Identification of insecticidal constituents of the essential oil of Acorus calamus rhizomes against Liposcelis bostrychophila Badonnel

Chemical Composition, Toxicity, and Repellency of Essential Oils from Three Hedychium Species Against Stored-Product Insects

Stored products are constantly infested by insects, so finding eco-friendly bioinsecticides for insect management is important. The work aimed to assess the insecticidal and repellent activity of essential oil (EO) from Hedychium glabrum S. Q. Tong, Hedychium coronarium Koen., and Hedychium yunnanense Gagnep. against Tribolium castaneum, Lasioderma serricorne, and Liposcelis bostrychophila. Results showed that 88 chemical components were identified in the extracted Hedychium EOs, indicating that they exhibited diversity in components. According to principal component analysis (PCA), the composition of the EO from the H. yunnanense stem and leaf (EOHYSL) was significantly different from other EOs due to the different organs and species. The biological activity also varied continuously with plant species and organs. Only the EO of H. yunnanense (EOHY) showed strong fumigant toxicity. While in the contact tests, EOHGR showed the strongest toxicity effect on L. bostrychophila, with a LC50 value of 71.76 μg/cm2, which was closest to the positive control (Pyrethrin). All EOs had remarkable repellent activities against the three target insects, and repellency increased with concentration. According to the results of the comprehensive score, EOHY had the highest potential, which ranged from 0.7999 to 0.8689. Thus, Hedychium EOs possess potential biorational traits to be biological insecticides.

Insecticidal toxicity of essential oil of Nepalese Acorus calamus (Acorales:Acoraceae) against Sitophilus zeamais (Coleoptera:Curculionidae)

Maize weevil (Sitophilus zeamais) (Coleoptera:Curculionidae) is an economic stored grain pest that causes significant damage to various stored products, including maize (Zea mays). In this study, we extracted essential oil from the rhizome of sweet flag (Acorus calamus) (Acorales:Acoraceae) by hydro-distillation and tested insecticidal property of the oil at 7 concentrations (10, 5, 2.5, 1.25, 0.625, 0.3125, 0.15625 and control) against maize weevil (Sitophilus zeamais) at the National Entomology Research Center, Nepal Agricultural Research Council in the year 2020/2021. Three different experiments were conducted: scintillating vial bioassay, repellency test, and exposing weevils to oil treated maize grains. Scintillating vial bioassay showed that higher the concentration of essential oil, lower the time required to cause 50 % maize weevil mortality. Median lethal concentration (LC50) at 3 and 24 h was calculated as 2.29 and 0.16 % of oil concentration in scintillating vial bioassay. When oil is treated to maize grain, LC50 for 10 and 16 days was calculated as 2.77 and 0.23 % of oil concentrations. In the same way, at 10 % concentration maize weevil showed highest repellent activity (98.75 %) as compared to 5, 2.5 and 1.25 % concentrations after 24 h of treatment. Weight loss and grain damage were significantly less in the oil treatments than the control. However, from the perspective of health benefits, Acorus calamus treated maize is still questionable for feed and food purpose. As β asarone has carcinogenic effects at certain level, it needs further residue tests of treated maize to know allowable maximum residue limit (MRL) before consumption as food or feed.

Critical Review on Nutritional, Bioactive, and Medicinal Potential of Spices and Herbs and Their Application in Food Fortification and Nanotechnology

Medicinal or herbal spices are grown in tropical moist evergreen forestland, surrounding most of the tropical and subtropical regions of Eastern Himalayas in India (Sikkim, Darjeeling regions), Bhutan, Nepal, Pakistan, Iran, Afghanistan, a few Central Asian countries, Middle East, USA, Europe, South East Asia, Japan, Malaysia, and Indonesia. According to the cultivation region surrounded, economic value, and vogue, these spices can be classified into major, minor, and colored tropical spices. In total, 24 tropical spices and herbs (cardamom, black jeera, fennel, poppy, coriander, fenugreek, bay leaves, clove, chili, cassia bark, black pepper, nutmeg, black mustard, turmeric, saffron, star anise, onion, dill, asafoetida, celery, allspice, kokum, greater galangal, and sweet flag) are described in this review. These spices show many pharmacological activities like anti-inflammatory, antimicrobial, anti-diabetic, anti-obesity, cardiovascular, gastrointestinal, central nervous system, and antioxidant activities. Numerous bioactive compounds are present in these selected spices, such as 1,8-cineole, monoterpene hydrocarbons, γ-terpinene, cuminaldehyde, trans-anethole, fenchone, estragole, benzylisoquinoline alkaloids, eugenol, cinnamaldehyde, piperine, linalool, malabaricone C, safrole, myristicin, elemicin, sinigrin, curcumin, bidemethoxycurcumin, dimethoxycurcumin, crocin, picrocrocin, quercetin, quercetin 4'-O-β-glucoside, apiol, carvone, limonene, α-phellandrene, galactomannan, rosmarinic acid, limonene, capsaicinoids, eugenol, garcinol, and α-asarone. Other than that, various spices are used to synthesize different types of metal-based and polymer-based nanoparticles like zinc oxide, gold, silver, selenium, silica, and chitosan nanoparticles which provide beneficial health effects such as antioxidant, anti-carcinogenic, anti-diabetic, enzyme retardation effect, and antimicrobial activity. The nanoparticles can also be used in environmental pollution management like dye decolorization and in chemical industries to enhance the rate of reaction by the use of catalytic activity of the nanoparticles. The nutritional value, phytochemical properties, health advantages, and both traditional and modern applications of these spices, along with their functions in food fortification, have been thoroughly discussed in this review.

Insecticidal activities of the essential oil of Rhynchanthus beesianus rhizomes and its constituents against two species of grain storage insects

The aim of this research was to evaluate insecticidal activities of the essential oil of Rhynchanthus beesianus rhizomes against adults of Liposcelis entomophila and Tribolium castaneum. Gas chromatography-mass spectrometry analyses revealed the presence of 44 compounds with β-eudesmol (19.1%), elemol (8.1%), α-terpineol (8.0%), methyl eugenol (6.5%), and caryophyllene (4.8%) being the major constituents. Bioactivity-directed chromatographic separation of the oil led to the isolation of four constituents, elemol, β-eudesmol, methyl eugenol, and α-terpineol. The essential oil exhibited fumigant toxicity against the adults of L. entomophila and T. castaneum with LC₅₀ values of 0.57 and 4.96 mg/L air while the two isolates, methyl eugenol and α-terpineol possessed fumigant toxicity against the booklice (LC₅₀ = 0.15 and 0.48 mg/L air, respectively) and the beetles (LC₅₀ = 1.81 and 4.96 mg/L air, respectively). The oil also possessed contact toxicity against the booklice and the beetles with LD₅₀ values of 121.56 μg/cm² and 54.93 μg/adult, respectively, while the two isolates β-eudesmol and elemol showed contact toxicity against L. entomophila (LD₅₀ = 99.21 and 35.19 μg/cm², respectively) and T. castaneum (LD₅₀ = 35.26 and 8.89 μg/adult, respectively). The results indicate that the oil of R. beesianus rhizomes and its isolates have potential as a source for natural insecticides.

