Insecticidal Agents Research Articles

Nematicidal, antifungal and insecticidal activities of Artemisia halodendron extracts: New polyacetylenes involved

The present study evaluates the nematicidal, antifungal and insecticidal effects of extracts from different organs (leaves, stems and roots) of Artemisia halodendron Turcz. ex Bess. Correlative analysis revealed that polyacetylenes were the main contributors to biological activities. Furthermore, five extraction techniques were compared and evaluated based on the yield of polyacetylenes and their activities. It was found that microwave-assisted extraction (MAE) was the best extracting approach. Additionally, two new polyacetylenes (1–2) and four known polyacetylenes (3–6) were isolated from the MAE extract. All polyacetylenes showed remarkable nematicidal effect against Meloidogyne incognita (Kofoid & White) Chitwood (50 % lethal concentration, LC50, 0.21–9.46 mg/L) compared with abamectin (LC50, 9.98 mg/L). In particular, nematicidal activity of the new compound 1 was 48-times higher than that of abamectin. Also, these polyacetylenes exhibited antifungal effects against five fungi (minimum inhibitory concentration, MIC, 4–128 mg/L). Moreover, polyacetylenes 1–4 showed remarkable insecticidal activity against Bradysia odoriphaga Yang & Zhang (50 % lethal dose, LD50, 19.31–36.51 mg/L), stronger than the azadirachtin (LD50, 39.30 mg/L). Together, the results gained from this study suggest that A. halodendron and the isolated polyacetylenes have great potential application in nematicide, fungicide and insecticide agent industry.

Synthesis, In-Silico Potential Enzymatic Target Predictions, Pharmacokinetics, Toxicity, Anti-Microbial and Anti-Inflammatory Studies of Bis-(2-methylindolyl) Methane Derivatives

Background: The bis(indolyl)methanes (BIMs) scaffold is reported for wide varieties of pharmacological profiles, including antibacterial, anti-proliferative, anticancer, cytotoxic, insecticidal, analgesic, antioxidant, and anti-inflammatory agents. Materials and Methods: A series of bis(indolyl)methanes have been synthesized by a greener and newer approach using the reaction of different substituted aldehydes and indole in the presence of an easily available and biodegradable base such as piperidine in acetic acid at room temperature and characterized with ultraviolet–visible spectrophotometry (UV–Vis or UV/Vis), Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), etc. The antibacterial and antifungal activities were also carried out against Staphylococcus aureus (RCMB 000106) and Bacillis subtilis (RCMB 000107), as two Gram-positive bacterial strains, and Salmonella typhi and Escherichia coli (RCMB 000103), as two Gram-negative bacterial strains. Fungal species such as Candida Albicans, Penicillium chrysogenum, Aspergillus niger were also used for in vitro antifungal evaluation. All our newly synthesized 14 compounds (4a-4n) were subjected for anti-inflammatory activity in vitro and compared with the known standard drug aceclofenac. Results: Our newly synthesized compounds showed good to moderate antibacterial agents, in silico ADMET, and anti-inflammatory profiles. Conclusion: We hope that our current study would aid future developments of bis(indolyl)methanes as antibacterial and anti-inflammatory agents.

Docking-based generation of antibodies mimicking Cry1A/1B protein binding sites as potential insecticidal agents against diamondback moth (Plutella xylostella).

