Insecticidal Activity Of Essential Oil Research Articles

Analysis of Essential Oils Extracted from Algerian Medicinal Plants and Their Aphicidal Effect Against the Melon Aphid Aphis Gossypii Glover (Homoptera: Aphididae)

Chemical insecticides are decisive in controlling insect pests, but they harm the environment. Reducing the use of chemical insecticides has become the main goal for ensuring healthy produce. However, research focusing on plant-based compounds has recently increased. The present study was carried out to analyze essential oils extracted from Algerian medicinal plants by gas chromatography coupled with mass spectrometry (GC-MS) to determine the insecticidal activity of essential oils from Juniperus phoenicea, Rosmarinus officinalis, Lavandula stoechas, Mentha pulegium and Pinus sylvestris, against Aphis gossypii Glover The main components constituting each essential oil were: α-pinene, β-Pinene 1,8- cineol, Linalool, Linalyl acetate, Fenchone, Pulegone, and Camphor. The toxicity of tested essential oils against Aphis gossypii was different and dependent on the concentration used (1000, 10000, and 100000 ppm), the duration of exposure (24, 48, and 72 h), and the chemical composition of the oil. The highest toxicity was for J. phoenicea, M. pulegium, and L. stoechas which were toxic as Actara® insecticide.

Exploring chemical composition and insecticidal activities of Alpinia calcarata rhizome essential oil against three major storage insects

Alpinia calcarata (Roscoe), generally recognized as snap ginger or lesser galangal of the Zingiberaceae family, undergoes widespread cultivation in tropical nations. It is characterized by its noteworthy pharmacological attributes, such as anti-inflammatory, analgesic, antinociceptive, reproductive, anti-cancer, and gastro-protective effects. Many storage pests now resist traditional chemical pesticides. Transitioning to organic alternatives is a preferable and sustainable solution. This research investigates the insecticidal activity of essential oil from A. calcarata rhizomes, obtained via hydro-distillation. Chemical analysis was conducted, and the study assessed its toxicity and repellent effects on Tribolium castaneum (Herbst), Lasioderma serricorne (F.), and Callosobruchus chinensis (L). A yield of 0.44 ± 0.02 % essential oil was obtained from dry rhizomes. Gas chromatography-mass spectrometry (GC-MS) characterization revealed the major chemical constituents as 1,8-cineole (25.71 %), ethyl iso-allocholate (16.01 %), and fenchyl acetate (15.15 %). The findings from the investigation into the pesticidal characteristics of essential oils derived from the rhizome of A. calcarata unveiled significant contact (LC50 at 24 h was 10.9 mg/cm2 for T. castaneum, 1.0 mg/cm2 for L. serricorne and 0.5 mg/cm2 for C. chinensis) and fumigant toxicity (LC50 at 24 h was 4.05 mg/L air for T. castaneum, 1.75 mg/L air for L. serricorne, and 1.03 mg/L air for C. chinensis). The repellent efficacy was evaluated through an area preference test, revealing robust repellent activity at various concentrations. Undoubtedly, the essential oil extracted from the rhizome of A. calcarata is valuable and has the potential to be a safe, organic pesticide for controlling storage pests.

Nematicidal and insecticidal activity of essential oils from Artemisia scoparia and Centratherum punctatum and their mixtures

The present study involves the phytochemical analysis and assessing potential synergies among essential oils (EOs) against pests. The EOs were obtained by hydrodistillation from the aerial part (ASAO) and the root part (ASRO) of Artimisia scoparia, and from the aerial part of Centratherum punctatum (CPAO). The EOs yield ranged from 0.5 to 0.1% (v/w). The GC-MS analysis revealed the presence of 35, 43, and 49 compounds, constituting 99.2%, 98.34%, and 99.93% in ASAO, ASRO, and CPAO, respectively. Capillene was identified as the dominant compound both in ASAO and ASRO, but in variable amounts. Caryophyllene oxide (36.4%) was identified as the major component of CPAO. Pure EOs were blended in binary and ternary mixtures at ratios to analyze their synergistic effect against pests. The nematicidal activity (percent mortality and egg hatchability against Meloidogyne incognita at different concentrations was evaluated and the ternary mixture (ASAO + ASRO + CPAO) was found to be most effective at 1 μL/mL with 55.67 ± 1.41% larval immobility at 96 h of exposure. The antifeedant activity of pure and blended EOs was examined against Spodoptera litura using the leaf-dip method. Individually ASAO was most effective with 66.91% feeding inhibition, however the ternary combination showed 58.03% feeding inhibition. Moreover, molecular docking of selected volatiles (≥4% area) from the tested samples was carried out to analyze the interactions with target protein; acetylcholinesterase (AChE) and glutathione S-transferases (GST-1) and the ligands interacted favourably with the target proteins. The blending of EOs resulted in synergistic effects, enhancing their efficacy. Data acquired highlighted that A. scoparia and C. punctatum essential oils could be natural alternatives for nematode control and pest control in agriculture.

