Identification of repellent and insecticidal constituents of the essential oil of Artemisia rupestris L. aerial parts against Liposcelis bostrychophila Badonnel

Formulation of Neem Leaf and Croton Seed Essential Oils as a Natural Insecticide Tested on Mosquitoes and Cockroaches

Essential oils are highly aromatic plant oils utilized as a new insect control alternative to synthetic insecticides because of environmental concerns. As a result, the purpose of this study was to evaluate the effects of essential oil extraction conditions on neem leaf and cotton seed, as well as to identify their chemical composition using gas chromatography-mass spectrometry. Moreover, both extracted oils were subjected to bioinsecticide formulation in individual as well as mixed forms, which were tested on mosquitoes and cockroaches using the conventional roach killer and a blank control as a comparison. The results revealed that the maximum yields of essential oils from neem leaf and croton seed were respectively 30.54 and 14.75%. The extraction process was greatly affected by the particle sizes because of the mass transfer limitation between solute-solvent interactions. The insecticidal evaluation showed that the blended form of essential oils at the 20% concentration has better efficiency than the individual oils, which accounted for 80% mosquito and 71.8% cockroach death rates within 4 h, whereas the synthetic roach killer completely killed all of the insects within the same time frame. Terpineol, α-terpinyl acetate, eucalyptol, and δ-cadinene are the active insecticidal compounds in neem leaf oil, whereas the active compounds of croton seed oil are epiglobulol, copaene, δ-cadinene, α-cubebene, and β-guaiene.

Phytochemical characterization, antioxidant activity and antihypertensive evaluation of Ocimum basilicum L. in l-NAME induced hypertensive rats and its correlation analysis

Ocimum basilicum Linn. (basil) is an aromatic culinary herb that has shown a great potential in therapeutic world. It has many promising pharmacological activities that make it centre for investigations for many researchers. Current study has been planned to determine chemical constituents of basil leaves extracts and their in-vitro and ex-vivo antioxidant and in-vivo antihypertensive potential. GC-MS studies of non-polar extracts showed presence of 75 compounds including monoterpenes, hydrocarbons, sesquiterpenes, triterpenes, phyto-sterols and phthalates. Higher percentages of fatty acids were also identified. The major compounds include linalool (7.65%), terpineol (1.42%), tau-cadinol (13.55%), methyl palmitate (14.24%), palmitic acid (14.31%), linolenic acid (1.30%) and methyl linolenate (17.72%). Electron spray ionization mass spectrometry ESI-HRMS/MS of the polar extracts revealed the presence of alkaloids, phenolic acid, amino acid, coumarin, lignin, flavanoid and terpene derivative. Total phenolic content and total flavonoid content were determined using spectrophotometric technique and calculated as gallic acid equivalents GAE/g dry weight and rutin equivalent RE/g of dry weight respectively. The highest phenolic content and flavonoid content were found in ethyl acetate extract 9.40 mg GAE/g and 15.9 mg RE/g of dry weight. All the extracts showed significant antioxidant activity in DPPH and ABTS cation decolorization assays. Dichloromethane extract possess the highest DPPH scavenging activity, i.e., 64.12% ± 0.23 at concentration of 4 mg/ml. Moreover in ex-vivo studies all the extracts showed prominent effect by inhibiting AAPS induce oxidation in Human erythrocytes being 69.24% ± 0.18 in dichloromethane extract, 64.44% ± 0.04 in ethyl acetate and 53.33% ± 0.09 in acetone extract. The methanol extract of O. basilicum exhibited significant decrease in systolic blood pressure in l-Name induced hypertensive rats at the dose of 50 mg/kg for 28 days. Total phenolic content had a higher linear correlation (r = 0.678) with antihypertensive activity, with a level of significance 95% showing that phenolic compounds in the leaves of the plant has important role in inhibiting l -NAME induced hypertension while flavonoid compounds may play a key role in the antioxidant activities of the plant, through synergism. Conclusively, O. basilicum leaves with bioactive metabolites are a potential source for the development of antihypertensive drugs.

