Ovicidal and adulticidal activity of Eucalyptus globulus leaf oil terpenoids against Pediculus humanus capitis (Anoplura: Pediculidae)

Robustanic acid as a glutaminase and Na+, K+-ATPase inhibitor from leaves of Eucalyptus globulus

This study was to compare glutaminase and Na+, K+-ATPase inhibitory activities of 20 herbal extracts and investigate the isolation, structural elucidation and those inhibitory activities of three triterpenes from the selected extract of Eucalyptus globulus Labill. Three triterpenes, ursolic acid (1), robustanic acid (2) and ursolic acid lactone (3), were identified by analyzing their NMR and MS spectral data and comparison of these with reported data. The IC50 values of 1-3 and the control compound against glutaminase, 6-diazo-5-oxo-l-norleucine (DON), were 443 μM, 334 μM, 963 μM and 134 μM, respectively. The IC50 values of 1, 2 and the control compound against Na+, K+-ATPase and ouabain, were 180 μM, 56 μM and 0.5 μM, respectively. Compounds 1 and 2 may serve as potential lead compounds for the prevention and treatment of neurodegenerative and lifestyle-related diseases by targeting glutaminase and Na+, K+-ATPase. This is the first report on glutaminase and Na+, K+-ATPase inhibitory activities of 2.

Antimicrobial, Herbicidal and pesticidal potential of Tunisian eucalyptus species: Chemoprofiling and biological evaluation

The Eucalyptus genus, characterized by its imposing stature and fragrant foliage, has been a source of fascination for humanity over the centuries. The focus of the present investigation was directed towards the essentials oils (EOs) of five Eucalyptus trees cultivated in Tunisia. The GC-MS analysis unveiled unique compositional profiles, a finding substantiated by both Hierarchical Clustering Analysis (HCA) and Principal Component Analysis (PCA) conducted on the leaves EOs. These analyses resulted in the formation of discrete HCA clades, delineating 23 significant components. Notably, the percentage of eucalyptol emerged as the pivotal factor demarcating the separation between three distinct groups. The statistical analysis revealed a dose-dependent relationship in both phytotoxicity evaluation and antibacterial activity. The EOs from Eucalyptus loxophleba and E. salubris exhibited the highest phytotoxicity, inhibiting radical elongation and germination of various seeds, especially Sinapis arvensis and Raphanus sativus. The antimicrobial assessment demonstrated significant inhibitory effects of the EOs on bacterial strains, with MIC values spanning from 14 to exceeding 50 mg/ml. The EOs also affected biofilm formation and cellular metabolism, displaying varied efficacy among different Eucalyptus species against some bacterial strains. The EOs exhibited selective inhibition against acetylcholinesterase (AChE), butyrylcholinesterase (BChE), α-amylase, and α-glucosidase. E. campaspe EO showed the highest AChE activity, while E. loxophleba and E. salubris EOs were most potent toward α-amylase. E. loxophleba EO demonstrated notable activity against α-glucosidase. Overall, these findings provide important data about the diverse biological activities of Eucalyptus EOs, suggesting potential applications in agriculture, medicine, and pharmacy.

Characterization of Larix decidua Mill. (Pinaceae) oleoresin's essential oils composition using GC-MS

Introduction

Larch oleoresin has been described regarding several biological activities and medicinal applications, such as wound healing and treatment of ulcers, but little is known about its chemical composition.

Material and methods

Eight oleoresins from Larix decidua Mill. obtained from four companies and one adulterated control were therefore investigated to determine their content of essential oils and to verify possible differences in their composition in relation to the harvest and manufacturing processes. Essential oils (EOs) were isolated by distillation and the yield was analysed.

Results and discussion

The yield of EO varied among all samples. The yield of the pure larch samples covered a range of 7.8% to 15.5%. A higher yield (19.0%) was observed for adulterated control, which contained oleoresins from different Pinaceae trees. Age of samples had no impact on yield. However, there was a significant statistical variation (p<0.05) in the yields of the mid-summer oleoresins (>10%) compared to early or late summer (<10%), emphasising the importance of the time of collection. Samples were subsequently analysed by GC-MS. EO samples confirmed the presence of various chemical classes, such as monoterpenes, sesquiterpenes, and diterpenes. α-pinene was the compound with the highest concentrations (>50%), followed by β-pinene (>6%), D-limonene (>2.5%), α-terpineol (>0.9%), β-myrcene (>0.2%), and 3-carene (>0.05%). Samples were grouped using multivariate data analysis (MVDA) with respect to the chemical variation between the oleoresins' EOs. The resulting four clusters were named low (low yield obtained for the samples), mixed (mixed oleoresin from different Pinaceae species, adulteration control), old (old oleoresin kept in the institute), and normal (other oleoresins) samples, each presenting distinct chemical biomarkers. There were considerable differences between site and time of collection. Essential oil yield did not always meet requirements as defined by the German Homeopathic Pharmacopoeia. In addition, adulterated or aged samples could be identified as compared to pure and fresh larch oleoresins.

Conclusion

We conclude that larch oleoresin used for pharmaceutical applications has to be carefully analysed and standardised to guarantee reproducible product quality.

Metabolite profiling of four Tunisian Eucalyptus essential oils and assessment of their insecticidal and antifungal activities

Aphids (Aphidoidea) and Fusarium spp. are widely recognized as destructive pests that cause significant damage to crops on a global scale. This study aimed to ascertain the chemical composition of essential oils (EOs) of four Tunisian Eucalyptus species and evaluate their toxicity against common aphids and phytopathogenic fungi. The EOs were obtained via hydrodistillation and subsequently analyzed using GC-MS. The chemical composition analysis revealed the presence of five distinct chemical classes in the EOs: monoterpene hydrocarbons (3.8-16.7 %), oxygenated monoterpenes (5.5-86.0 %), sesquiterpene hydrocarbons (0.2-2.2 %), oxygenated sesquiterpenes (4.2-86.7 %), and non-terpene derivatives (0.1-14.1 %).Hierarchical clustering analysis (HCA) and principal component analysis (PCA) of the Eucalyptus leaf EOs highlighted significant differences among them, leading to the generation of distinct HCA clades representing at least twelve major components. The statistical analysis clearly demonstrated a dose-response relationship, indicating the impact of the tested EOs on the growth of insects and fungal mycelium. The observed effects varied due to the variability in the chemical compositions of the EOs. Notably, among the EOs tested, Eucalyptus lesoufii Maiden exhibited particularly potent effects against the targeted insect and fungal species. This research contributes to the ongoing exploration of natural alternatives to chemical pesticides, providing further insights for potential industrial applications. It underscores the versatility of these EOs and their potential as valuable candidates in strategies for pest and disease management.

