Volatile Organic Compounds Mediate Host Selection of Wheat Midge, Sitodiplosis Mosellana (Géhin) (Diptera: Cecidomyiidae) between Preanthesis and Postanthesis Stages of Wheat.

The orange wheat blossom midge, Sitodiplosis mosellana (Géhin) (Diptera: Cecidomyiidae), is a significant wheat pest in the Prairie Provinces of Canada and northern regions of the USA. Wheat phenology plays a critical role in wheat midge oviposition. We hypothesized that S. mosellana oviposition behaviour is influenced by volatile organic compounds (VOCs) emitted by wheat at two adjacent wheat growth stages: preanthesis and postanthesis. A higher number of S. mosellana eggs laid on preanthesis than postanthesis spikes in an oviposition choice experiment using the susceptible spring wheat cultivar 'Roblin'. In preanthesis, wheat emitted higher amounts of Z-3-hexenyl acetate (Z3-06:OAc) than at the postanthesis stage. Higher amounts of methyl ketones such as 2-tridecanone, 2-pentadecanone, and 2-undecanone were emitted by wheat in the postanthesis stage and these VOCs were sensitive to S. mosellana antennae used in the Gas Chromatography-Electroantennographic Detection. Females were attracted to synthetic Z3-06:OAc but were deterred by 2-tridecanone relative to the solvent control in the vertical Y-tube olfactometer. 2-Undecanone and 2-pentadecanone did not show any attractiveness or deterrence. In a no-choice oviposition experiment, fewer eggs were laid in preanthesis wheat exposed to a synthetic VOC blend of Z3-06:OAc, 2-undecanone, 2-tridecanone, and 2-pentadecanone at the concentrations released by postanthesis spikes. This study shows that the reduction of Z3-06:OAc, in the VOC mix, and possibly the increase in 2-tridecanone, are likely responsible for the reduction in oviposition on postanthesis wheat. These results elucidate for the first time the role of specific VOCs mediating S. mosellana oviposition in preanthesis and postanthesis wheat.

In vitro acaricidal activity of essential oils and their binary mixtures against ixodes scapularis (Acari: Ixodidae).

Ixodes scapularis ticks are vectors of infectious agents that cause illness in humans, including Lyme disease. Recent years have seen a surge in tick-borne diseases (TBD) resulting in a high demand for tick management products. Plants offer a valuable source of active compounds for the development of novel, eco-friendly tick control products, reducing potential risks to human and animal health. Essential oils (EOs) have emerged as potential acaricides and repellents against ticks providing an alternative to synthetic chemicals and aiding in the prevention of TBD by lowering the risk of tick bites. We investigated the acaricidal activity of EOs from lemongrass (Cymbopogon citratus), geranium (Pelargonium x asperum), savory thyme (Thymus saturejoides), and white thyme (Thymus zygis) on I. scapularis. The interactions (i.e., synergistic, antagonistic, or additive) of their binary mixtures were also evaluated. EO samples were analyzed via gas chromatography-mass spectrometry to determine their chemical composition. The adult immersion test was used to determine the lethal concentration (LC50) of each EO alone and in mixtures. Quantitative assessment of synergistic, additive, or antagonistic effect of the binary mixtures was performed by calculating the combination index. Strong acaricidal activity was recorded for savory thyme and white thyme EOs, with LC50 values of 28.0 and 11.0 µg/µL, respectively. The LC50 of lemongrass and geranium EOs were 49.0 and 39.7 µg/µL, respectively. Among the tested EOs, savory thyme and white thyme had a strong acaricidal effect on I. scapularis, which might be linked to the presence of carvacrol (26.05 % ± 0.38) and thymol (53.6 % ± 2.31), main components present in savory thyme and white thyme EOs, respectively. The tick killing efficacy of lemongrass and geranium EOs was lower when mixed than when used separately (LC50 of 65.3 µg/µL). The same happened with savory thyme and white thyme EOs, except at 9.75 µg/µL where they had a synergistic effect (LC50 of 58.3 µg/µL). Lemongrass and savory thyme EOs had a synergistic effect at low concentrations, and an antagonistic effect at higher concentrations (LC50 of 95.4 µg/µL). Lemongrass and white thyme EOs had a synergistic effect against ticks from 15 to 120 µg/µL (LC50 of 18.5 µg/µL) similar to white thyme EO. Geranium and savory thyme EOs had an antagonistic effect at all concentrations, with an LC50 of 66.8 µg/µL. Geranium and white thyme EOs also had an antagonistic effect, except at 12.7 µg/µL where they had a synergistic effect (LC50 of 66.8 µg/µL). The interaction observed when combining selected essential oils suggests promising potential for developing acaricidal formulations aimed at controlling ticks and curbing the transmission of tick-borne disease agents.

