Effective Essential Oils Research Articles

Essential oils application as Bacillus cereus antispore agent in food hygiene

Adherence of Bacillus cereus spores to dairy industry equipment is a serious problem, causing food spoilage and, occasionally, outbreaks of foodborne diseases. Antimicrobial essential oils (EOs) have been proposed as an alternative to synthetic disinfectants due to their environmentally friendly properties. The aim of this study was to assess the effect of Cymbopogon winterianus and Juniperus phoenicea EOs on planktonic and adherent B. cereus spores to stainless steel surfaces. Eleven strains of B. cereus were used in this study. The chemical composition of the C. winterianus and J. phoenicea oils was analyzed by gas chromatography (GC)/mass spectrometry (MS). Ninety components were identified for C. winterianus, being geranial (37 %), neral (29 %), beta-myrcene (16 %) and geraniol (4 %) the most abundant constituents. Twelve components were identified for J. phoenicea, being alpha-pinene (65 %) the most abundant constituent. The results of the minimal inhibitory concentration and minimal bactericidal concentration revealed that C. winterianus was the most effective EO (p < 0.05) against all eleven strains. In addition, there was a large log10 reduction (from 4.93 to 2.42; p < 0.05) between spores in planktonic form versus spores adhered to stainless steel surface. C. winterianus can be used for effective detachment of B. cereus spores capable to adhere and form biofilms on stainless steel surfaces, being a valid alternative for the development of natural disinfectant that may reduce negative effects of synthetic chemical disinfectants.

Synergistic Effect of Essential Oils and Antifungal Agents in Fighting Resistant Clinical Isolates of Candida auris.

Recently, a large number of nosocomial infections have been caused by an emerging pathogen that is rising as a worldwide issue in human health: Candida auris. This yeast is considered resistant to antifungals of the first-line therapies, and consequently it is related to morbidity and mortality. Therefore, the aim of this research was to determine the in vitro anti-C. auris activity against twenty-three resistant clinical strains of different essential oils (EOs), pure or in combination with traditional antifungal agents, mainly caspofungin, fluconazole, micafungin and 5-flucytosine. Broth dilution assay was performed to evaluate the fungistatic and fungicidal effectiveness of fifteen EOs towards all the C. auris isolates. The data demonstrated that EOs were able to prevent C. auris growth, with MIC values ranging from 0.03 to 1% for the efficacious EOs (thyme, cinnamon, geranium, clove bud, lemongrass and mentha of Pancalieri), whereas the MICs were >1% for the ineffective ones. Thereafter, the six most effective EOs were used to perform the checkerboard experiments by assaying simultaneously the activity of EOs and traditional antifungals towards two selected strains. The most promising synergic combinations towards C. auris, depending on the isolate, were those with micafungin and geranium, thyme, cinnamon, lemongrass or clove bud EOs, with fluconazole and mentha of Pancalieri EO, and with 5-flucytosine and mentha of Pancalieri EO. These EOs and their combinations with antifungal drugs may provide a useful therapeutic alternative that could reduce the dose of the individual components, limiting the overall side effects. These associations might be a prospective option for the future treatment of infections, thus helping to overcome the challenging issue of resistance in C. auris.

Coatings Based on Essential Oils for Combating Antibiotic Resistance.

In the current era of widespread antimicrobial resistance, the utilization of essential oils (EOs) derived from plants has emerged as a promising alternative in combating pathogens that have developed resistance to antibiotics. This review explores the therapeutic potential of essential oils as valuable tools in restoring the efficacy of antibiotics, highlighting their unique ability to affect bacteria in multiple ways and target various cellular systems. Despite the challenge of elucidating their precise mode of action, EOs have shown remarkable results in rigorous testing against a diverse range of bacteria. This review explores the multifaceted role of EOs in combating bacterial microorganisms, emphasizing their extraction methods, mechanisms of action, and comparative efficacy against synthetic antibiotics. Key findings underscore the unique strategies EOs deploy to counter bacteria, highlighting significant differences from conventional antibiotics. The review extends to advanced coating solutions for medical devices, exploring the integration of EO formulations into these coatings. Challenges in developing effective EO coatings are addressed, along with various innovative approaches for their implementation. An evaluation of these EO coatings reveals their potential as formidable alternatives to traditional antibacterial agents in medical device applications. This renaissance in exploring natural remedies emphasizes the need to combine traditional wisdom with modern scientific advancements to address the urgent need for effective antimicrobial solutions in the post-antibiotic era.