Forest Biomass as a Promising Source of Bioactive Essential Oil and Phenolic Compounds for Alzheimer's Disease Therapy

Alzheimer’s disease (AD) is the most common neurodegenerative disorder affecting elderly people worldwide. Currently, there are no effective treatments for AD able to prevent disease progression, highlighting the urgency of finding new therapeutic strategies to stop or delay this pathology. Several plants exhibit potential as source of safe and multi-target new therapeutic molecules for AD treatment. Meanwhile, Eucalyptus globulus extracts revealed important pharmacological activities, namely antioxidant and anti-inflammatory properties, which can contribute to the reported neuroprotective effects. This review summarizes the chemical composition of essential oil (EO) and phenolic extracts obtained from Eucalyptus globulus leaves, disclosing major compounds and their effects on AD-relevant pathological features, including deposition of amyloid-β (Aβ) in senile plaques and hyperphosphorylated tau in neurofibrillary tangles (NFTs), abnormalities in GABAergic, cholinergic and glutamatergic neurotransmission, inflammation, and oxidative stress. In general, 1,8-cineole is the major compound identified in EO, and ellagic acid, quercetin, and rutin were described as main compounds in phenolic extracts from Eucalyptus globulus leaves. EO and phenolic extracts, and especially their major compounds, were found to prevent several pathological cellular processes and to improve cognitive function in AD animal models. Therefore, Eucalyptus globulus leaves are a relevant source of biological active and safe molecules that could be used as raw material for nutraceuticals and plant-based medicinal products useful for AD prevention and treatment.

Histological Study for Median lethal Dose (LD50) of Eucalyptus Oil Administrated Orally in ( Mice mus musculus)

Eucalyptus oil is used in a wide range of medicinal and other uses, and the current study aims to estimate the median lethal dose LD50 of eucalyptus oil of Eucalyptus camaldulensis and estimate the pathological effect of eucalyptus oil in mice. Eucalyptus oil was obtained in the study by extracting the leaves of the plant Eucalyptus camaldulensis using hydrodistillation. Toxicity testing was performed by dividing mice into groups that you treated with different doses of eucalyptus oil 1200, 1600, 2000, and 2400 mg/kg. The current study showed that the average lethal dose, the LD50, was 1820 mg/kg. The study suggested the emergence of clinical signs in mice when consuming eucalyptus oil in high doses, such as slow movement, suffocation, and convulsion, compared with the control group and the group that administered a lower dose, It was observed that high doses of eucalyptus oil could cause damage to the lung, liver, kidneys, and heart, as the lung was the organ most affected by the oil, followed by the liver, kidneys, and then the heart, and it was less affected by eucalyptus oil, and this indicates that eucalyptus oil, when administered orally in high doses, causes clear toxicity effects. Eucalyptus oil is a safe medicine for external use. Keywords. Eucalyptus oil, LD50; Administrated; Lung; Liver; Heart; Kidney; Mice.

Chemical Composition and Effect against Skin Alterations of Bioactive Extracts Obtained by the Hydrodistillation of Eucalyptus globulus Leaves

Eucalyptus globulus is planted extensively for pulp, paper and wood production. Although bioactive compounds obtained from its biomass are used as cosmetics ingredients, the skin effects were not yet fully explored. In order to fill this gap, this work aimed to study the protective effect against skin damage provided by the essential oil (EO) obtained from the hydrodistillation of Eucalyptus globulus leaves, and by an extract obtained from the hydrodistillation residual water (HRW). The major compound identified in the EO was 1,8-Cineole, and the phenolic acids in the HRW included gallic acid as the main phenolic constituent. Moreover, non-toxic EO and HRW concentrations were shown to have anti-aging skin effects in vitro, decreasing age-related senescence markers, namely β-galactosidase and matrix metalloproteinases activation, as well as collagen type 1 upregulation. In addition, EO and HRW were found to exhibit depigmenting effects by inhibiting tyrosinase and melanin production, along with potent anti-inflammatory properties. Furthermore, the absence of skin irritation and sensitization in cells exposed to EO and HRW revealed the safety of both extracts for topical use. Taken together, these results highlight the beneficial effects of extracts obtained from Eucalyptus globulus biomass for skin aesthetic and health purposes, which should be explored deeply for the prediction of future pharmaceutical and dermocosmetics industrial applications.

Ultrasound extraction optimization for bioactive molecules from Eucalyptus globulus leaves through antioxidant activity

Antioxidant products present a very high added value and are demanded in the market. The optimization of their extraction is a high-stakes matter for both economic and environmental points of view. Ultrasound extraction has been considered one of the most promising methods, so the relative importance of key parameters may have decisive economic significance. For this reason, different parameters that have influence on the extraction capacity such as ultrasound power, time, temperature, pH and % ethanol in water have been studied to know the relationships between the independent parameters and their influence on the extraction from Eucalyptus globulus leaves. An experimental Box-Behnken factorial design and subsequent analysis by neural networks have been used. The relative influence of each parameter varies according to the nature of the extracted compound. In this regard, the higher capacity of extraction of the selected antioxidant compounds by means of the variation of the operation conditions can be facilitated. For all the studied compounds, temperature has been the most important parameter for their extraction. The relative content (%) of bioactive compounds (terpenes) in the optimized Eucalyptus globulus extract has been performed by GC-MS analysis.

Potential use of essential oils in cosmetic and dermatological hair products: A review

BACKGROUND

Essential oils have great interest among the increasing demand for herbal cosmetics in the market. They are natural sources of biologically active ingredients due to the wide application of such compounds as well as their particular chemical composition. Several researches have evaluated the effectiveness of these bioactive ingredients for use in cosmeceuticals, mainly in both hair scalp and shaft hair damage repair. Thus, the amounts and their associations define the properties of these compositions with interest for hair cosmetic use, such as antioxidant, inflammatory, and antimicrobial activities. Because they are complex compounds, their actions on the skin, hair scalp, and shaft are not yet fully understood.

AIMS

The purpose of this review is to highlight the relevant researches and findings on essential oils in hair care.

METHODS

In order to achieve this objective, the present work comprises an updated bibliographic review related to essential oils used in hair care.

RESULTS

It was possible to observe that cosmeceuticals containing essential oils applied to the scalp are preferable for topical activity. Also, it was noticed that there are few reports regarding their use in hair shaft. However, it was found that some oils are used to intensify the brightness and fix the hair color.

CONCLUSIONS

This work demonstrated that the use of essential oils in both cosmetic products (industrial application) and those associated with oils carriers (as individual protocols) may lead to satisfactory results in the treatment of some scalp dysfunctions.

Chemical composition and acaricidal activity of Eucalyptus globulus essential oil against the vector of tropical bovine piroplasmosis, Rhipicephalus (Boophilus) annulatus

Ticks are of great economic importance to humans and animals due to their role in disease transmission. The application of synthetic, chemical acaricides on the animal and/or the environment (the most used tick control method globally) has led to the selection of tick populations that are resistant. Their adverse effects on ecology and human and animal health cannot be overemphasised. As a result, the search for alternatives that are natural and can overcome these adverse effects are strongly indicated. Using gas chromatography-mass spectrometry (GC-MS) and adult immersion test (AIT), this study evaluated the chemical composition and acaricidal activity, respectively, of Eucalyptus globulus essential oil (EO) on Rhipicephalus (Boophilus) annulatus ticks. This is a major tick species implicated for the transmission of bovine piroplasmosis in Nigeria. The acaricidal activity was evaluated using different concentrations (0.625, 1.25, 2.5, 5 and 10%) of E. globulus EO. Amitraz (1 and 2%) and cypermethrin (2%) served as the positive control and 2% dimethylsulfoxide in distilled water was the negative control. Three replicates of 10 engorged female ticks each were immersed in the test samples for 2 min and the experiment was done twice. The GC-MS analysis identified the major constituents of E. globulus EO as eucalyptol (1,8-cineole) (78%), menthol (20%) and menthone (3%). Eucalyptus globulus EO caused 97% acaricidal mortality at 10% concentration. The lower concentrations reduced tick fecundity up to 90% in a dose-dependent manner. This study provides support for plant EOs as alternative tick control strategy for humans and animals.