Broad use of insecticidal Cry proteins from Bacillus thuringiensis in biopesticides and transgenic crops has resulted in cases of practical field resistance, highlighting the need for novel approaches to insect control. Previously we described an anti-Cry1Ab idiotypic-antibody (B12-scFv) displaying toxicity against rice leafroller (Cnaphalocrocis medinalis) larvae, supporting the potential of antibodies for pest control. The goal of the present study was to generate insecticidal antibodies against diamondback moth (Plutella xylostella) larvae. Four genetically engineered antibodies (GEAbs) were designed in silico from B12-scFv using three-dimensional (3D) structure and docking predictions to alkaline phosphatase (ALP) as a Cry1Ac receptor in P. xylostella. Among these GEAbs, the GEAb-dVL antibody consisting of two light chains had overlapping binding sites with Cry1A and Cry1B proteins and displayed high binding affinity to P. xylostella midgut brush border membrane (BBM) proteins. Proteins in BBM identified by pull-down assays as binding to GEAb-dVL included an ABC transporter and V-ATPase subunit A protein. Despite lacking the α-helical structures in Cry1A that are responsible for pore formation, ingestion of GEAb-dVL disrupted the P. xylostella larval midgut epithelium and resulted in toxicity. Apoptotic genes were activated in gut cells upon treatment with GEAb-dVL . This study describes the first insecticidal GEAb targeting P. xylostella by mimicking Cry proteins. Data support that GEAb-dVL toxicity is associated to activation of intracellular cell death pathways, in contrast to pore-formation associated toxicity of Cry proteins. This work provides a foundation for the design of novel insecticidal antibodies for insect control. © 2021 Society of Chemical Industry.

Methodological approaches to the assessment of health risks associated with the use of repellent and insecticide agents

Introduction. The study’s relevance is due to the demand for repellent and insecticidal agents in the consumer market and their widespread use as protection against mosquitoes. At the same time, the problem of the impact on the human health of these funds has not been sufficiently studied. In this regard, analyzing the safety of repellents and insecticides for human health is of scientific interest. The aim of the study is to substantiate methodological approaches to assessing the risk to human health associated with the use of insecticides and repellents. Materials and methods. Authors used methods of analysis of scientific literature, toxicological methods for the study of health safety, methods of quantitative chemical analysis, biochemical methods for the study of blood serum, methods of mathematical modeling, health risk assessment methodology. Results. The assessment of the risk of negative responses from organs and systems of the body when exposed to repellents and insecticides has been carried out. Methodological approaches to assessing health risks under various scenarios for repellents and insecticides have been developed and tested. Conclusion. A feature of the proposed methodological approaches is the ability to take into account dose loads for various routes of entry of active substances into the body, the duration of exposure to a repellent or insecticide during regular use, and possible use in regimes exceeding normal use. As a result of the experiment, it was found that with the inhalation of an insecticide with 1% transfluthrin, the level of acceptable risk is observed at a level of exposure of transfluthrin in the air up to 0.0272 mg/m3. Under a percutaneous intake of the 50% DEET repellent, the acceptable risk level was noted at exposure less than 1200 mg/kg/day. In case of percutaneous arrival of the DETA repellent 7.5%, the level of acceptable risk is established under exposure up to 250 mg/kg/day.

EFFICIENCY OF ORIGANUM MAJORANA ESSENTIAL OIL AS INSECTICIDAL AGENT AGAINST RHYNCHOPHORUS FERRUGINEUS THE RED PALM WEEVIL (OLIVIER) (COLEOPTERA: CURCULIONIDAE)

Rhynchophorus ferrugineus is the most dangerous palm pest in Egypt and the Middle East. A lot of efforts have been made since three decades up to date to solve this problem. In this study, the essential oil of Origanum majorana was tested in vitro against larvae, pupa and adult stages of R. ferrugineus. In addition, the chemical composition of the essential oil was elucidated by gas chromatography and mass spectrometry (GC-MS) analysis. Two main toxic components (benzonitrile, 2-hydroxy 23.67%and L-linalool16.32%) were found. A significant mortalities were achieved after exposure to three concentrations (5, 10 and 15%) of O. majorana oil. Each concentration contains five replicates with 5 larva, pupa or adultfor each replicate. The effect reached 50% for 10% concentration at 96 hrs, 48 hrs and 12 hrs for larva, pupa and adult, respectively. In addition, the cuticle of treated larvae was investigated histopathologically, and corrugation and a thinning surface were found. These results suggest that O. majorana essential oil is a promising alternative to chemicalpesticides and can be used as a biopesticide against larvae, pupa and adult of R. ferrugineus.

Biochemistry of Terpenes and Recent Advances in Plant Protection.

