and the synthetic trial of the HMHA was not successful. This led us to synthesize nodupetide derivative by replacing HMHA with its a-hydroxy acid to give the analogue [(2S,3S)-Hmp]2-nodupetide. A combination of solid- and solution-phase peptide synthesis was applied in the synthesis nodupetide analogue. Esterification on the resin for synthesis [(2S,3S)-Hmp]2-nodupetide was achieved by placing the reaction at the last stage of the linear peptide synthesis and obtained in overall yield of 4.3 %. We also conducted antimicrobial activity screening for [(2S,3S)-Hmp]2-nodupetide and its linear precursor, showing inactive activity. The alter of hydrophobicity on the nodupetide analogue has very important role in the difference of bioactivity compared to their parent compound. HIGHLIGHTS The synthesized analogue compound has not been reported previously we studied the synthesis strategy of cyclodepsipeptide. We studied the change of beta hydroxy carboxylic acid residue to alpha hydroxy carboxylic acid, which has a very significant effect on biological activity. GRAPHICAL ABSTRACT

Bio-Pesticidal Potential of Nanostructured Lipid Carriers Loaded with Thyme and Rosemary Essential Oils against Common Ornamental Flower Pests

The encapsulation of essential oils (EOs) in nanostructured lipid carriers (NLCs) represents a modern and sustainable approach within the agrochemical industry. This research evaluated the colloidal properties and insecticidal activity of NLCs loaded with thyme essential oil (TEO-NLC) and rosemary essential oil (REO-NLC) against three common arthropod pests of ornamental flowers: Frankliniella occidentalis, Myzus persicae, and Tetranychus urticae. Gas chromatography–mass spectrometry (GC-MS) analysis identified the major chemical constituents of the EOs, with TEO exhibiting a thymol chemotype and REO exhibiting an α-pinene chemotype. NLCs were prepared using various homogenization techniques, with high shear homogenization (HSH) providing the optimal particle size, size distribution, and surface electrical charge. A factorial design was employed to evaluate the effects of EO concentration, surfactant concentration, and liquid lipid/solid lipid ratio on the physicochemical properties of the nanosuspensions. The final TEO-NLC formulation had a particle size of 347.8 nm, a polydispersity index of 0.182, a zeta potential of −33.8 mV, an encapsulation efficiency of 71.9%, and a loading capacity of 1.18%. The REO-NLC formulation had a particle size of 288.1 nm, a polydispersity index of 0.188, a zeta potential of −34 mV, an encapsulation efficiency of 80.6%, and a loading capacity of 1.40%. Evaluation of contact toxicity on leaf disks showed that TEO-NLC exhibited moderate insecticidal activity against the western flower thrips and mild acaricidal activity against the two-spotted spider mite, while REO-NLC demonstrated limited effects. These findings indicate that TEO-NLCs show potential as biopesticides for controlling specific pests of ornamental flowers, and further optimization of the administration dosage could significantly enhance their effectiveness.

The Insecticidal Activity of Secondary Metabolites Produced by Streptomyces sp. SA61 against Trialeurodes vaporariorum (Hemiptera: Aleyrodidae).

Trialeurodes vaporariorum Westwood poses a significant threat to vegetable and ornamental crops in temperate zones, resulting in notable reductions in yield and substantial economic burdens. In order to find compounds with high insecticidal activity against T. vaporariorum, five compounds were isolated and identified from the crude extract of Streptomyces sp. SA61. These include three new polyketides, named strekingmycins F-H (1-3); one new diterpenoid, named phenalinolactone CD8 (4); and one known compound, strekingmycin A (5). Their structures were analyzed using high-resolution electrospray ionization mass spectrometry and one-dimensional and two-dimensional nuclear magnetic resonance spectroscopy data and by comparing them with previously reported data. The insecticidal activities of compounds 1-5 against T. vaporariorum were evaluated. Among them, compound 5 exhibited the highest insecticidal activity, with an LC50 of 6.949 mg/L against T. vaporariorum at 72 h using the leaf-dip method. Lower insecticidal activities were found in compounds 1-4, with LC50 values of 22.817, 19.150, 16.981 and 41.501 mg/L, respectively. These data indicate that strekingmycin could be a potential candidate for a novel insecticide to control T. vaporariorum.

