Repellent Effects Of Essential Oils Research Articles

Contact Toxicity and Repellent Effects of Essential Oils from Toddalia asiatica Against Two Stored-Product Insects.

Insect infestations continually endanger stored goods, underscoring the significance of discovering eco-friendly insecticides for pest management. Essential oils (EOs) from different parts of Toddalia asiatica (leaf, fruit and branch) were extracted by hydrodistillation and analyzed by GC-MS. Carvene, p-cymene and muurolene are the principal compounds of T. asiatica leaf (TAL), T. asiatica fruit (TAF) and T. asiatica branch (TAB) EO respectively. Our work aimed to assess the contact toxicity and repellent effects of EOs on two storage pests, Tribolium castaneum and Lasioderma serricorne. All tested EOs exhibited obvious contact toxicity, especially, TAL EO against T. castaneum (33.48 μg/adult) and TAF EO against L. serricorne (16.42 μg/adult). Repellency tests revealed that TAL and TAF EOs, at a concentration of 78.63 nL/cm2, achieved nearing 100 % efficiency against T. castaneum. These results suggest that EOs of T. asiatica could be used as effective botanical insecticides for managing stored-product insects.

Volatiles from essential oils of three Lamiaceae plants repel the winged cotton aphid, disturb its feeding behavior and reduce its fecundity.

Insects use odor detection to sense their surroundings. Use of volatile compounds, such as essential oils (EOs) of plants, to repel pests and disrupt their olfaction-driven behaviors has great practical potential for use in integrated pest management. Despite the available information on the repellent effects of EOs on herbivorous insects, the olfaction-based mechanisms remain unknown. Y-tube olfactometer tests showed that the EOs of three Lamiaceae plants - Mentha arvensis L., Mentha piperita L. and Lavandula angustifolia Mill. - were significantly repellent to winged cotton aphid, Aphis gossypii Glover. Electrical penetration graph (EPG) tests indicated the EOs reduced phloem feeding and increased the level of non-productive probing by the aphids. The EOs also reduced the fecundity of winged Aphis gossypii. Electrophysiological bioassays and gas chromatography-mass spectrometry (GC-MS) identified five physiologically active volatiles, that is menthone, isomenthone, neomenthol and menthol from Mentha piperita; menthone and menthol from Mentha arvensis; and linalool from L. angustifolia. Behavioral tests confirmed that all five compounds repelled winged Aphis gossypii. Under field conditions, the growth rate of aphid populations after 7 days was significantly lower in fields treated with these compounds than in the control fields. Our findings demonstrated that three EOs not only repelled winged Aphis gossypii but also interfered with the aphid's feeding behavior and reduced its fecundity. These EOs and their active constituents have great potential as eco-friendly control products for use against Aphis gossypii. The effects of these EOs also exceed other repellents that only keep pests away from host plants. © 2024 Society of Chemical Industry.

Larvicidal and repellent effects of essential oils on the brown dog tick (Rhipicephalus sanguineus Sensu lato) with description of new larval repellent activity test method

The aim of this research was to investigate the larvicidal and repellent effects of essential oils (EOs) obtained from two Lamiaceae plant species, Origanum minutiflorum O. Schwarz & P.H. Davis and Dorystoechas hastata Boiss. & Heldr. ex Bentham, both endemic to Turkey, on Rhipicephalus sanguineus s.l. Latreille (Acari: Ixodidae). The study also introduces a new test method that can be used to assess the repellent effects against ticks. Both plant EOs exhibited the highest larvicidal activity against brown dog tick larvae after 24 h and LC50 and LC90 values were determined as 0.101% and 0.125% for O. minutiflorum essential oil and 0.937% and 2.1% for D. hastata essential oil, respectively. In this study, we have described a detailed protocol for a novel larval repellent activity test (LRAT) for essential oils and extracts, using simple equipment. The advantages and limitations of LRAT, when compared to other tests commonly used to determine repellent effect against ticks, are also included in this study. The LRAT was developed with modifications of the larval immersion test (LIT) and proves to be a highly efficient and easily observable method. It can be used to test any active substance that may be toxic to humans and animals. According to the LRAT, at the end of 3 h, O. minutiflorum essential oil showed a high repellent effect, varying between 84.14% and 100% at 1% concentration. This result was not statistically different from the DEET, the positive control. When comparing the larvicidal and repellent activities, O. minutiflorum essential oil was found to be more effective than D. hastata essential oil.

