Evaluation of some essential oils as botanical fungitoxicants in management of post-harvest rotting of citrus fruits

During screening of some essential oils against Penicillium italicum, the oils of Mentha arvensis, Ocimum canum and Zingiber officinale were found to exhibit absolute fungitoxic activity against the test fungus. The oils were subsequently standardized through physico-chemical and fungitoxic properties. Practical applicability of the essential oils was observed in control of blue mould rot of oranges and lime fruits caused by P. italicum during storage. The Mentha oil-treated oranges and lime fruits showed enhancement of storage life of 6 and 8 days, respectively. The storage life of Ocimum oil-treated oranges and lime fruits was found to be enhanced by 6 days while in the case of Zingiber oil, it was 4 and 8 days enhancement of shelf life of oranges and lime fruits, respectively. This revised version was published online in August 2006 with corrections to the Cover Date.     

Acute toxicity of kaolin and essential oils from Mentha pulegium and Zingiber officinale against different stages of Callosobruchus maculatus under laboratory conditions

Naturally derived compounds such as essential oils and natural mineral are relatively cheap, non-toxic to food grains and environmentally friendly and would be suitable alternatives for currently used chemical insecticides if they have high insecticidal effectiveness. In the present study, acute toxicity of kaolin and essential oils from Mentha pulegium and Zingiber officinale were assessed on different stages of Callosobruchus maculatus at 28?±?2?°C, 65?±?5% R. H and dark condition. The calculated LC₅₀ values on the egg, larvae and adult stages of C. maculatus were 1.15, 2.33 and 2.18?μl/ml air for Z. officinale and 0.07, 0.11 and 0.09?μl/ml air for M. pulegium, respectively. The result showed that M. pulegium was more effective essential oil against different stages of C. maculatus compared with the Z. officinale, and also the egg and adult stages of C. maculatus were more susceptible against essential oils compared with larval stage. The LC₅₀ values of kaolin were 0.71 and 0.18?mg/cm² on egg and adult of C. maculatus, respectively. The combination of tested essential oils with kaolin increased mortality of C. maculatus adults compared with their application alone. It was found that tested essential oils and kaolin had high potential in controlling different stages of C. maculatus.     

嗜线虫致病杆菌抑制灰葡萄孢的效应

[背景] 灰葡萄孢（Botrytis cinerea）是引起葡萄采后病害的主要病原菌之一,严重影响葡萄的贮期和品质,给葡萄产业带来极大损失。利用拮抗微生物抑制采后病原菌生长已逐渐成为防治葡萄采后灰霉病的重要手段。[目的] 利用昆虫病原线虫共生细菌广谱高效的抑菌特性,从现有共生细菌资源中筛选对灰葡萄孢具有高拮抗作用的菌株,为葡萄采后灰霉病的抑制提供新的材料和研究方向。[方法] 通过平板对峙培养法和菌丝生长速率法分离筛选拮抗共生细菌,并对优选的高效拮抗共生细菌进行16S rRNA基因序列进化分析,采用扫描电镜观察其对灰葡萄孢菌丝生长的影响,利用损伤接种法对红地球葡萄防治效果进行验证。[结果] 初步分离筛选共获得9株拮抗菌,复筛与复测得到一株抑菌效果显著的共生细菌（命名为ALL）,经进化分析其为嗜线虫致病杆菌（Xenorhabdus nematophila）,其16S rRNA基因序列的Genbank登录号为MW488402,与菌株Xenorhabdus nematophi la NC116聚于同一分支,相似性达99.79%。扫描电镜观察该菌株导致灰葡萄孢菌丝扭曲变形、表面皱缩、失水塌陷,该菌株发酵（36 h）上清液浓度为1%时对灰葡萄孢菌丝抑制率达44.5%。在葡萄常温防效实验中,与对照组比较,ALL菌株发酵上清液对灰霉菌防治效果较好,3 d后防效为63.50%。[结论] 本研究应用昆虫病原线虫共生细菌生物防治葡萄贮期灰霉病,筛选出一株高效拮抗灰葡萄孢的昆虫病原线虫共生细菌,而且其上清液对灰葡萄孢具有良好的抑制效果,为生物防治贮期葡萄灰霉病提供了新的生物材料和相关研究基础。     