Structure of an antennally-expressed carboxylesterase suggests lepidopteran odorant degrading enzymes are broadly tuned.

Insects rely on the detection of chemical cues present in the environment to guide their foraging and reproductive behaviour. As such, insects have evolved a sophisticated chemical processing system in their antennae comprised of several types of olfactory proteins. Of these proteins, odorant degrading enzymes are responsible for metabolising the chemical cues within the antennae, thereby maintaining olfactory system function. Members of the carboxyl/cholinesterase gene family are known to degrade odorant molecules with acetate-ester moieties that function as host recognition cues or sex pheromones, however, their specificity for these compounds remains unclear. Here, we evaluate expression levels of this gene family in the light-brown apple moth, Epiphyas postvittana, via RNAseq and identify putative odorant degrading enzymes. We then solve the apo-structure for EposCCE24 by X-ray crystallography to a resolution of 2.43 Å and infer substrate specificity based on structural characteristics of the enzyme's binding pocket. The specificity of EposCCE24 was validated by testing its ability to degrade biologically relevant and non-relevant sex pheromone components and plant volatiles using GC-MS. We found that EposCCE24 is neither capable of discriminating between linear acetate-ester odorant molecules of varying chain length, nor between molecules with varying double bond positions. EposCCE24 efficiently degraded both plant volatiles and sex pheromone components containing acetate-ester functional groups, confirming its role as a broadly-tuned odorant degrading enzyme in the moth olfactory organ.

Common yarrow (Achillea millefolium) essential oil and main components as potential repellents and acaricides against Ixodes scapularis and Dermacentor variabilis (Acari: Ixodidae) ticks.

Repellent and acaricidal activities of essential oils (EO) extracted from common yarrow (Achillea millefolium L.) and main chemical components were evaluated against Ixodes scapularis and Dermacentor variabilis adult ticks and nymphs. Flowers and leaves were collected from two locations, Harvest Moon trail (HMT) and Port Williams (PW) in Nova Scotia (Canada), and EO were extracted via hydro-distillation. Samples were analyzed using GC-MS, and differences in chemical composition and quantity of compounds detected were reported in relation to the collection site and plant parts. EO were both rich in germacrene D (HMT EO 21.5 ± 1.31% wt; PW EO 25.5 ± 0.76% wt); however, HMT flower EO has a higher concentration of camphor (9.9 ± 0.08% wt) compared to PW flower EO (3.0 ± 0.01% wt). Significant acaricidal activity was reported against I. scapularis adult ticks, particularly for HMT flower EO with a LD50 of 2.4% v/v (95% confidence interval = 1.74-3.35) at 24 h post-exposure. Germacrene D had the lowest LD50 of 2.0% v/v (95% CI 1.45-2.58) among the four compounds after 7 days. No significant acaricidal effect was observed on D. variabilis adult ticks. Yarrow PW flower EO exerted repellent activity towards I. scapularis nymphs (100% repellency up to 30 min); however, repellency significantly declined over time. Yarrow EO exert promising acaricidal and repellent properties, that may be used to manage Ixodes ticks and the diseases they vector.

Indole Alkaloids from Psychoactive Mushrooms: Chemical and Pharmacological Potential as Psychotherapeutic Agents.