Insecticidal and Repellent Effects of the Essential Oils Extract from Zanthoxylum myriacanthum against Three Storage Pests

The co-storage of two or more Chinese herbal medicines can effectively prevent the herbs from the damage by pests. Thus, it is important to protect herbs and crops to study Chinese herbal medicines and their medicinal components against storage pests. This study aimed to assess the insecticidal activities and repellent effect of essential oils (EOs) extracted from fruits at different periods from Zanthoxylum myriacanthum Wall. ex Hook. f. (1 h, 2 h, 3-5 h and 5-7 h), and their major compounds against three kinds of pests (Tribolium castaneum, Lasioderma serricorne, and Liposcelis bostrychophila). The results of gas chromatography-mass spectrometer analysis revealed homomyrtenol (22.56 %, 28.01 %, 28.48 % and 28.41 %, respectively) and p-cymene (30.58 %, 13.95 %, 24.97 % and 6.85 %, respectively) were the common major compounds of the EOs at 1 h, 2 h, 3-5 h, and 5-7 h. m-Cymene contents in EOs of fruits, 1 h, 2 h and 3-5 h were 3.85 %, 0.95 %, 6.71 %, and 6.15 %, respectively. According to Principal component analysis (PCA), the composition of fruits' EO was significantly different from other EOs due to the different collection times. The bio-assays showed that EOs and major compounds were toxic to all three pests, but the fumigation effect on L. bostrychophila was not noticeable. EOs extracted at different times had a repellent effect on the three pests at the highest concentration (78.63 nL/cm2 ), but the attractive effects of the EOs of 3-5 h, 5-7 h, and p-cymene were observed at the low concentrations (3.15, 0.63 and 0.13 nL/cm2 ). Our results suggest that Z. myriacanthum have the potential to be developed as biological insecticides.

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.

Evaluation of Lethal and Sublethal Effects of Methyl Benzoate on the Generalist Predator Orius laevigatus (Fieber)

Methyl benzoate (MBe), a volatile organic molecule, has been shown to have insecticidal effects on a variety of agricultural, stored products, and urban arthropod pests in recent investigations. However, the toxicity of MBe against nontarget organisms has rarely been investigated. This study investigated the lethal and sublethal effects of MBe on the generalist predator Orius laevigatus (Fieber) (Hemiptera: Anthocoridae) via different exposure routes. This species is an important natural enemy of thrips, aphids, and mites in biological control programs globally. Acute toxicity bioassays conducted on O. laevigatus showed that the lethal median concentration (LC50) values of MBe for topical and residual toxicity were 0.73 and 0.94%, respectively, after 24 hr of exposure. Importantly, a sublethal concentration of MBe (LC30 = 0.51%) did not affect the survival and reproduction of O. laevigatus. In addition, prey consumption by O. laevigatus under different exposure conditions with varying densities of Aphis gossypii (Glover) (Hemiptera: Aphididae) adults demonstrated a good fit for a Type II functional response. The sublethal concentration of MBe did not affect the attack rate and handling time of O. laevigatus compared to untreated insects, nor did it affect the longevity and fecundity of O. laevigatus females. Thus, according to the International Organization for Biological Control, the sublethal MBe concentration for O. laevigatus is categorized as harmless and may be used in conjunction with this predator species for integrated control of many agricultural insect pests.

Repellency, contact toxicity, and anti-oviposition effects of three ethanol-extracted plant essential oils on Bemisia tabaci (Hemiptera: Aleyrodidae)

There are more than 1200 species of whiteflies found across the globe. Due to the high level of resistance of whitefly against synthetic insecticides, alternate pest management measures have their significance. Plant essential oils (EOs) affect insect pests in many ways, such as via stimulatory, deterrent, toxic, and hormonal effects. This study was designed to determine the repellency of EOs, toxicity, and oviposition deterrent activities of Allium ascalonicum, Cinnamomum camphora, and Mentha haplocalyx against adult whiteflies. In repellency determination experiments, a single tomato plant was treated with 10 ml of ethanol-extracted EO with 1000 ppm concentration. Results showed that C. camphora EO was the most repellent for whitefly compared to M. haplocalyx and A. ascalonicum. The oviposition deterrent experiments revealed that C. camphora has the highest oviposition deterrent effect, followed by M. haplocalyx and A. ascalonicum. A single plant treatment method was used to assess the contact toxicity of three EOs against whitefly after 12, 24, 48, and 72 h of exposure. The results revealed that C. camphora is more toxic to whitefly than M. haplocalyx and A. ascalonicum. After determining the antagonistic effects of these EOs, the oils were analyzed using gas chromatography/mass spectrometry to identify the chemical components. It can be concluded that C. camphora is the most effective oil EO in terms of toxicity, repellence, and oviposition deterrence, followed by M. haplocalyx and A. ascalonicum under greenhouse conditions. Our results introduce some new eco-friendly plant EOs to control whiteflies.