Effects of storage on the oxidative stability of acorn oils extracted from three different Quercus species

BACKGROUND

Acorn fruit and its components and by-products are receiving renewed interest due to their nutritional and phytochemical features. In particular, the oil extracted from acorns is recognized for having high nutritional quality and for being rich in bioactive compounds. Despite the growing interest, few papers are available that consider the evolution of acorn-oil characteristics during storage. Our aim was to investigate the storage-related changes in acorn oils extracted from three Quercus species grown in Algeria (Q. ilex, Q. suber, and Q. coccifera) 180 days after production, with a focus on polar and volatile compounds, not yet investigated. Basic quality parameters, phenolic content, antioxidant activity and induction time were also monitored.

RESULTS

The oxidation markers (peroxide value and UV absorptions) increased during storage, whereas antioxidants decreased. A distinctive volatile profile was observed at the time of production, which underwent changes during storage. Polar compounds increased, whereas induction time decreased. The oil extracted from Quercus suber L. was the most affected by storage time.

CONCLUSION

Floral and fruity volatile compounds detected in the oils' headspace could explain the pleasant flavor of acorn oils reported by other authors. As with other vegetable oils, storage depletes both volatiles and antioxidants and produces oxidation compounds, such as oxidized triacylglycerols. However, the acorn oils that were studied were quite stable under storage in the dark at room temperature for 6 months. © 2020 Society of Chemical Industry.

Evaluation of essential oils as an ecological alternative in the search for control Rhipicephalus microplus (Acari: Ixodidae)

The cattle tick Rhipicephalus microplus is a significant problem for livestock, causing losses of billions of dollars per year. This work aimed to determine the chemical composition of essential oils obtained from Laurus nobilis and Copaifera officinalis and evaluate activity against engorged R. microplus females. Chemical composition analyzed by GC-MS revealed the presence of 39 components accounting for 95.38% of the oil in L. nobilis, the most abundant being 1,8-cineol (25.7%), trans-sabinene-hydrate (20.8%), and α-terpinil acetate (15.0%). Chemical analysis of C. officinalis oil identified 25 components corresponding to 80.5% of the total constituents, where the major compounds were β-caryophyllene (21.1%), caryophyllene oxide (10.7%), and α-trans-bergamotene (9.3%). Adult immersion test (AIT) showed that L. nobilis essential oil at 5% or 10% caused 80.5% mortality of engorged females after 24 h and reached 96.9% and 100% mortality on the third day after treatment, respectively. While the essential oil from C. officinalis caused 84.7% mortality after six days at 10% and at 5%, achieved approximately 100% mortality rate at the end of the experiment (day 15). Both essential oils and the combination significantly inhibited egg-laying; however, the combination treatment showed higher effectiveness than the isolated oils at 2.5%. A possible synergic action of L. nobilis and C. officinalis against the cattle tick R. microplus is therefore suggested. The present work introduces a potential alternative for the development of a formulation environment-friendly (green pesticide) used to control cattle tick infestations.

Toxicity, repellency and anti-cholinesterase activities of thymol-eucalyptus combinations against phenotypically resistant Rhipicephalus annulatus ticks

The current study was designed to compare the acaricidal activity of pure thymol (T) crystals, eucalyptus oil (E), and their combinations (T + E) at concentrations ranging from 0.625 to 10% against phenotypically deltamethrin-resistant Rhipicephalus annulatus ticks. The adulticidal, larvicidal, ovicidal, and repellent activities of the tested compounds and their possible mechanism of action were studied. Thymol showed 93.3% adulticidal activity at 10% concentration, whereas at 2.5% it achieved 100% larvicidal activity. Eucalyptus oil had a significant effect on tick adults at concentrations > 5%, and at 10% concentration it showed 96.7% adulticidal activity and stopped the egg hatching. On deltamethrin-resistant larvae, the median lethal concentration (LD₅₀) was 0.61, 7.5, and 0.61% for T, E, and T + E combinations, respectively, and repellent activities were 85.7, 62.5, and 100% at the 10% concentration used. Combinations of T + E did not induce additional effects as adulticidal and larvicidal in a comparison with T treatments. The tick's acetylcholinesterase significantly decreased as a result of all treatments including deltamethrin, whereas lipid peroxidation significantly increased compared with the control untreated ticks. The glutathione content significantly decreased as a result of all treatments except for treatments with 10% thymol and its combination with eucalyptus oil. Moreover, 10% eucalyptus oil significantly decreased the tick's glutathione peroxidase and catalase activities reflecting the attenuation of antioxidant defense in the ticks. In conclusion, thymol and eucalyptus oil showed excellent activities against deltamethrin-resistant R. annulatus isolates. Their action may be mediated via acetylcholinesterase inhibition. The effect of thymol-eucalyptus combinations recorded higher activities as an ovicidal and as a repellent.

Alpha-Terpineol production from an engineered Saccharomyces cerevisiae cell factory

Background

Alpha-Terpineol (α-Terpineol), a C₁₀ monoterpenoid alcohol, is widely used in the cosmetic and pharmaceutical industries. Construction Saccharomyces cerevisiae cell factories for producing monoterpenes offers a promising means to substitute chemical synthesis or phytoextraction.

Results

α-Terpineol was produced by expressing the truncated α-Terpineol synthase (tVvTS) from Vitis vinifera in S. cerevisiae. The α-Terpineol titer was increased to 0.83 mg/L with overexpression of the rate-limiting genes tHMG1, IDI1 and ERG20^F96W-N127W. A GSGSGSGSGS linker was applied to fuse ERG20^F96W-N127W with tVvTS, and expressing the fusion protein increased the α-Terpineol production by 2.87-fold to 2.39 mg/L when compared with the parental strain. In addition, we found that farnesyl diphosphate (FPP) accumulation by down-regulation of ERG9 expression and deletion of LPP1 and DPP1 did not improve α-Terpineol production. Therefore, ERG9 was overexpressed and the α-Terpineol titer was further increased to 3.32 mg/L. The best α-Terpineol producing strain LCB08 was then used for batch and fed-batch fermentation in a 5 L bioreactor, and the production of α-Terpineol was ultimately improved to 21.88 mg/L.

Conclusions

An efficient α-Terpineol production cell factory was constructed by engineering the S. cerevisiae mevalonate pathway, and the metabolic engineering strategies could also be applied to produce other valuable monoterpene compounds in yeast.