Biodiversity is adversely affected by the growing levels of synthetic chemicals released into the environment due to agricultural activities. This has been the driving force for embracing sustainable agriculture. Plant secondary metabolites offer promising alternatives for protecting plants against microbes, feeding herbivores, and weeds. Terpenes are the largest among PSMs and have been extensively studied for their potential as antimicrobial, insecticidal, and weed control agents. They also attract natural enemies of pests and beneficial insects, such as pollinators and dispersers. However, most of these research findings are shelved and fail to pass beyond the laboratory and greenhouse stages. This review provides an overview of terpenes, types, biosynthesis, and their roles in protecting plants against microbial pathogens, insect pests, and weeds to rekindle the debate on using terpenes for the development of environmentally friendly biopesticides and herbicides.

Insecticidal activity of twin compounds from podophyllotoxin and cytisine

To explore natural-product-based insecticide candidates, and high value-added application of natural plants in agriculture, a series of twin compounds were prepared from two natural products podophyllotoxin and cytisine, which are isolated from the plants Podophyllum hexandrum and Thermopsis lanceolata, respectively. Compounds IIa (X = Cl, Y = R1 = R2 = H), IIIc (X = Y = R1 = R2 = Cl) and IVd (X = R1 = R2 = Br, Y = H) exhibited >2-fold potent insecticidal activity of podophyllotoxin against armyworm with FMRs greater than 60%. SARs were also observed. It is noteworthy that the idea of twin insecticides was addressed for the first time. We hope this idea will be conducive to design new twin insecticidal agents, and lay the foundation for future high value-added application of the plants P. hexandrum and T. lanceolata as potentially botanical pesticides in agriculture.

Physical characteristics, chemical compositions, and insecticidal activity of plant essential oils against chicken lice (Menopon gallinae) and mites (Ornithonyssus bursa)

A preparation of essential oils to control chicken lice (Menopon gallinae) and mites (Ornithonyssus bursa) was developed. Each essential oil was effective against lice and mite in vitro. Citronella oil at the lowest concentration of 0.208 µg/cm2 resulted in a mortality rate of 100% in chicken lice, whereas a higher concentration of cloves, lemongrass, ginger, Makwan oil (0.416 µg/cm2), and Litsea oil (0.832 µg/cm2) was also found to be effective. A 100% rate of mortality for mites was observed using citronella and ginger oil at a concentration of 0.416 µg/cm2. At the same concentration, cloves, lemongrass, Litsea, and Makwan oil exhibited mortality rates in mites of 77.96%, 93.33%, 87.30%, and 93.49%, respectively. The efficacy of citronella oil and ginger oil against lice and mites was further examined in vivo. Citronella and ginger oil affected the rate of decline in lice from day 1 to day 14, whereas the number of mites living in nests declined from day 1 to day 7. The reduction of these parasitic insects may be correlated with the chemical constituents present in each essential oil. The active ingredients likely acted insecticidal agents against both parasitic insects. Moreover, the preparation developed here did not cause any side effects, such as dermatitis and respiratory disorders, during animal trials. Hence, preparations comprised of the essential oils of citronella and ginger can be further developed and used as insecticidal agents to control and/or eliminate chicken lice and mites on commercial farms.

Development of larvicide nanoemulsion from the essential oil of Aeollanthus suaveolens Mart. ex Spreng against Aedes aegypti, and its toxicity in non-target organism

The widespread use of synthetic insecticides to control diseases such as those transmitted by the vector Aedes aegypti (Linnaeus, 1762) has caused widespread resistance to mosquitoes and adverse effects on non-target organisms, such as humans and animals. In this sense, nanotechnology emerges as a strategy for developing new promising insecticidal agents against this vector. Therefore, this research developed a nanoemulsion containing A. suaveolens essential oil, as well as to evaluate the larvicidal activity of the nanoemulsion against A. aegypti and toxicity in non-target mammals. The essential oil was identified by gas chromatography coupled to a mass spectrometer, and the nanoemulsions were prepared using a low-energy method and characterized by photon correlation spectroscopy. The larvicidal activity was evaluated against A. aegypti larvae at the third stage of development, and acute oral toxicity was assessed on mice. The results showed that the main compounds found were Massoialactone (64.79%), Linalool (7.83%), and (E)-β-Farnesene (6.17%). The most stable nanoemulsion was produced in HLB 15 with a particle size of 126.73 ± 0.20 nm, polydispersity index of 0.125 ± 0.01, and zeta potential of −16.25 ± 1.48 mV after 21 days. The LC50 and LC90 values in A. aegypti larvae after 24 h were 54.23 µg.mL−1 and 96.96 µg.mL−1, respectively. After 48 h, the values were LC50 of 46.06 µg.mL−1 and LC90 of 75.31 µg.mL−1. Regarding the acute oral toxicological evaluation, the results showed that despite A. suaveolens essential oil nanoemulsion (NEOAS) having a lethal dose (LD50) greater than 2000 mg.kg−1, histological changes were observed in the kidneys and liver of treated animals. In this sense, this study allowed the development of an ecological and low-cost larvicidal nanoformulation for the control of A. aegypti.

