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Tetranychus urticae, a prominent pest mite in strawberry and vegetable cultivation in China, has developed escalating resistance due to extensive chemical pesticide application. Consequently, there is an urgent need to identify safe and efficacious methods to reduce resistance development. In this study, 38 commercially available plant essential oils (EOs) were screened for their acaricidal potential and ability to inhibit oviposition. The findings revealed that 13 EOs exhibited notable acaricidal activity, with lemon EO demonstrating the highest toxicity, followed by sage, patchouli, frankincense, lemongrass, palmarosa, and oregano EOs. In addition, 18 EOs displayed significant inhibitory effects on oviposition, with lemon EO exhibiting the highest inhibition rate (99.15%) and inhibition index (0.98). Subsequently, sage, frankincense, clove, lemongrass, oregano, patchouli, myrrh, black pepper, palmarosa, and geranium EOs also showed inhibition rates exceeding 50%. Despite black pepper, clove, myrrh, and oregano EOs demonstrating relatively low toxicity against T. urticae, they exhibited heightened efficacy in inhibiting oviposition and suppressing population expansion. This study conducted a comparative assessment of the acaricidal and oviposition inhibition activities of EOs and their principal constituents, thus providing a theoretical basis for the development of botanical acaricides against T. urticae. [ABSTRACT FROM AUTHOR]

In this study, we analyzed the components of Mentha spp. essential oils (EOs) and evaluated their major constituents and binary combinations against Reticulitermes dabieshanensis. We also determined the activities of esterases (ESTs), glutathione S-transferases (GSTs), and acetylcholinesterase activity (AChE) in treated insects. According to our findings, the most effective oils were those obtained from M. citrata (with the major constituent linalool constituting 45.1%), M. piperita (menthol, 49.1%), and M. spicata (carvone, 69.0%), with LC50 values of 0.176, 0.366, and 0.146 μL/L, respectively. The LC50 values were recorded for linalool (0.303 μL/L), followed by menthol (0.272 μL/L), and carvone (0.147 μL/L). The insecticidal potency increased with binary mixtures of major active constituents, with carvone strongly synergizing the toxicity of linalool and menthol against R. dabieshanensis. Compared to the control, except for M. citrata treated with no difference in α-NA or GST activity, the activities of ESTs and GST in other treatment groups were significantly increased. Additionally, our results found that Mentha spp. EOs and their major constituents inhibited the activity of AChE in vivo and in vitro. Finally, we performed a structure-based virtual screening of linalool, menthol, and carvone to identify that linalool had the greatest potential to bind to the active site of AChE. The present study suggests that Mentha spp. EOs could provide an additional approach for the management of termites over synthetic insecticides. [ABSTRACT FROM AUTHOR]

Background: Research interest in plant essential oils has increased significantly due to their natural properties and consumer demand for safer methods of food preservation. Plants produce large amounts of secondary metabolites, which have potential activity against fungal pathogens. This study aimed at screening essential oils for their antifungal effects on citrus against Penicillium digitatum, morphological effect and finally determine which essential oils are the most effective. Results: The EC50 of seven selected cinnamon (0.424 μL/mL), patchouli (0.513 μL/mL), vetiver (0.612 μL/mL), dill (1.597 μL/mL), origanum (1.971 μL/mL) and ylang (2.214 μL/mL) was determined. In addition, cinnamon substantially reduced sporulation (100%) followed by patchouli (86.02%), vetiver (82.73%), and chamomile (79.04%), respectively. Our GC–MS result determined variance in concentration of essential oils compound composition. The total compound composition in all seven essential oils > 1% was found to be 3 in cinnamon, 5 in dill, 10 in origanum, 13 in ylang, 11 in patchouli, 9 in chamomile and 16 in vetiver. Addition of essential oils significantly altered fungal morphology by scanning electron cryomicroscopy. Patchouli and origanum showed broken hyphae while there was an indication of severe deformation and collapse of spores in cinnamon and chamomile. Conclusion: Based on our findings, we report that these essential oils could potentially be applicable in controlling P. digitatum with reduced concern for human health, environmental contamination and possibly replacement of synthetic treatments. [ABSTRACT FROM AUTHOR]

