Biological effects of essential oils - A review

In recent years, the use of essential oils (EOs) derived from aromatic plants as low-risk insecticides has increased considerably owing to their popularity with organic growers and environmentally conscious consumers. EOs are easily produced by steam distillation of plant material and contain many volatile, low-molecular-weight terpenes and phenolics. The major plant families from which EOs are extracted include Myrtaceae, Lauraceae, Lamiaceae, and Asteraceae. EOs have repellent, insecticidal, and growth-reducing effects on a variety of insects. They have been used effectively to control preharvest and postharvest phytophagous insects and as insect repellents for biting flies and for home and garden insects. The compounds exert their activities on insects through neurotoxic effects involving several mechanisms, notably through GABA, octopamine synapses, and the inhibition of acetylcholinesterase. With a few exceptions, their mammalian toxicity is low and environmental persistence is short. Registration has been the main bottleneck in putting new products on the market, but more EOs have been approved for use in the United States than elsewhere owing to reduced-risk processes for these materials.

Essential oils in insect control: low-risk products in a high-stakes world.

Green Pesticides: Essential Oils as Biopesticides in Insect-pest Management

Objective(s): Garlic (Allium sativum L. family Liliaceae) is well known in Iran and its leaves, flowers, and cloves have been used in traditional medicine for a long time. Research in recent decades has shown widespread pharmacological effects of A. sativum and its organosulfur compounds especially Allicin. Studies carried out on the chemical composition of the plant show that the most important constituents of this plant are organosulfur compounds such as allicin, diallyl disulphide, S-allylcysteine, and diallyl trisulfide. Allicin represents one of the most studied among these naturally occurring compounds. In addition to A. sativum, these compounds are also present in A. hirtifolium (shallot) and have been used to treat various diseases. This article reviews the pharmacological effects and traditional uses of A. sativum, A. hirtifolium, and their active constituents to show whether or not they can be further used as potential natural sources for the development of novel drugs. 

Materials and Methods: For this purpose, the authors went through a vast number of sources and articles and all needed data was gathered. The findings were reviewed and classified on the basis of relevance to the topic and a summary of all effects were reported as tables. 

Conclusion: Garlic and shallots are safe and rich sources of biologically active compounds with low toxicity. Further studies are needed to confirm the safety and quality of the plants to be used by clinicians as therapeutic agents.

Therapeutic Uses and Pharmacological Properties of Garlic, Shallot, and Their Biologically Active Compounds

Leaf-cutting ants of the Attini tribe are a major pest of agricultural and forestry productions in the New World. Economic losses caused by these ants were estimated at several million dollars per year. These ants need to live in symbiosis with a basidiomycete fungus. Due to their mutualistic interaction with the symbiotic fungus, management of Attini ants can be done with insecticides or fungicides or both. So far, synthetic pesticides were the main control means, albeit with negative effects on the environment. Very few studies describe alternative methods for the control of leaf-cutting ants such as the use of insecticidal and fungicidal plant extracts. There is therefore a need of knowledge on phytochemicals and plants that could be used as insecticides and fungicides. Here, we review chemicals of plant origin and species with insecticidal and fungicidal activities. We establish a list of plants and phytochemicals that could manage leaf-cutting ants and also other insects, notably insects that use fungus-based agriculture. An exhaustive literature search of 1965 references from 1923 to 2010 was conducted using scientific databases, chemical databases, botanical databases, and books to identify published papers related to insecticidal and fungicidal chemical compounds stemmed from plant species. The major points are the following: (1) 119 and 284 chemicals have been cited in the literature for their insecticidal and fungicidal activities, respectively; (2) 656 and 1,064 plant species have significant insecticidal and fungicidal activities, respectively; (3) 3 main chemical classes were most cited for these activities: alkaloids, phenolics, and terpenoids; (4) 20 interesting chemicals with the both insecticidal and fungicidal activities were found; and (5) 305 plant species containing these chemicals were cited. To conclude, 20 chemicals: caryophyllene oxide, cinnamaldehyde, eugenol, helenalin, linalool, menthone, myristicin, pulegone, thymol, anethole, anisaldehyde, elemicin, isopimpinellin, plumbagin, podophyllotoxin, psoralen, xanthotoxin, anonaine, solamargine, and tomatine; two main plant families, Lamiaceae and Apiaceae; and 17 species of these families were particularly interesting for the management of leaf-cutting ants.