Conchocarpus J. C. Mikan (Rutaceae): Chemical Constituents and Biological Activities.

Rutaceae Juss. stands out as a botanical family recognized for its remarkable diversity in taxonomy, worldwide distribution, chemical composition, and biological activity exhibited by its compounds. Conchocarpus J. C. Mikan is one of the main genera of this family, comprising 50 species distributed throughout the Neotropical America. Brazil is the main center of diversity for this genus, hosting 72% of the species as endemic. This is the first review concerning the genus Conchocarpus, emphasizing its chemical composition and biological activities. The selected papers for this review cover studies on 11 species, of which were identified 88 compounds. Among these, quinoline and acridone alkaloids predominate (57%), followed by flavonoids, amides, coumarins and terpenoids. The biological activities of extracts and compounds indicate trypanocidal and leishmanicidal actions, as well as cytotoxic, fungicidal, molluscicidal, insecticidal, anticholinesterase and antioxidant activities.

The attrition, physical and insecticidal durability of two dual active ingredient nets (Interceptor® G2 and Royal Guard®) in Benin, West Africa: results from a durability study embedded in a cluster randomised controlled trial.

Studies evaluating the attrition, physical and insecticidal durability of dual active ingredient (AI) insecticide-treated nets (ITNs) are essential for makingprogrammatic decisions regarding their deployment. We performed a prospective study embedded in a cluster randomised controlled trial (cRCT) to evaluate the attrition, fabric integrity and insecticidal durability of Interceptor® G2 (alpha-cypermethrin-chlorfenapyr) and Royal Guard® (alpha-cypermethrin-pyriproxyfen), compared to Interceptor® (alpha-cypermethrin) in Benin. A total of 2428 study nets in 1093 randomly selected households in five clusters per arm of the cRCT were monitored for ITN attrition and fabric integrity every 6-12months post-distribution. Householders were further surveyed to investigate non-study net use and their preference for ITN fabric types used in the study nets. A second cohort of 120 nets per ITN type were withdrawn every 12months and assessed for chemical content and insecticidal activity in laboratory bioassays. Alpha-cypermethrin bioefficacy was investigated using the susceptible Anopheles gambiae Kisumu strain, and chlorfenapyr and pyriproxyfen bioefficacy were investigated using the pyrethroid-resistant Anopheles coluzzii Akron strain. Net pieces were tested in WHO cone bioassays and tunnel tests for alpha-cypermethrin and in tunnel tests for chlorfenapyr; pyriproxyfen activity was assessed in cone bioassays as the reduction in fertility of blood-fed survivors using ovary dissection. Bioefficacy was expressed as the proportion of ITNs passing predetermined WHO criteria, namely knock-down ≥ 95% or 24/72h mortality ≥ 80% or reduction in fertility ≥ 50%. Overall ITN survivorship was 52% at 24months and fell to 15% at 36months. Median ITN survival time was lower with Royal Guard® relative to Interceptor® [1.6 vs 2.3years; hazard ratio (HR) 1.49, 95% confidence interval (CI) 1.36-1.66; p < 0.001] and Interceptor® G2 (1.6 vs 2.1years; HR 1.33, 95% CI 1.20-1.47; p < 0.001). Householders overwhelmingly preferred polyester nets over polyethylene nets (96%), and more Royal Guard® nets were replaced with spare polyester nets from previous campaigns. All Royal Guard® nets passed efficacy criteria for alpha-cypermethrin at all time points (100%) while ITN pass rates after 24months had fallen to < 40% for pyriproxyfen and chlorfenapyr. The chemical content analysis showed a higher loss rate of the non-pyrethroid insecticides relative to the pyrethroids in each dual ingredient AI ITN; 74% vs 47% for Royal Guard® and 85% vs 63% for Interceptor® G2 at 36months. The median ITN survival time for Interceptor® G2 (2.1years) and Royal Guard® (1.6years) in Benin is substantially lower than 3years. Royal Guard® nets were discarded more quickly by householders, partly due to their low preference for polyethylene nets. The insecticidal activity of the non-pyrethroid insecticides in both dual AI ITNs was short-lived compared to alpha-cypermethrin. The results corroborate the findings from the cRCT conducted in Benin.