Control of stored grain pest,Callosobruchus maculatus (F.) (Coleoptera: Bruchidae), using the essential oils isolated from Zingiber officinale (L.) and Mentha pulegium (L.) in laboratory condition

Fumigant activity of essential oil vapours distilled from Zingiber officinale (L.) and Mentha pulegium (L.) was tested against eggs, larvae and adults of Callosobruchus maculatus (F.). Fumigant toxicity was assessed at 27?±?1?°C and 60?±?5% RH, in dark condition. The influence of different concentrations of the essential oil vapours on egg hatchability, larval and adult mortality was significant. Data probit analysis showed that lethal concentration of the essential oil to kill 50% of the population (LC₅₀) for egg, larvae and adult was found to be 1.151, 2.336 and 2.183?μl/l air of Z. officinale, followed by 0.072, 0.113 and 0.093?μl/l air essential oil of M. pulegium, respectively. Between these essential oils, Z. officinale is almost more toxic than M. pulegium on all growth stages of C. maculatus. The present study suggests that essential oils from these medicinal plants may be potential grain protectants as botanical alternative fumigants and could be used in the management of various life stages of C. maculatus.     

Evaluation of Eupatorium cannabinum Linn. oil in enhancement of shelf life of mango fruits from fungal rotting

Essential oils extracted from 17 higher plants belonging to different families were screened against Botryodiplodia theobromae and Colletotrichum gloeosporioides causing stem end rot disease and anthracnose disease in mango respectively. The essential oil of Eupatorium cannabinum was found to be fungitoxic in nature against both the mango-rotting fungi. Eupatorium oil was standardized through physico-chemical and fungitoxic properties. Gas Liquid Chromatography (GLC) analysis of the oil led to the identification of 16 components, which represented 77.97% of the oil. Germacrene D (16.11%) was found to be the major component. The oil showed a broad fungitoxic spectrum and was recorded to be more efficient than some synthetic fungicides. The oil also showed an inhibitory effect on pectinase and cellulase enzymes. The oil enhanced the shelf life of mango fruits by protecting from fungal rotting when tested as a fumigant. The LD₅₀ of Eupatorium oil was found to be 22.01 ml/kg body weight on mammalian mice.     

Antifungal activities of essential oils applied by dip-treatment on areca palm (Areca catechu) leaf sheath and persistence of their potency upon storage

The antifungal activities of cinnamon oil, clove oil, anise oil, and peppermint oil, and their main components (cinnamaldehyde, eugenol, trans-anethole, and menthol, respectively) against molds identified from areca palm leaf sheath (Mucor dimorphosporus, Penicillium sp., Aspergillus niger, and Rhizopus sp.) were investigated. An agar dilution method was employed to determine the minimum inhibitory concentration (MIC) of essential oils and their main components. Zone inhibition tests and the inhibitory effect of the leaf sheath dip-treated with essential oils against those molds were examined. Major components of essential oils on the leaf sheath during storage were quantified by gas chromatography analysis. The MIC values of essential oils on agar and on the leaf sheath were identical. With an MIC of 50 ??g ml⁻¹, cinnamon oil had the strongest inhibitory effect. At their MICs the oils were capable of providing protection against mold growth on the leaf sheath for at least 12 weeks during storage at 25 °C and 100% RH. Scanning electron microscope examination showed that essential oils prevented spore germination. Except for menthol in peppermint oil, the main components of the essential oils, which were fairly stable over the storage period, largely contributed to the antifungal activity.     

Effect of extracts from in vitro-grown shoots of <Emphasis Type="Italic">Quillaja saponaria</Emphasis> Mol. on <Emphasis Type="Italic">Botrytis cinerea</Emphasis> Pers.