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

Study on Gas Chromatographic Fingerprint of Essential Oil from Stellera chamaejasme Flowers and Its Repellent Activities against Three Stored Product Insects

The objective of this study was to establish the chromatographic fingerprints of the essential oil (EO) from Stellera chamaejasme flowers collected from various natural sites by gas chromatography (GC) combined with chemometric methods. The EO was obtained by hydrodistillation, and its chemical composition was analyzed by gas chromatography-mass spectrometry (GC-MS). Most components were identified as ketones and the relatively high-content components were fitone (38.973%), n-hentriacontane (5.807%), myristic acid (4.944%) and phytol (3.988%). In addition, the repellent activities of the EO from S. chamaejasme flowers and its four main chemical compounds were evaluated against three stored product pests (Tribolium castaneum, Lasioderma serricorne, Liposcelis bostrychophila) for the first time. In this work, the EO and the four chemical compounds showed a repellent effect against three storage pests after 2 and 4 h exposure. The experimental method and repellent activity of S. chamaejasme flower EO could provide a basis for the development of botanical pesticide and the utilization of the rich plant resources of S. chamaejasme in the future.

Mosquitocidal activity of twenty-eight plant essential oils and their binary mixtures against Culex quinquefasciatus, (Diptera: Culicidae)

Background

Mosquito control programme using synthetic insecticides has been facing the challenges of resistance development. However, synergistic combinations of plant essential oils (EOs) having different modes of actions and potent lethal toxicity may further negate the concern of resistance development.

Methods

In this study, the toxicity of 28 EOs and the two synthetic insecticides, Temephos and Malathion were evaluated individually and based on the performance, binary combinations of effective EOs were prepared and tested against the larval and adult stages of Culex quinquefasciatus. Mixtures were prepared by blending LC10 or LD10 concentration/doses of candidates at different volume ratios.

Results

Results demonstrated that among 155 numbers of combinations of different volume ratios, 1:1 ratio of A. sativum (bulbs) L.+C. paradisi (peels) Macfd. (AsB + CpP) was found to be the most potent against adults, whereas, 1:1 volume ratio of Allium sativum (bulbs)+ Citrus paradisi (leaves) (AsB + CpL) was found to possess highest activity against larvae after considering its dose and synergistic interaction. GC-MS analysis revealed the presence of diallyl trisulfide, diallyl disulfide, beta-citronellol, ocimene as major constituents of AsB + CpP combination and diallyl disulfide, linalool, citronellal, caryophyllene oxide etc. in AsB + CpL combination.

Conclusions

Therefore, the said mixtures of the plant essential oils and or mixtures of the constituent compounds can be used as effective control agents for the control of the filarial vector, C. quinquefasciatus.

Insecticidal and biochemical activity of essential oil from Citrus sinensis peel and constituents on Callosobrunchus maculatus and Sitophilus zeamais

Essential oils are promising substitute for chemical pesticides with the inherent resistance by pests, environmental and health effects on humans. In this study, the chemical composition of essential oil extracted from Citrus sinensis peel was characterized, the insecticidal activities of the oil and its constituents against Callosobrunchus maculatus (Cowpea weevil) and Sitophilus zeamais (maize weevil) were investigated and the underlying insecticidal mechanism were elucidated. The essential oil was extracted by hydro-distillation and characterized using gas chromatography-mass spectrometry (GC-MS). Insecticidal activity was determined by contact and fumigant toxicity assay. The inhibitory effect of the oil and its constituents on acetylcholinesterase (AChE), Na⁺/K⁺-ATPase and glutathione-S- transferase (GST) activity were assayed using standard protocols. The total number of volatile compounds detected in C. sinensis essential oil was eighteen (18). d-limonene (59.3%), terpineol (8.31%) and linalool (6.88%) were the major compounds present in the essential oil. Among the tested essential oil compounds, terpineol showed highest contact toxicity against C. maculatus (LD₅₀ =17.05 μg/adult) while 3-carene showed highest contact toxicity against S. zeamais (LD₅₀ =26.01 μg/adult) at 24 h exposure time. Citral exhibited the highest fumigant toxicity against C. maculatus and S. zeamais with LC₅₀ value 0.19 and 2.02 μL/L air at 24 h respectively. Acetylcholinesterase and Na⁺/K⁺-ATPase activities were significantly inhibited by C. sinensis oil and its constituents in both C. maculatus and S. zeamais as compared to control. This study indicates that C. sinensis essential oil and its constituents have potential to be developed into botanical pesticides.

