Essential oils and their components control behaviour of yellow mealworm (Tenebrio molitor) larvae

Simple Summary This study investigated the use of essential oils (EOs) from different plants to control the behaviour of Tenebrio molitor L., a pest of grain and flour. Among the EOs tested, spearmint was the most effective repellent for mealworm larvae, followed by clove. East-Indian lemongrass, thymus, lavandin, and eucalyptus EOs showed lower repellent properties. Terpinene-4-ol and carvone, were the most effective repellents, while limonene, myrcene, and & gamma;-terpinene had no significant activity. Beetle Tenebrio molitor L. (Coleoptera, Tenebrionidae) is a well-known pest of grain and flour in food stores and grocery shops. Recently, commercial cultivation of the insect was started for human food and animal feed. Behaviour control of this insect using natural repellents is promising both for grain protection and commercial cultivation. We analysed if natural products of plant origin, namely essential oils (EOs), could be used for this purpose. Behavioural tests were performed using EOs of six plants: thymus (Thymus vulgaris), eucalyptus (Eucalyptus globulus), spearmint (Mentha spicata), lavandin (Lavandula x hybrida), East-Indian lemongrass (Cymbopogon flexuosus), and clove (Eugenia caryophyllus). The most effective repellent for mealworm larvae was EO of spearmint, moderate activity showed that of clove and the least repellent were EOs of lemongrass thymus and lavandin. EO of eucalyptus caused almost no or very low effect. Six of the most abundant compounds of the EOs were selected for testing. The most effective single compounds were terpinene-4-ol and carvone, low-effective cis-sabinene hydrates and those of no significant activity were limonene, myrcene and & gamma;-terpinene

Variations in Yield, Essential Oil, and Salicylates of <i>Filipendula ulmaria</i> Inflorescences at Different Blooming Stages

Meadowsweet (Filipendula ulmaria) is an essential oil-bearing, pharmacologically valuable medicinal plant growing wild in floodlands that are either not usually used for agriculture or have low economic value. The aim of this work was to understand the relationship between the yield of F. ulmaria inflorescences and the qualitative and quantitative composition of the essential oil during flowering stages in different habitats. Five different habitats of F. ulmaria were investigated for evaluation of inflorescence characteristics (length and weight) and the quantitative and qualitative composition of essential oils in early and late blooming stages (growing stage BBCH 62–63 and BBCH 65–67/72–73, respectively). The results showed significant (p p F. ulmaria in 1 ha in the late blooming stage was 18–56% higher than in the early blooming stage; however, the yield of essential oil in the early flowering stage was 1.5–1.6 times higher than in the late flowering stage. The obtained research data suggest that the low economic value of floodlands—the habitats of F. ulmaria—can be increased by using these areas as natural industrial plots

Toxic, radical scavenging, and antifungal activity of rhododendron tomentosum H. essential oils

The chemical composition of eight (seven shoot and one inflorescence) essential oils (EOs) of Rh. tomentosum H. plants growing in Eastern Lithuania is reported. The plant material was collected during different phases of vegetation (from April to October). The oils were obtained by hydrodistillation from air-dried aerial parts (leaves and inflorescences). In total, up to 70 compounds were identified by GC−MS and GC (flame-ionization detector, FID); they comprised 91.0 ± 4.7%–96.2 ± 3.1% of the oil content. Sesquiterpene hydrocarbons (54.1 ± 1.5%–76.1 ± 4.5%) were found to be the main fraction. The major compounds were palustrol (24.6 ± 2.6%–33.5 ± 4.4%) and ledol (18.0 ± 2.9%–29.0 ± 5.0%). Ascaridol isomers (7.0 ± 2.4%–14.0 ± 2.4% in three oils), myrcene (7.2 ± 0.3% and 10.1 ± 1.3%), lepalol (3.3 ± 0.3% and 7.9 ± 3.0%), and cyclocolorenone isomers (4.1 ± 2.5%) were determined as the third main constituents. The toxic activity of marsh rosemary inflorescence and shoot oils samples was evaluated using a brine shrimp (Artemia sp.) bioassay. LC50 average values (11.23–20.50 µg/mL) obtained after 24 h of exposure revealed that the oils were notably toxic. The oil obtained from shoots gathered in September during the seed-ripening stage and containing appreciable amounts of palustrol (26.0 ± 2.5%), ledol (21.5 ± 4.0%), and ascaridol (7.0 ± 2.4%) showed the highest toxic activity. Radical scavenging activity of Rh. tomentosum EOs depended on the plant vegetation stage. The highest activities were obtained for EOs isolated from young shoots collected in June (48.19 ± 0.1 and 19.89 ± 0.3 mmol/L TROLOX (6-hydroxy-2,5,7,8-tetra-methylchromane-2-carboxylic acid) equivalent obtained by, respectively, ABTS•+ (2,20-amino-bis(ethylbenzothiazoline-6-sulfonic acid) diammonium salt) and DPPH•(2,2-diphenyl-1-picrylhydrazyl) assays). Agar disc diffusion assay against pathogenic yeast Candida parapsilosis revealed the potential antifungal activity of EOs. An alternative investigation of antifungal activity employed mediated amperometry at yeast Saccharomyces cerevisiae-modified electrodes. The subjection of yeast cells to vapors of EO resulted in a three to four-fold increase of electrode responses due to the disruption of yeast cell membranes