Comparing the efficacy of nutmeg essential oil and a chemical pesticide against Musca domestica and Chrysomya albiceps for selecting a new insecticide agent against synantropic vectors

The insecticidal activity of Myristica fragrans (Houtt) essential seed oil, (Nutmeg) was evaluated against Musca domestica (Linnaeus) and Chrysomya albiceps (Wiedemann); both important infectious pathogenic disease vectors. The oil was extracted by distillation, and 21 components were identified during chemical analysis; principally β-pinene (26%), α-pinene (10.5%), Sabinene (9.1%) and γ-terpinen (8.5%). Insecticidal properties were identified through larvicide and adulticide tests. Using the immersion method, the oil at 5% was found to be very effective (90 ± 1%) against M. domestica larvae. The results for adulticide activity varied by fly species, dosage, time, and method of exposure. Topical application (on the insect thorax) was more toxic to C. albiceps, where the lethal concentration at 50% (LC50) was 2.02 ± 0.56, and 8.57 ± 2.41 for the common flies. When the insects were exposed to oil impregnated paper, the results were similar for M. domestica and C. albiceps adults with respective LC50 values of 2.74 ± 0.24, and 3.65 ± 0.48. Thus, the results demonstrated that M. fragrans oil presents insecticidal activity and can be used for control of Musca domestica and Chrysomya albiceps.

From Chemistry to Biology: Applications and Advantages of Green, Biosynthesized/Biofabricated Metal- and Carbon-based Nanoparticles

Metal- and carbon-based nanoparticles (MBNPs/CBNPs) with different nanometric dimensions have unique combinations of physical and chemical properties. The physico-chemical properties, morphology, and interactions of nanomaterials with biological systems differ according to the source of synthesis and the extent and type of functionalization involved, which have many advantages for exciting nanotechnological applications in the fields of chemical and biological sciences. The biosynthesis and biofabrication of nanomaterials are achieved in a myriad of ways using plants and microorganisms. Greener synthesis has been conducted using the extracts of plants or other biological entities. This review focuses on the recent insights in the green and biological synthesis of MBNPs based on cadmium, cerium, copper, gold, iron, manganese, nickel, palladium, platinum, selenium, silver, titanium, yttrium, zinc, and zirconium, and CBNPs, such as carbon dots (CDs), as well as their chemical and biological applications, such as chemical catalysis, anticancer, antioxidant, antimicrobial, antibiofilm, antidiabetic, insecticidal, scolicidal, antileshmanial, angiogenesis, and immunostimulant agents, and as tools for bioimaging, biosensing, and drug delivery.

Insecticidal synergy of essential oils from Cymbopogon citratus (Stapf.), Myristica fragrans (Houtt.), and Illicium verum Hook. f. and their major active constituents