Neuropsychiatric diseases such as depression, anxiety, and post-traumatic stress represent a substantial long-term challenge for the global health systems because of their rising prevalence, uncertain neuropathology, and lack of effective pharmacological treatments. The approved existing studies constitute a piece of strong evidence whereby psychiatric drugs have shown to have unpleasant side effects and reduction of sustained tolerability, impacting patients' quality of life. Thus, the implementation of innovative strategies and alternative sources of bioactive molecules for the search for neuropsychiatric agents are required to guarantee the success of more effective drug candidates. Psychotherapeutic use of indole alkaloids derived from magic mushrooms has shown great interest and potential as an alternative to the synthetic drugs currently used on the market. The focus on indole alkaloids is linked to their rich history, their use as pharmaceuticals, and their broad range of biological properties, collectively underscoring the indole heterocycle as significant in drug discovery. In this review, we aim to report the physicochemical and pharmacological characteristics of indole alkaloids, particularly those derived from magic mushrooms, highlighting the promising application of such active ingredients as safe and effective therapeutic agents for the treatment of neuropsychiatric disorders.

Balsam fir (Abies balsamea) needles and their essential oil kill overwintering ticks (Ixodes scapularis) at cold temperatures.

The blacklegged tick, Ixodes scapularis, vectors Borrelia burgdorferi, a bacterium that causes Lyme Disease. Although synthetic pesticides can reduce tick numbers, there are concerns about their potential effects on beneficial insects, such as pollinators. Plant-based pest control agents such as essential oils could provide an alternative because they have low environmental persistency; however, these products struggle to provide effective control. We found a new natural acaricide, balsam fir (Abies balsamea) needles, that kill overwintering I. scapularis ticks. We extracted the essential oil from the needles, analyzed its chemical composition, and tested it for acaricidal activity. We placed ticks in tubes with substrate and positioned the tubes either in the field or in incubators simulating winter temperatures. We added balsam fir essential oil, or one of the main components of balsam fir essential oil (i.e., ß-pinene), to each tube. We found that both the oil and ß-pinene kill overwintering ticks. Whole balsam fir needles require several weeks to kill overwintering ticks, while the essential oil is lethal within days at low temperatures (≤ 4 °C). Further, low temperatures increased the efficacy of this volatile essential oil. Higher temperatures (i.e., 20 °C) reduce the acaricidal effectiveness of the essential oil by 50% at 0.1% v/v. Low temperatures may promote the effectiveness of other natural control products. Winter is an overlooked season for tick control and should be explored as a possible time for the application of low toxicity products for successful tick management.

Repellent and acaricidal activities of basil (Ocimum basilicum) essential oils and rock dust against Ixodes scapularis and Dermacentor variabilis ticks.

Repellent and acaricidal activity of essential oils extracted from three varieties of basil (Ocimum basilicum L.) were evaluated on blacklegged ticks (Ixodes scapularis Say) and American dog ticks (Dermacentor variabilis Say) in laboratory conditions. Essential oils were extracted and characterized through gas chromatography-mass spectrometry, and tested at different concentrations for long-term repellent activity using horizontal bioassays. In addition, basil essential oils were combined with an inert material (i.e., granite rock dust) with known insecticidal and miticidal properties to assess acaricidal activities against adult ticks. Among the tested basil varieties, var. Jolina essential oil at 15% vol/vol concentration repelled 96% of tested ticks up to 2 h post-treatment. The EC50 for I. scapularis nymphs was 4.65% vol/vol (95% confidence interval: 4.73-4.57). In acaricidal tests, the combination of essential oil from var. Aroma 2 at 10% wt/wt with rock dust resulted in 100% tick mortality after only 24 h post-exposure, with a LD50 of 3.48% wt/wt (95% CI 4.05-2.91) for freshly prepared treatment tested on I. scapularis adults. The most common compounds detected in basil essential oils by GC-MS were linalool (52.2% in var. Nu Far, 48.2% in Aroma 2, 43.9% in Jolina), sabinene (6.71% in Nu Far, 8.99% in Aroma 2, 8.11% in Jolina), eugenol (11.2% in Jolina, 8.71% in Aroma 2), and estragole (18.2% in Nu Far). The use of essential oils alone and in combination with rock dust provides an innovative and environmentally friendly approach for managing ticks and inhibiting vector-borne disease transmission.