The role of centrifugal partition chromatography in the removal of β-asarone from Acorus calamus essential oil

Β-asarone is a phenylpropane derivative present in the rhizomes of Acorus calamus, that was proved to exhibit toxic effects in humans. Because of its presence the whole plant that is commonly used in traditional medicine for its sedative, anti-inflammatory, neuroprotective and other properties has limited application nowadays. In the study, qualitative and quantitative analysis of a collection of nine essential oil (EO) samples of European and Asian origin was performed. The final content of β-asarone in the tested samples ranged between 0.265 and 1.885 mg/mL. Having in mind a possible application of the EO as a biopesticide, this research aimed at the development of CPC-based purification protocol that could help remove β-asarone from EO. It was proved that the biphasic solvent system composed of n-hexane/EtOAc/MeOH/water, 9:1:9:1 (v/v/v/v) was capable of the removal of the toxic constituent in the CPC chromatograph operated in the ascending elution mode with 2200 rpm and a flow rate of 5 mL/min. The chromatographic analysis that lasted only 144 min effectively separated β-asarone (purity of 95.5%) and α-asarone (purity of 93.7%) directly from the crude Acorus calamus rhizome EO.

Advances in extraction methods, chemical constituents, pharmacological activities, molecular targets and toxicology of volatile oil from Acorus calamus var. angustatus Besser

Acorus calamus var. angustatus Besser (ATT) is a traditional herb with a long medicinal history. The volatile oil of ATT (VOA) does possess many pharmacological activities. It can restore the vitality of the brain, nervous system and myocardial cells. It is used to treat various central system, cardiovascular and cerebrovascular diseases. It also showed antibacterial and antioxidant activity. Many studies have explored the benefits of VOA scientifically. This paper reviews the extraction methods, chemical components, pharmacological activities and toxicology of VOA. The molecular mechanism of VOA was elucidated. This paper will serve as a comprehensive resource for further carrying the VOA on improving its medicinal value and clinical use.

Stomata at the crossroad of molecular interaction between biotic and abiotic stress responses in plants

Increasing global food production is threatened by harsh environmental conditions along with biotic stresses, requiring massive new research into integrated stress resistance in plants. Stomata play a pivotal role in response to many biotic and abiotic stresses, but their orchestrated interactions at the molecular, physiological, and biochemical levels were less investigated. Here, we reviewed the influence of drought, pathogen, and insect herbivory on stomata to provide a comprehensive overview in the context of stomatal regulation. We also summarized the molecular mechanisms of stomatal response triggered by these stresses. To further investigate the effect of stomata-herbivore interaction at a transcriptional level, integrated transcriptome studies from different plant species attacked by different pests revealed evidence of the crosstalk between abiotic and biotic stress. Comprehensive understanding of the involvement of stomata in some plant-herbivore interactions may be an essential step towards herbivores' manipulation of plants, which provides insights for the development of integrated pest management strategies. Moreover, we proposed that stomata can function as important modulators of plant response to stress combination, representing an exciting frontier of plant science with a broad and precise view of plant biotic interactions.

Identification and characterization of three nearly identical linalool/nerolidol synthase from Acorus calamus

Acorus calamus is a perennial aromatic medicinal plant from the Acorusaceae family, known for its pharmaceutical and medicinal value. A combined chemical, biochemical, and molecular study was conducted to evaluate the differential accumulation of volatile organic compounds (VOCs) in rhizomes and leaves of A. calamus essential oil. Here, we performed VOC profiling and transcriptome-based identification and functional characterization of terpene synthase (TPS) genes. A total of 110 VOCs were detected from the rhizomes and leaves of A. calamus, and some VOCs showed significant differences between them. The further transcriptome-based analysis led to the identification of six putative TPSs genes. In phylogenetic analysis, three TPSs belonged to the TPS-g clade, one to each of the TPS-a, TPS-c, and TPS-e clades. The heterologous E. coli-based expression of recombinant TPSs identified three genes (AcTPS3, AcTPS4, and AcTPS5) as bifunctional linalool/nerolidol synthase. The correlation of TPS gene expression and VOC metabolite profiles supported the function of these genes in A. calamus. Our findings provide a roadmap for future efforts to enhance the molecular mechanisms of terpene biosynthesis and our understanding of Acorus-insect interactions.

Integrated Experimental Approach, Phytochemistry, and Network Pharmacology to Explore the Potential Mechanisms of Cinnamomi Ramulus for Rheumatoid Arthritis

Cinnamomi Ramulus (CR) has been extensively used as a remedy for inflammatory diseases in China. This study adopted an integrative approach of experimental research, phytochemistry, and network pharmacology to investigate its alleviative effects on rheumatoid arthritis (RA) and the underlying potential mechanisms. CR extract (50, 100, and 200 mg/kg) and methotrexate (MTX) significantly ameliorated RA symptoms in the collagen-induced arthritis (CIA) rat model. They also reduced paw volume, arthritis index, proinflammatory cytokines (TNF-α, IL-17A, IL-6, and IL-1β), and oxidative damage. Sixty-three compounds were systematically identified as the basic components of CR. Fifty-five common genes obtained from compounds and GEO databases were employed to construct the protein-protein interaction (PPI) network. Among them, 20 hub genes were identified via the cytoHubba. Enrichment analysis of the common genes indicated that the TNF signaling pathway and IL-17 signaling pathway might be the potential key pathways. Moreover, molecular docking methods confirmed the high affinity between the top 10 bioactive components of CR and the top 10 targets. In addition, in vitro results showed that CR extract (0.2, 0.4, and 0.8 mg/mL) inhibited inflammation and oxidative damage in MH7A cells stimulated by lipopolysaccharide (LPS). In summary, this study adopted multiple approaches to elucidate the protective effect and potential mechanisms of CR on RA, indicating that CR might be a promising herbal candidate for further investigation of RA treatment.