Toxicity of Essential Oil from Plectranthus amboinicus (Lamiales: Lamiaceae) against Sitophilus zeamais (Coleoptera: Curculionidae)

Abstract Maize weevil, Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), is a major insect pest of stored grain products, causing extensive damage to both grain quantity and quality. The application of synthetic insecticides to control this insect has a negative impact on human health and the environment. Essential oils derived from natural plants are recognized as user- and environmentally friendly alternatives. The use of essential oils from Lamiaceae, which exhibit toxic properties through contact, fumigation, and repellency, provides another option for protecting stored products from various insect pests. The aim of this research was to study the chemical constituents and insecticidal activity of essential oil extracted from the leaves of Indian borage, Plectranthus amboinicus (Lour.) (Lamiales: Lamiaceae), against S. zeamais adults.The chemical composition of the essential oil was analyzed using gas chromatography–mass spectrometry, and the insecticidal activity against adult maize weevils was investigated in the laboratory. The experimental plan followed a completely randomized design with five replications of seven treatments or concentrations of the essential oil: 0, 0.5, 1, 1.5, 2, 2.5, and 3 µl/ml air. The results revealed that the essential oil from the leaves of P. amboinicus contained 23 chemical constituents (97.51%). Thymol (49.96%) was identified as the main compound followed by caryophyllene, trans-α-bergamotene, 3-methyl-4-isopropylphenol, γ-terpinene, p-cymene, caryophyllene oxide, humulene, 4-hydroxy-2-methylacetophenone, 2-hydroxy-2-phenylbutyramide, (2-oxazolidinylidene)malononitrile, hexestrol, terpinen-4-ol, 1-octen-3-ol, (1R,7S,E)-7-isopropyl-4,10-dimethylenecyclodec-5-enol, α-bisabolene, isoaromadendrene epoxide, α-farnesene, 4-carene, α-muurolene, 3-hexen-1-ol, ledene oxide-(II), and α-myrcene, respectively. The fumigation toxicity (median lethal concentration) to maize weevil adults at 48 h was 292.53 µl/ml air. The essential oil from the leaves of P. amboinicus, when applied at a concentration of 2 µl/ml air for 144 and 168 h, resulted in adult maize weevil mortality exceeding 90%. The highest concentration tested (3 µl/ml air) led to exceptionally high mortality rates, with 99–100% of the maize weevils succumbing to the treatment. These findings demonstrate that essential oil from P. amboinicus leaves holds promise as a fumigation insecticide for reducing the population of maize weevils, a significant pest in stored products.

Insecticidal activity of essential oils and plant extracts on cowpea aphid

Aphid population’s reduction occurs through chemical management, but the indiscriminate use of these products can cause environmental impacts and health risks. This study aimed to determine the insecticidal effects of essential oils and plant extracts as an alternative for aphid control management. The experimental design was entirely randomised in a 5x5 factorial scheme with five replications. Essential oils of rosemary, citronella, corn mint, and hydroethanolic extracts of garlic and cinnamon at five concentrations (0, 10, 20, 40, 80 μL.L−1) were used. In the exposure period of 96 h, the cinnamon hydroethanolic extract and the essential oil of corn mint (Mentha arvensis) showed a greater effect on aphid mortality. The other products evaluated showed lower mortalities but with the potential to be effective with dosages above 80 μL.L−1.