Essential oil compounds modulate nutritional quality and stress response in Botrytis cinerea-infected grape (Vitis vinifera L. cv. ‘Karaerik’)

Grapes, rich in vitamins and minerals, could offer a healthy alternative. However, their potential contamination by the fungus Botrytis cinerea poses serious health risks, necessitating cautious consumption, particularly among those on restricted diets, to mitigate adverse effects. Therefore, the study investigated the effects of individual and combined application of individual components of essential oils (EOs) such as thymol, eugenol, and 1,8-cineole on various parameters such as antioxidant enzymes, mineral elements, anthocyanins, and phenolic compounds in the treatment of B. cinerea infection in 'Karaerik' grapes. Our study provided important information about physiology and pathogen response, and results indicated that the pathogen-infected groups had higher levels of oxidative stress indicators, such as proline, malondialdehyde (MDA), and hydrogen peroxide (H2O2). On the other hand, EOs elevate the activity of antioxidant enzymes, notably superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), whereas thymol treatments effectively reduced oxidative stress to levels comparable to the control group. Under thymol and eugenol treatments, nitrogen (N), potassium (K), phosphorus (P), calcium (Ca), magnesium (Mg), sulfur (S), zinc (Zn), manganese (Mn), boron were significantly higher than the control groups. Increases were also determined in the concentrations of mineral elements such as (B) and copper (Cu). Anthocyanin profiles were preserved by EO treatments, with combined EO applications yielding higher anthocyanin profiles percentages compared to individual treatments. In our results, there were notable differences in the overall quantities of phenolic compounds, and the combination of EO applications caused higher levels of phenolic compounds, especially in the groups that include the fungal infection. Overall, the study showed how effective EO treatments are at reducing B. cinerea infections and maintaining grape quality, which has significance for long-term disease control plans and maintaining berry quality in viticulture.

Antibacterial Activity of Some Iranian Herbal Essential Oils as Disinfectant Agents on Surfaces Contaminated with Methicillin -resistant -Staphylococcus Aureus and Carbapenem - resistant -Pseudomonas Aeruginosa

Background &amp; Objectives: Different essential oils (EOs) with antibacterial activities are promising natural sources for providing novel disinfectant agents for hospital surfaces Materials &amp; Methods: The component and antibacterial effects of six EOs, including Cuminum cyminum (CCEO), Artemisia sieberi (ASEO), Laurus nobilis (LNEO), Ferula gummosa (FGEO), Lippia citriodora (LCEO), and Cymbopogon citratus (CIEO) were assessed by GC -MS and 96 -well micro -plates (IC50), against Staphylococcus aureus (S. aureus) ATCC 25923, Pseudomonas aeruginosa (P. aeruginosa) ATCC 27853 and clinical isolates of methicillin -resistant S. aureus (MRSA) and metallo -beta -lactamase (MBL) -producing P. aeruginosa. Then, the antibacterial effects of FGEO, the most effective EO, were evaluated on the trolley surface in a hospital for 1, 3, 5 and 10 min intervals. Results: CCEO, ASEO, and FGEO exerted the highest antibacterial activity against S. aureus, while CIEO and LNEO inferred the highest activity against P. aeruginosa. In addition, FGEO mitigated the growth of S. aureus and P. aeruginosa on the trolley surface (P&lt;0.05). Conclusion : The studied EOs could be novel encouraging agents to develop further green antimicrobial agents against different infections. In addition, FGEO exhibited considerable antibacterial effects on the surface of the trolley.