Acaricidal effects of methyl benzoate against Tetranychus urticae Koch (Acari: Tetranychidae) on common crop plants

BACKGROUND

Methyl benzoate (MB) is a small, hydrophobic organic compound isolated from the freshwater fern Salvinia molesta (Salviniales: Salviniaceae). It is used as a fragrance and flavor enhancer owing to its pleasant smell. It has also demonstrated potential as a green pesticide for various groups of insects. However, its effects on mites are yet to be studied.

RESULTS

Here, we assessed the acaricidal and repellent effects of MB against the two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), under laboratory and greenhouse conditions. MB demonstrated concentration-dependent contact toxicity against eggs and adults of the mite. A leaf-dipping assay using 1% MB prevented the hatching of 92.7% of eggs and killed 100% of adults within 48 h of treatment. Concentration-mortality statistics were subjected to probit analysis, and the median lethal concentration (LC₅₀ ) values for eggs and adults were 0.25% and 0.5%, respectively. Treatment with 1% MB showed the highest mortality (100%), with a median lethal time (LT₅₀ ) estimated of 8.1 h. The efficacy of MB against adults of T. urticae on tomato plants under greenhouse conditions was 97.5% within 96 h post-treatment. Further, MB showed significant repellent activity against adult females of T. urticae, although this declined with time. Spraying with 1% MB (three times per plant) was not phytotoxic to bean, cucumber, pepper, or tomato plants.

CONCLUSION

MB is highly acaricidal and repellent, but not phytotoxic, and is a promising green pesticide.

Evaluating cytotoxicity of methyl benzoate in vitro

Methyl benzoate (MB) is a small, hydrophobic organic compound that is isolated from the freshwater fern, Salvinia molesta. Because of its pleasant odor, it has been used as a fragrance and flavor enhancer. In addition, it is used to attract orchid bees for pollination in the farm and has been tested for its potential to be developed as a green pesticide targeting a diverse group of insects. In spite of its wide applications, the safety of MB to humans remains poorly understood. In this study, we tested the cytotoxicity of MB against cultured human cells, including kidney, colon, and neuronal cells. Furthermore, other natural and synthetic benzoic acids such as ethyl benzoate (EB) and vinyl benzoate (VB) were compared with MB for their similarity and broad commercial and industrial applications. We found that MB and VB have the least and most overall toxicity to the tested human cells, respectively. In addition, the expression of some genes involved in cell cycle, protein quality control, and neurotransmission such as cyclin D1, HSP70, and ACHE genes was differentially expressed in the presence of these chemicals, most noticeably in treatment of VB. Our study provided the LC₅₀ values of these benzoic acids for human cells in vitro and suggested their mild toxicity that should be considered in the industrial and agricultural applications to be within safe limits.

Bioactive Compounds and Health Benefits ofArtemisiaSpecies

Artemisia L. is a genus of small herbs and shrubs found in northern temperate regions. It belongs to the important family Asteraceae, one of the most numerous plant groupings, which comprises about 1000 genera and over 20000 species. Artemisia has a broad spectrum of bioactivity, owing to the presence of several active ingredients or secondary metabolites, which work through various modes of action. It has widespread pharmacological activities and has been used as traditional medicine since ancient times as an anthelmintic, antispasmodic, antirheumatic, and antibacterial agent and for the treatment of malaria, hepatitis, cancer, inflammation, and menstrual-related disorders. This review comprises the updated information about the ethnomedical uses and health benefits of various Artemisia spp. and general information about bioactive compounds and free radicals.

Flavonoids from Artemisia rupestris and their synergistic antibacterial effects on drug-resistant Staphylococcus aureus

This study seeks to discover flavonoids from a traditional Chinese herb, Artemisia rupestris L., with synergistic antibacterial effects against multidrug-resistant Staphylococcus aureus. Five flavonoids, artemetin (1), chrysosplenetin (2), pachypodol (3), penduletin (4) and chrysoeriol (5) were obtained by various column chromatographic methods. Their chemical structures were determined on the basis of comprehensive spectroscopic analysis and comparison with literature data. Three of the compounds (2, 4 and 5) exhibited synergistic activity when combined with norfloxacin against SA1199B, an effluxing fluoroquinolone-resistant strain. The fractional inhibitory concentration indices (FICIs) of 2, 4 and 5 in combination with norfloxacin were 0.375, 0.079 and 0.266 respectively, suggesting synergy. Compound 5 also showed synergistic effects against EMRSA-15 and EMRSA-16 when combined with ciprofloxacin and oxacillin exhibiting FICIs of 0.024 and 0.375 respectively. Real time ethidium bromide (EtBr) efflux assay, qRT-PCR and molecular docking were employed to explore the mechanisms of the synergistic effects.