In vitro Safety and Efficacy of Lavender Essential Oil (Lamiales: Lamiaceae) as an Insecticide Against Houseflies (Diptera: Muscidae) and Blowflies (Diptera: Calliphoridae)

Essential oils are considered an alternative for replacement of conventional insecticides that have provoked an increasing number of resistant species and damages to health. The objective of this work was to investigate the insecticidal activity of Lavandula dentata L. (Lamiales: Lamiaceae) oil against the species Musca domestica L. (Diptera: Muscidae) and Chrysomya albiceps Wiedemann (Diptera: Calliphoridae). Extraction of the essential oil from the aerial parts of the plant was carried out using hydro-distillation. Its principal compounds (1,8-cineol, camphor, and linalool oxide) were identified. Insecticidal activity was determined by evaluating adulticidal effect using topical application methods and exposure to impregnated paper; larvicidal effect was determined using immersion method. The essential oil presented toxicity in M. domestica and C. albiceps adults; the lethal concentration values (LC50) in the superficial application method were respectively 3.13 ± 0.64 and 1.39 ± 0.19% live weight (l/v). Toxicity was also found in the oil impregnated paper exposure test; the LC50 results for M. domestica and C. albiceps were respectively 4.15 ± 0.64 and 5.14 ± 0.81%. Larvicidal effect was observed on third stage M. domestica larvae when exposed to an oil concentration of 2.5% (m/v). In addition, the oil was evaluated for cytotoxicity, mutagenicity, and genotoxicity in human cells, and the in vitro safety of this oil in human cells was verified. Thus, L. dentata oil presented insecticidal activity in M. domestica and C. albiceps and can be used as an alternative for control of these dipterans.

Ovicidal effect of essential oils from Zingiberaceae plants and Eucalytus globulus on eggs of head lice, Pediculus humanus capitis De Geer

BACKGROUND

Head lice infestation is an important public health problem worldwide. Chemical pediculicides have lost their efficacy because lice have developed resistance to them. Therefore, alternative pediculicides such as essential oils and herbal products have been proposed for treating head lice infestation.

STUDY DESIGN

To determine the efficacy of essential oils from three Zingiberaceae plants (Curcuma xanthorrhiza, Curcuma zedoaria and Zingiber zerumbet) against head lice eggs and to investigate an augmenting substance (Eucalyptus globulus EO) for improving the efficacy of these essential oils in killing head lice eggs, especially on the inhibition of their hatching process. Permethrin pediculicide, soyabean oil, and drinking water were used as positive, negative, and neutral controls, respectively.

METHODS

An immersion test was used to evaluate the ovicidal activity of 12 essential oil formulations. Head lice eggs were immersed for 1, 5 and 10 min in the treatments. Mortality rate was observed on day 7 and day 14; mortality was checked under a stereomicroscope.

RESULTS

All head lice eggs that were immersed in a combination of 10% C. zedoaria EO and 10% E. globulus EO for 5 min did not hatch at all for 7-14 days of incubation. All head lice eggs that were immersed in soyabean oil and drinking water for 1, 5, and 10 min showed 100% hatching rate in 7-14 days of incubation. All head lice eggs that were immersed in permethrin pediculicide for 1, 5 min, showed 100% hatching rate, but when they were immersed for 10 min, permethrin provided 4.0-6.0% inhibition rate with 94.0-96.0% hatching rate for 7-14 days of incubation. All combinations of Zingiberaceae EOs and E. globulus EO at low and high concentrations (5 and 10%) exhibited high ovicidal activities against head lice eggs, and the combinations showed a synergistic effect with an increase in the inhibition rate of more than 50%.

CONCLUSION

These results demonstrated that Zingiberaceae EOs augmented with E. globulus EO are promising ovicidal agents for head lice control.

Chemical Composition, Toxicity, and Acaricidal Activity of Eucalyptus Globulus Essential Oil from Algeria

The study was aimed at determining the chemical composition, toxicity effect and field varroacidal efficacy of the essential oil distilled from the leaf of Eucalyptus globulus (Eg) grown in Algeria. Brine shrimp lethality (BSL) assay and bee hives infected by Varroa destructor were used to assess the toxicity and acaricidal effect, respectively. Steam distillation of leaves yielded 0.93 % (v/w) of essential oil (EO). GC/MS Analysis revealed 39 compounds, essentially oxygenated monoterpenes (86.01%). The main constituents of the oil were 1,8-cineole (78.45 %), o-cymene (2.18 %), isopinocarveole (1.74 %), α-pinene (1.69 %), pinocarvone (1.34%) and veridiflorol (1.31%). The BSL assay revealed a highly toxic value of LC50 (67.55 μg/mL). Furthermore, field efficacy testing on bee hives infected with Varroa destructor has confirmed the effectiveness of Eucalyptus globulus essential oil (EgEO) or thymol as varroacidal agents. Moreover, a EgEO + thymol association was more effective than EgEO or thymol alone. Finally, the use of EgEO + thymol may constitute a viable alternative to the thymol-based commercial treatment

Biological, medicinal and toxicological significance of Eucalyptus leaf essential oil: a review

The genus Eucalyptus L'Heritier comprises about 900 species, of which more than 300 species contain volatile essential oil in their leaves. About 20 species, within these, have a high content of 1,8-cineole (more than 70%), commercially used for the production of essential oils in the pharmaceutical and cosmetic industries. However, Eucalyptus is extensively planted for pulp, plywood and solid wood production, but its leaf aromatic oil has astounding widespread biological activities, including antimicrobial, antiseptic, antioxidant, chemotherapeutic, respiratory and gastrointestinal disorder treatment, wound healing, and insecticidal/insect repellent, herbicidal, acaricidal, nematicidal, and perfumes, soap making and grease remover. In the present review, we have made an attempt to congregate the biological ingredients of leaf essential oil, leaf oil as a natural medicine, and pharmacological and toxicological values of the leaf oil of different Eucalyptus species worldwide. © 2017 Society of Chemical Industry.

Case report: a new method for treatment of permethrin - resistant head lice

Head lice (Pediculus humanus capitis) infestation is an important disease worldwide, especially in children under 11 years old. Permethrin is the most common insecticide for treatment of human pediculosis, but nowadays resistance to permethrin and other pyrethroids has caused many treatment failures. The second treatment of choice is malathion.

Chemical Variability and Biological Activities of Eucalyptus spp. Essential Oils

Many plant species produce mixtures of odorous and volatile compounds known as essential oils (EOs). These mixtures play important roles in Nature and have been utilized by mankind for different purposes, such as pharmaceuticals, agrochemicals, aromatherapy, and food flavorants. There are more than 3000 EOs reported in the literature, with approximately 300 in commercial use, including the EOs from Eucalyptus species. Most EOs from Eucalyptus species are rich in monoterpenes and many have found applications in pharmaceuticals, agrochemicals, food flavorants, and perfumes. Such applications are related to their diverse biological and organoleptic properties. In this study, we review the latest information concerning the chemical composition and biological activities of EOs from different species of Eucalyptus. Among the 900 species and subspecies of the Eucalyptus genus, we examined 68 species. The studies associated with these species were conducted in 27 countries. We have focused on the antimicrobial, acaricidal, insecticidal and herbicidal activities, hoping that such information will contribute to the development of research in this field. It is also intended that the information described in this study can be useful in the rationalization of the use of Eucalyptus EOs as components for pharmaceutical and agrochemical applications as well as food preservatives and flavorants.