Chemical composition of essential oils and local knowledge of Myrica gale in Lithuania

Myrica gale L. (Myricaceae) is an essential oil-bearing plant that is rare in Lithuania and naturally grows only in the western part of the country. The aim of this study was to analyze the composition of essential oils of Myrica gale in different habitats in Lithuania and in different parts of the plant, as well as evaluate the local knowledge about M. gale as a medicinal and aromatic plant. Samples of fruits and leaves (from one and three M. gale populations, respectively) were studied separately. Essential oils were isolated from dried fruits and leaves by hydrodistillation and analyzed by GC/FID and GC/MS methods. Results showed that M. gale fruits accumulated 4.03 ± 2.13% essential oils, meanwhile leaves—up to 19 times less. A total of 85 compounds were identified in the essential oils of the M. gale. Monoterpene hydrocarbons accounted for about half of the total essential oil content; meanwhile, either monoterpene hydrocarbons or sesquiterpene hydrocarbons (depending on habitat) dominated in leaves. The main compounds (depending on habitat) in essential oils of fruits and leaves were α-pinene, 1,8-cineole, limonene, δ-cadinene, and (E)-nerolidol. The high variation in the composition of M. gale essential oils suggests the presence of different chemotypes within the studied habitats of this plant. Evaluation of local knowledge of M. gale through the survey of 74 residents of 15 villages in western Lithuania showed that only 7% of respondents knew this plant. Poor knowledge of M. gale could be related to the narrow range of the natural species’ distribution in Lithuania

Composition of essential oil of „Hypericum maculatum“ growing in some places of Lithuania

Genus Hypericum L. belongs to family Hypericaceae. Nowadays this family is classified as a subfamily Hypericoideae of family Clusiaceae (Guttiferae), and comprises more than 450 species. The genus Hypericum is common all over the world. In Lithuania 6 species are growing wild [1], among them 3 are included into Lithuanian Red Book data [2]. The majority of worldwide studies on this genus refer to the species Hypericum perforatum, as a consequence of its application in the traditional medicine and modern phytotherapy [3]. Essential oils of Hypericum are used for their antiviral, antifungal and antibacterial effects [4,5]. These oils are applicable externally (in form of the oil) for haemorrhoids, burns, wounds, cuts, muscular pain, sciatica, neuralgia, for newborn infant’s gastric spasms [6]. Internally (in form of the tea) Hypericum is used in case of for moderate depression, insomnia and gastrointestinal ailments (stomach ulcer, liver and bile ailments, jaundice). In folk medicine Hypericum is used as the herb with astringent, calmative properties. Nowadays special interest is taking in Hypericum antidepressant effects [7]. Essential oils are synthesized either in translucent glands or secretory ducts localized in leaves and various parts of the flowers (petals, sepals and pistil) [8] that is why organ specificity is documented in most studies of Hypericum. According to the quantity and quality, the components of essential oils may be linked with the phenological stage of the plant [9]. In addition, there is evidence about differences in essential oils of Hypericum collected in various geographical regions [10]. In Lithuania 2 species of Hypericum are widely distributed – H. perforatum and H. maculatum, although biology and biochemistry of H. maculatum has got less attention when compared to H. perforatum. [...]Biologijos katedraChemijos institutasVytauto Didžiojo universiteta

Allelopathic Activity of Canadian Goldenrod (<i>Solidago canadensis</i> L.) Extracts on Seed Germination and Growth of Lettuce (<i>Lactuca sativa</i> L.) and Garden Pepper Cress (<i>Lepidium sativum</i> L.)