This study attempted to find safe and effective green insecticidal agents against Musca domestica L., which is a major public health pest in tropical and subtropical countries that have already developed resistance to synthetic pesticides. Plant essential oil-based insecticides are new, effective, and eco-friendly alternatives. Today, they are a housefly control method of choice. The study evaluated the insecticidal effect against M. domestica adults of essential oils (EOs) from Cymbopogon citratus (Stapf.), Illicium verum Hook. f., and Myristica fragrans (Houtt.) as well as their major active chemical constituents. Formulations of these individual and combined compounds were evaluated to see whether they were synergistic against M. domestica. Chemical compositions of these EOs were also analyzed by GC–MS. The major constituent of C. citratus was found to be geranial (45.4 %); that of I. verum was trans-anethole (94.0 %), and that of M. fragrans was α-pinene (21.6 %). Formulation CB3 (0.5 % I. verum EO + 0.5 % geranial) exhibited the highest synergistic effect (SI = 0.04), with 100 % knockdown and mortality rates, a 50 % knockdown time (KT50) of 4.0 min, and a 50 % lethal time (LT50) of 6.0 min. CB3 was more effective than 1% w/v cypermethrin, followed by CB5 (0.5 % M. fragrans EO + 0.5 % geranial), CB7 (0.5 % α-pinene + 0.5 % geranial), and CB8 (0.5 % geranial + 0.5 % trans-anethole). To conclude, some formulations of combined C. citratus, I. verum, and M. fragrans were strongly synergistic against M. domestica and more effective than cypermethrin. Moreover, since they have been long used as natural food ingredients and in traditional medicine, they are also safe for humans, non-target organisms, and the environment.

Microwave-assisted regioselective reaction of furanone derivative supported by DFT stimulation and molecular docking to afford controlling insecticidal agents

The furanone 1 was allowed to react with different nitrogen nucleophiles such as hydrazine hydrate, hydroxyl amine, anisidine, anthranilic acid, glycine, ethylglycinate and isatin and some carbon nicleophiles under Michael reaction conditions assisted by microwave irradiation. They afforded new synthesized some important heterocyclic compounds 2–16. The structures of the synthesized new compounds were characterized by spectral data and elemental analysis. DFT calculation is serving to clarify not only the active electrophilic sites attacked by suitable nucleophiles in the organic reaction but also the bioactivity of the larvicidal compounds. The larvicidal activities of the synthesized compounds were tested against Plutella xylostella and Helicoverpa armigera larvae in vitro. The results revealed that the synthesized compounds 4, 13 and 14 showed good insecticidal activity against Plutella xylostella larvae with 100%, 87.2% and 91.4% activities, respectively, while 13 and 14 displayed 92% and %, 94.8 activities, respectively, against Helicoverpa armigera larvae. Therefore, they exhibited good larvicidal activity. The executed molecular docking simulations evinced the selective binding of the novel synthesized compounds toward acetylcholinesterase (AchE) of Drosophila Melanogaster, which signifies their role as a prominent larvicides. Compound 4, 13 and 14 showed clear docking affinity and to the assumed binding sites in terms of both calculated binding energies and the types of interactions, which provided a solid rationalization for the conducted experimental results.

Surface-modified nanosilica-chitinase (SiNp-Chs)-doped nano enzyme conjugate and its synergistic pesticidal activity with plant extracts against armyworm Spodoptera litura (Fab.) (Lepidoptera: Noctuidae).

A laboratory experiment was conducted to evaluate enhanced pesticidal activity of silica nanoparticles‐doped chitinase nano enzyme conjugate against an economically important insect pest Spodoptera litura (Fab.) (Lepidoptera; Noctuidae). Silica nanoparticles were synthesized by hydrolysis and condensation of precursor tetraethylorthosilicate (TEOS) followed by functionalization with functioning agent 3‐aminopropyltriethoxysilane. Functionalized silica nanoparticles thus acquired were doped with chitinase enzyme produced by Serratia marcescens SU05. Doped nanosilica–chitinase nano enzyme conjugate was loaded with pesticidal plant extracts to study the improved pesticidal activity. Synthesized nano enzyme conjugate revealed high stable, monodisperse spherical nanoparticles and exhibited effective loading with respective plant extracts. Nano enzyme conjugates and plant extracts loaded with nano enzyme conjugate recorded high rate of mortality against the larval instars and brought about a distinct effect on the life stage parameters of S.litura. Non‐target toxic effect of nano enzyme conjugate was carried out by determination of lethality and changes in protein profiling against brine shrimp (Artemia salina) that shows less lethality and no distinct changes in protein profiling which suggest the effective utilization of silica nanoparticles doped chitinase as an insecticidal agent against economically important insect pests associated with various crops.