Novel ß-Cyclodextrin and Catnip Essential Oil Inclusion Complex and Its Tick Repellent Properties.

Cyclodextrin inclusion complexes have been successfully used to encapsulate essential oils, improving their physicochemical properties and pharmacological effects. Besides being well-known for its effects on cats and other felines, catnip (Nepeta cataria) essential oil demonstrates repellency against blood-feeding pests such as mosquitoes. This study evaluates the tick repellency of catnip oil alone and encapsulated in ß-cyclodextrin, prepared using the co-precipitation method at a 1:1 molar ratio. The physicochemical properties of this inclusion complex were characterized using GC-FID for encapsulation efficiency and yield and SPME/GC-MS for volatile emission. Qualitative assessment of complex formation was done by UV-Vis, FT-IR, 1H NMR, and SEM analyses. Catnip oil at 5% (v/v) demonstrated significant tick repellency over time, being comparable to DEET as used in commercial products. The prepared [catnip: ß-CD] inclusion complex exerted significant tick repellency at lower concentration of the essential oil (equivalent of 1% v/v). The inclusion complex showed that the release of the active ingredient was consistent after 6 h, which could improve the effective repellent duration. These results demonstrated the effective tick repellent activity of catnip essential oil and the successful synthesis of the inclusion complex, suggesting that ß-CDs are promising carriers to improve catnip oil properties and to expand its use in repellent formulations for tick management.

Synthesis and Characterization of ß-Cyclodextrin-Essential Oil Inclusion Complexes for Tick Repellent Development.

Essential oils (EOs) are used in several pest management applications. Due to their volatility, EOs may experience bioactivity reduction, thus requiring protection to extend their properties. In the present study, we investigated the inclusion complex formation (IC) of ß-cyclodextrin (ß-CD) with selected EOs with known tick repellent activity using two co-precipitation methods. ICs were characterized by evaluating EO mass concentration and inclusion efficiency (% IE) and other instrumental methods. Co-precipitation method 2 yielded the highest EO mass concentration (88 ± 6 µg/mg ß-CD) for the 1:1 molar ratio geranium Egyptian EO IC. The EO volatile release over time from the ICs was investigated by headspace SPME/GC-MS analysis. ICs were also tested in tick repellency bioassays. ICs reported significant tick repellent activity, with lemongrass IC performing best overall. Method 1 showed the best combination of high mass concentration EO, controlled volatile release, and tick repellency with lemongrass EO. The results demonstrated that ß-CD had selectively encapsulated different EOs. Moreover, the formation of ICs may improve EO tick repellent properties protecting the active ingredients and providing a better, long-lasting repellent action. These findings will allow the development of more effective naturally derived repellent products to protect individuals from tick bites and prevent tick-borne illnesses.

Preliminary Evaluation of a Granite Rock Dust Product for Pest Herbivore Management in Field Conditions.

The effects of granite rock dust in dry and aqueous formulations were evaluated under field conditions for control of insect pests in different crop systems and ornamental plants. We tested efficacy of crop protection following foliar applications on lily, squash, and cabbage plants by evaluating subsequent pest damage, overall plant health, and quantity of crops produced over one season. Lily plants treated with dry and aqueous formulations of rock dust were subject to lower herbivore damage (>1% and 11% herbivory damage, respectively) when compared to the controls (30% herbivory damage). Treatment on cabbage was less effective to protect plants against herbivory damage, and no statistically significant differences were reported within treatments. The foliar applications (dry and aqueous formulations) had positive impacts on growth of squash fruit resulting in a 2.5-fold increase in size relative to the control squash fruit. These results support the potential field application of granite dust to protect ornamental plants against herbivory attack, and reveal an alternative positive effect of the silica-based product on plant growth and development.

Production of Plant-Associated Volatiles by Select Model and Industrially Important Streptomyces spp.