Chemical Diversity and Anti-Insect Activity Evaluation of Essential Oils Extracted from Five Artemisia Species

As a source of aromatic plants, the genus Artemisia has long been considered to have the potential to develop plant pesticides. In this study, components of essential oils from A. dalai-lamae, A. tangutica, A. sieversiana, A. tanacetifolia and A. ordosica were identified by GC-MS. A total of 56 constituents were analysed, and each species consisted of 9 to 24 constituents. Principle component analysis (PCA) revealed that A. dalai-lamae, A. tangutica and A. tanacetifolia are characterised by monoterpene hydrocarbons and oxygenated monoterpenes. Hierarchical cluster analysis (HCA) showed the most remarkable similarity between A. sieversiana and A. ordosica, but the similarity was still lower than 50%. Contact toxicity and repellency of essential oils were evaluated by bioassays; A. ordosica oil exhibited the most substantial contact toxicity (LD50 = 52.11 μg/cm2) against Liposcelis bostrychophila, while A. tangutica oil showed the most potent contact toxicity (LD50 = 17.42 μg/adult) against Tribolium castaneum. Except for A. dalai-lamae, the other four species showed the same level (p > 0.05) of repellent activity as the positive control against both pests at high concentrations. The results indicated that these five Artemisia species had high chemical diversity and great potential to be developed into more effective and environmentally friendly anti-insect agents.

Composition and Insecticidal Activity of Elsholtzia kachinensis Prain, a Traditional Vegetable and Herbal Medicine

In recent years, secondary metabolites of plants have attracted researchers' interest as a substitute for synthetic insecticides with many advantages. Elsholtzia kachinensis is an annual herb with medicinal and edible value. In this study, the essential oil (EO) of the aerial part of E. kachinensis was extracted by hydrodistillation, and GC-MS analysed essential oil components. The results show that carvone and dehydroelsholtzia ketone are the main components of the essential oil, accounting for 32.298% and 31.540%, respectively. EO, carvone and dehydroelsholtzia ketone are used to determine the effects against stored-product insects Lasioderma serricorne, Tribolium castaneum, Sitophilus oryzae and Liposcelis bostrychophila. The essential oil showed the most vital contact and fumigation toxicity to L. serricorne, of which LD₅₀ and LC₅₀ values were 3.85 μg/adult and 7.74 mg/L air, respectively. S. oryzae did not show repellent activity, but the repellent rate of the other three species reached 90% under EO treatment at a concentration of 78.63 nL/cm². Therefore, the essential oil of E. kachinensis has an insecticidal effect and has the potential to be developed as a new eco-friendly insecticide.

Chemical Composition and Insecticidal Properties of Essential Oil Obtained from Artemesia songarica Schrenk

ABSTRACT

Artemisia songarica Schrenk is a dominant sand fixation plant growing in the People's Republic of China. At present, there are rare studies on the chemical composition and biological activity of A. songarica. The chemical composition of the original oil was analyzed by gas chromatography-mass spectrometry, and 16 compounds were determined. The main compounds were bisabolol oxide II (28.7%), nerolidol (18.6%), bisabolol (12.9%), bisaboloxide A (10.0%), and spathulenol (6.0%). The contact toxicity and repellent activity of A. songarica essential oil and four selected compounds (bisabolol, geranyl butyrate, nerolidol, and santalol) were assessed against Tribolium castaneum Herbst and Liposcelis bostrychophila Badonnel. Bioassays showed that the crude essential oil exhibited strong insecticide and repellent activities against both pests. Santalol possessed the strongest contact toxicity (50% lethal dose [LD50] = 1.29 μg per adult) against T. castaneum. Nerolidol, santalol, and geranyl butyrate showed fair contact activity against L. bostrychophila. In particular, geranyl butyrate exhibited outstanding activity (LD50 = 11.53 μg/cm2). In addition, all of the four compounds did not detect a difference between compounds and the positive control (P > 0.05) against two pests at five tested concentrations. These results indicated that A. songarica and its selected compounds could be used as prospective insecticidal and repellent agents for further development and use.

HIGHLIGHTS

Insecticidal and Repellent Activity of Thymus quinquecostatus Celak. Essential Oil and Major Compositions against Three Stored-Product Insects

Thymus quinquecostatus Celak. of the Lamiaceae family has a long history of dual use of medicine and food with high economic value, and has been proved to have good antioxidative, antimicrobial, and antidiabetic activities. Essential oil (EO) extracted from the aerial part of T. quinquecostatus was obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC/MS) and GC. Totally 45 compounds were identified accounting for 98.5 % of the EO. The major constituents of the EO were linalool (52.003 %), borneol (10.911 %) and anethole (5.325 %). Fumigant, contact and repellent activity of T. quinquecostatus essential oil (EO) against Tribolium castaneum (Coleoptera: Tenebrionidae), Lasioderma Serricorne (Coleoptera: Anobiidae), Liposcelis bostrychophila (Psocoptera: Liposcelididae) were evaluated in this work. T. quinquecostatus EO and three major constituents showed varying degrees of insecticidal and repellent activities to three stored-product insects. Anethole stated the best fumigant and contact activity than others did to all three insect species. EO and compounds showed general repellent activity against three target insects. This work suggests that the EO of T. quinquecostatus has promising potential to be developed into botanical pesticides and repellents controlling pest damage in warehouses and grain stores.

Essential oils and their bioactive compounds as eco-friendly novel green pesticides for management of storage insect pests: prospects and retrospects

The control of storage insect pests is largely based on synthetic pesticides. However, due to fast growing resistance in the targeted insects, negative impact on humans and non-target organisms as well as the environment, there is an urgent need to search some safer alternatives of these xenobiotics. Many essential oils (EOs) and their bioactive compounds have received particular attention for application as botanical pesticides, since they exhibited high insecticidal efficacy, diverse mode of action, and favourable safety profiles on mammalian system as well as to the non-target organisms. Data collected from scientific articles show that these EOs and their bioactive compounds exhibited insecticidal activity via fumigant, contact, repellent, antifeedant, ovicidal, oviposition deterrent and larvicidal activity, and by inhibiting/altering important neurotransmitters such as acetylcholine esterase (AChE) and octopamine or neurotransmitter inhibitor γ-amino butyric acid (GABA), as well as by altering the enzymatic [superoxide dismutase (SOD), catalase (CAT), peroxidases (POx), glutathione-S-transferase (GST) and glutathione reductase (GR)] and non-enzymatic [glutathione (GSH)] antioxidant defence systems. However, in spite of promising pesticidal efficacy against storage pests, the practical application of EOs and their bioactive compounds in real food systems remain rather limited because of their high volatility, poor water solubility and susceptibility towards degradation. Nanoencapsulation/nanoemulsion of EOs is currently considered as a promising tool that improved water solubility, enhanced bio-efficacy, stability and controlled release, thereby expanding their applicability.