The ethanolic and aqueous extracts from in vitro shoots of Quillaja saponaria Mol. (Quillay) were studied for their antifungal activity against the phytopathogenic fungus Botrytis cinerea Pers. These extracts reduced conidial germination and mycelial growth of B. cinerea, ethanolic extracts being more active than aqueous extracts. In addition, the damage areas produced by this fungus on tomato leaves and strawberry fruits pre-treated with quillay extracts were diminished. The fungitoxic effect of in vitro-grown quillay extract was similar to those obtained with commercial fungicides of both natural (BC-1000) and synthetic (iprodione–dicarboximide) origin. On the other hand, the antifungal action of quillay extracts obtained from adult trees naturally grown was only slightly superior to the fungitoxic activity of the extract from in vitro plants. HPLC analysis of the extract showed that it contained saponins and some phenolic compounds such as chlorogenic, caffeic, vanillic, and salicylic acids, and scopoletin, which have been identified as antifungal agents on phytopathogenic fungi. The results obtained in this work, suggests that extracts of in vitro-grown quillay have an important protective effect against B. cinerea and support the use of an in vitro culture system as a biotechnological alternative to obtain environmental safe antifungal quillay extracts to control B. cinerea, contributing to the preservation of this indigenous Chilean species.     

Effect of Citrus reticulata and Cymbopogon citratus Essential Oils on Aspergillus flavus Growth and Aflatoxin Production on Asparagus racemosus

Essential oils extracted from Citrus reticulata and Cymbopogon citratus were tested in vitro against the toxigenic strain of Aspergillus flavus, isolated from the tuberous roots of Asparagus racemosus, used in preparation of herbal drugs. The essential oils completely inhibited the growth of A. flavus at 750 ppm and also exhibited a broad fungitoxic spectrum against nine additional fungi isolated from the roots. Citrus reticulata and Cymbopogon citratus essential oils completely inhibited aflatoxin B₁ production at 750 and 500 ppm, respectively. During in vivo investigation, the incidence of fungi and aflatoxin B₁ production decreased considerably in essential oil-treated root samples. The findings thus indicate possible exploitation of the essential oils as effective inhibitor of aflatoxin B₁ production and as post-harvest fungitoxicant of traditionally used plant origin for the control of storage fungi. These essential oils may be recommended as plant-based antifungals as well as aflatoxin B₁ suppressors in post-harvest processing of herbal samples.     

Essential Oil of Zingiber cassumunar Roxb. and Zingiber officinale Rosc.: A Comparative Study on Chemical Constituents,Antibacterial Activity,Biofilm Formation,and Inhibition of Pseudomonas aeruginosa Quorum Sensing System

Pseudomonas aeruginosa can regulate its pathogenicity via quorum sensing (QS) system. Zingiber cassumunar and Z. officinale have been used for the treatment of infectious diseases. The study aimed to evaluate and compare the chemical constituents, antibacterial, and QS inhibitor of Z. cassumunar essential oils (ZCEO) and Z. officinale essential oils (ZOEO). The chemical constituent was analysed using GC/MS. Broth microdilution and spectrophotometry analysis were used to evaluate their antibacterial and QS inhibitor activities. The main constituent of ZOEO with percent composition above 6 % (α-curcumene, α-zingiberene, β-sesquiphellandrene, and β-bisabolene, α-citral, and α-farnesene) were exist in a very minimal percentage less than 0.7 % in Z. cassumunar. All major components of ZCEO with percentages higher than 5 % (terpinen-4-ol, sabinene, γ-terpinene) were present in low proportion (<1.18 %) in Z. officinale. ZCEO demonstrated moderate antibacterial activity against P. aeruginosa. The combination of ZCEO and tetracycline showed a synergistic effect (FICI of 0.5). ZCEO exhibited strong activity in inhibiting biofilm formation. ZCEO at MIC (62.5 μg/mL) was able to reduce pyoverdine, pyocyanin, and proteolytic activity. This is the first report on the activity of ZCEO in the inhibition of P. aeruginosa QS system and it may be used to control the pathogenicity of P. aeruginosa.     