Efficacy of bornyl acetate and camphene from Valeriana officinalis essential oil against two storage insects

The essential oil was extracted from the roots of Valeriana officinalis L. by hydrodistillation. The qualitative and quantitative analysis of its chemical constituents was conducted on GC-MS and GC-FID in this study. Seventeen compounds were detected and the major constituents included bornyl acetate (48.2%) and camphene (13.8%). The toxic and repellent effects of the essential oil and its two major constituents were evaluated on Liposcelis bostrychophila and Tribolium castaneum. The results of bioassays indicated that the essential oil showed the promising fumigant and contact toxicity against L. bostrychophila (LC₅₀ = 2.8 mg/L air and LD₅₀ = 50.9 μg/cm², respectively) and the notable contact effect on T. castaneum (LD₅₀ = 10.0 μg/adult). Meanwhile, the essential oil showed comparable repellent effect on T. castaneum at all testing concentrations. Bornyl acetate and camphene also exhibited strong fumigant and contact toxicity against both species of pests (LC₅₀ = 1.1, 10.1 mg/L air and LD₅₀ = 32.9, 701.3 μg/cm² for L. bostrychophila; > 126.3, 4.1 mg/L air, and 66.0, 21.6 μg/adult for T. castaneum). Bornyl acetate and camphene showed moderate repellent effect on T. castaneum and conversely showed attractant effect on L. bostrychophila. This work highlights the insecticidal potential of V. officinalis, which has been noted as a traditional medicinal plant.

Computational insight to putative anti-acetylcholinesterase activity of Commiphora myrrha (Nees), Engler, Burseraceae: a lessen of archaeopharmacology from Mesopotamian Medicine I

Commiphora spp., Burseraceae family and their resinous matter, myrrh, are used in Mesopotamian medicine as fragrance or antiinsectant. Based on in vitro, leaves, bark, and resin methyl alcohol extract of C. myrrha showed similar inhibitory effects of 17.00, 26.00, and 29.33% for acetylcholinesterase (AChE) as compared to eserine, respectively. The ADMET properties and putative anticholinesterase activity of phytochemicals of myrrh were computationally predicted using in silico tools. Phytochemicals of C. myrrha had acceptable binding affinity (BA) towards principal sites of AChE ranging from - 5.8 (m-cresol) to - 10.5 (abietic acid) kcal/mol. In this regard, all terpenoid compounds (25 out of 28) of myrrh were dual inhibitors since they hydrophobically interacted with both catalytic triad and peripheral anionic site (PAS) of AChE while alpha-terpineol, elemol, and eugenol employed hydrogen bonds with AChE. Cuscohygrine as a pyrrolidine alkaloid has been docked with AChE through hydrogen bonds with PAS and through hydrophobic interactions with catalytic triad thereby we initially proposed it as dual inhibitor of AChE. M-cresol as a methylphenol has been loosely docked with AChE via hydrogen bond and would be a hit molecule for further drug synthesis. This study not only confirmed archaeopharmacological applications of myrrh as antiinsectant or nootropics but also offered an array of terpenoid compounds, cuscohygrine, and m-cresol as a good starting point for hit-to-lead-to-drug optimization phase in synthesis of phyto-nootropics and ecofriendly insecticides.