Native to N. America, Canadian goldenrod (Solidago canadensis L.) was introduced to Europe as an ornamental plant and quickly spread here and in other parts of the world. The rapid spread of the plant is due to several reasons: phenotypic plasticity, broad climatic tolerance, propagation via underground rhizomes and seeds that mature in large numbers, etc. Additionally, the success of Canadian goldenrod’s invasion is determined by its allelochemicals that affect seed germination, root formation and whole growth of nearby plants. Allelopathy of various extracts and essential oils (EOs) of S. canadensis on seed germination and growth of lettuce (Lactuca sativa L.) and garden pepper cress (Lepidium sativum L.) was evaluated and compared with other Solidago species (S. virgaurea, S. × niederederi) collected from the same growing locality in Lithuania. Soil characteristics (conductivity, pH and major elements) of the collecting site were determined. Aqueous flower extracts of all studied Solidago species showed the highest inhibitory effect on model plants. Canadian goldenrod leaf water/diethyl ether extract showed highest inhibitory effect in all relative concentrations (1.0; 0.1; 0.01) suppressing growth of L. sativa (from 0 to 2.3 mm compared with 22.7 mm for control samples) and L. sativum (from 0.5 to 16.8 mm compared with 35.3 mm in control). It was noticed that garden pepper cress was more susceptible to Solidago spp. inhibitory effects than lettuce. S. canadensis root EOs comprised mainly of limonene (35.0%) and β-pinene (26.2%) and inflorescence oils containing α-pinene (21.6%), germacrene D (15.1%), limonene (10.2%) and lupenyl acetate (9.8%) exhibited the highest inhibitory effect on lettuce and garden pepper cress growth. Relative germination and vigor index of model plants was conducted. Chemical composition of extracts and EOs was determined by HPLC/DAD/TOF and GC/MS techniques

Essential oils of Mentha arvensis and Cinnamomum cassia exhibit distinct antibacterial activity at different temperatures in vitro and on chicken skin

The bacterial contamination of meat is a global concern, especially for the risk of Salmonella infection that can lead to health issues. Artificial antibacterial compounds used to preserve fresh meat can have negative health effects. We investigated the potential of natural essential oils (EOs), namely Mentha arvensis (mint) and Cinnamomum cassia (cinnamon) EOs, to prevent contamination of the food pathogen, Salmonella enterica subsp. enterica serotype Typhimurium, in vitro and on chicken skin. The gas chromatography–mass spectrometry (GC-MS) technique was used to determine the compositions of mint EO (MEO) and cinnamon EO (CEO); the most abundant compound in MEO was menthol (68.61%), and the most abundant compound was cinnamaldehyde (83.32%) in CEO. The antibacterial activity of MEO and CEO were examined in vapor and direct contact with S. typhimurium at temperatures of 4 °C, 25 °C, and 37 °C. The minimal inhibitory concentration at 37 °C for MEO and CEO reached 20.83 µL/mL, and the minimal bactericidal concentration of CEO was the same, while for MEO, it was two-fold higher. We report that in most tested conditions in experiments performed in vitro and on chicken skin, CEO exhibits a stronger antibacterial effect than MEO. In the vapor phase, MEO was more effective against S. typhimurium than CEO at 4 °C. In direct contact, the growth of S. typhimurium was inhibited more efficiently by MEO than CEO at small concentrations and a longer exposure time at 37 °C. The exploration of CEO and MEO employment for the inhibition of Salmonella bacteria at different temperatures and conditions expands the possibilities of developing more environment- and consumer-friendly antibacterial protection for raw meat

Caryophyllene oxide-rich essential oils of "Artemisia campestris L." from Lithuania and their toxicity

Biologijos katedraChemijos institutasVytauto Didžiojo universiteta

Sea buckthorn Hippophae rhamnoides and fruit flies Rhagoletis batava: Search for volatile semiochemicals involved in pest attraction

Rhagoletis batava (Diptera: Tephritidae), is the most important pest of Hippophae rhamnoides fruits. For detection and monitoring of R. batava, traps supplied with nonspecific attractants are used. Thus, new, more specific attractants for environment-friendly pest control are needed. Such attractants could be fruit-related semiochemicals that are involved in the host location by flies. Behavioural Y-olfactometer tests revealed that R. batava males were attracted to ripe fruit odour, while females preferred unripe and semi-ripe fruits. Thermal desorption gas chromatography-mass spectrometry (GC-MS) analysis revealed substantial quantitative and qualitative changes in volatiles between unripe and ripe fruits. In the unripe fruit emission, 41 volatile compounds were isolated, whereas 64 compounds were sampled from the ripe fruits. The total amount of volatiles increased five times during the fruit ripening. Gas chromatography-electroantennogram detection (GC-EAD) and GC-MS analyses of the fruit headspace volatiles revealed at least 26 compounds in unripe and 27 compounds in ripe fruits eliciting antennal responses of R. batava for both sexes. The fruits of these two ripening stages differed qualitatively in the single EAD-active compound only, i.e., 3-methylbutyl 2-methylpropionate. Esters were the most abundant volatiles, composing 84% and 93% of EAD-active compounds in the emissions of unripe and ripe fruits, respectively. Based on the persistent EAG responses, 17 compounds were selected as the most promising candidates for kairomone attractants of the sea buckthorn pest R. batava