The volatile metabolites of Salvia sclarea, Rosmarinus officinalis, Thymus serpyllum, Mentha spicata, Melissa officinalis, Origanum majorana, Mentha piperita, Ocimum basilicum and Lavandula angustifolia were determined by gas chromatography–mass spectrometry. The vapor insecticidal properties of the analyzed essential oils and their compounds were screened using Reticulitermes dabieshanensis workers. The most effective oils were S. sclarea (major constituent linalyl acetate, 65.93%), R. officinalis (1,8-cineole, 45.56%), T. serpyllum (thymol, 33.59%), M. spicata (carvone, 58.68%), M. officinalis (citronellal, 36.99%), O. majorana (1,8-cineole, 62.29%), M. piperita (menthol, 46.04%), O. basilicum (eugenol, 71.08%) and L. angustifolia (linalool, 39.58%), which exhibited LC50 values ranging from 0.036 to 1.670 μL/L. The lowest LC50 values were recorded for eugenol (0.060 μL/L), followed by thymol (0.062 μL/L), carvone (0.074 μL/L), menthol (0.242 μL/L), linalool (0.250 μL/L), citronellal (0.330 μL/L), linalyl acetate (0.712 μL/L) and 1,8-cineole (1.478 μL/L). The increased activity of esterases (ESTs) and glutathione S-transferase (GST) were observed but only alongside the decreased activity of acetylcholinesterase (AChE) in eight main components. Our results indicate that S. sclarea, R. officinalis, T. serpyllum, M. spicata, M. officinalis, O. marjorana, M. piperita, O. basilicum and L. angustifolia essential oils (EOs) and their compounds, linalyl acetate, 1,8-cineole, thymol, carvone, citronellal, menthol, eugenol and linalool could be developed as control agents against termites. [ABSTRACT FROM AUTHOR]

The citrus red mite, Panonychus citri (McGregor), is an important pest of citrus in China, where pesticides are commonly used in citrus orchards. In order to reduce the use of chemical pesticides against P. citri and the development of resistance, the screening of biological control agents has attracted the attention of students. In this study, seven plant essential oils with high toxicity were selected from 40 plant essential oils by the leaf-dip bioassay, including plant essential oils of lemongrass, patchouli, juniper berry, sage, clove, frankincense, and citrus. The LC50 after 72 h treatment were 3.198 μL/mL, 8.312 μL/mL, 3.244 μL/mL, 6.701 μL/mL, 8.350 μL/mL, 21.953 μL/mL, and 8.788 μL/mL, respectively. According to the LT50, the essential oils' acute toxicity to P. citri from high to low were lemongrass, juniper berry, patchouli, citrus, sage, vetiver, and frankincense essential oils. In general, lemongrass and juniper berry essential oils have the best acaricidal effect and have high application value for the biological control of P. citri, which provides a basis for the development of botanical acaricides. [ABSTRACT FROM AUTHOR]

The essential oil (EO) of Thymus serpyllum and thymol were evaluated for their insecticidal activity against the housefly (Musca domestica) larvae and pupae. Contact toxicity and fumigation bioassays were used. Chemical composition analysis of T. serpyllum EO by gas chromatographic mass spectrometry (GC-MS) revealed that thymol (41.6%), p-cymene (21.9%), and γ-terpinene (19.2%) were the major components. For larval assays, the LC50 value of T. serpyllum EO was 0.4 μl/cm2 for contact toxicity and 20.9 μl/l for fumigation toxicity. For thymol, the contact toxicity LC50 value was 0.035 μl/cm2 and the fumigation LC50 value was 2.0 μl/l. For the pupal assay, T. serpyllum EO had a percentage inhibition rate (PIR) value of 100% for both contact toxicity (1.0 μl/cm2) and fumigation toxicity assay (25 μl/l), whereas thymol had a PIR of 100% for contact toxicity (0.1 μl/cm2) and fumigation assay (5 μl/l). This study shows that T. serpyllum EO and thymol are toxic to housefly larvae and pupae and have the potential for use in the population control of this species. [ABSTRACT FROM AUTHOR]