β-asarone suppresses HCT116 colon cancer cell proliferation and liver metastasis in part by activating the innate immune system

Studies have revealed that β-asarone exerts a powerful inhibitory effect on the proliferation of human cancer cells. The authors' previous study demonstrated that β-asarone could induce LoVo colon cancer cell apoptosis in vitro and in vivo, indicating its anticancer properties. The present study aimed to determine the antineoplastic effect of β-asarone in HCT116 colon cancer cells. An in vitro proliferation assay using a real time cell analyzer demonstrated that β-asarone effectively decreased HCT116 cell proliferation in a dose-dependent manner. Bioinformatics analysis revealed that differentially expressed genes following β-asarone inhibition were involved in the ‘cell cycle’, ‘cell division’, ‘cell proliferation’ and ‘apoptosis’. Subsequently, a xenograft assay evidenced the inhibitory effect of β-asarone on the growth of HCT116 tumors in vivo. Further detection of immune-associated cytokines and cells suggested that β-asarone might be involved in the antitumor immune response by stimulating granulocyte-colony stimulating factor and increasing the number of macrophage cells in the spleen. Additionally, a murine model of splenic-transplantation verified the strong suppressive role of β-asarone in colon cancer liver metastasis in vivo. Taken together, the results of the current study revealed that β-asarone decreased HCT116 colon cancer cell proliferation and liver metastasis potentially by activating the innate immune system, supporting the multi-system regulation theory and providing a basis for further mechanistic studies on colon cancer.

Toxicity and repellent activity of essential oil from Mentha piperita Linn. leaves and its major monoterpenoids against three stored product insects

The essential oil (EO) from leaves of Mentha piperita was extracted by hydrodistillation. Twenty-one chemical components, accounting for 97.5% of the total oil, were determined by GC-MS and GC-FID. The major chemical components included menthol (41.6%), L-menthone (24.7%), isomenthol (6.3%), and limonene (5.0%). The bioactivity of the obtained EO and its two major components against Tribolium castaneum, Lasioderma serricorne, and Liposcelis bostrychophila adults were evaluated by fumigation, contact, and repellent activity bioassay. The EO showed significant fumigation and contact toxicity against T. castaneum (LC₅₀ = 18.1 mg/L air and LD₅₀ = 2.9 μg/adult, respectively), L. serricorne (LC₅₀ = 68.4 mg/L air and LD₅₀ = 12.6 μg/adult, respectively), and L. bostrychophila (LC₅₀ = 0.6 mg/L air and LD₅₀ = 49.8 μg/adult, respectively) adults. Meanwhile, the repellent effect of the EO on T. castaneum and L. serricorne adults was comparable to that of the positive control at the highest tested concentration. Menthol and L-menthone were two major components in total oil. Among them, L-menthone exhibited significant insecticidal activity on target insects, and menthol showed notable repellent effects. The results indicated that the EO of M. piperita leaves and two tested components have potential to be developed as natural insecticides and repellents for the control of stored product insect pests. Graphical abstract.

Candidate detoxification-related genes in brown planthopper, Nilaparvata lugens, in response to β-asarone based on transcriptomic analysis

Nilaparvata lugens(Stål) is a serious pest of rice and has evolved different levels of resistance against most chemical pesticides. β-asarone is the main bioactive insecticidal compound of Acorus calamus L. that shows strong insecticidal activity against pests. In this study, we conducted a bioassay experiment to determine the contact toxicity of β-asarone to N. lugens nymphs. The LD₃₀ sublethal dose was 0.106 μg per nymph, with 95% confidence limits of 0.070-0.140 μg. We applied the LD₃₀ concentration of β-asarone to nymphs for 24 h or 72 h and then performed a transcriptome sequence analysis by referencing the N. lugens genome to characterize the variation. The transcriptomic analysis showed that several GO terms and KEGG pathways presented significant changes. Individually, 126 differentially expressed genes (DEGs), including 72 upregulated and 54 downregulated genes, were identified at 24 h, and 1771 DEGs, including 882 upregulated and 889 downregulated genes, were identified at 72 h. From the DEGs, we identified a total of 40 detoxification-related genes, including eighteen Cytochrome P450 monooxygenase genes (P450s), three Glutathione S-transferase genes, one Carboxylesterase gene, twelve UDP-glucosyltransferases and six ATP-binding cassette genes. We selected the eighteen P450s for subsequent verification by quantitative PCR. These findings indicated that β-asarone presented strong contact toxicity to N. lugens nymphs and induced obvious variation of detoxification-related genes that may be involved in the response to β-asarone.

Insecticidal and repellent efficacy against stored-product insects of oxygenated monoterpenes and 2-dodecanone of the essential oil from Zanthoxylum planispinum var. dintanensis

Essential oils (EOs) extracted from leaves (EL) and fruit pericarp (EFP) of Zanthoxylum planispinum var. dintanensis were analyzed for their chemical composition by GC-MS technique and evaluated for their fumigant, contact toxicity and repellency against three stored-product insects, namely Tribolium castaneum, Lasioderma serricorne, and Liposcelis bostrychophila adults. Results of GC-MS analysis manifested that EL and EFP of Z. planispinum var. dintanensis were mainly composed of oxygenated monoterpenes. Major components included linalool, sylvestrene and terpinen-4-ol. The obvious variation observed between two oil samples was that EL contained 2-dodecanone (11.52%) in addition to the above mentioned components, while this constituent was not detected in EFP. Bioassays of insecticidal and repellent activities were performed for EL, EFP as well as some of their individual compounds (linalool, terpinen-4-ol and 2-dodecanone). Testing results indicated that EL, EFP, linalool, terpinen-4-ol and 2-dodecanone exhibited potent insecticidal and repellent activities against the three target insects selected. Among the three individual compounds, 2-dodecanone was significantly toxic to T. castaneum (LD₅₀ = 5.21 μg/adult), L. serricorne (LD₅₀ = 2.54 μg/adult) and L. bostrychophila (LD₅₀ = 23.41 μg/cm²) in contact assays and had beneficial repellent effects on L. serricorne at 2 and 4 h post-exposure. The anti-insect efficacy of Z. planispinum var. dintanensis EO suggests it has potential to be used as botanical insecticide or repellent to control pest damage in warehouses and grain stores.