In Vitro Evaluation of Synergistic Essential Oils Combination for Enhanced Antifungal Activity against Candida spp.

In recent years, a significant number of infections have been attributed to non-albicidal Candida species (NAC), mainly due to the increasing resistance of NAC to antifungal agents. As only a few antifungal agents are available (azoles, echinocandins, polyenes, allylamines and nucleoside analogues), it is very important to look for possible alternatives to inhibit resistant fungi. One possibility could be essential oils (EOs), which have been shown to have significant antifungal and antibacterial activity. Therefore, in this study, the efficacy of 12 EOs and their combinations was evaluated against four yeasts of the genus Candida (C. albicas, C. glabrata, C. tropicalis and C. parapsilosis). GC-MS and GC-MS FID techniques were used for the chemical analysis of all EOs. VITEK-2XL was used to determine the antifungal susceptibility of the tested Candida spp. strains. The agar disc diffusion method was used for primary screening of the efficacy of the tested EOs. The broth dilution method was used to determine the minimum inhibitory concentrations (MICs) of the most potent EOs. After MIC cultivation, the minimum fungicidal concentration (MFC) was determined on Petri dishes (60 mm). The synergistic effect of combined EOs was evaluated using the checkerboard method and expressed as a fractional inhibitory concentration index (FICI). The results showed that ginger > ho-sho > absinth > dill > fennel > star anise > and cardamom were the most effective EOs. For all Candida species tested, the synergy was mainly observed in these combinations: ginger/fennel for C. albicans FICI 0.25 and C. glabrata, C. tropicalis and C. parapsilosis FICI 0.5 and absinth/fennel for C. albicans FICI 0.3125, C. tropicalis FICI 0.3125 and C. parapsilosis FICI 0.375. Our results suggest that the resistance of fungal pathogens to available antifungals could be reduced by combining appropriate EOs.

Influence of molecular descriptors of plant volatilomics on fumigant action against the three major stored product beetle pests.

Plant volatilomics such as essential oils (EOs) and volatile phytochemicals (PCs) are known as potential natural sources for the development of biofumigants as an alternative to conventional fumigant pesticides. This present work was aimed to evaluate the fumigant toxic effect of five selected EOs (cinnamon, garlic, lemon, orange, andpeppermint) and PCs (citronellol, limonene, linalool, piperitone, andterpineol) against the Callosobruchus maculatus, Sitophilus oryzae, and Tribolium castaneum adults. Furthermore, for the estimation of the relationship between molecular descriptors and fumigant toxicity of plant volatiles, quantitative structural activity relationship (QSAR) models were developed using principal component analysis and multiple linear regression. Amongst the tested EOs, garlic EO was found to be the most toxic fumigant. The PCs toxicity analysis revealed that terpineol, limonene, linalool, and piperitone as potential fumigants to C. maculatus (< 20 µL/L air of LC50), limonene and piperitone as potential fumigants to T. castaneum (14.35 and 154.11 µL/L air of LC50, respectively), and linalool and piperitone as potential fumigants to S. oryzae (192.27 and 69.10 µL/L air of LC50, respectively). QSAR analysis demonstrated the role of various molecular descriptors of EOs and PCs on the fumigant toxicity in insect pest species. In specific, dipole and Randic index influence the toxicity in C. maculatus, molecular weight and maximal projection area influence the toxicity in S. oryzae, and boiling point and Dreiding energy influence the toxicity in T. castaneum. The present findings may provide insight of a new strategy to select effective EOs and/or PCs against stored product insect pests.

Insecticidal Activity of Essential Oils and Their Synergistic Effect on Improving the Efficacy of β-Cypermethrin against Blattella germanica.