Atividade inseticida e repelente do capim-limão nativo e exótico no gorgulho do milho

Corn crop, due to its easy adaptation to the most diverse agroecosystems, spreads throughout the different regions of the world, making it one of the most important agricultural crops. In this crop, pest insects stand out for causing losses both in the field and in warehouses. The application of essential oils can be an important technique to be investigated in the management of insects due to its known insecticidal activity and low risk to the environment. The objective of the work was to value the insecticide and repellent effect of essential oils of exotic lemongrass (Cymbopogon citratus) and native lemongrass (Elionurus sp.) for the management of maize weevil (Sitophilus zeamais (Mots., 1855, Coleoptera: Curculionidae)). The chemical analysis of the oils made by CG-MS showed that the chemical composition of the native and exotic lemongrass is similar, however, the exotic species presented a greater number of compounds. The essential oils of native and exotic lemon grass have efficiency on maize weevil mortality, and it is verified that the increase in the applied dose reflects in a reduction in the insect's exposure time for death to occur. The essential oil of both species showed repellent capacity at all times evaluated. Thus, it can be said that both species have the capacity and potential to be used in the management of corn weevil, and can be an alternative for smallhorders farmers and organic production.

Assessment of Contact Toxicity and Repellent Effects of Essential Oils from Piper Plants Piper yunnanense and Piper boehmeriifolium against Three Stored-Product Insects.

Storage is a crucial part during grain production for the massive spoilage caused by stored product insects. Essential oils (EOs) of plant origin have been highly recommended to combating insects which are biodegradable and safe mode of action. Hence, to make the fullest use of natural resources, essential oils of different parts from Piper yunnanense (the whole part, PYW; fruits, PYF; leaves, PYL) and Piper boehmeriifolium (leaves, PBL) were extracted by steam distillation method in the present study. Gas chromatography-mass spectrometry (GC-MS) characterization revealed bicyclogermacrene (PYW), γ-muurolene (PYF), δ-cadinene (PYL) and methyl 4,7,10,13,16,19-docosahexaenoate (PBL) as the principal compound of each essential oil. Sesquiterpene hydrocarbons were also recognized as the richest class accounting for 56.3 %-94.9 % of the total oil. Three storage pests, Tribolium castaneum, Lasioderma serricorne and Liposceis bostrychophila, were exposed to different concentrations of EOs to determine their insecticidal effects. All tested samples performed modest contact toxicity in contrast to a bioactive ingredient pyrethrin, among which the most substantial effects were observed in PYF EOs against T. castaneum (35.84 μg/adult), PBL EOs against L. serricorne (15.76 μg/adult) and PYW EOs against L. bostrychophila (57.70 μg/cm2 ). In terms of repellency tests, essential oils of PYF at 78.63 nL/cm2 demonstrated to have a remarkable repellence against T. castaneum at 2h and 4h post-exposure. The investigations indicate diverse variations in the chemical profiles and insecticidal efficacies of P. yunnanense and P. boehmeriifolium EOs, providing more experimental evidence for the use of the Piper plants.

Insecticidal and Repellent Effects of the Essential Oils Extract from Zanthoxylum myriacanthum against Three Storage Pests.

The co-storage of two or more Chinese herbal medicines can effectively prevent the herbs from the damage by pests. Thus, it is important to protect herbs and crops to study Chinese herbal medicines and their medicinal components against storage pests. This study aimed to assess the insecticidal activities and repellent effect of essential oils (EOs) extracted from fruits at different periods from Zanthoxylum myriacanthum Wall. ex Hook. f. (1 h, 2 h, 3-5 h and 5-7 h), and their major compounds against three kinds of pests (Tribolium castaneum, Lasioderma serricorne, and Liposcelis bostrychophila). The results of gas chromatography-mass spectrometer analysis revealed homomyrtenol (22.56 %, 28.01 %, 28.48 % and 28.41 %, respectively) and p-cymene (30.58 %, 13.95 %, 24.97 % and 6.85 %, respectively) were the common major compounds of the EOs at 1 h, 2 h, 3-5 h, and 5-7 h. m-Cymene contents in EOs of fruits, 1 h, 2 h and 3-5 h were 3.85 %, 0.95 %, 6.71 %, and 6.15 %, respectively. According to Principal component analysis (PCA), the composition of fruits' EO was significantly different from other EOs due to the different collection times. The bio-assays showed that EOs and major compounds were toxic to all three pests, but the fumigation effect on L. bostrychophila was not noticeable. EOs extracted at different times had a repellent effect on the three pests at the highest concentration (78.63 nL/cm2 ), but the attractive effects of the EOs of 3-5 h, 5-7 h, and p-cymene were observed at the low concentrations (3.15, 0.63 and 0.13 nL/cm2 ). Our results suggest that Z. myriacanthum have the potential to be developed as biological insecticides.