Development and assessment of Nirgundi-Chakramardha biopesticide against Diamondback Moth on Cabbage

Introduction: The global population is rapidly approaching 9.7 billion by 2050, with Africa and Asia playing significant roles in this growth. This surge necessitates increased crop production, highlighting the importance of effective pest control to ensure food security. India, facing an annual crop loss of about 30% due to pests and diseases, emphasizes the urgency of maintaining ecological balance in natural ecosystems. The diamond back moth (Plutella xylostella L.) poses a substantial threat to cruciferous plants globally, causing severe yield losses of 50–80% in infested cabbage. Addressing this challenge is crucial for minimizing crop losses and securing successful harvests. Our study aimed to analyze the emergence and abundance of small, medium, and large-sized larvae before and after applying treatments. Materials and Methods: A study with five treatments, including Nirgundi-chakramardha biopesticide and a control (Cypermethrin), was conducted. Each treatment was replicated four times, and the entire experiment was set up using a randomized block design. Results: After chemical application, all treatments displayed significant differences. The biopesticide in our study produced notable results within trial groups. Notably, the control group exhibited excellent results compared to the other treatments. Conclusion: The Nirgundi-chakramardha Biopesticide exhibited insecticidal activity against Diamondback moth pests, specifically targeting medium-sized larvae. Although not statistically significant compared to the control group, its efficacy in pest control, especially during the larval stage, indicates its potential as a viable pest management option. Further research and optimization could improve its effectiveness in combating Diamondback moth infestations.

Expression of a novel NaD1 recombinant antimicrobial peptide enhances antifungal and insecticidal activities

This study aimed to increase the antifungal and insecticidal activities of NaD1, as an antimicrobial peptides (AMP), by improving its interaction with the fungal cell wall and chitin monomeric units in insect midguts. Hence, the chitin-binding domains (CBDs) of wheat germ agglutinin protein (WGA) were fused to either N- or C-terminus of NaD1 generating transgenic Nicotiana tabacum hairy roots (HRs). Molecular assessments confirmed the integration of NaD1 transgenes, their transcription and production of recombinant peptides in the HR lines. Total protein of (CBD)4-NaD1 and NaD1-(CBD)4 transgenic lines inhibited the growth of Pyricularia oryzae mycelium, suggesting that fusion of CBD to NaD1 can increase NaD1 half-life, leading to higher affinity toward cell wall chitin. Furthermore, feeding the third-instar larvae of Chilo suppressalis with both (CBD)4-NaD1 and NaD1-(CBD)4 extracts exhibited a higher mortality rate. Both NaD1-CBDs caused a significant decrease in trypsin (TRY) and chymotrypsin (CTR) activities in the larvae, while enhancing the activity of antioxidant enzymes CAT, POD, APX, and SOD. Therefore, feeding the larvae by total extract of NaD1-(CBD)4 and (CBD)4-NaD1 HR lines probably increased affinity to midgut chitin in C. suppressalis, enhancing insecticidal activities. Overall, the results indicate that recombinant peptides are effective in enhancing fungal and insect resistance.