We screened the contact activity of 32 commercial essential oils (EOs) and their synergistic effect with β-cypermethrin against Blattella germanica. Results showed that the most effective EOs against B. germanica were from Illicium verum, Syzygium aromaticum, and Cinnamomum camphora, with LD50 values of less than 500 μg/insect. The most potent synergistic effects of β-cypermethrin on B. germanica were from Dysphania ambrosioides and Mentha canadensis. Both oils have a co-toxic factor of 133.33. The results of the major compound testing of the EOs showed that trans-anisaldehyde and thymol have the best insecticidal activity against B. germanica, with LD50 values of 141.30 and 138.61 μg/insect, respectively. The compounds with the best synergistic effect on β-cypermethrin were γ-terpinene and linalool at a concentration of 0.5%. The co-toxic factors for γ-terpinene and linalool were 150 and 133.33, respectively, which were similar to the synergistic effect observed with 2% piperonyl butoxide.

The efficiency of Thymus vulgaris, Lavandula angustifolia, and Cupressus sempervirens essential oils in suppression of Hymenoscyphus fraxineus on Fraxinus angustifolia seedlings

AbstractDue to intense ash dieback, this research tested the bioactivity of Thymus vulgaris, Lavandula angustifolia, and Cupressus sempervirens essential oils (EO) against Hymenoscyphus fraxineus. In vitro testing showed that EOs had a pronounced fungitoxic effect on H. fraxineus. The most effective EO was extracted from T. vulgaris, while EOs obtained from L. angustifolia and C. sempervirens were less effective and showed the same effect. At a concentration of 1%, all tested EOs inhibited mycelial growth, while 0.01% and 0.1% concentrations of EO extracted from T. vulgaris also inhibited the growth of H. fraxineus. The in planta test of EO extracted from T. vulgaris conducted on three‐year‐old Fraxinus angustifolia seedlings showed a reduction in the size of necrotic lesions and a better crown condition compared to untreated seedlings. This research demonstrates, for the first time, the efficiency of EOs in suppressing ash dieback making a path for the development of new biological protection measures against H. fraxineus.

IN VITRO ANTIFUNGAL ACTIVITY OF ESSENTIAL OILS (FAMILY LAMIACEAE) AGAINST CLADOSPORIUM SP. STRAINS – POSTHARVEST PATHOGENS OF FRUITS

Essential oils (EOs) are a suitable alternative for extending the shelf life of foods. The aim of this research was to test the effect of fifteen EOs extracted from plants of the Lamiaceae family on five strains of Cladosporium cladosporioides. Cladosporium cladosporioides is frequently found on fruit and may be involved in fruit spoilage. The strains used in the study were isolated directly from lesions on berries. The growth of the fungi on the fruit was the reason for its rejection from sale. The antifungal activity of EOs against Cladosporium cladosporioides strains was determined by the microatmospheric method (625 μl EO/L air) during 14 days of cultivation. Thirteen EOs: thyme and red thyme (from Thymus vulgaris L.), mitcham mint (Mentha x piperita L. var. Mitcham), peppermint (Mentha x piperita L.), savory (Satureja hortensis L.), sage (Salvia officinalis L.), spearmint (Mentha spicata L. var. crispa), lavender (Lavandula angustifolia Mill.), marjoram (Origanum majorana L.), bergamot-mint (Mentha citrata Erh.), wild thyme (Thymus serpyllum L.), hyssop (Hyssopus officinalis L.), and oregano (Origanum vulgare L.) were shown to inhibit growth of all strains to 100%. Basil (Ocinum basilicum L.) and rosemary (Rosmarinus officinalis L.) EOs did not have a 100% inhibitory effect on all strains throughout the cultivation period. Subsequently, minimum inhibitory concentrations (MIDs) were determined using the microatmospheric method. LD90 and LD50 values were estimated by probit analysis. Based on the MID, LD90, and LD50 results, the essential oils can be divided into three groups. The first group (most effective): thyme, red thyme, spearmint, wild thyme, and oregano EO; the second group: peppermint, lavender, mitcham mint and savory EO; the third group: sage, marjoram, bergamot-mint and hyssop EO. The most effective EOs can be used to suppress the growth of Cladosporium cladosporioides in the vapour phase.