The Streptomyces produce a great diversity of specialized metabolites, including highly volatile compounds with potential biological activities. Volatile organic compounds (VOCs) produced by nine Streptomyces spp., some of which are of industrial importance, were collected and identified using gas chromatography-mass spectrometry (GC-MS). Biosynthetic gene clusters (BGCs) present in the genomes of the respective Streptomyces spp. were also predicted to match them with the VOCs detected. Overall, 33 specific VOCs were identified, of which the production of 16 has not been previously reported in the Streptomyces. Among chemical classes, the most abundant VOCs were terpenes, which is consistent with predicted biosynthetic capabilities. In addition, 27 of the identified VOCs were plant-associated, demonstrating that some Streptomyces spp. can also produce such molecules. It is possible that some of the VOCs detected in the current study have roles in the interaction of Streptomyces with plants and other higher organisms, which might provide opportunities for their application in agriculture or industry.

Chemosensory and Behavioural Responses of Ixodes scapularis to Natural Products: Role of Chemosensory Organs in Volatile Detection.

Blacklegged ticks, Ixodes scapularis, represent a significant public health concern due to their vectoring of tick-borne disease. Despite their medical importance, there is still limited knowledge of the chemosensory system of this species, and thus a poor understanding of host-seeking behaviour and chemical ecology. We investigated the electrophysiological sensitivity of adult female blacklegged ticks to attractants and plant-derived compounds via an electrode inserted into the scutum. The response of female ticks to binary mixtures with a constant concentration of a selected attractant (butyric acid) and increasing concentration of volatile organic compounds (VOCs) (geraniol, phenethyl alcohol, ß-citronellol, and citral) was recorded. A strict relationship between increasing volatile concentration and a decreasing response was observed for each VOC. Y-tube bioassays confirmed that tick attraction towards butyric acid decreased with the presence of a VOC, which exerted a deterrent effect. To determine the specific role of sensory appendages involved in the detection of attractant chemical stimuli, we tested tick electrophysiological response after removing appendages that house chemosensory sensilla (foretarsi, pedipalps, or both). The chemosensory response was related to the molecular structure of attractant odorant, and the lack of pedipalps significantly reduced olfactory responses, suggesting they play an important role in detecting attractants. This study provides new insight into the neurophysiological mechanisms underlying tick olfaction and the potential for interactions between attractant and deterrent chemical detection.

Soil and foliar application of rock dust as natural control agent for two-spotted spider mites on tomato plants.

Mineral-based products represent a valid alternative to synthetic pesticides in integrated pest management. We investigated the effects of a novel granite dust product as an agent for controlling two-spotted spider mites, Tetranychus urticae Koch (Acari: Tetranychidae), on tomato plants (Solanum lycopersicum L.). Two-choice tests for repellency and repulsiveness, and no-choice bioassays with different type of applications (soil, foliar, and soil-foliar) were used in order to evaluate performance and action of the product. Evaluation of epidermal micromorphology and mesophyll structure of treated plants and elemental analyses of leaves were performed. In repulsiveness experiments, almost all dust treatments significantly inhibited mites from migrating to and/or settling on the treated leaf. In repellency experiments, foliar and soil dust treatments were not significantly different from control. Significant mortality was observed for all dust treatments in two-choice and in no-choice bioassays, suggesting mites are susceptible to rock dust by contact, and by indirect interaction through the feeding on plants subjected to soil application of rock dust. Leaf epidermal micromorphology and mesophyll structure of treated plants showed structural variation due to mineral accumulation, which was also confirmed by elemental analyses of leaves. These results demonstrate for the first time that granite rock dust interacts with two-spotted spider mites by modifying pest behavior and via acaricidal action, providing more insights in understanding the mechanism of this novel natural product as pest management tool.

Behavioral responses of Ixodes scapularis tick to natural products: development of novel repellents.