Plutella xylostella L. is a cosmopolitan pest of wild and cultivated crucifer vegetables worldwide. It has developed resistance to almost all commercial chemicals, making them one of the most problematic field pests in China. The natural plant extracts and essential oils (EOs) could be a safe alternative for agricultural pests. The development and production of EOs decrease the negative effects of synthetic chemicals. In the present study, the fumigation activity of 8 pure monoterpenes against P. xylostella was evaluated. Results from fumigation tests revealed that 8 tested compounds exhibited various degrees of toxicity against adults of the diamondback moth. Cuminaldehyde was the most toxic compound based on the 12-h LC50 (0.17 mg/L) and 24-h LC50 (0.12 mg/L) values, respectively. Also for larvae and eggs, cuminaldehyde was the most toxic compound. The 12-h LC50 value for cuminaldehyde to 1st, 2nd, and 3rd instar larvae was 0.10 mg/L, 0.12 mg/L, and 0.55 mg/L, respectively. The 24-h LC50 value for the different instar larvae was 0.07 mg/L, 0.09 mg/L, and 0.35 mg/L, respectively. The 24-h LC50 value for eggs (endpoint hatching rate) was 1.95 mg/L for cuminaldehyde, followed by carvacrol and eugenol (2.05 mg/L and 2.31 mg/L, respectively). Cuminaldehyde was very friendly to the larvae and adults of Harmonia axyridis and did not cause any mortality. Our results indicated that cuminaldehyde had potential insecticidal activity against P. xylostella and could be utilized in the novel biological pesticide development. [ABSTRACT FROM AUTHOR]

The toxicity of Origanum vulgare essential oil to the housefly Musca domestica L. was evaluated. The major constituents of the O. vulgare essential oil by gas chromatographic mass spectrometry (GC-MS) analysis were carvacrol (58.13%), p-cymene (17.85%), thymol (8.15%), γ-terpinene (4.96%), and linalool (3.69%). Toxicity of O. vulgare essential oil against larvae and pupae was evaluated using fumigation and contact assays. The contact toxicity (LC50) of O. vulgare essential oil and carvacrol for larvae was 0.23 and 0.03 μL/cm2, respectively. The fumigation toxicity (LC50) of O. vulgare essential oil and carvacrol for larvae was 9.52 and 2.78 μL/L, respectively. Pupal toxicity was evaluated by percentage inhibition rate (PIR). PIR of O. vulgare essential oil at 0.25 μL/cm2 was 90.9% for the contact assay and 100% at 20 μL/L for the fumigation assay. PIR of carvacrol was 29.5% (0.025 μL/cm2) and 81.8% (1.25 μL/L) for the contact toxicity and fumigation assay, respectively. O. vulgare essential oil and carvacrol have significant toxicity to the housefly and are potential insecticides for housefly control. [ABSTRACT FROM AUTHOR]

Biodegradation of wood by fungi is recognized as one of the most serious problems for wooden structures and forest management. This study evaluated the fungicidal activity of 6 plant essential oils ( Origanum vulgare , Cymbopogon citratus , Thymus vulgaris , Pelargonium graveolens , Cinnamomum zeylanicum and Eugenia caryophyllata ) against the wood-rot fungi, Trametes hirsuta and Laetiporus sulphureus . Results from antifungal tests revealed that six essential oils showed good antifungal activities, in which, O. vulgare was the most toxic to the wood-rot fungi, with the IC 50 values against T. hirsuta and L. sulphureus of 79.1 and 36.9 μg/mL, respectively. The composition of six essential oils was indentified by using gas chromatographic-mass spectrometry. The six major compounds from 6 essential oils were tested individually for their fungicidal activities against two wood-rot fungi. Results from the antifungal tests demonstrated that the six major compounds exhibited strong fungicidal activity. In addition, carvacrol was the most toxic against the wood-rot fungi, with the IC 50 values against T. hirsuta and L. sulphureus of 33.6 and 17.2 μg/mL, respectively. Furthermore, phenol and aldehyde groups were more toxic than alcohol. The results show that the six plant essential oils and their major chemical constituents have potential for the development of natural wood preservatives. [ABSTRACT FROM AUTHOR]