The potency and effectiveness of six essential oils in controlling grapevine trunk diseases in Morocco

The objective of this study was to evaluate the antifungal activity (AA) of essential oils (EOs) extracted from Eucalyptus globulus Labill. (Eucalyptus), Citrus limonum (L.) Burm. (Lemon), Cinnamomum zeylanicum Blume. (Cinnamon), Lavandula latifolia aspic (Lavender), Rosmarinus officinalis L. (Rosemary), and Mentha spicata L. (Peppermint) against four pathogenic fungi responsible for grapevine trunk diseases in Moroccan vineyards. The EOs with the highest in vitro efficacy were selected for further testing on autoclaved grape wood assays against Diplodia mutila, Neoscytalidium novaehollandiae, Trichothecium roseum, and Neopestalotiopsis vitis. The major chemical constituents of the tested EOs were determined through GasChromatography–Mass Spectrometry (GC-MS) analysis, and their relative percentages were recorded. All tested EOs demonstrated significant antifungal activity against the four pathogens, as evidenced by in vitro results. Redundancy analysis (RDA) confirmed the efficacy of the tested EOs against grapevine fungal pathogens. The efficacy of each EO varied depending on the pathogen being targeted. For example, lavender had the highest efficacy across EOs (81.37%) against T. roseum, while peppermint was the most effective in inhibiting D. mutila (47.45%). Cinnamon was the most effective EO in controlling N. vitis (73.33%), while rosemary had the best effect in controlling N. novaehollandiae (56.79%), with the most effective EC50 value (8.66 µL/ml) being attributed to the rosemary EO. The in vitro results were further confirmed through autoclaved grape wood assays, with inhibition of proliferation ranging between 93.14% and 66.32%. These findings represent a novel application of EOs extracted from various medicinal plants to control fungal diseases in grapevine plantations.

Multidrug resistant and multivirulent avian bacterial pathogens: tackling experimental leg disorders using phytobiotics and antibiotics alone or in combination

Locomotor disorders caused by multidrug-resistant (MDR) bacterial pathogens denote one of the most detrimental issues that collectively threaten the poultry industry leading to pronounced economic losses across the world. Hence, searching for effective alternatives, especially those extracted from plant origins became of great priority targeting a partial or complete replacement of chemical antimicrobials to tackle their developing resistance. Therefore, we aimed to determine the prevalence and antimicrobial resistance of Staphylococcus aureus (S. aureus), Salmonella species, Mycoplasma synoviae (M. synoviae), and Escherichia coli (E. coli) recovered from 500 broilers and ducks (250 each) with locomotor disorders in various farms in Dakahlia and Sharkia Governorates, Egypt. Additionally, we assessed, for the first time, the in vitro antimicrobial effectiveness of marjoram, garlic, ginger and cinnamon essential oils (EOs) against MDR and multivirulent bacterial isolates as well as the in vivo efficiency of the most effective antibiotics and EOs either separately or in combination in the treatment of experimentally induced poultry leg disorders. The overall prevalence rates of S. aureus, E. coli, Salmonella species, and M. synoviae were 54, 48, 36, and 2%, respectively. Salmonella species and S. aureus prevailed among ducks and broilers (36 and 76%, respectively). Notably, MDR was observed in 100, 91.7, 81.1, and 78.5% of M. synoviae, E. coli, Salmonella, and S. aureus isolates, respectively. Our in vitro results displayed that marjoram was the most forceful EO against MDR and multivirulent chicken vancomycin-resistant S. aureus (VRSA) and duck S. Typhimurium isolates. The current in vivo results declared that marjoram in combination with florfenicol or amoxicillin/clavulanic acid succeeded in relieving the induced duck and chicken leg disorders caused by S. Typhimurium and VRSA, respectively. This was evidenced by improvement in the clinical and histopathological pictures with a reduction of bacterial loads in the experimental birds. Our encountered successful in vitro and in vivo synergistic effectiveness of marjoram combined with florfenicol or amoxicillin/clavulanic acid recommends their therapeutic application for leg disorders and offers opportunities for reducing the antibiotics usage in the poultry industry.