Insecticidal and antifungal chemicals produced by plants: a review

Plant essential oils from 40 plant species were tested for their insecticidal activities against larvae of Lycoriella ingenue (Dufour) using a fumigation bioassay. Good insecticidal activity against larvae of L. ingenua was achieved with essential oils of Chenopodium ambrosioides L., Eucalyptus globulus Labill, Eucalyptus smithii RT Baker, horseradish, anise and garlic at 10 and 5 µL L−1 air. Horseradish, anise and garlic oils showed the most potent insecticidal activities among the plant essential oils. At 1.25 µL L−1, horseradish, anise and garlic oils caused 100, 93.3 and 13.3% mortality, but at 0.625 µL L−1 air this decreased to 3.3, 0 and 0% respectively. Analysis by gas chromatography-mass spectrometry led to the identification of one major compound from horseradish, and three each from anise and garlic oils. These seven compounds and m-anisaldehyde and o-anisaldehyde, two positional isomers of p-anisaldehyde, were tested individually for their insecticidal activities against larvae of L. ingenua. Allyl isothiocyanate was the most toxic, followed by trans-anethole, diallyl disulfide and p-anisaldehyde with LC50 values of 0.15, 0.20, 0.87 and 1.47 µL L−1 respectively. Copyright © 2006 Society of Chemical Industry

Fumigant activity of plant essential oils and components from horseradish (Armoracia rusticana), anise (Pimpinella anisum) and garlic (Allium sativum) oils against Lycoriella ingenua (Diptera: Sciaridae).

Abstract Recently, insufficient attractiveness of Conogethes punctiferalis Guenée adult males to sex pheromone, (E)-10-hexadecenal and (Z)-10-hexadecenal, has been reported. To identify the other essential components of sex pheromone, male and female body extracts were analyzed. Two hydrocarbon components, (Z)-9-heptacosene (Z9–27:HC) and (3Z,6Z,9Z)-tricosatriene (Z3,Z6,Z9–23:HC), were identified from only female body extract. There was a significant difference in the electroantennogram (EAG) response of male antennae to Z3,Z6,Z9–23:HC and Z9–27:HC at all test concentrations compared to the response to the hexane control. In field attraction testing, the addition of Z9–27:HC and Z3,Z6,Z9–23:HC to binary aldehyde pheromones significantly increased trap catches of C. punctiferalis male adults. Based on the female and male body extract analysis and field attraction test, Z9-27:HC and Z3,Z6,Z9–23:HC were determined to be other essential sex pheromone components of the Korean C. punctiferalis population. No significant difference was observed in the number of male captures between the bucket trap and delta trap. Pheromone traps with a color close to yellow shade attracted more male adults than traps with a color close to blue shade.

Field Confirmation of (Z)-9-Heptacosene and (3Z,6Z,9Z)-Tricosatriene as Key Sex Pheromone Components of Korean Conogethes punctiferalis Guenée (Lepidoptera: Crambidae)

II-Kwon Park

Papers

Fumigant activity of plant essential oils and components from horseradish (Armoracia rusticana), anise (Pimpinella anisum) and garlic (Allium sativum) oils against Lycoriella ingenua (Diptera: Sciaridae).

Field Confirmation of (Z)-9-Heptacosene and (3Z,6Z,9Z)-Tricosatriene as Key Sex Pheromone Components of Korean Conogethes punctiferalis Guenée (Lepidoptera: Crambidae)