The essential oils of composition obtained from the leaves ofCryptomeria fortunei, collected at different seasons in Wuhan (China), were analyzed by gas chromatography (GC) GC–mass spectrometry (GC–MS). Fifty constituents were identified, constituting 92.3–97.7% of the essential oils. Our results showed that seasonal differences did not have an effect on the composition of oils but on the amount of oil components. The main components of the oil were kaur-16-ene (30.9–42.4%), elemol (16.8–18.9%), α-eudesmol (7.4–13.6%), α-pinene (1.9–8.0%) and γ-eudesmol (4.0–7.5%). On the basis of the results obtained, some suggestions are made concerning the optimal season for theC.fortuneioils. [ABSTRACT FROM PUBLISHER]

Abstract: Essential oils were extracted by hydrodistillation from the leaves of Cryptomeria fortunei from the principal habitats in China. The essential oil yields of samples from various locations ranged from 0.61 to 1.66% (w/w). GC–MS analysis revealed eighty-seven compounds, constituting 85.89–94.75% of the total essential oils. The main constituents were kaurene (0–44.69%), phyllocladene (0.07–32.98%), kaur-16-ene (0–32.28%), elemol (5.28–18.92%), α-cadinol (0–11.39%), α-eudesmol (0–11.21%), α-pinene (2.32–9.15%). The samples were separated into 3 chemotypes by hierarchical cluster analysis, according to the composition of the corresponding essential oils. Chemical composition of essential oils was significantly related to nine geographic distributions among populations. Our results revealed chemical polymorphism in the essential oils of the C. fortunei leaf in China. The chemical variability could be attributed to genetic and environmental factors. The chemical diversity of the oils offers opportunity to choose C. fortunei leaves and essential oils with preferential compound for green plant protection, pharmaceutical, perfume and food industries. [Copyright &y& Elsevier]

Abstract: The essential oils obtained by hydrodistillation from leaves of Chinese native Cryptomeria japonica and Cryptomeria fortunei were analyzed by GC and GC–MS. Fifty-seven compounds were identified in the essential oils of C. japonica with α-elemol (20.12%), kaur-16-ene (14.84%), β-phellandrene (5.97%), β-elemene (5.87%), α-eudesmol (5.62%) and β-eudesmol (5.03%) as main constituents. Forty components were identified in the oil of C. fortunei with kaurene (34.04%), α-elemol (13.34%), γ-eudesmol (10.80%), β-eudesmol (10.16%), α-pinene (2.75%) and γ-cadinene (1.92%) as the most abundant components. This study demonstrated the occurrence of α-elemol chemotype in C. japonica and kaurene chemotype in C. fortunei from China. The essential oil compositions of two Cryptomeria samples were shown that they can be used for green plant protection, pharmaceutical, perfume and food industries. [Copyright &y& Elsevier]

The global impact of termites that damage wood products causes quite significant losses. Synthetic insecticides have been extensively employed to combat termites. However, as the long-term application of insecticides developed adverse effects on humans and the environment, the use of essential oils (EOs) has emerged as an alternative approach for controlling termites. Hence, the present report assessed the fumigation activity of three Cymbopogon EOs toward Reticulitermes flaviceps workers. The results showed that C. citratus (with the major constituent citral (mixture of neral and geranial) at 78.58 %), C. khasans (geraniol, 38.54 %), and C. nardus (citronellal, 26.99 %) had respective LC 50 values of 0.39, 0.45 and 0.48 μL/L. These values for citral, geraniol, and citronellal were 0.35, 0.34, and 0.40 μL/L. The duration of fumigation using Cymbopogon EOs and their primary compounds exhibited a positive correlation with the knockdown and mortality rates of R. flaviceps while displaying a negative correlation with grasping ability. In addition, each component caused a concentration-dependent reaction measured using electroantennography (EAG) and triggered a significant response at 100 μg/μL. The activities of detoxifying enzymes like β-esterase and glutathione S-transferase were remarkably increased in treated R. flaviceps. The findings also demonstrated that both Cymbopogon EOs and their primary components effectively suppressed acetylcholinesterase (AChE) in vitro and in vivo. In silico structural analyses of citral, geraniol, and citronellal revealed that citronellal exhibited the highest potential for binding to the active site of AChE. Similarly, the activity of acid phosphatases, alkaline phosphatases, aspartate aminotransferase, and lactate dehydrogenase was elevated in treated R. flaviceps , whereas that of alanine aminotransferase was diminished. This study may provide a robust foundation for developing and using Cymbopogon EOs to control R. flaviceps in an environmentally friendly manner. [Display omitted] • Cymbopogon EOs and their major constituents have toxic effects on R. flaviceps. • Major detoxifying agents are affected by Cymbopogon EOs and their major constituents. • Cymbopogon and their constituents inhibited activity of AChE in in vivo and in vitro. [ABSTRACT FROM AUTHOR]