Antibacterial effect of essential oils and their components against Xanthomonas arboricola pv. pruni revealed by microdilution and direct bioautographic assays.

Bacterial spot of stone fruits caused by Xanthomonas arboricola pv. pruni (Xap) is one of the most significant diseases of several Prunus species. Disease outbreaks can result in severe economic losses while the control options are limited. Antibacterial efficacy of essential oils (EOs) of thyme, cinnamon, clove, rosemary, tea tree, eucalyptus, lemon grass, citronella grass, and lemon balm was assessed against two Hungarian Xap isolates. The minimal inhibitory concentration (MIC) was determined by broth microdilution assay and for the identification of active EOs' components a newly introduced high-performance thin-layer chromatography (HPTLC)-Xap (direct bioautography) method combined with solid-phase microextraction-gas chromatography/mass spectrometry (SPME-GC/MS) was applied. All EOs inhibited both bacterium isolates, but cinnamon proved to be the most effective EO with MIC values of 31.25 µg/mL and 62.5 µg/mL, respectively. Compounds in the antibacterial HPTLC zones were identified as thymol in thyme, trans-cinnamaldehyde in cinnamon, eugenol in clove, borneol in rosemary, terpinen-4-ol in tea tree, citral (neral and geranial) in lemon grass and lemon balm, and citronellal and nerol in citronella grass. Regarding active compounds, thymol had the highest efficiency with a MIC value of 50 µg/mL. Antibacterial effects of EOs have already been proven for several Xanthomonas species, but to our knowledge, the studied EOs, except for lemon grass and eucalyptus, were tested for the first time against Xap. Furthermore, in case of Xap, this is the first report demonstrating that direct bioautography is a fast and suitable method for screening anti-Xap components of complex matrices, like EOs.

THE IN VITRO ANTIFUNGAL AND SYNERGISTIC ACTIVITY OF SELECTED PLANT EXTRACTS AND ESSENTIAL OILS AGAINST CANDIDA SPP.

This study aimed to evaluate the antifungal activity and the potential synergistic activity of ten plant extracts (EXs) and ten essential oils (EOs) obtained from the same plant species, namely Agrimonia eupatoria L., Arctium lappa L., Arnica montana L., Bidens cernua L., Corylus avellana L., Echinacea purpurea L. (Moench), Menta piperita L., Trifolium pratense L., Syzygium aromaticum L., and Angelica sinensis (Oliv.) Diels were used. Three species of the genus Candida, namely C. albicans, C. glabrata, and C. tropicalis, isolated from polluted estuarine water, were used in this study. The chemical composition of all EOs was evaluated by gas chromatography coupled with mass spectrometry (GC–MS) and gas chromatography with flame ionization detector (GC–FID) analysis. Firstly, the susceptibility of Candida spp. strains to EXs and EOs was screened by the agar disc diffusion method. Then the minimum inhibitory concentration (MIC) of the tested EXs and EOs was determined in a concentration range from 256 to 0.125 µL/mL. Following that, the effective EXs and EOs were divided into two groups (strong effect and weak effect) and tested in combination (strong + weak) at various concentrations depending on the tested strain to determine their potential synergistic effect using the chessboard pattern. The most sensitive strain to treatments with EXs and EOs tested alone and in mixtures was C. albicans. The most potent combinations with other EXs/EOs were observed with Syzygium aromaticum L., for both plant extract and essential oil, respectively. In this study the EOs and EXs tested in combination were much more effective than when acting on the growth of Candida spp. separately. So, the synergistic effect of the combinations of the EXs and EOs can lead to a reduction in the doses of commercial antifungals and can provide an effective way to reduce the infections caused by yeasts of the genus Candida.