Antispasmodic Effect of Essential Oils and Their Constituents: A Review

The antispasmodic effect of drugs is used for the symptomatic treatment of cramping and discomfort affecting smooth muscles from the gastrointestinal, billiary or genitourinary tract in a variety of clinical situations.The existing synthetic antispasmodic drugs may cause a series of unpleasant side effects, and therefore the discovery of new molecules of natural origin is an important goal for the pharmaceutical industry. This review describes a series of recent studies investigating the antispasmodic effect of essential oils from 39 plant species belonging to 12 families. The pharmacological models used in the studies together with the mechanistic discussions and the chemical composition of the essential oils are also detailed. The data clearly demonstrate the antispasmodic effect of the essential oils from the aromatic plant species studied. Further research is needed in order to ascertain the therapeutic importance of these findings.

Chromatographic Study on Traditional Natural Preservatives Used for Palm Leaf Manuscripts in India

Extracts from plants have been used traditionally for the preservation of palm leaf manuscripts in India. Although these methods are slowly being replaced by modern chemicals, art conservators still prefer herbal plant extracts as fungicides and insecticides. In this study, several traditional herbal extracts from the state of Odisha were studied using GC-MS and their long-term impact on palm leaf manuscripts was substantiated by visual observation. GC-MS results showed the presence of different herbal plant extracts from walnut fruit, Artemisia oil, cinnamon oil, equisetum stem, circium roots, Rhizophora leaf, tobacco leaf, and beggar-tick plant oil in palm leaf manuscripts. Illustrated manuscripts were also studied using FTIR spectroscopy which showed the presence of starch paste and pectin as binding media mixed in the pigments and writing inks for palm leaf manuscripts.

Toxicity and repellency of essential oil from Evodia lenticellata Huang fruits and its major monoterpenes against three stored-product insects

In this work, the essential oil (EO) was extracted from the fruits of Evodia lenticellata, and the fumigant toxicity, contact toxicity and repellency against three stored-product insect species were evaluated for the obtained EO and several of its chemical components. The target insects were the adults of Tribolium castaneum (Coleoptera: Tenebrionidae), Lasioderma serricorne (Coleoptera: Anobiidae) and Liposcelis bostrychophila (Psocoptera: Liposcelididae). The EO was obtained with hydrodistillation and its chemical components were analyzed with the gas chromatography-mass spectrometry (GC-MS). Twenty-seven compounds, accounting for 83.1% of the total amount of the oil, were identified from the EO sample. The main compounds included linalool (12.0%), β-pinene (11.5%), 3-carene (9.6%), caryophyllene oxide (8.7%) and β-caryophyllene (7.9%). Among them, the amounts of monoterpenes and sesquiterpenes were as high as 52.7% and 22.7% to the total amount of EO respectively. The results of bioactivity test showed that the EO and its testing compounds had interspecific toxicity and repellent activity. So that, it might be expected that the EO extracted from the fruits of E. lenticellata could be developed to a new type of eco-friendly natural insecticide or repellent for the control of stored-product insects.

Acorus calamus: a bio-reserve of medicinal values

Many plants are found to possess reliable pharmacological properties and have started to attract the attention of researchers. One such holistic plant is Acorus calamus, commonly known as sweet flag, belonging to the rhizomatous family Acoraceae. The different parts of this plant, such as the leaves and rhizomes, are used traditionally in different medicinal preparations for the treatment of various ailments including arthritis, neuralgia, diarrhoea, dyspepsia, kidney and liver troubles, eczema, sinusitis, asthma, fevers, bronchitis, hair loss, and other disorders. Many reports have also appeared in mainstream scientific journals confirming its nutritional and medicinal properties. Biochemical analysis of the plant has revealed a large number of secondary metabolites that may be responsible for its rich medicinal properties. Basic scientific research has uncovered the mechanisms by which itexerts its therapeutic effects. Medicinal herbs such as A. calamus are quite promising in the recent therapeutic scenario, with a large number of people favouring remedies and health approaches that are free from the side effects often associated with synthetic chemicals. In this review, we try to summarise the ethno-medicinal uses, botanical descriptions, phytochemical constituents, and biological activity of the plant parts, as well as the molecular targets of A. calamus, which we hope will serve as a good base for further work on this plant.

Toxic and Repellent Effects of Volatile Phenylpropenes from Asarum heterotropoides on Lasioderma serricorne and Liposcelis bostrychophila

Toxic and repellent effects of the essential oil from Asarum heterotropoides Fr. Schmidt var. mandshuricum (Maxim.) Kitag. were evaluated against Lasioderma serricorne and Liposcelis bostrychophila. The essential oils (EOs) from roots (ER) and leaves (EL) of A. heterotropoides were obtained separately by hydrodistillation and characterized by gas chromatography-mass spectrometry (GC-MS) analysis. Major components of ER and EL included methyleugenol, safrole, and 3,5-dimethoxytoluene. Both ER and EL of A. heterotropoides showed certain toxicity and repellency against L. serricorne and L. bostrychophila. 3,5-Dimethoxytoluene, methyleugenol, and safrole were strongly toxic via fumigation to L. serricorne (LC50 = 4.99, 10.82, and 18.93 mg/L air, respectively). Safrole and 3,5-dimethoxytoluene possessed significant fumigant toxicity against L. bostrychophila (LC50 = 0.83 and 0.91 mg/L air, respectively). The three compounds all exhibited potent contact toxicity against the two insect species. Here, the EL of A. heterotropoides was confirmed to have certain toxicity and repellency against stored product insects, providing a novel idea for the comprehensive use of plant resources.