Lethal and Inhibitory Activities of Plant-Derived Essential Oils Against Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) Biotype B in Tomato

The silverleaf whitefly Bemisia tabaci (Genn.) biotype B (Hemiptera: Aleyrodidae) is one of the most severe tomato pests in the world. The damage caused by this insect may compromise up to 100% of crop production, and management of this pest has relied on spraying of synthetic insecticides. However, due to the environmental issues associated with this practice, alternative methods such as the use of botanical pesticides are now used as a strategy of integrated pest management (IPM). We evaluated the effects of essential oils of five plant species on B. tabaci biotype B in tomato and demonstrate that the essential oils (0.5%) of Piper callosum (PC-EO), Adenocalymma alliaceum (AA-EO), Pelargonium graveolens (PG-EO), and Plectranthus neochilus (PN-EO) inhibit the settlement and oviposition of B. tabaci biotype B adults in tomato plants. In fumigation tests, A. alliaceum (AA-EO) at 0.4 μL/L of air after 72 h and 0.1 μL/L of air after 6 h was the most effective against nymphs and adults of B. tabaci biotype B, respectively. The major chemical constituents of PC-EO were identified as being safrole (29.3%), α-pinene (19.2%), and β-pinene (14.3%), whereas diallyl trisulfide (66.9%) and diallyl disulfide (23.3%) were the major compounds identified in AA-EO. This is the first report on the reduction of oviposition by the use of P. callosum (PC-EO) and A. alliaceum (AA-EO). In addition, the fumigant effect of A. alliaceum (AA-EO) on nymphs and adults has also been reported here for the first time.

Improving the effectiveness of three essential oils against Aedes aegypti (Linn.) and Anopheles dirus (Peyton and Harrison)

Repellency of essential oil extracted from Curcuma longa, Eucalyptus globulus, and Citrus aurantium at various concentrations (5, 10, 15, 20, and 25 %) with and without 5 % vanillin was evaluated against female mosquitoes: Aedes aegypti and Anopheles dirus. The comparisons were made with a commercial chemical repellent (N,N-diethyl-3-methylbenzamide (DEET) 25 % w/w; KOR YOR 15) by arm in cage method. It was found that the essential oils with 5 % vanillin gave the longest lasting period against two mosquitoes as follows: Curcuma longa gave 150 min for Ae. aegypti, 480 min for An. dirus; Eucalyptus globulus gave 144 min for Ae. aegypti, 390 min for An. dirus; and Citrus aurantium gave 120 min for Ae. aegypti, 360 min for An. dirus. The 25 % Curcuma longa essential oil exhibited the best efficiency as equal as a commercial repellent (480 min against An. dirus). Vanillin can extend the period of time in protection against the two mosquitoes. This study indicates the potential uses of the essential oils (Curcuma longa, Eucalyptus globulus, and Citrus aurantium) with vanillin as natural mosquito repellents.

In vitro acaricidal activity of 1,8-cineole against Sarcoptes scabiei var. cuniculi and regulating effects on enzyme activity

1,8-Cineole found in many essential oils is a monoterpene and acts as a repellent against Sarcoptes scabiei var. cuniculi. In the present study, the acaricidal activity of 1,8-cineole against S. scabiei var. cuniculi was evaluated and the acaricidal mechanism was also investigated by assaying enzyme activities. The results showed that the lethal concentration of 50% (LC50) value (95% confidence limit (CL)) and the lethal time of 50% (LT50) value (95% CL) of 1,8-cineole were 2.77 mg/mL and 3.606 h, respectively. The pathological changes under transmission electron microscopy showed that the morphology of the mitochondria was abnormal, the cell nuclear membrane was damaged, and the nuclear chromatin was dissoluted. The activities of superoxide dismutase (SOD), glutathione-s-transferases (GSTs), monoamine oxidase (MAO), nitric oxide synthase (NOS), and acetylcholinesterase (AChE) were significantly changed after treatment with 1,8-cineole for 4, 8, 12, and 24 h. SOD and GSTs are associated with the protection mechanism of scabies mites. And, the activities of SOD and GSTs were increased as compared with the control group. MAO, AChE, and NOS are associated with the nervous system of scabies mites. The activity of MAO was increased whereas the AChE was suppressed. The activity of NOS was suppressed in the high-dose group whereas increased in the middle-dose group and low-dose group. These results indicated that the mechanism of 1,8-cineole mainly attributed to the changes of these enzyme activities related to the nervous system of scabies mites.

Relative Toxicity of Leaf Extracts of Eucalyptus globulus and Centella asiatica against Mosquito Vectors Aedes aegypti and Anopheles stephensi

The larvicidal activity of different solvent leaf extracts (hexane, diethyl ether, dichloromethane, and methanol) of Eucalyptus globulus and Centella asiatica against two geographically different strains of Aedes aegypti and Anopheles stephensi was investigated. The extracts were tested against the late third instar larvae of Aedes aegypti and Anopheles stephensi, and larval mortality was observed after 24 hours of treatment. LC50 and LC90 were calculated. The LC50 values of hexane extract of Eucalyptus globulus against the late third instar larvae of the BSN and JPN strains of Aedes aegypti and the DLC and KNG strains of Anopheles stephensi were 225.2, 167.7, 118.8, and 192.8 ppm, while those of the hexane extract of Centella asiatica were 246.5, 268.7, 50.6, and 243.5 ppm, respectively. The LC50 values of diethyl ether extract of Centella asiatica were 339.6, 134.5, 241, and 14.7 ppm. The hexane extracts of both plants and the diethyl ether extract of C. asiatica presented the highest potential for the control of Aedes aegypti and Anopheles stephensi. The present findings also reveal the necessity of assaying multiple strains of a species to fully comprehend the larvicidal efficacy of a compound.

Repellency of cassia bark, eucalyptus, and star anise oils and their major constituents to Leptotrombidium pallidum (Acari: Trombiculidae)

Leptotrombidium pallidum (Nagoya, Miyagawa, Mitamura & Tamiya) is a primary vector of Orientia tsutsugamushi (Hyashi), the causative agent of scrub typhus. An assessment is made of the repellency to L. pallidum larvae (chiggers) of cassia bark, eucalyptus, and star anise oils and major constituents (E)-cinnamaldehyde, 1,8-cineole, and (E)-anethole of the corresponding oils. Results were compared with those of conventional repellents DEET (N,N-diethyl-3-methylbenzamide), IR3535 [(ethyl 3-[acetyl(butyl)amino]propanoate)], and permethrin. Based on the median repellent concentration (RC50) values, (E)-cinnamaldehyde, (E)-anethole, cassia bark oil, and star anise oil (RC50, 0.95-1.52 mg/cm2) exhibited significantly more potent repellency than DEET (3.85 mg/cm2). (E)-cinnamaldehyde, (E)-anethole, cassiabark oil, 1,8-cineole, and star anise oil were approximately 43, 16, 11, 8, and 4 times more effective than IR3535 (CC5, 6.51%) as judged by the median climbing distance-disturbing concentration (CC50) values. The median residual duration time of repellency (RT50) was significantly more pronounced in DEET (RT50, 323 min) than in all essential oils and constituents (108-167 min). In the light of global efforts to reduce the level of highly toxic synthetic repellents, the three essential oils and their major constituents described merit further study as potential biorepellents for the control of L. pallidum populations.