Structural characterization of a PCP–R didomain from an archaeal nonribosomal peptide synthetase reveals novel interdomain interactions

Nonribosomal peptide synthetases (NRPSs) are multimodular enzymes that produce a wide range of bioactive peptides, such as siderophores, toxins, and antibacterial and insecticidal agents. NRPSs are dynamic proteins characterized by extensive interdomain communications as a consequence of their assembly-line mode of synthesis. Hence, crystal structures of multidomain fragments of NRPSs have aided in elucidating crucial interdomain interactions that occur during different steps of the NRPS catalytic cycle. One crucial yet unexplored interaction is that between the reductase (R) domain and the peptide carrier protein (PCP) domain. R domains are members of the short-chain dehydrogenase/reductase family and function as termination domains that catalyze the reductive release of the final peptide product from the terminal PCP domain of the NRPS. Here, we report the crystal structure of an archaeal NRPS PCP–R didomain construct. This is the first NRPS R domain structure to be determined together with the upstream PCP domain and is also the first structure of an archaeal NRPS to be reported. The structure reveals that a novel helix–turn–helix motif, found in NRPS R domains but not in other short-chain dehydrogenase/reductase family members, plays a major role in the interface between the PCP and R domains. The information derived from the described PCP–R interface will aid in gaining further mechanistic insights into the peptide termination reaction catalyzed by the R domain and may have implications in engineering NRPSs to synthesize novel peptide products.

Acute toxicity of an insecticidal little containing ivermectin and fipronil for white mice

Toxicological assessment is a mandatory research step in the development of new insecticidal drugs. At the All-Russian Research Institute of Veterinary Entomology and Arachnology, a prototype of the insecticidal bait Mukhnet IF was obtained with an active ingredient content of 0.06% ivermectin and 0.015% fipronil, which showed a highly effective effect against houseflies. This work presents the results of the study of acute oral toxicity of the above agent. For this, male white mice with a live weight of 16-26 g were selected. They were kept on a starvation diet for one day in individual houses with water. The drug was given in mg/kg body weight the next day. A total of 33 doses have been tested, ranging from 100 mg/kg to 40,000 mg/kg. The animals were observed for 14 days. According to the research results, it was revealed that at doses up to 20,000 mg/kg there were no signs of intoxication, but when tested at 25,000 mg/kg in some mice, these signs were noted, and at 30,000, 35,000 and 40,000 mg/kg deaths were recorded 20±10, 45±30 and 60±20%, respectively. It was not possible to test the drug over the last above dose due to incomplete eaten by mice. According to the degree of danger for warm-blooded animals, the drug belongs to the 4th class of low-hazard drugs (average lethal dose of 5000 mg/kg or more) in accordance with the classification of GOST 12.1.007-76. When analyzing the literature data on the toxicological characteristics of preparations containing ivermectin and chlorfenapyr, it was revealed that the insecticidal agent in its acute toxicity for warm-blooded animals is comparable to known analogues.

Insecticidal bait development for control of Musca Domestica L.

The control of houseflies (Musca domestica L.) in veterinary surveillance premises is an important measure for the welfare of animals against infectious and invasive diseases. For this purpose, the most effective chemical insecticides are used. To prevent possible resistance to them, bait insecticides with two active binary ingredients from different chemical classes are used. The work was carried out in the laboratory of the Tyumen Scientific Center and in the production conditions of ZAO Pyshminskaya Poultry Farm. This material presents the main stages in the development of a prototype of the insecticidal bait Mukhnet AX containing two insecticides: 1.5% acetamiprid and 6% chlorfenapir. For this purpose, adults of houseflies Musca domestica L. 3-5 days old were used. Under laboratory conditions, effective rational doses of the above insecticides were determined by group feeding, feeding and by the method of assessing food insecticidal baits when fighting flies from 0.00002 to 4% concentrations. According to the results of laboratory studies, it was found that the optimal doses causing 100% death of insects were 0.5% for acetamiprid and 2% for chlorfenapir. The insecticidal efficiency of the developed bait Mukhnet AH against flies in production conditions on the first day after the treatment of the livestock building was 91.25%. The insecticidal effect of the measures taken lasted for at least 6 days. The restoration of the number to the previous level of the number of insects occurred after 10 days. Based on the results obtained, the Method of using the composition of an insecticidal bait agent in the fight against Musca domestica was proposed and patented.