Synergistic larvicidal and repellent effects of essential oils of three Origanum species on Rhipicephalus annulatus tick.

Ticks are of great economic importance worldwide, both because they represent major obstacles to livestock productivity and because of their ability to transmit diseases to humans and animals. Although synthetic acaricides are the most common method for tick control, their overuse has led to the development of resistance as well as unacceptable residual levels in animal products and in the environment in general. There is therefore an urgent need to identify alternative treatments. Among such alternative approaches for tick control is plant essential oil (EO) therapy. In the present study, we investigated the synergistic effect of EOs of three oregano species-Origanum onites, O. majorana and O. minutiflorum-against Rhipicephalus annulatus larvae. Gas chromatography-mass spectrometry profiles of the three EOs revealed that carvacrol was their major component, with a concentration of 86.2% in O. majorana, 79.1% in O. minutiflorum and 77.4% in O. onites. The results of larvicidal assays revealed that the doses that lead to the death of 50% of the ticks (LC50) were 22.99, 25.08 and 27.06 µL/mL for O. majorana, O. minutiflorum and O. onites EOs, respectively, whereas the doses that lead to the death of 99% (LC99) were 41.26, 43.62 and 48.96 µL/mL. In addition, the LC50 and LC99 of the three oils combined was lower (viz., 4.01 and 6.97 µL/mL) than that of each oil alone. The tested EOs were also able to repel larvae of R. annulatus to varying degrees, with O. onites oil exhibiting the greatest repellent effect, as shown by the lowest RC50 dose, followed by O. minutiflorum and O. majorana. Interestingly, this means that the oil that was least effective in killing the larvae was the most effective in repelling them. The calculated synergistic factor of any combination was higher than 1 which means that combinations have a synergistic effect. In conclusion, the combination of all three oils showed higher toxic and repellent activities than either oil separately or combinations of any two oils, suggesting synergistic effects with low doses. Further studies including field trials and the establishment of the mode of action and side effects are urgently needed to expand on these findings, and other tick stages such as adults should also be tested.

Evaluation of the insecticidal potential of two medicinal plants and an entomopathogenic fungi against Tribolium confusum Jacquelin du Val. (Coleoptera: Tenebrionidae), a pest of stored foods

Stored products are among the most important foods in human nutrition. However; these products are under the pressure of many harmful organisms.One of these pests is Tribolium confusum Jacquelin du Val. (Coleoptera: Tenebrionidae). In this study, effects of two essential oils (Mentha rotundifolia and Satureja calamintha) and an enthomopathogenenic fungi on Tribolium confusum has been tried under the laboratory conditions, contact and repellent effects of essential oils and contact effect of dry plant extract were determined.As a result, essential oil, 3, 5, 10, 15 and 20 μl / ml doses of Mentha rotundifolia showed 100% effect after 24 hours, while Satureja calamintha reached 100% effect after 96 hours.15 μl / ml dose of M. rotundifolia and 20 μl / ml dose of S. calamintha reached 100% detrimental effect after two hours. Powder doses of 0.6, 0.8 and 1.0 g of these plants, which were applied, caused the death of all the male and female individuals after 24 hours. In addition, the effects of 1x107 conidia / mL dose of the entomopathogenic fungus Beauveria bassiana after 24, 48 and 72 hours were 87.5%, 97.5% and 100%, respectively. It was seen that both essential oils and B. bassiana were successfully in suppressing the depot pest Tribolium confusum.

Sesquiterpenoid-rich Essential Oils from Two Magnolia Plants: Contact and Repellent Activity to Three Stored-product Insects.