Monoterpenes are the major components of essential oils from many aromatic plants, partly contributed to the insecticidal properties of essential oils. In this study, the fumigation activity of 40 pure monoterpenes against fruitfly, Drosophila melanogaster , were evaluated. Results from fumigation tests revealed that terpinolene, 3-carene, eugenol, thymol, carvacrol, isoeugenol, citral, (±)-citronellal, cuminaldehyde, (−)-verbenone, and (+)-pulegone exhibited strong fumigation activity against D . melanogaster . In addition, the (±)-citronellal and (+)-pulegone (aldehydes and ketones) were the most toxic monoterpenes to D . melanogaster with LC 50 values of 0.015 and 0.02 μl/L, respectively. Oxygenated monoterpenes were found to be with higher toxicity as compared with monoterpene hydrocarbons. The present results indicated that (±)-citronellal and (+)-pulegone exhibit a potential for the development of new botanical insecticides against the D . melanogaster , suggesting that further studies of a number of medically important dipterans might be warranted. [ABSTRACT FROM AUTHOR]

• Spearmint EO and its major constituents have toxic effects on R. dabieshanensis. • The toxic efficacy increased with increasing temperature against R. dabieshanensis. • Carvone highly synergized the toxicity of limonene and dihydrocarvone. • All treated termite showed the increased activity of detoxifying enzymes. • Spearmint EO and its constituents inhibited activity of AChE in vivo and in vitro. This study evaluated the chemical components of spearmint essential oil, and determined individually the efficacy of spearmint EO and its major constituents, and their mutual binary combination against Reticulitermes dabieshanensis. We also evaluated the activities of esterases (ESTs), glutathione S-transferases (GST) and Acetylcholinesterase (AChE) enzymes in treated insects. GC–MS analysis showed that the major constituents of spearmint EO were carvone (52.25 %), limonene (19.78 %), and dihydrocarvone (11.1 %). In fumigant toxicity assay, the spearmint EO achieved a LC 50 value of 0.194 μl/L. The three major constituents, carvone, dihydrocarvone, and limonene were most effective against R. dabieshanensis , with LC 50 values of 0.074, 0.155, and 2.650 μl/L, respectively. The toxicity assay of binary mixtures of carvone + dihydrocarvone, carvone + limonene and limonene + dihydrocarvone in all the used ratios showed the three major constituents exhibited synergistic effects against R. dabieshanensis. Spearmint EO and its major constituents showed significantly stronger insecticidal efficacies at the high temperature, with rapid insecticidal action. The increased activity of ESTs and GST were observed, but with the decreased activity of AChE in all treatments. In vitro experiments, all treatments showed significant inhibition of AChE activity, except for dihydrocarvone, with IC 50 values were 0.871, 2.405, 2.653 and 4.343 μl/mL for limonene, carvone, carvone + limonene and carvone + dihydrocarvone, respectively. The results showed that the insecticidal efficacy of spearmint EO can be attributed to the major component, possibly carvone, with strong AChE inhibition properties. Hence, spearmint EO and its bioactive constituents have the potential to be used as new environmentally safe insecticides for controlling R. dabieshanensis. [ABSTRACT FROM AUTHOR]