Contact Toxicity and Repellency of the Essential Oils of Evodia lenticellata Huang and Evodia rutaecarpa (Juss.) Benth. Leaves against Three Stored Product Insects

The essential oils (EOs) extracted from Evodia lenticellata Huang and Evodia rutaecarpa (Juss.) Benth. leaves are screened to evaluate their contact toxicity and repellency towards Tribolium castaneum (Coleoptera: Tenebrionidae), Lasioderma serricorne (Coleoptera: Anobiidae) and Liposcelis bostrychophila (Psocoptera: Liposcelididae) adults. The EOs are obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS). The principal components in the E. lenticellata EO are identified to be caryophyllene oxide (28.5%), β-caryophyllene (23.1%), β-elemene (14.5%), and β-cubebene (4.7%), while the main components of the E. rutaecarpa EO are α-pinene (39.4%), β-elemene (13.5%), α-ocimene (7.6%), and α-selinene (4.0%). These two kinds of EOs and their individual compounds all showed different levels of contact toxicity and repellent activity against three stored-product insects.

Systems Pharmacological Approach to Investigate the Mechanism of Acori Tatarinowii Rhizoma for Alzheimer's Disease

In traditional Chinese medicine (TCM), Acori Tatarinowii Rhizoma (ATR) is widely used to treat memory and cognition dysfunction. This study aimed to confirm evidence regarding the potential therapeutic effect of ATR on Alzheimer's disease (AD) using a system network level based in silico approach. Study results showed that the compounds in ATR are highly connected to AD-related signaling pathways, biological processes, and organs. These findings were confirmed by compound-target network, target-organ location network, gene ontology analysis, and KEGG pathway enrichment analysis. Most compounds in ATR have been reported to have antifibrillar amyloid plaques, anti-tau phosphorylation, and anti-inflammatory effects. Our results indicated that compounds in ATR interact with multiple targets in a synergetic way. Furthermore, the mRNA expressions of genes targeted by ATR are elevated significantly in heart, brain, and liver. Our results suggest that the anti-inflammatory and immune system enhancing effects of ATR might contribute to its major therapeutic effects on Alzheimer's disease.

Botanical essential oils and uses as mosquitocides and repellents against dengue

Plants naturally produce bioactive compounds along with many secondary metabolites which serve as defensive chemical against herbivorers including insect pests. One group of these phytochemicals are the 'Essential Oils' (EO's), which possess an extensive range of biological activity especially insecticidal and insect repellents. This review provides a comprehensive viewpoint on potential modes of action of biosafety plant derived Essential Oils (EO's) along with their principal chemical derivatives against larvae and adult mosquito vectors of dengue virus. The development and use of Essential Oils (EO's) effectively applied in small rural communities provides an enormous potential for low cost effective management of insect vectors of human pathogens which cause disease.

Molecular Targets for Components of Essential Oils in the Insect Nervous System-A Review

Essential oils (EOs) are lipophilic secondary metabolites obtained from plants; terpenoids represent the main components of them. A lot of studies showed neurotoxic actions of EOs. In insects, they cause paralysis followed by death. This feature let us consider components of EOs as potential bioinsecticides. The inhibition of acetylcholinesterase (AChE) is the one of the most investigated mechanisms of action in EOs. However, EOs are rather weak inhibitors of AChE. Another proposed mechanism of EO action is a positive allosteric modulation of GABA receptors (GABArs). There are several papers that prove the potentiation of GABA effect on mammalian receptors induced by EOs. In contrast, there is lack of any data concerning the binding of EO components in insects GABArs. In insects, EOs act also via the octopaminergic system. Available data show that EOs can increase the level of both cAMP and calcium in nervous cells. Moreover, some EO components compete with octopamine in binding to its receptor. Electrophysiological experiments performed on Periplaneta americana have shown similarity in the action of EO components and octopamine. This suggests that EOs can modify neuron activity by octopamine receptors. A multitude of potential targets in the insect nervous system makes EO components interesting candidates for bio-insecticides.

Toxicity of Plant Secondary Metabolites Modulating Detoxification Genes Expression for Natural Red Palm Weevil Pesticide Development

This study aimed to explore the larvicidal and growth-inhibiting activities, and underlying detoxification mechanism of red palm weevil against phenylpropanoids, an important class of plant secondary metabolites. Toxicity of α-asarone, eugenol, isoeugenol, methyl eugenol, methyl isoeugenol, coumarin, coumarin 6, coniferyl aldehyde, diniconazole, ethyl cinnamate, and rosmarinic acid was evaluated by incorporation into the artificial diet. All of the phenylpropanoids exhibited dose- and time-dependent insecticidal activity. Among all the tested phenylpropanoids, coumarin exhibited the highest toxicity by revealing the least LD50 value (0.672 g/L). In addition, the most toxic compound (coumarin) observed in the current study, deteriorated the growth resulting tremendous reduction (78.39%) in efficacy of conversion of digested food (ECD), and (ECI) efficacy of conversion of ingested food (70.04%) of tenth-instar red palm weevil larvae. The energy-deficient red palm weevil larvae through their intrinsic abilities showed enhanced response to their digestibility resulting 27.78% increase in approximate digestibility (AD) compared to control larvae. The detoxification response of Rhynchophorus ferrugineus larvae determined by the quantitative expression of cytochrome P450, esterases, and glutathione S-transferase revealed enhanced expression among moderately toxic and ineffective compounds. These genes especially cytochrome P450 and GST detoxify the target compounds by enhancing their solubility that leads rapid excretion and degradation resulting low toxicity towards red palm weevil larvae. On the other hand, the most toxic (coumarin) silenced the genes involved in the red palm weevil detoxification mechanism. Based on the toxicity, growth retarding, and masking detoxification activities, coumarin could be a useful future natural red palm weevil-controlling agent.

β-Asarone inhibits gastric cancer cell proliferation

β-Asarone is the main volatile oil of Chinese herb Rhizoma Acori Tatarinowii. It exhibits a wide range of biological activities in many human organs. However, few studies have investigated the effect of β-asarone on gastric cancer. The present study investigated the effect of β-asarone on the proliferation and apoptosis of three types of differentiated human gastric cancer cell lines (SGC-7901, BGC-823 and MKN-28) in vitro as well as the related molecular mechanisms. Methyl thiazolyl tetrazolium assay, Annexin V/PI double staining, immunofluorescence test and transmission electron microscopy all confirmed that β-asarone had an obvious dose-dependent inhibitive effect on the proliferation of human gastric cancer cells and induced apoptosis of the cell lines. Transwell invasion, wound-healing and matrix‑cell adhesion experiments confirmed that β-asarone inhibited the invasion, migration and adhesion of human gastric cancer BGC-823 cells. Quantitative real-time PCR and western blotting found that β-asarone significantly activated caspase-3, caspase-8, caspase-9, Bax, Bak and suppressed Bcl-2, Bcl-xL and survivin activity. Moreover, β-asarone increased the expression of RECK, E-cadherin and decreased the expression of MMP-2, MMP-9, MMP-14 and N-cadherin. The present study demonstrated that β-asarone effectively inhibits the proliferation of human gastric cancer cells, induces their apoptosis and decreased the invasive, migratory and adhesive abilities.