The spread of blacklegged ticks (Ixodes scapularis) and growing threat of Lyme disease transmission has increased demand for effective, safe and environmentally friendly repellent products. Plant-derived essential oils are natural products that exhibit insecticidal and repellant activities and represent a promising alternative to synthetic repellants. However, mechanisms by which ticks detect odor stimuli and how such stimuli may function as repellents are not well understood. We examined the repellent activity of selected essential oil components towards I. scapularis in short- and long-term dose-response trials. To determine the specific olfactory organs involved in detection of chemical stimuli, we tested tick behavioral response in repellency bioassays after removing appendages that house chemosensory sensilla (e.g., foretarsi or pedipalps). New prototype formulae were tested in longevity trials repelling up to 95% of tested ticks after 1 h post-application. This study provides new insight regarding tick olfaction and behavior, and innovative methods for selecting appropriate chemicals for development of novel plant-based repellent products for protection from ticks.

Plant Essential Oils Synergize and Antagonize Toxicity of Different Conventional Insecticides against Myzus persicae (Hemiptera: Aphididae).

Plant-derived products can play an important role in pest management programs. Essential oils from Lavandula angustifolia (lavender) and Thymus vulgaris (thyme) and their main constituents, linalool and thymol, respectively, were evaluated for insecticidal activity and synergistic action in combination with insecticides against green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae). The essential oils and their main constituents exerted similar insecticidal activity when aphids were exposed by direct sprays, but were non-toxic by exposure to treated leaf discs. In synergism experiments, the toxicity of imidacloprid was synergized 16- to 20-fold by L. angustifolia and T. vulgaris essential oils, but far less synergism occurred with linalool and thymol, indicating that secondary constituents of the oils were probably responsible for the observed synergism. In contrast to results with imidacloprid, the insecticidal activity of spirotetramat was antagonized by L. angustifolia and T. vulgaris essential oils, and linalool and thymol. Our results demonstrate the potential of plant essential oils as synergists of insecticides, but show that antagonistic action against certain insecticides may occur.

Monoterpene derivatives from the flowers of Ferulago campestris, (Apiaceae).

Ferulago campestris (Besser) Grec., (Ferula galbanifera (Mill) Kock. = F. campestris), finocchiazzo, is an annual or perennial herb of the Mediterranean area. In this paper the phytochemical studies of the CH2Cl2 and MeOH extracts of the flowers are described. Several ferulol derivatives and a new 10-hydroxy-verbenone ester (7) were isolated. The structure of the new compound was established by extensive NMR analysis, including HMBC and HSQC pulse sequences.

Antimicrobial and antioxidant activities of coumarins from the roots of Ferulago campestris (Apiaceae).

We report the isolation of several coumarins and the stereochemical assessment of some pyranocoumarins, as well as the antibacterial and antioxidant activities of the three most abundant ones (grandivittin, agasyllin and aegelinol benzoate) isolated from the roots of Ferulago campestris collected in Sicily and of the hydrolysis product (aegelinol). Aegelinol and agasyllin showed antibacterial activity against nine ATCC and the same clinically isolated Gram-positive and Gram-negative bacterial strains. At a concentration between 16 and 125 mg/mL both coumarins showed a significant antibacterial effect against both Gram-negative and Gram-positive bacteria. In particular the ATCC strains Staphylococcus aureus, Salmonella thypii, Enterobacter cloacae and Enterobacter earogenes (MIC = 16 and 32 mg/mL for aegelinol and agasyllin, respectively) were the most inhibited. Antibacterial activity was also found against Helicobacter pylori: a dose-dependent inhibition was shown between 5 and 25 mg/mL. The antioxidant activity of the coumarins was evaluated by their effects on human whole blood leukocytes (WB) and on isolated polymorphonucleate (PMN) chemiluminescence (CL), PMA-stimulated and resting.

The cytotoxic properties of natural coumarins isolated from roots of Ferulago campestris (Apiaceae) and of synthetic ester derivatives of aegelinol.

Grandivittin (1), agasyllin (2), aegelinol benzoate (3) and felamidin (20), four natural coumarins isolated from Ferulago campestris, and several synthetic ester derivatives of aegelinol (4) were tested against four tumor cell lines. Some of them were shown to be marginally cytotoxic against the A549 lung cancer cell line.