Lethal and sublethal effects of Citrus aurantium and Citrus sinensis essential oils and their major component limonene on Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae)

Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) is an insect pest with great socio-economic importance in different agricultural regions worldwide. This species is highly adaptive and polyphagous, feeding on wild and cultivated host plants. Successive pesticide applications, which negatively affect the environment, are mainly used for managing H. armigera. Studies have investigated alternative methods with low environmental and socioeconomic impacts, including using essential oils. Essential oils are secondary plant-derived metabolites with insecticidal activity in different insect pest populations. Thus, the objective of this study was to evaluate the insecticidal activity of essential oils of Citrus aurantium (Linnaeus) (Rutaceae) and Citrus sinensis (Linnaeus) (Rutaceae) as well as their major component limonene on the biology and reproduction of H. armigera. The essential oils were characterized using gas chromatography-mass spectrometry. Further, their toxicity and the effects of their lethal and sublethal concentrations in larvae and on biological and reproductive parameters in adults were evaluated. All treatments exhibited insecticidal activity and lethal and sub-lethal effects on the biology and reproduction of H. armigera. Therefore, these essential oils could be used to control H. armigera.

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.

Insecticidal activity of essential oils derived from lavender, laurel and peppermint against lesser grain borer, Rhyzopertha dominica (Fabricius, 1792) (Coleoptera: Bostrichidae)

Fumigant effects of the essential oils from Laurus nobilis L., 1753 (Laurales: Lauraceae), Mentha piperita L., 1753 and Lavandula x intermedia Emeric ex Loisel, 1828 (Lamiales: Lamiaceae) were determined using the lesser grain borer [Rhyzopertha dominica (Fabricius, 1792) (Coleoptera: Bostrychidae)], an important pest species of stored grains. The experiments were conducted in the 2021 in the Department of Crop Protection, Faculty of Agriculture, Malatya Turgut Özal University. The experiments were conducted in a controlled-climate chamber at 27 ± 1°C, 50 ± 10% RH and in the dark. The fumigant effects of essential oils were determined at five concentrations (1, 5, 20, 50 and 200 μl/L air) with larva, pupa and adult stages of R. dominica. The highest fumigant effect was with R. dominica larvae was complete mortality with 200 μl/L L. nobilis essential oil and for the adults, 200μl/L of either L. nobilis and M. piperita essential oil also caused complete mortality. However, the complete mortality of pupal stage was not obtained and the highest mortality was 49% with L. nobilis. As a result, it is considered that both L. nobilis and M. piperita essential oils have the potential to be used as effective biofumigants for stored product pests.

Bio-efficacy of Xanthium strumarium L. Essential Oil against Castor Semilooper, Achaea janata L. (Lepidoptera: Noctuidae)

Background: Although use of synthetic insecticides causes excellent control of insect pests, it leads to adverse effects on non-target organisms as well as the environment. The present study determining the chemical composition and insecticidal activities of essential oil extracted from the leaves of rough cocklebur, Xanthium strumarium and its bioefficacy against the castor semilooper, Achaea janata shall show a new dimension in formulating an ecofriendly management strategy towards castor crop. Methods: Xanthium strumarium leaf essential oil was isolated through hydro-distillation method using Clevenger apparatus and the chemical composition was analysed using GC-MS. The ovicidal and insecticidal activity of the essential oil was determined by dipping and topical application methods, respectively. Larval feeding deterrence and growth inhibitory properties of the essential oil was evaluated through the diet incorporation method. Result: GC-MS analysis of the X. strumarium essential oil revealed the presence of 14 chemical compounds, of which the majority are the terpenes (94.48%). The LC50 values in terms of ovicidal and insecticidal activities were recorded to be 69.70 µL/mL and 0.30 µL/larvae, respectively. The fifty per cent larval feeding deterrence (DC50) and growth inhibitory properties (EC50) were recorded to be 1.88 µl/cm² and 213.94 µL/mL, respectively.

Chemical composition, antifungal, antibacterial, and insecticidal activity of Echinophora chrysantha essential oil