Mrlac1, an extracellular laccase, is required for conidial morphogenesis as well as the well adaptability in field of Metarhizium rileyi

Acting as an extremely promising fungal pesticide, Metarhizium rileyi exhibits robust insecticidal activity against Lepidoptera pests, particularly the larvae. Though there is a slight delay in efficacy, biopesticides offer salient advantages over traditional chemical pesticide especially in environmental safety, cyclic infection and resistant inhibition. In this study, an exterior T-DNA was randomly inserted into the genome of M. rileyi, resulting in the acquisition of a mutant strain that displayed a colour transition from green to yellow within its conidia. The disruption of Mrlac1, a laccase, has been confirmed to attribute to the epigenetic alterations. Mrlac1 is a secreted protein harboring an N-terminal signaling peptide that undergoes in vivo synthesis and accumulates on the cell wall of M. rileyi. Targeted knock-out mutant exhibited alterations not just in conidia coloration, but significantly diminished capacity to withstand external stressors, particularly non-biological factors such as high humidity, Congo red exposure, and UV radiation. The disruptant suffered a constraint on hyphal polar growth, alteration in conidial surface structure, as well as noticeable increase in adhesion forces between conidia, the core infection factors. There is a remarkable diminution in virulence of Mrlac1 deletion variant against larvae of Spodoptera litura by topical inoculation, but not hemolymph injection. Our findings suggest that Mrlac1 acts as a positive regulator in the normal morphogenesis of fungal conidia, encompassing pigment production, inter-conidia adhesion, and conidial cell wall integrity, while the preservation of these structures holds paramount importance for the survival and infection of M. rileyi in the field.

Pesticide and antimicrobial evaluation of three labdane-type diterpenes, and one flavonoid glycoside, isolated from rhizomes of Hedychium coronarium J. Koenig

Three labdane-type diterpenes, namely coronalactoside I, hedychilactone A, and (E)-labda-8(17),12-dien-15(16)-olide, along with the flavonoid glycoside Isolinariin A, were isolated from Heydichium coronarium. Structural elucidation employed spectroscopic techniques (IR, MS, NMR, and DEPT) and comparison with literature data. Pesticidal and antimicrobial activities were assessed. Isolinariin A exhibited potent nematicidal activity (71.33% mortality) against Meloidogyne incognita, while Coronalactoside I demonstrated strong inhibition of nematode egg hatchability (26.00% at 1 µg/mL). In insecticidal activity against Spodoptera litura, (E)-labda-8(17),12-dien-15(16)-olide displayed significant mortality (93.66% at 100 µg/mL). Molecular docking studies indicated favourable interactions with target proteins, suggesting potential in pest management. These findings propose the application of these compounds to mitigate the ecological impact of synthetic pesticides.

From Proline to Chlorantraniliprole Mimics: Computer-Aided Design, Simple Preparation, and Excellent Insecticidal Profiles.

Chlorantraniliprole (CHL), a favored agricultural insecticide, is renowned for its high efficiency and broad-spectrum effectiveness against lepidoptera insects. However, the urgency for new insecticide development is underscored by the intricate multistep preparation process and modest overall yields of CHL, along with the escalating challenge of insect resistance. In response, we have crafted CHL mimics from proline employing computer-aided drug design. Molecular docking analysis of CHL's interactions with the ryanodine receptor (RyR) revealed that the nitrogen atom within the pyrazole moiety does not engage in pivotal interactions. Its removal may not abolish bioactivity entirely but could substantially simplify the synthetic process, thereby enhancing atom economy. This revelation prompted the exclusion of nitrogen and the subsequent formation of a pyrrole ring, enabling the meticulous design of synthetic pathways characterized by cost-effective precursors, streamlined synthesis, the avoidance of toxic reagents, minimal instrumentation, and high yields in the pursuit of innovative RyR modulators. Among these modulators, A1 and B1, obtained with yields exceeding 60%, showcased exceptional insecticidal potency, with LC50 values spanning from 0.12 to 1.47 mg L-1 against P. xylostella and M. separate. The inhibitory effects of these two compounds on insect detoxification enzymes imply a reduced likelihood of eliciting resistance in comparison to CHL, a finding further corroborated by their insecticidal potency against resistant pests. Moreover, molecular docking, MD simulations, and DFT calculations provided valuable structural insights, potentially unraveling the superior insecticidal activity of these two molecules, and thus paving the way for developing more potent insecticides.