Pimenta pseudocaryophyllus Derivatives: Extraction Methods and Bioactivity Against Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae)

Plant-based insecticides can play an important role in integrated insect pest management (IPM), especially in protecting stored grains. The aim of this study was to evaluate the bioactivity of derivatives (powder, ethanolic extract, and essential oil (EO)) from the leaves of Pimenta pseudocaryophyllus (Myrtaceae), a Brazilian native species, against Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), the main insect pest of stored corn. The powder and essential oil prepared from leaves showed a repellent effect. Moreover, the EO exhibited promising insecticidal activity through residual contact (LC50 = 1522 mg kg(-1)) and significantly decreased the F 1 progeny and the percentage of damaged grains. However, the essential oil obtained from P. pseudocaryophyllus leaves did not result in significant mortality of S. zeamais adults after 72 h of exposure by fumigation in concentrations up to 400 μL L(-1) of air. Based on GC-MS analysis, 20 compounds were identified in the essential oil of P. pseudocaryophyllus leaves, being chavibetol (38.14%), methyl eugenol (11.35%), and terpinolene (9.17%) as the major constituents. Essential oil from P. pseudocaryophyllus leaves is an interesting source of compounds with grain-protectant properties and should be analyzed in future studies aiming to develop new bioinsecticides to use in the IPM of stored grains.

Repellant and insecticidal activities of shyobunone and isoshyobunone derived from the essential oil of Acorus calamus rhizomes

CONTEXT

It was found that the essential oil of Acorus calamus rhizomes showed insecticidal activity.

AIM

The aim of this study was to determine the chemical composition of the essential oil from A. calamus rhizomes, evaluate insecticidal and repellant activity against Lasioderma serricorne (LS) and Tribolium castaneum (TC), and to isolate any insecticidal constituents from the essential oil.

MATERIALS AND METHODS

Essential oil from A. calamus was obtained by hydrodistillation and analyzed by gas chromatography (GC) flame ionization detector and GC-mass spectrometry. The insecticidal and repellant activity of the essential oil and isolated compounds was tested using a variety of methods.

RESULTS

The main components of the essential oil were identified to be isoshyobunone (15.56%), β-asarone (10.03%), bicyclo[6.1.0]non-1-ene (9.67%), shyobunone (9.60%) and methylisoeugenol (6.69%). Among them, the two active constituents were isolated and identified as shyobunone and isoshyobunone. The essential oil showed contact toxicity against LS and TC with LD50 values of 14.40 and 32.55 μg/adult, respectively. The isolated compounds, shyobunone and isoshyobunone also exhibited strong contact toxicity against LS adults with LD50 values of 20.24 and 24.19 μg/adult, respectively, while the LD50 value of isoshyobunone was 61.90 μg/adult for TC adults. The essential oil, shyobunone and isoshyobunone were strongly repellent (98%, 90% and 94%, respectively, at 78.63 nL/cm(2), after 2 h treatment) against TC.

CONCLUSION

The essential oil, shyobunone and isoshyobunone possessed insecticidal and repellant activity against LS and TC.

Chemical Composition and Insecticidal Activities of the Essential Oil of Clinopodium chinense (Benth.) Kuntze Aerial Parts against Liposcelis bostrychophila Badonnel

Water-distilled essential oil from Clinopodium chinense (Labiatae) aerial parts at the flowering stage was analyzed by gas chromatography-mass spectrometry. Thirty-five compounds, accounting for 99.18% of the total oil, were identified, and the main components of the essential oil of C. chinense were spathulenol (18.54%), piperitone (18.9%), caryophyllene (12.04%), and bornyl acetate (8.14%). Based on bioactivity-directed fractionation, bornyl acetate, caryophyllene, and piperitone were identified from the essential oil. The essential oil possessed fumigant toxicity against booklice (Liposcelis bostrychophila) with a 50% lethal concentration (LC50) value of 423.39 μg/liter, while the isolated constituents, bornyl acetate and piperitone, had LC50 values of 351.69 and 311.12 μg/liter against booklice, respectively. The essential oil also exhibited contact toxicity against L. bostrychophila with an LC50 value of 215.25 μg/cm(2). Bornyl acetate, caryophyllene, and piperitone exhibited acute toxicity against booklice with LC50 values of 321.42, 275.00, and 139.74 μg/cm(2), respectively. The results indicated that the essential oil and its isolated constituents have potential for development into natural insecticides or fumigants for control of insects in stored grains.

Chemical Composition and Bioactivities of the Essential Oil from Etlingera yunnanensis against Two Stored Product Insects

The chemical composition of the essential oil of Etlingera yunnanensis rhizomes and its contact and repellent activities against Tribolium castaneum (Herbst) and Liposcelis bostrychophila (Badonnel) were investigated. The essential oil obtained from E. yunnanensis rhizomes with hydrodistillation was performed by gas chromatography-flame ionization detection and gas chromatography-mass spectrometry. The main components of the essential oil were identified to be estragole (65.2%), β-caryophyllene (6.4%), 1,8-cineole (6.4%), limonene (5.2%), and α-pinene (2.4%). It was found that the essential oil of E. yunnanensis rhizomes possessed contact toxicity against T. castaneum and L. bostrychophila (LD₅₀ = 23.33 μg/adult and LD₅₀ = 47.38 μg/cm², respectively). Estragole, 1,8-cineole, and limonene exhibited stronger contact toxicity (LD₅₀ values of 20.41, 18.86, and 13.40 μg/adult, respectively) than β-caryophyllene (LD₅₀ = 41.72 μg/adult) against T. castaneum adults. Estragole possessed stronger contact toxicity (LD₅₀ = 30.22 µg/cm²) than β-caryophyllene, 1,8-cineole, and limonene (LD₅₀ values of 74.11, 321.20, and 239.62 μg/adult, respectively) against L. bostrychophila adults. Repellency of the crude oil was also evaluated. The essential oil and constituents possessed strong repellent activity against T. castaneum adults. The four individual constituents showed weaker repellent activity than the essential oil against L. bostrychophila adults. The results indicated that the essential oil of E. yunnanensis rhizomes and the individual constituents had the potential to be developed as a natural insecticide and repellent for the control of T. castaneum and L. bostrychophila.