Cleaner production of essential oils from Indian basil, lemongrass and coriander leaves using ultrasonic and ohmic heating pre-treatment systems

Indian basil (Ocimum basillicum), lemongrass (Cymbopogon flexuosus) and coriander (Coriandrum sativum) leaves are a good source of aromatic oils; however, their extraction volume is low. Hence, two pre-treatment systems (ohmic-heating and ultrasonic) were devised for extraction of essential oils (EO) from the leaves of these three plant spp., which consequently enhanced the EO yield and saved the time and energy. First of all, an experimental set-up was developed for ohmic-heating pre-treatment which was subjected to the optimization of electric conductivity of lemongrass and coriander leaves at 26.25 V/cm and for Indian basil at 22.5 V/cm voltage gradient. An Experimental setup was also developed for ohmic heating-assisted hydro-distillation (OHD). Finally, conventional Clevenger hydro-distillation (CHD), OHD, ultrasonic-assisted conventional hydro-distillation (UACHD) and ultrasonic-assisted ohmic-heating hydro-distillation (UAOHD) methods were evaluated for their effectiveness in the extraction of the EOs. The OHD took 3.5 h time with 410 W power consumption compared to 5 h time and 500 W power consumption in CHD of sleeted leaves. Likewise, a saving of ~ 86% in time and 74% in energy consumption was observed for EO extraction through UAOHD over CHD. Quantity of EOs extracted from all three aromatic plant spp. leaves followed the trend of UAOHD > UACHD > OHD > CHD methods, respectively. Overall, ultrasonic pre-treatment coupled with ohmic-heating assisted hydro-distillation (UAOHD) proved as an innovative and effective clean EO extraction technology which took shorter extraction time and lesser energy consumption with better EO yield over the UACHD, OHD and CHD methods from the leaves of Indian basil, lemongrass and coriander.

Bioefficacy of essential oils emulsion and predatory mite, Euseius scutalis (Athias-Henriot) (Acari: Phytoseiidae) for the management of citrus brown mite, Eutetranychus orientalis (Klein) (Acari: Tetranychidae)

The citrus brown mite, Eutetranychus orientalis (Klein), is a significant pest that is widely distributed in different agricultural systems. It causes significant damage to field crops and fruit trees. The most common method of control is the use of chemical acaricides. However, the extensive use of such chemicals developed resistance in addition to environmental and health hazards. Plant-derived acaricides might therefore be an environmentally friendly alternative to synthetic ones in order to increase agricultural production efficiency and to protect consumer health. Following this prospective, the present study was aimed to evaluate the toxic effects of anise (Pimpinella anisum), rosemary (Rosmarinus officinalis), eucalyptus (Eucalyptus globulus), clove (Eugenia caryophyllus), and garlic (Allium sativum) essential oils (EO) against the eggs and adult’s females of E. orentalis under laboratory conditions. Additionally, Euseius scutalis, a predator mite, was investigated as a bioagent to control E. orientalis under field conditions. GC-MS was used to assess the chemical components of the tested EOs. The results showed that anethole; 9, 12-Octadecadienoic acid (Z, Z); camphor; octatriacontyl pentafluoropropiona; and eugenol, were the major components for anise, rosemary eucalyptus, garlic, and cloves, respectively. Comparably, anise has been shown to be the most effective EO against E. orentalis eggs and adults as it exhibited a high level of efficiency and required the lowest concentration to reach the LC50. Additionally, the three Euseius scutalis release rates significantly reduced the Eutetranychus orientalis population. Ten individuals /seedlings in particular induced the highest reduction (84.95%). Based on our findings, we suggest using Euseius scutalis release and anise essential oil as alternative strategies to control of E. orentalis.