Co-application of Validamycin A and dsRNAs targeting trehalase genes conferred enhanced insecticidal activity against Laodelphax striatellus

The small brown planthopper (SBPH), Laodelphax striatellus, poses a significant threat to rice crops, necessitating innovative pest control strategies. This study evaluated the potential of validamycin A (Val A) and RNA interference (RNAi) targeting trehalase genes (LsTre1 and LsTre2) in controlling SBPH. Our results demonstrated that Val A treatment of rice seedlings led to a dose-dependent mortality of SBPH. Concurrently, Val A induced the upregulation of LsTre1 and LsTre2, suggesting a compensatory feedback mechanism. Furthermore, foliar-applied chimeric dsRNA targeting LsTre1 and LsTre2 exhibited higher insecticidal activity than individual dsLsTre1 and dsLsTre2 or mixed dsRNAs. Remarkably, co-application of Val A and chimeric dsRNA increased SBPH mortality due to the suppression of Val A-induced LsTre1 and LsTre2 upregulation by chimeric dsRNA. These results suggest that the co-application of Val A and chimeric dsRNA targeting trehalase genes could be an effective SBPH control strategy.

Scaffold hopping approach to the novel hexacyclic pyrazol-3-amide derivatives as potential multi-target insect growth regulators candidates

Ecdysone receptor (EcR) and three insect chitinases (OfChtI, OfChtII, and OfChi-h) are considered as attractive targets for the development of novel insect growth regulators (IGRs) since they are closely related to the insect molting. In this study, to develop potent multi-target IGRs, a series of hexacyclic pyrazol-3-amide derivatives were rationally designed by utilizing the scaffold hopping strategy with the previously reported compound 6j (N-(4-bromobenzyl)-2-phenyl-4,5,6,7-tetrahydro-2H-indazole-5-carboxamide) as a lead compound. The bioassay results indicated that most of the target compounds exhibited obvious insecticidal activity. Especially, compounds a5 and a21 displayed excellent insecticidal activities against P. xylostella with LC50 values of 82.29 and 69.45 mg/L, respectively, exceeding that of 6j (263.78 mg/L). Compounds a5 and a21 also dramatically disturbed the growth and development of O. furnacalis larvae, and their LC50 values were 124.71 and 127.54 mg/L, respectively, superior to the lead 6j (267.33 mg/L). The action mechanism study revealed that the most active compound a21 could act simultaneously on EcR (21.4 % binding activity at 8 mg/L), OfChtI (94.9 % inhibitory at 10 μM), OfChtII (23.1 % inhibitory at 10 μM), and OfChi-h (94.3 % inhibitory at 10 μM), significantly higher than that of the lead compound 6j. The result of molecular docking indicated that transferring the carboxamide group from pyrazole position 5 to 3 enhanced the interactions of a21 with the key amino acid residues of the OfChtI, OfChtII, and OfChi-h, resulting in stronger affinity to the three targets than 6j. The present work offers a useful guidance for the further development of novel multi-target IGRs.