Origin of (−)-Geosmin on Grapes: On the Complementary Action of Two Fungi, <Emphasis Type="Italic">Botrytis Cinerea</Emphasis> and <Emphasis Type="Italic">Penicillium Expansum</Emphasis>

One of the consequences of rot on grapes is the development of volatile compounds giving fungal, mouldy or earthy odours. Among these compounds, (−)-geosmin (trans-1,10-dimethyl-trans-9-decalol), a powerful aromatic compound with an earthy smell is a persistent defect in grape juice and wines made with at least partially rotten grapes. A microbiota analysis of rotten grapes containing (−)-geosmin was carried out on sites from four French regions from 1999 to 2002, to clarify the involvement in geosmin appearance of Streptomyces spp. and Penicillium spp., two types of microorganisms present on grape, that are known for their ability to produce geosmin. In earthy grapes, Botrytis cinerea was largely present. Different species of Streptomyces were also isolated, but their pH sensitivity was an extremely limiting parameter for their development on grape juice, grapes or stem, and consequently for their potentiality to generate geosmin in the vineyard. Penicillium expansum, producing geosmin on a model medium, was omnipresent. Penicillium carneum, which is also a geosmin producer, was represented by a single colony during the 4 years of this study. P. expansum alone was able to produce geosmin on a model medium but not on grapes. However, after 7 days’ pre-culture of some B. cinerea strains on grape juice, this juice became favourable to geosmin production by P. expansum. We demonstrated the necessary and complementary action of B. cinerea and P. expansum in geosmin production in grape juice and in crushed grape berries.     

Essential oils of three asiatic artemisia species

The steam-distilled essential oils from the aerial parts of three Asiatic Artemisia, A. glabella, A. rupestris and A. persica, were analysed by GC/MS. In all about 100 compounds were identified; davanone is one of the main components of A. persica.     

Effect of fungicidal essential oils against Botrytis cinerea and Rhizopus stolonifer rot fungus in vitro conditions

The development of natural crop protection products as alternatives to the use of synthetic fungicides is currently popular. The aim of this study is to evaluate the antifungal effects of several essential oils against the fungal pathogens, Botrytis cinerea and Rhizopus stolonifer, under in vitro condition. Four essential oils (fennel, black caraway, peppermint and thyme) were each tested at five concentrations (0, 200, 400, 600 or 800 μl l^?1). In vitro results showed that the essential oil of black caraway and fennel had the highest fungicidal effect against B. cinerea and R. stolonifer, respectively. The growth of B. cinerea was completely inhibited by the essential oil of black caraway at 400 μl l^?1. Fennel oil perfectly inhibited growth of R. stolonifer fungus colonies at concentration higher than 600 μl L^?1 in potato dextrose agar medium. Percentage of spores germination was the lowest in medium of Fennel and black caraway essential oils, and was the highest in Thyme ones. These results show that plant essential oils can have a strong effect on reducing post-harvest decay. These plant essential oils could provide an alternative to synthetic chemicals to control post-harvest phytopathogenic fungi on fruit.     

Essential Oils as Biocides for the Control of Fungal Infections and Devastating Pest (Tuta absoluta) of Tomato (Lycopersicon esculentum Mill.)

Thymus capitatus and Tetraclinis articulata essential oils as well their major components (carvacrol and α‐pinene) were evaluated for their antifungal and insecticidal activities. Both oils showed good in vitro antifungal activity against Fusarium oxysporum, Aspergillus niger, Penicillium sp., Alternaria alternata, and Botrytis cinerea, the fungi causing tomato rot. In vivo results indicate the efficacies of both essential oils and carvacrol of reduce postharvest fungal pathogens, such as B. cinerea and Al. alternata that are responsible of black and gray rot of tomato fruit. Disease incidence of Al. alternata and B. cinerea decreased on average from 55% to 80% with essential oil of Th. capitatus and pure carcvacrol, while Te. articulata essential oil exhibited inhibition of fungal growth of 55% and 25% against Al. alternata and B. cinerea, respectively, with concentration of 0.4 μl/l air. The insecticidal activity of Th. capitatus and Te. articulata essential oils exhibited also a good insecticidal activity. At the concentration of 0.2 μl/ml air, the oils caused mortality over 80% for all larval stages of Tuta absoluta and 100% mortality for the first‐instar after 1.5 h only of exposure. α‐Pinene presented lower insecticidal and antifungal activities compared to essential oils of Th. capitatus, Te. articulata and pure carvacrol. Thus, these essential oils can be used as a potential source to develop control agents to manage some of the main pests and fungal diseases of tomato crops.     