This study presents an investigation of the chemical composition and biological activities of the essential oil (EO) extracted from aerial parts of Echinophora chrysantha (EC). Gas chromatography-mass spectrometry (GC-MS) analysis revealed the presence of twenty-two components, representing 97.5% of the total oil. Major constituents were determined as α-phellandrene (55.74%), β-phellandrene (17.41%), and p-cymene (8.95%). The EO was screened for antimicrobial and antifungal activity against a panel of bacteria and fungi using a broth micro-dilution and fumigant activity assay, respectively. EO sample exhibited better activity against Listeria monocytogenes, Staphylococcus aureus Enterococcus faecium with 31.25, 31.25, and 62.5 μg/mL MIC values. EOs showed moderate mycelium growth inhibitory activity against Phytophthora infestans (32.9±1.9%), Verticillium dahliae (42.3±1.8%), and Fusarium oxysporum f. sp. lycopersici (53.0±2.9%) at 8 μL/petri concentration. The insecticidal activity of EO was also evaluated against two insects (Rhyzopertha dominica and Tribolium confusum) showing moderate activity with mortality rates of 25.8±0.6% and 37.9±1.2% at a 5% (v/v) concentration. Literature search has not revealed any previous work on the antimicrobial, antifungal, and insecticidal activities of the EO from E. chrysantha. In conclusion, this is the first report describing the biological activities of this plant EOs. Additionally, these findings highlight the practical implications of the utilizing essential oil of EC as a potential natural remedy against a spectrum of microbial threats in both pharmaceutical and food preservation applications.

Three Togolese aromatic plants' essential oils diurnal variations and their insecticidal activities against the dengue vector Aedesaegypti

The present reported work deals with the ability of Togolese plants’ essential oils (EOs) to act as repellents for Aedes aegypti mosquitoes in order to use them as personal protective requirements or actions against mosquito bites and therefore to drastically reduce the risk of contracting dengue or yellow fever. EOs studied here were extracted from dry leaves of Ageratum conyzoides L., Eucalyptus citriodora Hook, and Lantana camara Linn, three plants that were collected at different daytimes (7 a.m., 1 p.m., and 7 p.m.) at various locations in Togo. Using a Clevenger-type device, EOs were obtained by the hydrodistillation method (Clevenger, 1928). The physical parameters of the EOs such as density, refractive index, rotatory power, and organoleptic properties were determined. Then, the characterization of EOs using gas chromatography equipped with a flame ionization detector (GC/FID) and gas chromatography coupled to mass spectrometry (GC/MS) was conducted. Chemical analyses showed the presence of several main compounds from EO samples of the three plants. The major compounds were characterized and identified as: (i) precocene I (67.7, 70.6, and 66.9%) and β-caryophyllene (17.4, 12.1, and 16.5%) for the EO of A. conyzoïdes; (ii) citronellal (63.3, 67.2, and 75.4%) and citronellol (24.5, 21.4, and 14.3%) for E. citriodora and (iii) β-caryophyllene (15.3, 11.7, and 12.4%), sabinene (28.4, 35, and 33.3%) and eucalyptol (11.5, 14.1, and 15.6%) for L. camara at 7 a.m., 1 p.m., and 7 p.m., respectively. The yield and the chemical composition of the oils vary according to harvesting time and sunlight.The insecticidal activity of EOs was evaluated following the CDC bottle method on Aedes aegypti females. All the EOs tested on the female adults of Aedes aegypti showed significant insecticidal activity. The EO of A. conyzoïdes at 1 p.m. and 7 p.m. resulted in 100% mortality after 8 min of exposure time at the lowest concentration (0.0025%). At the same concentration for the EO of E. citriodora, the mortality rates were 83%, 38.8%, and 30.80% at 7 a.m., 1 p.m., and 7 p.m., respectively for an exposure time of 8 min. The EO extracted from the leaves of L. camara harvested at 7 a.m. was effective after an exposure time of 15 min for a concentration of 0.02%. For the same concentration, the mortality rates of the EO of L. camara harvested at 1 p.m. and 7 p.m., after 8 min were 62.9% and 52%, respectively.From these interesting results reported for the first time in Togo, EOs from leaves of three Togolese plants harvested at different times of the day appear to be a valuable alternative for mosquito vector control in Togo or abroad countries in which dengue and yellow fever constitute a terrible scourge.

Insecticidal activity of essential oils from Piper aduncum against Ctenocephalides felis felis: a promising approach for flea control.