Antibacterial and Insecticidal Activities of Bacillus licheniformis SKS7 Methanolic Extract

Antibacterial and Insecticidal Activities of Bacillus licheniformis SKS7 Methanolic Extract

Evaluating the persistence and insecticidal effects of emulsifiable concentrate containing Cananga odorata essential oil on survival and enzymatic activity of Spodoptera littoralis

AbstractThe essential oil of Cananga odorata was prepared as an emulsifiable concentrate formulation and examined for its insecticidal activity against Spodoptera littoralis larvae. The effectiveness of C. odorata oil in both pure and EC formulations was investigated in terms of enzymatic activity and survival. In addition, their persistence effect was studied in semi-field conditions. Benzyl benzoate (18.86%), benzyl acetate (9.18%), β-Maaliene (15.53%), alloaromadendrene (6.41%), cis-Thujopsene (6.16%), cedrene (5.35%), and benzyl alcohol (5.98%) were the most abundant compounds found in C. odorata oil by gas chromatography-mass spectrometry analysis. The EC formulation exhibited the highest toxicity and produced LC values of 0.47, 1.02, and 3.78% for LC40, LC50, and LC90, respectively, compared to 1.05, 1.70, and 4.96%, respectively, resulted from pure oil after 72 h of exposure. Following EC application, the mean survival time was only 3.60 ± 0.57 days, compared to pure oil treatment (7.70 ± 1.11 days) and control (14.0 ± 0.0 days). The LC40 of EC formulation induced a more potent inhibitory effect for the detoxification enzyme carboxylesterases (CarE; α- and β-esterase) and the oxidative stress enzyme superoxide dismutase (SOD). Under semi-field conditions, the cumulative mortality of S. littoralis larvae increased by increasing the exposure time to LC90 of both formulations. The EC formulation had the highest mortality rates for the total exposure period (7 days). According to these results, C. odorata EC formulation demonstrated enhanced toxicity and persistence effects, and it can be utilized as a green bio-insecticide for the management of S. littoralis larvae.

Defense Molecules of the Invasive Plant Species Ageratum conyzoides

Ageratum conyzoides L. is native to Tropical America, and it has naturalized in many other tropical, subtropical, and temperate countries in South America, Central and Southern Africa, South and East Asia, Eastern Austria, and Europe. The population of the species has increased dramatically as an invasive alien species, and it causes significant problems in agriculture and natural ecosystems. The life history traits of Ageratum conyzoides, such as its short life cycle, early reproductive maturity, prolific seed production, and high adaptive ability to various environmental conditions, may contribute to its naturalization and increasing population. Possible evidence of the molecules involved in the defense of Ageratum conyzoides against its natural enemies, such as herbivore insects and fungal pathogens, and the allelochemicals involved in its competitive ability against neighboring plant species has been accumulated in the literature. The volatiles, essential oils, extracts, residues, and/or rhizosphere soil of Ageratum conyzoides show insecticidal, fungicidal, nematocidal, and allelopathic activity. The pyrrolizidine alkaloids lycopsamine and echinatine, found in the species, are highly toxic and show insecticidal activity. Benzopyran derivatives precocenes I and II show inhibitory activity against insect juvenile hormone biosynthesis and trichothecene mycotoxin biosynthesis. A mixture of volatiles emitted from Ageratum conyzoides, such as β-caryophyllene, β-bisabolene, and β-farnesene, may work as herbivore-induced plant volatiles, which are involved in the indirect defense function against herbivore insects. Flavonoids, such as nobiletin, eupalestin, 5′-methoxynobiletin, 5,6,7,3′,4′,5′-hexamethoxyflavone, and 5,6,8,3,4′,5′-hexamethoxyflavone, show inhibitory activity against the spore germination of pathogenic fungi. The benzoic acid and cinnamic acid derivatives found in the species, such as protocatechuic acid, gallic acid, p-coumaric acid, p-hydroxybenzoic acid, and ferulic acid, may act as allelopathic agents, causing the germination and growth inhibition of competitive plant species. These molecules produced by Ageratum conyzoides may act as defense molecules against its natural enemies and as allelochemicals against neighboring plant species, and they may contribute to the naturalization of the increasing population of Ageratum conyzoides in new habitats as an invasive plant species. This article presents the first review focusing on the defense function and allelopathy of Ageratum conyzoides.