Toxicity of Zanthoxylum piperitum and Zanthoxylum armatum oil constituents and related compounds to Stomoxys calcitrans (Diptera: Muscidae)

Zanthoxylum plants (Rutaceae) have drawn attention because they contain insecticidal principles against insects. An assessment was made of the insecticidal and acetylcholinesterase (AChE) inhibitory activities of Zanthoxylum piperitum steam distillate and Zanthoxylum armatum seed oil, their 28 constituents, and eight structurally related compounds against female stable fly, Stomoxys calcitrans (L.). Results were compared with those of two organophosphorus insecticides chlorpyrifos and dichlorvos. Potent fumigant toxicity was observed with cuminaldehyde, thymol, (1S)-(-)-verbenone, (-)-myrtenal, carvacrol, (S)-(Z)-verbenol, Zanthoxylum piperitum steam distillate, cuminyl alcohol, Zanthoxylum armatum seed oil, piperitone, (-)-(Z)-myrtanol, and citronellal (LC50, 0.075-0.456 microg/cm3). However, they were five orders of magnitude less toxic than either chlorpyrifos or dichlorvos. An in vitro bioassay using female fly heads indicates that strong AChE inhibition was produced by citronellyl acetate, alpha-pinene, thymol, carvacrol, and alpha-terpineol (1.20-2.73 mM), but no direct correlation between fly toxicity and AChE inhibition by the test compounds was observed. Structure-activity relationships indicate that structural characteristics, such as carbon skeleton, degrees of saturation and types of functional groups, and vapor pressure parameter, appear to play a role in determining toxicities of the test monoterpenoids to stable flies. Global efforts to reduce the level of highly toxic synthetic insecticides in the agricultural environment justify further studies on Z. piperitum and Z. armatum oil-derived materials as potential insecticides for the control of stable fly populations.

Compositional analysis and insecticidal activity of Eucalyptus globulus (family: Myrtaceae) essential oil against housefly (Musca domestica)

The essential oil of Eucalyptus globulus (Myrtales: Myrtaceae) was evaluated for its chemical composition and insecticidal activity against the housefly, Musca domestica L. (Diptera: Muscidae). Chemical composition of E. globulus oil revealed 1,8-cineole (33.6%), α-pinene (14.2%) and d-limonene (10.1%) as major constituents, while vapour profile of E. globulus oil determined through solid phase microextraction (SPME) analysis showed 1,8-cineole (56.5%), α-pinene (16.9%), d-limonene (5.5%) and linalool acetate (3.4%) as principal components. Vapour phase of the oil showed increase in the contents of oxygenated monoterpenes. Insecticidal activity of E. globulus oil was assessed against larvae and pupae of housefly, through two different bioassays: contact toxicity and fumigation. Contact toxicity assay with larva showed lethal concentration, LC(50), between 2.73 and 0.60μl/cm(2) for different observation days while lethal time, LT(50), varied between 6.0 and 1.7 days. In fumigant assay for housefly larvae, LC(50) values of 66.1 and 50.1μl/l were obtained in 24h and 48h, respectively. Oil treated larvae showed surface shrinkage, spinous cells proliferation and bleb formation in scanning electron microscopy (SEM) observation. Pupicidal effectivity was measured in terms of percentage inhibition rate (PIR) which was 36.0-93.0% for contact toxicity and 67.9-100% for fumigation toxicity assay. Considerable activity of E. globulus oil against larvae and pupae of housefly demonstrates its potentiality as a viable option for the development of eco-friendly product for housefly control.

Fresh, dried or smoked? Repellent properties of volatiles emitted from ethnomedicinal plant leaves against malaria and yellow fever vectors in Ethiopia

BACKGROUND

In the search for plant-based mosquito repellents, volatile emanations were investigated from five plant species, Corymbia citriodora, Ocimum suave, Ocimum lamiifolium, Olea europaea and Ostostegia integrifolia, traditionally used in Ethiopia as protection against mosquitoes.

METHODS

The behaviour of two mosquitoes, the malaria vector Anopheles arabiensis and the arbovirus vector Aedes aegypti, was assessed towards volatiles collected from the headspace of fresh and dried leaves, and the smoke from burning the dried leaves in a two-choice landing bioassay and in the background of human odour.

RESULTS

Volatile extracts from the smoke of burning dried leaves were found to be more repellent than those from fresh leaves, which in turn were more repellent to mosquitoes than volatiles from dried leaves. Of all smoke and fresh volatile extracts, those from Co. citriodora (52-76%) and Oc. suave (58-68%) were found to be the most repellent, Os. integrifolia (29-56%) to be intermediate while Ol. europaea (23-40%) and Os. integrifolia (19-37%) were the least repellent. One volatile present in each of the fresh leaf extracts of Co. citriodora, Oc. suave and Os. integrifolia was ß-ocimene. The levels of ß-ocimene reflected the mosquito repellent activity of these three fresh leaf extracts. Female host-seeking mosquitoes responded dose-dependently to ß-ocimene, both physiologically and behaviourally, with a maximal behavioural repulsion at 14% ß-ocimene. ß-ocimene (14%) repels mosquitoes in our 6-minute landing assays comparable to the synthetic insect repellent N,N-diethyl-m-toluamide (10% DEET).

CONCLUSIONS

Volatiles in the smoke of burning as well as fresh leaves of Co. citriodora and Oc. suave have significant repellent properties against host seeking An. arabiensis and Ae. aegypti mosquitoes. ß-ocimene, present in the fresh leaf headspace of Co. citriodora, Oc. suave and Os. integrifolia, is a significantly effective volatile mosquito repellent in the laboratory. In addition to its repellent properties, ß-ocimene has long approved safe for use in food and cosmetics, making this volatile an intriguing compound to pursue in further tests in the laboratory and field to validate its mosquito repellent activity and potential for use in a commercial product. Also, the landing bioassay with humanised membranes is a potentially useful repellent screening technique that does not require the exposure of humans to the vectors, however further tests in parallel with conventional techniques are advised.

Insecticidal compounds from the essential oil of Chinese medicinal herb Atractylodes chinensis

BACKGROUND

In a screening programme for new agrochemicals from Chinese medicinal herbs, the essential oil of Atractylodes chinensis (DC.) Koidz was found to possess strong insecticidal activity against the common vinegar fly, Drosophila melanogaster L. The essential oil was extracted via hydrodistillation, and its constituents were determined by GC-MS analysis.

RESULTS

The main components of A. chinensis essential oil were β-eudesmol (21.05%), β-selinene (11.75%), γ-elemene (7.16%) and isopetasam (5.36%). Bioactivity-directed chromatographic separation on repeated silica gel columns led to the isolation of five compounds, namely atractylon, α-elemol, β-eudesmol, hinesol and β-selinene. β-Selinene, α-elemol and hinesol showed pronounced contact toxicity against D. melanogaster adults, with LD(50) values of 0.55, 0.65 and 0.71 µg adult(-1) respectively. Atractylon and β-eudesmol were also toxic to the fruit flies (LD(50) = 1.63 and 2.65 µg adult(-1) respectively), while the crude oil had an LD(50) value of 2.44 µg adult(-1) .

CONCLUSION

The findings suggested that the essential oil of Atractylodes chinensis and its active constituents may be explored as natural potential insecticides.