In vivo transcriptome analysis provides insights into host-dependent expression of virulence factors by Yersinia entomophaga MH96, during infection of Galleria mellonella.

The function of microbes can be inferred from knowledge of genes specifically expressed in natural environments. Here, we report the in vivo transcriptome of the entomopathogenic bacterium Yersinia entomophaga MH96, captured during initial, septicemic, and pre-cadaveric stages of intrahemocoelic infection in Galleria mellonella. A total of 1285 genes were significantly upregulated by MH96 during infection; 829 genes responded to in vivo conditions during at least one stage of infection, 289 responded during two stages of infection, and 167 transcripts responded throughout all three stages of infection compared to in vitro conditions at equivalent cell densities. Genes upregulated during the earliest infection stage included components of the insecticidal toxin complex Yen-TC (chi1, chi2, and yenC1), genes for rearrangement hotspot element containing protein yenC3, cytolethal distending toxin cdtAB, and vegetative insecticidal toxin vip2. Genes more highly expressed throughout the infection cycle included the putative heat-stable enterotoxin yenT and three adhesins (usher-chaperone fimbria, filamentous hemagglutinin, and an AidA-like secreted adhesin). Clustering and functional enrichment of gene expression data also revealed expression of genes encoding type III and VI secretion system-associated effectors. Together these data provide insight into the pathobiology of MH96 and serve as an important resource supporting efforts to identify novel insecticidal agents.

First discovery of pimprinine derivatives and analogs as novel potential herbicidal, insecticidal and nematicidal agents

Pimprinine and streptochlorin are indole natural products produced by many species of organisms, and they are reported to possess a wide range of biological activities, such as anticancer, antiviral, antifungal activity and so on. In this study, three series of pimprinine derivatives or analogs were efficiently synthesized under the optimized methods. Biological assays conducted at Syngenta firstly indicated the pimprinine derivatives or analogs possessed potential herbicidal and insecticidal activity, and this is highlighted by compounds 21g, 21h, 21i, 21j, 21l, 22h, 22i and 23h, they possessed significant biological activity as well as broad spectrum. Meanwhile, compounds with benzothiophene-oxazole core (21h, 22h and 23h), showed effective nematicidal activity in primary screening. Compounds 21g and 21i were identified as the most promising lead structures for further study.

Biomimetic Synthesis of Iridoid Alkaloids as Novel Leads for Fungicidal and Insecticidal Agents.

Monoterpenoid alkaloids are well known for their broad and excellent biological activities, but their extremely low content and complex chemical structure limit their practical application. This study used the biosynthetic precursor genipin as a basic material to conduct a biomimetic synthesis of iridoid alkaloids. The structures of the iridoid alkaloids were characterized by 1H and 13C NMR spectroscopy and high-resolution mass spectrometry, and their fungicidal and insecticidal activities were evaluated. Bioassay results indicated that iridoid alkaloids possess good to excellent activities against phytopathogenic fungi, diamondback moth, bean aphid, and spider mite. Compound 3s had the most promising activity against three important phytopathogenic fungi Fusarium graminearum (LC50 value of 34.5 μg/mL with a 95% confidence interval of 33.4-35.5 μg/mL), Rhizoctonia solani (18 μg/mL, 15.7-20.8 μg/mL), and Botrytis cinerea (26 μg/mL, 22.4-30.4 μg/mL), thereby emerging as a potential new fungicidal lead. The structure-activity relationship research has shown that the electrical property and steric hindrance sizes of iridoid alkaloids apparently influence fungicidal activity. Moreover, compound 3n exhibited good insecticidal activity against diamondback moth with an LC50 (35.6 μg/mL, 95% confidence interval 19.0-66.6 μg/mL) comparable to that of the commercial insecticide rotenone (35.4 μg/mL, 95% confidence interval 22.2-56.4 μg/mL). This outcome indicates that this compound deserves further study as a potential lead for development of new insecticides.