Methyl benzoate exhibits insecticidal and repellent activities against Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae)

Methyl benzoate (MB) is a plant-derived volatile organic compound with insecticidal properties, but such activity has not been evaluated against the sweetpotato whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), a major crop pest. In this study, we tested methyl benzoate control efficacy on B. tabaci infecting tomato plants in a greenhouse, specifically measuring contact and fumigant toxicity, as well as repellent activity. For direct spray applications of 0% (control), 0.1%, 0.25%, 0.5%, 1%, 2% MB onto tomato leaves infested with adults of B. tabaci (< 5-d-old), 2% MB showed the highest corrected mortality (100%) at 24 h post-treatment. For residual toxicity in which the same MB solutions were sprayed onto tomato leaves and allowed to dry for 2 h before < 5-d-old adults were released, the 2% MB also showed the highest corrected mortality (100%) at 48 h post-treatment. The lethal median concentration (LC50) for eggs, fourth-instar nymphs, and adults were 0.3%, 0.2%, and 0.2%, respectively. In pot culture experiments, 1% MB concentration was found more effective at killing nymphs and preventing adult eclosion than all other concentrations, and gave 100 percent population reduction compared with the control. MB repelled adult whiteflies and caused 96.5% fumigant toxicity within 10 h post-treatment. Repellency and anti-oviposition rates against B. tabaci had median effective doses of 0.24% and 0.16%, respectively. Our results suggest that MB has strong potential as an environmentally friendly biopesticide for control of B. tabaci but field trials and further greenhouse studies are required to establish efficacy under more natural conditions.

Psocoptera (Psocodea) in Spice and Medicinal Dehydrated Plants Sold in Bulk in a Big Metropolis in Brazil

In Brazil, the production of dried herbs and condiments is on a smaller scale than that of its other agricultural sectors; however, it has been growing and attracting new producers, driven by the stimulus to provide healthy and gourmet foods. Insects in the order Psocoptera may cause loss of quality in such dried foods, and because of their small size, these insects can be easily transported by commerce. No information is available on how these insects may be entering Brazil via the importation of dehydrated products or how they may be exported with the increase of Brazilian dried food production. To examine these issues, 10 sites offering foods sold in bulk within the city of São Paulo, Brazil, were chosen. At each food site, the same 20 species of aromatic spice and medicinal dehydrated plants were purchased. In the laboratory, they were analyzed for the presence of insects immediately after acquisition. After removal of nymphal and adult psocopterans, the plants were kept in vials under environmental conditions to be investigated 40 days later. Psocopterans were found in 12 of the 20 dehydrated plant species. Eleven psocopteran species were recorded, including six species of unidentified Liposcelis. Liposcelis bostrychophila (Badonnel) was found in all samples with the presence of insects. The other frequent species were Liposcelis entomophila (Enderlein) and Lepinotus reticulatus (Enderlein). Lepinotus reticulatus constitutes the first record in Brazil. In total, 1,021 insects were recorded in the evaluation right after purchase, and this number grew to 3,734 individuals recovered 40 days later under laboratory conditions. The data show that in a relatively short period of storage, a population increase occurs that may cause loss of product quality and a decrease in organoleptic properties. Thus, it is necessary to have greater surveillance of the products so that consumers have access to quality dehydrated foods.

An online survey of personal mosquito-repellent strategies

Background

Mosquito repellents can be an effective method for personal protection against mosquito bites that are a nuisance and carry the risk of transmission of mosquito-borne pathogens like plasmodia, dengue virus, chikungunya virus, and Zika virus. A multitude of commercially available products are currently on the market, some of them highly effective while others have low or no efficacy. Many home remedies of unknown efficacy are also widely used.

Methods

We conducted a survey study to determine what kind of mosquito repellents and other mosquito control strategies people use. Our online survey was focused on unconventional methods and was answered by 5,209 participants.

Results

The majority of participants resided in the United States, were female (67%), had higher education (81% had a university degree), and were 18 to 37 years old (50%). The most commonly used repellent was DEET spray (48%), followed closely by citronella candles (43%) and ‘natural’ repellent sprays (36%). We collected a plethora of home remedies and other strategies people use that warrant further research into their effectiveness.

Discussion

Our study lays the foundation for future research in alternative, unconventional methods to repel mosquitoes that may be culturally acceptable and accessible for people.

Repellency, toxicity, and anti-oviposition of essential oil of Gardenia jasminoides and its four major chemical components against whiteflies and mites