SELECTED PLANT ESSENTIAL OILS OF THE LAMIACEEAE AND APIACEAE FAMILY AS THE ANTIFUNGAL AGENTS IN THE VAPOUR PHASE AGAINST RHIZOPUS STOLONIFER AND RHIZOPUS ORYZAE ISOLATED FROM MOULDING BREADS

Species of the Rhizopus genus are often involved in the moulding of bread and bakery products. Essential oils (EOs) are a suitable alternative to extend the shelf life of food. This research was focused on testing the effect of selected EOs on the growth of Rhizopus species. Tested strains were isolated from mouldy breads. The antifungal activity of EOs against R. stolonifer and R. oryzae strains was determined by micro-atmospheric method (625 μL EO/L air) during 7 days of cultivation. Eight EOs, thyme, red thyme, savory, caraway, marjoram, wild thyme, and oregano 100% inhibited the growth of all strains. Basil, sage, and anise EOs only partially inhibited the growth of strains. Subsequently, the minimum inhibitory doses were determined using micro-atmospheric method. Minimal inhibition doses were 250 μL/L for thyme and red thyme EO, 250 and 500 μL/L for savory EO, 250 and 500 μL/L for oregano EO, 500 and ˃500 μL/L for wild thyme EO, ˃500 μL/L for caraway and marjoram EOs. Strains of the genus Rhizopus reacted differently to the presence of EOs. Thyme and red thyme were evaluated as the most effective EOs in this study.

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

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

Synergistic properties of essential oils of eucalyptus (Eucalyptus globulus) and lemon grass (Cymbopogon flexuosus) against cattle tick, Rhipicephalus microplus

ABSTRACT The anti-tick efficacy of eight commercially available essential oils (EOs), viz., Neem (Azadirachta indica), castor (Ricinus communis L.), lemon grass (Cymbopogon flexuosus), eucalyptus (Eucalyptus globulus), curry leaves (Murraya koenigii), garlic (Allium sativum), sage (Salvia officinalis), and rosemary (Rosmarinus officinalis), was screened in vitro against Rhipicephalus microplus ticks. Each of the EOs were diluted in 2% Triton X-100 and 10% ethanol to prepare working concentrations and were tested against IVRI-I strain of Rhipicephalus microplus. The mortality, egg masses, and inhibition of oviposition (IO) were used to determine treatment effectiveness. The EOs of C. flexuosus, E. globulus, S. officinalis, and R. officinalis showed more than 95% efficacy at the tested concentrations. While, EOs of A. indica, R. communis, M. koenigii, and A. sativum were found 16–33% efficacious. Six different combinations of the most effective EOs (C. flexuosus and E. globulus) were prepared and tested for anti-tick activity. The combination C, F, and H showed 100% mortality at 4% concentration. The combination H was found more economical than ivermectin for animal treatment indication that it can be used effectively for the development of potent antitick formulation for the management of tick populations.

Determination of chemical compositions and antibacterial effects of selected essential oils against human pathogenic strains.

Increasing the rates of drug resistant bacteria, having adverse effects and also high costs of antibiotics lead to essential oils (EOs) with antibacterial properties have gained importance. The present study was predicted to evaluate antibacterial activity of cinnamon, lavender, tea tree, lemon, coconut, oregano, mint, laurel and eucalyptus EOs alone and in combination. Chemical components of effective EOs were examined through gas chromatography/mass spectrometry (GC/MS). Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) assays were used to identify antibacterial effects of EOs against bacterial strains. The Fractional Inhibitory Concentration index (FICI) of the binary combinations of EOs was determined by checkerboard method. Carvacrol, linalool, linalyl acetate, 1,8-cineole, cinnamaldehyde, terpinen-4-ol and p-cymene were found main components of EOs. Oregano, cinnamon and tea tree EOs exhibited the strongest antibacterial activity with the MIC range between 0.03125-1.00% (v/v). Tea tree/lavender and cinnamon/lavender mixtures showed a synergistic effect against Streptococcus pyogenes and Streptococcus agalactiae. Oregano with tea tree and laurel exhibited a synergistic effect against Staphylococcus aureus. Oregano showed a synergistic effect when combined with cinnamon, lavender and tea tree against S.agalactiae. Our findings indicated that EOs either alone or in combination against pathogens should be preferred as potential antibacterial agents.