Contact Toxicity and Repellency of the Main Components From the Essential Oil of Clausena anisum-olens Against Two Stored Product Insects

The essential oil of Clausena anisum-olens (Blanco) Merr. showed strong contact toxicity and repellency against Lasioderma serricorne and Liposcelis bostrychophila adults. The components of the essential oil obtained by hydrodistillation were determined by gas chromatography-mass spectrometry. It was found that the main components were myristicin (36.87%), terpinolene (13.26%), p-cymene-8-ol (12.38%), and 3-carene (3.88%). Myristicin and p-cymene-8-ol were separated by silica gel column chromatography, and their molecular structures were confirmed by means of physicochemical and spectrometric analysis. Myristicin and p-cymene-8-ol showed strong contact toxicity against L. serricorne (LD50 = 18.96 and 39.68 μg per adult) and Li. bostrychophila (LD50 = 20.41 and 35.66 μg per adult). The essential oil acting against the two grain storage insects showed LD50 values of 12.44 and 74.46 μg per adult, respectively. Myristicin and p-cymene-8-ol have strong repellent toxicity to Li. bostrychophila.

Chemical constituents and activities of the essential oil from Myristica fragrans against cigarette beetle Lasioderma serricorne

Essential oil extracted from nutmeg seeds (Myristica fragrans Houtt.) by hydrodistillation was subjected to GC/MS and GC analysis. A total of 27 constituents were identified, of which eugenol (19.9%), methylisoeugenol (16.8%), methyleugenol (16.7%), sabinene (11.8%), and terpinen-4-ol (8.5%) were the major components. The essential oil was tested against Lasioderma serricorne for insecticidal and repellent activity, the LD50 value at the end of 24 h exposure period was 19.3 μg/adult. Six active compounds were isolated by bioassay-guided fractionation. They were identified as eugenol (1), methyleugenol (2), methylisoeugenol (3), elemicin (4), myristicin (5), and safrole (6). Among these isolates, 4 showed the strongest contact toxicity against L. serricorne adults with an LD50 value of 9.8 μg/adult. Repellency of crude oil and active compounds were also determined. Compounds 1, 2, 4, and 5 were strongly repellent against the cigarette beetle and exhibited the same level of repellency compared with the positive control, DEET. The results indicate that the essential oil of M. fragrans and its active constituents have potential for development as natural insecticides and repellents to control L. serricorne.

Analysis of the essential oil of Illicium henryi Diels root bark and its insecticidal activity against Liposcelis bostrychophila Badonnel

Water-distilled essential oil from Illicium henryi (Illiciaceae) root bark was analyzed by gas chromatography-mass spectrometry. Thirty-four compounds, accounting for 97.86% of the total oil, were identified. The main components of the essential oil of I. henryi root bark were safrole (46.12%), myristicin (20.39%), and 1,8-cineole (6.17%), followed by α-cadinol (3.784%) and linalool (3.22%). The essential oil had higher levels of phenylpropanoids (66.89%) than of monoterpenoids (14.83%) and sesquiternoids (16.14%). Three constituents were isolated from the oil based on bioactivity fractionation. The essential oil possessed fumigant toxicity against booklice (Liposcelis bostrychophila), with a 50% lethal concentration (LC50) of 380.39 μg/liter of air, while the two isolated constituents myristicin and safrole had LC50s of 121.95 and 322.54 μg/liter, respectively. Another constituent, 1,8-cineole, showed weaker toxicity, with an LC50 of 1,120.43 μg/liter. The essential oil also exhibited contact toxicity against L. bostrychophila, with an LC50 of 96.83 μg/cm(2). Myristicin (LC50, 18.74 μg/cm(2)) and safrole (LC50, 69.28 μg/cm(2)) exhibited stronger acute toxicity than 1,8-cineole (LC50, 1,049.41 μg/cm(2)) against the booklice. The results indicated that the essential oil and its constituent compounds have potential for development into natural insecticides for control of psocids in stored grains.

Contact toxicity and repellency of the essential oil of Liriope muscari (DECN.) bailey against three insect tobacco storage pests

In order to find and develop new botanical pesticides against tobacco storage pests, bioactivity screening was performed. The essential oil obtained from the aerial parts of Liriope muscari was investigated by GC/MS and GC/FID. A total of 14 components representing 96.12% of the oil were identified and the main compounds in the oil were found to be methyl eugenol (42.15%) and safrole (17.15%), followed by myristicin (14.18%) and 3,5-dimethoxytoluene (10.60%). After screening, the essential oil exhibit potential insecticidal activity. In the progress of assay, it showed that the essential oil exhibited potent contact toxicity against Tribolium castaneum, Lasioderma serricorne and Liposcelis bostrychophila adults, with LD50 values of 13.36, 11.28 µg/adult and 21.37 µg/cm2, respectively. The essential oil also exhibited strong repellency against the three stored product insects. At the same concentrations, the essential oil was more repellent to T. castaneum than to L. serricorne adults. The results indicate that the essential oil of Liriope muscari has potential to be developed into a natural insecticide or repellent for controlling insects in stored tobacco and traditional Chinese medicinal materials.

Isolation of Insecticidal Constituents from the Essential Oil ofAgeratum houstonianumMill. againstLiposcelis bostrychophilaBadonnel

The aim of this research was to determine chemical composition and insecticidal activities of the essential oil ofAgeratum houstonianumMill. aerial parts against booklice,Liposcelis bostrychophilaBadonnel, and to isolate any insecticidal constituents from the oil. Essential oil ofA. houstonianumwas obtained by hydrodistillation and analyzed by GC-MS. A total of 35 components in the essential oil were identified. The major compounds were precocene II (62.68%), precocene I (13.21%), andβ-caryophyllene (7.92%). Based on bioactivity-guided fractionation, precocene II and precocene I were isolated and identified as the active constituents. The essential oil exhibited contact toxicity againstL. bostrychophilawith an LC50value of 50.8 μg/cm2. Precocene II (LC50= 30.4 μg/cm2) exhibited stronger acute toxicity than precocene I (LC50= 64.0 μg/cm2) against the booklice. The essential oil and the two isolated constituents also possessed strong repellent activity againstL. bostrychophila. The results indicated that the essential oil and its constituent compounds have potential for development into natural insecticides or repellents for control of insects in stored grains.