We examined the repellent, insecticidal, and anti-oviposition activities of the ethanol-extracted essential oil of Gardenia jasminoides against Bemisia tabaci and Tetranychus urticae adult and nymph stages under laboratory and greenhouse conditions. We used GC-MS to identify the main chemicals in the essential oil and selected four compounds, squalene, ethyl linoleate, n-hexadecanoic acid and 9-12-octadecadienoic, to evaluate their activity on whiteflies and mites. In the laboratory experiments, the essential oil of G. jasminoides showed maximum effects in fumigation against whitefly adults (81.48%) and contact toxicity against whitefly nymphs (46.44%), adult mites (49.81%), and mite nymphs (66.46%). In the greenhouse experiments, squalene showed maximum repellency against whitefly adults at 24 (89.59%) and 48 h (84.76%), whitefly nymphal toxicity at 24 (80.08%) and 48 h (77.28%), and mite toxicity at 24 (78.74%) and 48 h (73.86%). The essential oil showed maximum anti-oviposition activity against whiteflies at 24 (63.58%) and 48 h (59.56%) and toxicity to mite nymphs at 24 (82.45%) and 48 h (57.14%) in the bioassay. The essential oil had LC₅₀ values of 2396.457, 2844.958, 56,990.975 and 21,468.619 against whitefly adults, whitefly nymphs, mite adults and mite nymphs, respectively. G. jasminoides and its major chemicals may effectively control the whiteflies and mites.

α-Terpineol, a natural monoterpene: A review of its biological properties

Terpineols are monocyclic monoterpene tertiary alcohols which are naturally present in plant species. There are five common isomers of terpineols, alpha-, beta-, gamma-, delta- and terpinen-4-ol, of which α-terpineol and its isomer terpinen-4-ol are the most common terpineols found in nature. α-Terpineol plays an important role in the industrial field. It has a pleasant odor similar to lilacs and it is a common ingredient in perfumes, cosmetics, and aromatic scents.

In addition, α-terpineol attracts a great interest as it has a wide range of biological applications as an antioxidant, anticancer, anticonvulsant, antiulcer, antihypertensive, anti-nociceptive compound. It is also used to enhance skin penetration, and also has insecticidal properties. This study reviews the relevance of α-terpineol based on scientific findings on Google Scholar, Pubmed, Web of Science, Scopus and Chemical Abstracts.

Collectively, the use of α-terpineol in medicine and in the pharmaceutical industry plays an important role in therapeutic applications. This review will, therefore, support future research in the utilization of α-terpineol.

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.

The Genus Artemisia: a 2012-2017 Literature Review on Chemical Composition, Antimicrobial, Insecticidal and Antioxidant Activities of Essential Oils

Essential oils of aromatic and medicinal plants generally have a diverse range of activities because they possess several active constituents that work through several modes of action. The genus Artemisia includes the largest genus of family Asteraceae has several medicinal uses in human and plant diseases aliments. Extensive investigations on essential oil composition, antimicrobial, insecticidal and antioxidant studies have been conducted for various species of this genus. In this review, we have compiled data of recent literature (2012-2017) on essential oil composition, antimicrobial, insecticidal and antioxidant activities of different species of the genus Artemisia. Regarding the antimicrobial and insecticidal properties we have only described here efficacy of essential oils against plant pathogens and insect pests. The literature revealed that 1, 8-cineole, beta-pinene, thujone, artemisia ketone, camphor, caryophyllene, camphene and germacrene D are the major components in most of the essential oils of this plant species. Oils from different species of genus Artemisia exhibited strong antimicrobial activity against plant pathogens and insecticidal activity against insect pests. However, only few species have been explored for antioxidant activity.

GC×GC-TOFMS Analysis of Essential Oils Composition from Leaves, Twigs and Seeds of Cinnamomum camphora L. Presl and Their Insecticidal and Repellent Activities

Interest in essential oils with pesticidal activity against insects and pests is growing. In this study, essential oils from different parts (leaves, twigs and seeds) of Cinnamomum camphora L. Presl were investigated for their chemical composition, and insecticidal and repellent activities against the cotton aphid. The essential oils, obtained by hydrodistillation, were analyzed by GC×GC-TOFMS. A total of 96 components were identified in the essential oils and the main constituents found in the leaves and twigs were camphor, eucalyptol, linalool and 3,7-dimethyl-1,3,7-octatriene. The major components found in the seeds were eucalyptol (20.90%), methyleugenol (19.98%), linalool (14.66%) and camphor (5.5%). In the contact toxicity assay, the three essential oils of leaves, twigs and seeds exhibited a strong insecticidal activity against cotton aphids with LC50 values of 245.79, 274.99 and 146.78 mg/L (after 48 h of treatment), respectively. In the repellent assay, the highest repellent rate (89.86%) was found in the seed essential oil at the concentration of 20 μL/mL after 24 h of treatment. Linalool was found to be a significant contributor to the insecticidal and repellent activities. The results indicate that the essential oils of C. camphora might have the potential to be developed into a natural insecticide or repellent for controlling cotton aphids.