Piper aduncum L., a Brazilian medicinal plant, is known for its bioactive properties, including repellent and insecticidal effects. This study investigated the insecticidal potential of essential oils (EOs) from P. aduncum, collected during the dry and rainy seasons, against fleas (Ctenocephalides felis felis Bouché, 1835) in egg and adult stages. The EOs were obtained by hydrodistillation using a modified Clevenger apparatus for 2 h. Qualitative and quantitative analysis were performed via gas chromatography. The findings revealed that dillapiole was the predominant substance in both EOs, accounting for 77.6% (rainy) and 85.5% (dry) of the EOs. These EOs exhibited high efficacy against the parasite C. felis felis, resulting in 100% egg mortality at a concentration of 100 μg/mL and 100% mortality for adult fleas starting from 1,000 μg/mL. Dillapiole standard was also effective but at a relatively high concentration. This finding suggested that EOs from P. aduncum exhibit cytotoxicity against these pests and might hold potential for commercial production, offering practical applications for such bioprospecting. This study uniquely revealed that the EOs from P. aduncum, which is rich in dillapiole, demonstrated pulicidal activity against the parasite C. felis felis, particularly in inhibiting the hatching of the eggs of these parasites.

Larvicidal and Insecticidal Activity of Essential Oils of Lemon Balm against Aedes aegypti

Larvicidal and Insecticidal Activity of Essential Oils of Lemon Balm against Aedes aegypti

Acaricidal and insecticidal activity of essential oils obtained from the aerial parts of three Mexican Bursera species

In search of new sustainable biopesticides, we determined the phytochemical profiles, acaricidal and insecticidal properties of EOs distilled from the aerial parts of three Mexican Bursera species. Results were obtained by GC–MS analysis and three different bioassays, indicating that the EO of Bursera glabrifolia exhibited high relative abundancies of α-pinene, β-myrcene, and α-phellandrene, as well as promising pesticidal activity against Spodoptera littoralis larvae (LD50,90 = 32.4, 107.2 µg/larva), and Musca domestica (LD50,90 = 23.2, 103.2, and 13.5, 77.4 µg/female or male adult, respectively) and Tetranychus urticae adults (LD50,90 = 7.4, 30.3 µg/cm2). The Bursera lancifolia and Bursera linanoe samples contained mainly D-limonene or linalyl acetate and linalool, respectively, and showed generally less potent pesticidal properties (S. littoralis larva, LD50,90 = 45.4, 154.4 and 52.2, 158.7 µg/larva, respectively; female M. domestica adult, LD50,90 = 69.2, 210.9 and 45.1, 243.8 µg/female adult, respectively; T. urticae adults, LD50,90 = 20.7, 90.5 and 17.5, 71.4 µg/cm2, respectively). However, the EO of B. linanoe exhibited an especially pronounced activity against male M. domestica adults (LD50,90 = 10.6, 77.2 µg/male adult). Our findings prove the pesticidal potential of Mexican Bursera species in the context of integrated pest management (IPM) and highlight the importance of conducting further research to elucidate both the active principles and possibly existing synergistic effects.

Insecticidal activity of essential oil from leaves of Eugenia stipitata McVaugh against Aedes aegypti

Aedes aegypti, a mosquito, is responsible for the spread of many diseases, including dengue, zika, and chikungunya. However, due to this mosquito's developed resistance to conventional pesticides, effectively controlling it has proven to be challenging. This study aimed to evaluate the insecticidal potential of the essential oil from the leaves of Eugenia stipitata against Ae. aegypti, offering a natural and sustainable alternative for mosquito control. Tests were conducted using third-stage larvae to evaluate larvicidal activity and pupae collected up to 14 h after transformation to investigate pupicidal activity. Throughout the bioassays, the organisms were exposed to various essential oil concentrations. The findings demonstrated that the essential oil of E. stipitata exhibited larvicidal action, resulting in 100% larval mortality after 24 h and an LC50 value of 0.34 mg/mL. The effectiveness of essential oil as a pupicidal agent was also demonstrated by its LC50 value of 2.33 mg/mL and 100% larval mortality in 24 h. It can be concluded that the essential oil of E. stipitata holds promise as a natural pest control agent. Its use may reduce the reliance on conventional chemical pesticides, providing a more sustainable and effective strategy to combat diseases spread by mosquitoes.