Schinus molle: a new source of natural fungitoxicant

The oil of Schinus molle exhibited the maximum fungitoxic activity during the screening of some essential oils against some common storage and animal pathogenic fungi. It showed absolute toxicity against animal pathogens and mild activity against storage fungi. The effective concentrations of the oil varied from 200 to 900 ppm. The toxicity of the oil persisted up to 80 degrees C and 90 days of storage but declined when autoclaved. It withstood heavy inoculum density. The oil exhibited a narrow range of activity and was found to be more effective than Multifungin, an antifungal drug. The oil was characterized by its various physicochemical properties. It was found to comprise 50 constituents. It appeared that some changes in the oil constituents during storage affected its fungitoxic potency.     

Schinus molle: a new source of natural fungitoxicant.

The oil of Schinus molle exhibited the maximum fungitoxic activity during the screening of some essential oils against some common storage and animal pathogenic fungi. It showed absolute toxicity against animal pathogens and mild activity against storage fungi. The effective concentrations of the oil varied from 200 to 900 ppm. The toxicity of the oil persisted up to 80 degrees C and 90 days of storage but declined when autoclaved. It withstood heavy inoculum density. The oil exhibited a narrow range of activity and was found to be more effective than Multifungin, an antifungal drug. The oil was characterized by its various physicochemical properties. It was found to comprise 50 constituents. It appeared that some changes in the oil constituents during storage affected its fungitoxic potency.     

Antimicrobial Activity of Syzygium aromaticum and Zanthoxylum xanthoxyloides Essential Oils Against Phytophthora megakarya

The aim of this study was to assess the chemical composition and the antimicrobial activity of essential oils of dried fruits and buds of Zanthoxylum xanthoxyloides (Z. xanthoxyloides) and Syzygium aromaticum (S. aromaticum or clove), respectively, against Phytophthora megakarya (P. megakarya). Essential oils were extracted by hydrodistillation, and their composition was determined by gas chromatography and by gas chromatography coupled with Mass Spectrometry. The minimal inhibitory concentration (MIC) and minimal lethal concentration (MLC) of the essential oils against P. megakarya were assessed by the Agar dilution method. The in vivo efficacy study consisted of spraying the essential oil emulsions on cocoa pod husk pieces (CPHP), followed by the inoculation with P. megakarya zoospores. The hydrodistillation yielded 10.54 and 1.89% of essential oils for S. aromaticum and Z. xanthoxyloides, respectively. Both oils were mainly made up of oxygenated monoterpenes (89.58 and 88.2%, respectively). Eugenol (83.02%) and eugenyl acetate (9.15%) were the main components of clove oil while α‐citronelol (25.83%) and trans‐geraniol (16.49%) were mostly found in the Z. xanthoxyloides oil. Clove oil exhibited stronger antimicrobial activity with a MIC of 250 μl/l than Z. xanthoxyloides with MIC of 350 μl/l. The symptoms were totally suppressed on pod husk treated with clove oil at 2000 μl/l. The decrease in the growth rate of the necrosis (GRN) and the sporulation of P. megakarya (PS) on cocoa husk after the successful infection was significant after the treatment with essential oils. These results are promising and indicate that the studied essential oils might be further investigated as natural alternatives to synthetic fungicides for the control of cocoa black pod diseases.     