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.

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.

Bioactivity of essential oil from Artemisia stolonifera (Maxim.) Komar. and its main compounds against two stored-product insects

Artemisia stolonifera, a perennial herb, is widely distrbuted in China. The aim of this study was to analyze the essential oil from the aerial parts of Artemisia stolonifera, as well as to evaluate the bioactivity of the oil and its main constituents. The essential oil was analyzed by gas chromatography-flame ionization detector and gas chromatography-mass spectrometry that allowed characterizing 22 compounds. The main components were eucalyptol (32.93%), β-pinene (8.18%), camphor (6.12%) and terpinen-4-ol (6.11%), and obtained from the essential oil after a further isolation. During the contact toxicity tests, the essential oil (LD50 = 8.60 μg/adult) exhibited stronger toxicity against Tribolium castaneum adults than those isolated constituents, however, camphor and terpinen-4-ol showed 1 and 2 times toxicity against Lasioderma serricorne adults than the essential oil (LD50 = 12.68 μg/adult) with LD50 values of 11.30 and 5.42 μg/adult, respectively. In the fumigant toxicity tests, especially on Tribolium castaneum, the essential oil (LC50 = 1.86 mg/L air) showed almost the same level toxicity as positive control, methyl bromide (LC50 = 1.75 mg/L air). Moreover, the essential oil and its four isolated constituents also exhibited strong repellency against two stored-product insects.

Evaluation of Contact Toxicity and Repellency of the Essential Oil of Pogostemon cablin Leaves and Its Constituents Against Blattella germanica (Blattodae: Blattelidae)

The aim of this research was to evaluate contact toxicity and repellency of the essential oil of Pogostemon cablin (Blanco) Bentham leaves against German cockroaches (Blattella germanica) (L.) and to isolate any active constituents. Essential oil of P. cablin leaves was obtained by hydrodistillation and analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Twenty-three components were identified in the essential oil, and the main constituents were patchoulol (41.31%), pogostone (18.06%), α-bulnesene (6.56%), caryophyllene (5.96%), and seychellene (4.32%). Bioactivity-directed chromatographic separation of the essential oil led to the isolation of pogostone, patchoulol, and caryophyllene as active compounds. The essential oil of P. cablin leaves exhibited acute toxicity against male B. germanica adults with an LC50 value of 23.45 μg per adult. The constituent compound, pogostone (LC50 = 8.51 μg per adult) showed stronger acute toxicity than patchoulol (LC50 = 207.62 μg per adult) and caryophyllene (LC50 = 339.90 μg per adult) against the male German cockroaches. The essential oil of P. cablin leaves and the three isolated constituents exhibited strong repellent activity against German cockroaches at a concentration of 5 ppm. The results indicated that the essential oil of P. cablin leaves and its major constituents have good potential as a source for natural insecticides and repellents.

Identification of Insecticidal Constituents from the Essential Oil ofValeriana jatamansiJones againstLiposcelis bostrychophilaBadonnel

The aim of this research was to determine chemical composition and insecticidal activities of the essential oil ofValeriana jatamansiJones roots against booklice,Liposcelis bostrychophilaBadonnel, and to isolate insecticidal constituents from the oil. Essential oil ofV. jatamansiwas obtained by hydrodistillation and analyzed by GC-MS. A total of 27 components in the essential oil were identified. The major compounds were patchoulol (24.3%),α-bulnesene (13.8%), isovaleric acid (12.9%),α-guaiene (8.7%), and 3-methylvaleric acid (8.4%). Based on bioactivity-guided fractionation, isovaleric acid, 3-methylvaleric acid, and patchoulol were isolated and identified as the active constituents. The essential oil exhibited contact toxicity againstL. bostrychophilawith an LC50value of 236.4 μg/cm2. Patchoulol (LC50= 61.35 μg/cm2) exhibited stronger acute toxicity than 3-methylvaleric acid (LC50= 210.69 μg/cm2) against the booklice. The essential oil also possessed fumigant toxicity againstL. bostrychophilawith an LC50value of 6.0 mg/L, while 3-methylvaleric acid and isovaleric acid had LC50values of 5.53 mg/L and 5.67 mg/L against the booklice, respectively. The results indicated that the essential oil and its constituent compounds have potential to develop into natural insecticides or fumigants for control of insects in stored grains.