Chemistry and Insecticidal Activity of Essential Oils against Trogoderma granarium Larvae

Chemistry and Insecticidal Activity of Essential Oils against Trogoderma granarium Larvae

Insecticidal activities of essential oil of Ocimun gratissimun in composite of modified saponins-clay montmorillonite and mango seed starch bioplastic

Insecticidal activities of essential oil of Ocimun gratissimun in composite of modified saponins-clay montmorillonite and mango seed starch bioplastic

Fumigant Contact and Repellent Actions of Essential Oils of Leaves, Fruits and Stems from Melicope pteleifolia Against Three Pests

Storage pests influence food production and conservation worldwide. The common control measures for these pests involve the use of synthetic pesticides, but these pesticides are harmful to the environment and human health. Thus, biological insecticides can substitute or reduce dependence on synthetic insecticides. This work aimed to study the insecticidal activities of essential oils (EOs) from leaves, fruits and stems of Melicope pteleifolia and their main compound against three kinds of pests, Tribolium castaneum, Lasioderma serricorne and Liposcelis bostrychophila. The Gas Chromatography - Mass Spectrometry (GC-MS) detection showed that β-cis-ocimene was the major compound in EOs from leaves and fruits of M. pteleifolia (26.96, and 65.99%, respectively). The main compound of stems EO is origanene (77.00%). In the fumigation test, EO of fruits and β-cis-ocimene were toxic to L. serricorne, and β-cis-ocimene was toxic to T. castaneum. The EOs and β-cis-ocimene had significant contact toxicity and repellent effect on these three species of pests. The results indicated that M. pteleifolia EOs are potential biological insecticides for controlling storage pests.

Insecticidal activity of essential oils from American native plants against Aedes aegypti (Diptera: Culicidae): an introduction to their possible mechanism of action

Searching for new bioactive molecules to design insecticides is a complex process since pesticides should be highly selective, active against the vector, and bio-safe for humans. Aiming to find natural compounds for mosquito control, we evaluated the insecticidal activity of essential oils (EOs) from 20 American native plants against Aedes aegypti larvae using bioassay, biochemical, and in silico analyses. The highest larvicide activity was exhibited by EOs from Steiractinia aspera (LC50 = 42.4 µg/mL), Turnera diffusa (LC50 = 70.9 µg/mL), Piper aduncum (LC50 = 55.8 µg/mL), Lippia origanoides (chemotype thymol/carvacrol) (LC50 = 61.9 µg/mL), L. origanoides (chemotype carvacrol/thymol) (LC50 = 59.8 µg/mL), Hyptis dilatata (LC50 = 61.1 µg/mL), Elaphandra quinquenervis (LC50 = 61.1 µg/mL), and Calycolpus moritzianus (LC50 = 73.29 µg/mL) after 24 h. This biological activity may be related to the disruption of the electron transport chain through the mitochondrial protein complexes. We hypothesized that the observed EOs' effect is due to their major components, where computational approaches such as homology modeling and molecular docking may suggest the possible binding pose of secondary metabolites that inhibit the mitochondrial enzymes and acetylcholinesterase activity (AChE). Our results provided insights into the possible mechanism of action of EOs and their major compounds for new insecticide designs targeting the mitochondria and AChE activity in A. aegypti for effective and safe insecticide.

Chemical Constituents, Antioxidant, Antimicrobial and Insecticidal Activities of the Essential Oils Extracted from Thymus guyonii de Noé and Thymus algeriensis Boiss. et Reut.

This study was designed to determine the chemical composition, antioxidant, antimicrobial and insecticidal activities of essential oils of Thymus guyonii and Thymus algeriensis. The essential oils (EOs) were isolated by hydrodistillation and analyzed by GC and GC-MS. The leading components of the oils were p-cymene (15.8%), γ-terpinene (15.3%), thymol methyl ether (15.7%) and thymol (19.1%) for T. guyonii and α-pinene (4.4%), camphor (4.6%), bornyl acetate (5.4%) and terpinenyl actate (28.1%) for T. algeriensis. The antioxidant activity was evaluated in terms of scavenging of free radicals DPPH● and ABTS●+. The essential oil of T. guyonii was the most efficient in inhibiting free radicals but less active compared to synthetic antioxidants (Trolox and BHT). Also, T. guyonii essential oil showed the highest effectiveness against the rice weevil, Sitophilus oryzae L. (Coleoptera: Curculionidae) as well as against five microorganisms, two gram-positive (Staphylococcus aureus and Bacillus subtilis), one gram-negative (Escherichia coli), one yeast (Candida albicans) and one fungus (Aspergillus brasiliensis). The results suggest that the EO of T. guyonii could be considered in pharmaceutical and food fields as well as for preservation of stored products from S. oryzae damage.