Contact and fumigant toxicity of hexane flower bud extract of Syzygium aromaticum and its compounds against Pediculus humanus capitis (Phthiraptera: Pediculidae)

The head lice, Pediculus humanus capitis De Geer is an obligate ectoparasite of humans that causes pediculosis capitis, a nuisance for millions of people worldwide, with high prevalence in children. P. humanus capitis has been treated by methods that include the physical remotion of lice, various domestic treatments, and conventional insecticides. None of these methods render complete protection, and there is clear evidence for the evolution of resistance and cross-resistance to conventional insecticides. Non-toxic alternative options are hence needed for head lice treatment and/or prevention, and natural products from plants are good candidates for safer control agents that may provide good anti-lice activity. The plant extracts are good and safe alternatives due to their low toxicity to mammals and easy biodegradability. The present study carried out the pediculocidal activity using the hexane flower bud extract of Syzygium aromaticum (Myrtaceae) against P. humanus capitis examined by direct contact and fumigant toxicity (closed- and open-container methods) bioassay. The chemical composition of S. aromaticum flower bud hexane extract was analyzed by gas chromatography-mass spectrometry. The major chemical constituent (58.79%) of flower bud hexane extract S. aromaticum was identified as chavibetol (5-allyl-2-methoxyphenol) by comparison of mass spectral data and retention times. The hexane extract of S. aromaticum was subjected to gas chromatography analysis, and totally 47 compounds were detected, of which chavibetol was predominantly present. The other major constituents present in the hexane extract were eugenol acetate (phenol,2-methoxy-4-(2-propenyl)-,acetate (15.09%), caryophyllene-(I1) (2,6,10,10-tetramethyl bicyclo [7.2.0] undeca-1,6-diene (13.75%), caryophyllene oxide (3.04%), 2,6,6,9-tetramethyl-1,4,8-cycloundecatriene (1.67%), and copaene (1.33%). The filter paper contact bioassay study showed pronounced pediculicidal activity in the flower bud hexane extract of S. aromaticum. The toxic effect was determined for every five in an 80-min treatment. The result showed percent mortality of 40, 82, and 100 at 5, 10, and 20 min, and the median lethal time (LT(50)) value was 5.83 (0.5 mg/cm(2)); 28, 82, and 100 at 5, 10, and 30 min. (LT(50) = 6.54; 0.25 mg/cm(2)); and 13, 22, 42, 80, and 100 at 5, 10, 20, 40, and 80 min (LT(50) = 18.68; 0.125 mg/cm(2)), respectively. The vapor phase toxicity was tested at 0.25 mg/cm(2). There was a significant difference in pediculicidal activity of S. aromaticum extract against P. humanus capitis between closed- and open-container methods. Adult mortalities were determined for every five in 60 min (closed method) and for every ten in 180 min (open method). The closed method showed the percent mortality was 45, 88, and 100 at 5, 10, and 15 min (LT(50) = 5.39), respectively. In the open-container method, the percent mortality was observed 5, 20, 47, 84, and 100 at 10, 20, 60, 120, and 180 min (LT(50) = 47.91), respectively. The mortality was more effective in the closed containers than in open ones, indicating that the effect of hexane extract was largely a result of action in the vapor phase exhibited fumigant toxicity. Studies of anti-lice activity of extract provide the basis for preliminary conclusions of structure activity relationships; although no clear patterns can yet be drawn. We here attempt to provide a concise compilation of the available information on anti-lice activity of plant extracts and plant-derived compounds.

Perspectives for the use of plant extracts to control the cattle tick Rhipicephalus (Boophilus) microplus

The evolution of resistance of Rhipicephalus (Boophilus) microplus to synthetic acaricides has given rise to the need for new scientific investigations on alternative ways to control this tick. In this regard, various studies on plants have been developed in an attempt to find extracts with acaricidal properties. Evaluations on plant extracts for controlling R. (B.) microplus have grown intensely over the last decade. There are many advantages from using plant extracts: for example, they can be used in organic cattle farming or even replace synthetic acaricides and they are associated with lower environmental and food contamination, slower development of resistance and lower toxicity to animals and humans. In vitro studies on plant extracts have shown promising results, but most of these extracts have not been tested on animals to validate their use. Difficulties in preparing proper formulations, differences in the chemical composition of plants of the same species due to extrinsic and intrinsic factors and sparse information on active acaricide compounds are hindrances that need to be addressed in order to enable progress within this scientific field.

Repellent activity of essential oils and some of their individual constituents against Tribolium castaneum herbst

A tool for integrated pest management is the use of essential oils (EOs) and plant extracts. In this study, EOs from Tagetes lucida , Lepechinia betonicifolia , Lippia alba , Cananga odorata , and Rosmarinus officinalis , species grown in Colombia, were analyzed by gas chromatography-mass spectrometry. These oils as well as several of their constituents were tested for repellent activity against Tribolium castaneum , using the area preference method. The main components (>10%) found in EOs were methylchavicol, limonene/α-pinene, carvone/limonene, benzyl acetate/linalool/benzyl benzoate, and α-pinene, for T. lucida, L. betonicifolia, L. alba, C. odorata, and R. officinalis, respectively. All EOs were repellent, followed a dose-response relationship, and had bioactivity similar to or better than that of commercial compound IR3535. EOs from C. odorata and L. alba were the most active. Compounds from EOs, such benzyl benzoate, β-myrcene, and carvone, showed good repellent properties. In short, EOs from plants cultivated in Colombia are sources of repellents against T. castaneum.

Control of the myiasis-producing fly, Lucilia sericata, with Egyptian essential oils

BACKGROUND

Myiasis caused by Lucilia sericata (Diptera: Calliphoridae) is widely distributed throughout the world and affects both humans and animals. In addition, L. sericata larvae and adults may play a role in spreading causal agents of mycobacterial infections. Therefore, it is important to establish new and safe alternative methods of controlling this blowfly.

METHODS

The insecticidal effectiveness of four commercially available essential oils [lettuce (Lactuca sativa), chamomile (Matricaria chamomilla), anise (Pimpinella anisum), rosemary (Rosmarinus officinalis)] against third larval instars of L. sericata was evaluated. The effects of sublethal concentrations of these oils on pupation rates, adult emergences, sex ratios, and morphological anomalies were also determined.

RESULTS

The oils were highly toxic to L. sericata larvae, with median lethal concentrations (LC(50) ) of 0.57%, 0.85%, 2.74%, and 6.77% for lettuce, chamomile, anise, and rosemary oils, respectively. Pupation rates were markedly decreased after treatment with 8% lettuce oil, and adult emergence was suppressed by 2% lettuce and chamomile oils. Morphological abnormalities were recorded after treatment with all tested oils, and lettuce was the major cause of deformation. There was a predominance of males over females (4 : 1) after treatment with lower concentrations of chamomile and rosemary; such a skew toward males would lead to a population decline.

CONCLUSIONS

The four tested oils are inexpensive and may represent new botanical insecticides for controlling blowflies.

In vitro screening of anti-lice activity of Pongamia pinnata leaves

Growing patterns of pediculocidal drug resistance towards head louse laid the foundation for research in exploring novel anti-lice agents from medicinal plants. In the present study, various extracts of Pongamia pinnata leaves were tested against the head louse Pediculus humanus capitis. A filter paper diffusion method was conducted for determining the potential pediculocidal and ovicidal activity of chloroform, petroleum ether, methanol, and water extracts of P. pinnata leaves. The findings revealed that petroleum ether extracts possess excellent anti-lice activity with values ranging between 50.3% and 100% where as chloroform and methanol extracts showed moderate pediculocidal effects. The chloroform and methanol extracts were also successful in inhibiting nymph emergence and the petroleum ether extract was the most effective with a complete inhibition of emergence. Water extract was devoid of both pediculocidal and ovicidal activities. All the results were well comparable with benzoyl benzoate (25% w/v). These results showed the prospect of using P. pinnata leave extracts against P. humanus capitis in difficult situations of emergence of resistance to synthetic anti-lice agents.