The inhibition of Candida albicans by selected essential oils and their major components

Many volatile oils are known to possess antifungal properties and are potentially applicable as antimycotic agents. By studying the efficacy of essential oils against different pathogenic mycetes, we have evaluated the in-vitro inhibiting activity of some essential oils and their main constituents against a strain of Candida albicans. Sixteen commercial essential oils and forty-two pure constituents (alcohols, aldehydes, ketons, phenols and hydrocarbons), were tested by using a semisolid agar antifungal susceptibility (SAAS) method. Gas chromatography/mass spectroscopy analyses of the oils tested were performed. The essential oils of Origanum vulgare, Satureja montana, Mentha piperita, Cinnamomum verum, Cymbopogon flexuosus showed maximum inhibitory activity (MIC = 500 ppm) after 7 days. According to the results of the examination of pure constituents, -phellandrene proved to be the most interesting component among cyclic monoterpenic hydrocarbons as it showed a strong activity (MIC = 50 ppm). The most active of phenols was carvacrol (MIC 100 ppm). The open-chain alcohol 1-decanol was the most active of alcohols at 50 ppm. Finally, among aldehydes, a strong activity was shown by trans-cynnamaldehyde (MIC 50 ppm).     

In-vitro anti-<Emphasis Type="Italic">Vibrio</Emphasis> spp. activity and chemical composition of some Tunisian aromatic plants

The chemical composition of five aromatic plants (Mentha longifolia, M. pulegium, Eugenia caryophyllata, Thymus vulgaris and Rosmarinus officinalis) frequently used in food preparation in Tunisia was analysed by GC-MS. The antimicrobial effect of the essential oils obtained from these plants was tested against Vibrio alginolyticus, Vibrio parahaemolyticus, Vibrio vulnificus and Vibrio fluvialis strains. Thyme oil exhibited a high level of antimicrobial activities against Vibrio spp. strains. The diameter of the zones of growth inhibition for V. parahaemolyticus species was interestingly high (ranging from 14.66 to 28 mm). The MIC and MBC values were interestingly low for thyme oil (MIC 0.078–0.156 mg/ml) and (MBC >0.31–1.25 mg/ml). These results showed that these plants especially thyme and clove, can be to be used for seafood preparation to protect against contamination by Vibrio spp. strains. An erratum to this article can be found at     

四种植物精油对黑翅土白蚁触杀和驱避作用

为筛选出高效防治黑翅土白蚁的天然植物精油,减少有机合成农药的使用,该文研究了大蒜精油、肉桂油、丁香油和印楝素油四种植物精油对黑翅土白蚁的触杀效果和驱避作用。结果表明:大蒜精油、肉桂油和丁香油的浓度为5和10 mg·m L~(-1)时,处理2 h后,黑翅土白蚁的校正死亡率达100%,而相同浓度的印楝素油和对照处理的黑翅土白蚁校正死亡率低于5%。随着处理时间延长,浓度为1.25和2.5 mg·m L~(-1)的大蒜精油、肉桂油和丁香油处理6 h时,黑翅土白蚁的校正死亡率仍达100%,而此时对应的印楝素油和对照处理的黑翅土白蚁校正死亡率仅为10%,说明大蒜精油、肉桂油和丁香油对黑翅土白蚁具有较强的触杀效果。大蒜精油、丁香油和肉桂油在处理黑翅土白蚁2 h后LC_(50)值(半致死量)分别为1.572、1.05和1.03mg·m L~(-1),说明肉桂油对黑翅土白蚁的毒性相对最大,触杀效果最好。此外,10 mg·m L~(-1)的大蒜精油、肉桂油、丁香油和印楝素油的驱避试验表明,处理4、6、8和12 h后,大蒜精油、肉桂油和丁香油三精油处理区的黑翅土白蚁数均显著低于对照区的,驱避率总体93%,而对应的印楝素油的驱避率总体28.5%,表明大蒜精油、丁香油和肉桂油三种植物精油对黑翅土白蚁均有显著的驱避活性。综上可知,四种植物精油中大蒜精油、肉桂油和丁香油在防治黑翅土白蚁方面应用潜力很好,是开发绿色环保白蚁防治药剂的可选材料。     

Antifungal properties of essential oils and their main components uponCryptococcus neoformans

Cryptococcus neoformans opportunistic fungus met in the last phasis of AIDS is inhibited in vitro by several essential oils on natural volatile compounds. The minimal inhibitory concentration may reach 100 µl/l and minimal fungicidal concentration 200 µl/l with Palmarosa or Cinnamon oils. Among phenolic compounds, thymol and carvacrol are most fungitoxic. Terpenoids, citral, geraniol, and citronellol show best activities.