Efficacy of a grapefruit extract on head lice: a clinical trial

Twenty children aging 2-9 years old--four boys with short hair and 16 girls with long hair--were included in a clinical test on the efficacy of a product against head lice (Pediculus humanus capitis). Their hair were exposed to Licatack, which is a recently developed new anti-louse medicinal product containing extracts of grapefruits besides high quality shampoo components. Prior to this field trial, the product Licatack was tested dermatologically to be skin safe receiving the grade "very good". The children's mothers combed the kids prior to the start of the test in order to confirm that they were all lice-infested. The obtained lice were used for in vitro tests. All children were heavily infested. After combing and preservation of the living lice, the hair was wet with tap water. Then, 50 ml of the Licatack shampoo was placed onto the top of each child's head. Then, the mothers distributed the rather fluid product all over the hair thoroughly from their base at the skin until the free end. During this process, a type of massage, the product became foamy and it was easily recognized where the product covered the hair, thus, avoiding untreated spots. The hair of half of the treated children were washed with tap water after 10 min of exposition; while in the other half of the children, the exposition period was prolonged to 20 min before washing. When combing the kids with a metal louse comb after the washing, the lice were found immobile and they did not recover during the following observation period of 4 h. Only two lice from the group with an exposition time of only 10 min showed some slight leg movements after they had been combed off, but they died within the next 2 h. Thus, this new anti-louse medicinal product has a very quick and efficient activity besides its advantages of being non-inflammable, skin safe, and nice smelling. None of the kids claimed any burning at the skin or other side effects, although the skin showed, prior to treatment, lots of scars due to louse bites. The dead lice always appeared considerably shrunken due to drying. The second treatment after 10 days revealed a few dead larval stages since, apparently, some larvae (apparently treated at an early stage of development when treated) had hatched from the extremely numerous nits in the period between first and second treatment. Experiments with cutoff nits, however, showed that the product also kills larval stages inside nits.

Chemical composition of Eucalyptus spp. essential oils and their insecticidal effects on Lutzomyia longipalpis

The chemical composition of essential oils from three species of plants belonging to the Eucalyptus genus was determined and, their insecticidal effects on egg, larva and adult phases of Lutzomyia longipalpis were assessed. The insects were collected in the municipality of Sobral in the State of Ceará, Brazil. Five treatments with different concentrations were performed along with two negative controls, distilled water and Tween 80 (3%), and a positive control, cypermethrin (0.196mg/ml). The tests were carried out in plastic pots internally coated with sterile plaster and filled with a substrate made of rabbit feces and crushed cassava leaves. The eggs, larvae and adults were sprayed with the oils. The hatched larvae were counted for 10 consecutive days and observed until pupation. Insect mortality was observed after 24, 48 and 72h. E. staigeriana oil was the most effective on all three phases of the insect, followed by E. citriodora and E. globulus oils, respectively. The major constituents of the oils were Z-citral and alpha-citral (E. staigeriana), citronellal (E. citriodora) and 1,8-cineole (E. globulus). The Eucalyptus essential oils constitute alternative natural products for the control of L. longipalpis since the median effective concentration (EC(50)) values revealed relevant action as compared with other natural products, some of their chemical constituents are already known for their insecticidal activity and these oils are produced in commercial scale in Brazil.

Lousicidal, ovicidal and repellent efficacy of some essential oils against lice and flies infesting water buffaloes in Egypt

The lousicidal and repellent effects of five essential oils were investigated for the first time against the buffalo louse, Haematopinus tuberculatus, and flies infesting water buffaloes in Qalyubia Governorate, Egypt. For the in vitro studies, filter paper contact bioassays were used to test the oils and their lethal activities were compared with that of d-phenothrin. Four minutes post-treatment, the median lethal concentration, LC50, values were 2.74, 7.28, 12.35, 18.67 and 22.79% for camphor (Cinnamomum camphora), onion (Allium cepa), peppermint (Mentha piperita), chamomile (Matricaria chamomilla) and rosemary oils (Rosmarinus officinalis), respectively, whereas for d-phenothrin, it was 1.17%. The lethal time (50) (LT50) values were 0.89, 2.75, 15.39, 21.32, 11.60 and 1.94 min after treatment with 7.5% camphor, onion, peppermint, chamomile, rosemary and d-phenothrin, respectively. All the materials used except rosemary, which was not applied, were ovicidal to the eggs of H. tuberculatus. Despite the results of the in vitro assays, the in vivo treatments revealed that the pediculicidal activity was more pronounced with oils. All treated lice were killed after 0.5-2 min, whereas with d-phenothrin, 100% mortality was reached only after 120 min. The number of lice infesting buffaloes was significantly reduced 3, 6, 4, 6 and 9 days after treatment with camphor, peppermint, chamomile, onion, and d-phenothrin, respectively. Moreover, the oils and d-phenothrin significantly repelled flies, Musca domestica, Stomoxys calcitrans, Haematobia irritans and Hippobosca equina, for 6 and 3 days post-treatment, respectively. No adverse effects were noted on either animals or pour-on operators after exposure to the applied materials. Consequently, some Egyptian essential oils show potential for the development of new, speedy and safe lousicides and insect repellents for controlling lice and flies which infest water buffaloes.

Ovicidal and adulticidal activities of Origanum majorana essential oil constituents against insecticide-susceptible and pyrethroid/malathion-resistant Pediculus humanus capitis (Anoplura: Pediculidae)

The toxicity of essential oil constituents from marjoram, Origanum majorana, to eggs and adult females of the susceptible KR-HL and dual malathion- and permethrin-resistant BR-HL strains of human head louse, Pediculus humanus capitis, was examined using contact + fumigant mortality bioassay. Results were compared with those following treatment with two pyrethroid pediculicides, d-phenothrin or pyrethrum. As judged by the lethal time to 50% mortality (LT(50)) values at the exposure rate of 0.25 mg/cm(2), 1,8-cineole (14.1 min) was the most toxic compound, followed by linalool (15.4 min) to KR-HL females. These compounds were faster acting than either d-phenothrin (24.1 min) or pyrethrum (33.4 min). Based on the lethal concentration causing 50% mortality (LC(50)) values, (-)-camphor (0.022 mg/cm(2)) was the most toxic compound, followed by linalool (0.035 mg/cm(2)), (-)-terpinen-4-ol (0.040 mg/cm(2)), alpha-terpineol (0.045 mg/cm(2)), and 1,8-cineole (0.068 mg/cm(2)) against KR-HL females. These monoterpenoids were less toxic than either d-phenothrin (LC(50), 0.0015 mg/cm(2)) or pyrethrum (0.0013 mg/cm(2)). However, the toxicities of these monoterpenoids were almost identical against females from either of the two strains, even though the BR-HL females exhibited high levels of resistance to d-phenothrin [resistance ratio (RR), 667] and pyrethrum (RR, 754). After a 24 h exposure to linalool, BR-HL egg hatch was inhibited 100 and 84% at 0.25 or 0.125 mg/cm(2), respectively, while (-)-terpinen-4-ol caused 94 and 69% inhibition of egg hatch at 0.25 and 0.125 mg/cm(2). alpha-Terpineol caused 88 and 76% inhibition of egg hatch at 0.5 and 0.25 mg/cm(2), respectively. Thus, certain monoterpenoids from O. majorana essential oil, particularly linalool, (-)-terpinen-4-ol and alpha-terpineol, merit further study as potential pediculicides and ovicides for the control of insecticide-resistant P. h. capitis populations as fumigants with contact action.