Stored products have been damaged by insects. Multiple approaches for pest management are employed. Among these approaches, botanical insecticide is an emerging one. This work investigated the pest management potential of Magnolia coriacea and Magnolia macclurei essential oils (EOs) to three major stored-product insects, namely the red flour beetle, cigarette beetle and booklouse. Magnolia coriacea and M. macclurei EOs showed promising contact toxicity to the cigarette beetle, with LD50 values of 11.7 and 12.3 μg/adult. The contact toxicity of M. coriacea EOs to the booklouse (LC50 = 95.5 μg/cm2) was much stronger than that of M. macclurei EOs (LC50 = 245.4 μg/cm2). To explore the contribution of individual compounds to insecticidal activity of EOs, chemical analysis was performed by GC-MS. Results showed that nerolidol (27.84%), agarospirol (18.34%), elixene (15.84%) and helminthogermacrene (12.69%) were major compounds of M. coriacea EOs, β-guaiene (60.31%) and elixene (20.42%) dominated in M. macclurei EOs. Nerolidol and β-guaiene showed contact activity to three insect species. Nerolidol showed stronger contact toxicity to the red flour beetle and cigarette beetle than M. coriacea EOs did, both samples were similar to the booklouse. β-Guaiene was much stronger to the red flour beetle and booklouse, but weaker to the cigarette beetle than M. macclurei EOs did. The repellent effects of EOs and compounds were at various levels. Generally, results suggested that the contact toxic potential of samples could serve as management for the cigarette beetle and booklouse, while repellent effect would be used to control the red flour beetle.

Acaricidal and Repellent Effects of Essential Oils against Ticks: A Review.

Tick control is a priority in order to prevent the transmission of vector-borne diseases. Industrial chemical acaricides and repellents have been the most efficient tools against hard ticks for a long time. However, the appearance of resistances has meant the declining effectiveness of the chemicals available on the market. The trend today is to develop alternative control methods using natural products to replace nonefficient pesticides and to preserve the efficient ones, hoping to delay resistance development. Traditional in vitro evaluation of acaricidal activity or resistance to synthetic pesticides have been reviewed and they mainly focus on just one species, the one host tick (Rhipicephalus (Boophilus) microplus (Acari: Ixodidae)). Recent reports have called for the standardization of natural product components, extraction techniques, and experimental design to fully discover their acaricidal potential. This study reviews the main variables used in the bibliography about the efficiency of natural products against ticks, and it proposes a unification of variables relating to ticks, practical development of bioassays, and estimation of ixodicidal activity.

Identification of Bioactive Compounds against Aedes aegypti (Diptera: Culicidae) by Bioassays and in Silico Assays.

Most of the hematophagous insects act as disease vectors, including Aedes aegypti, responsible for transmitting some of the most critical arboviruses globally, such as Dengue. The use of repellents based on natural products is a promising alternative for personal protection compared to industrial chemical repellents. In this study, the repellent effect of essential oils extracted from Lippia thymoides, Lippia alba, Cymbopogon winterianus, and Eucalyptus globulus leaves was evaluated. Essential oils used showed repellent activity against Ae. aegypti in laboratory bioassays, obtaining protection rates above 70 % from 3.75 mg/mL and higher concentration for all analyzed oils. GC/MS identified 57 constituents, which were used in the ligand-based pharmacophore model to expose compounds with requirements for repellents that modulate mosquitoes behavior through odorant-binding protein 1 Ae. aegypti. Ligand-based pharmacophore model approach results suggested that repellent activity from C. winterianus, L. alba, and L. thymoides essential oils' metabolites is related to Citronelal (QFIT=26.77), Citronelol (QFIT=11.29), Citronelol acetate (QFIT=52.22) and Geranil acetate (QFIT=10.28) with synergistic or individual activity. E. globulus essential oil's repellent activity is associated with Ledol (0.94 %; QFIT=41.95). Molecular docking was applied to understand the binding mode and affinity of the essential oils' data set at the protein binding site. According to molecular docking, Citronelol (ChemPLP=60.98) and geranyl acetate (ChemPLP=60.55) were the best-classified compounds compared to the others and they can be explored to develop new repellents.

Contact and repellent effects of essential oils of Chromolaena odorata (L.) and Uvaria chamae (P. Beauv) against Macrotermes bellicosus (Smeathman)

Macrotermes bellicosus, though a beneficial termite species causes serious damage to wood and wood products, fabrics and many agricultural crops and ornamental trees. This study was conducted to assess the potentials of essential oils of the leaves of Chromolaena odorata and roots of Uvaria chamae in the control of M. bellicosus. The repellency, knockdown and insecticidal effects of the oils to M. bellicosus were tested using the filter paper and cotton ball impregnation technique. Each test oil (0.05, 0.075 and 0.10 ml) was separately used in the repellency assay, for an exposure period of 30 and 60 minutes. For the knockdown and toxicity test, termites were exposed to 0.05, 0.075, 0.10, 0.125 and 0.15 ml of each oil for an exposure period of 60 minutes and 6 hours, respectively. Each test and control (untreated) group had three replicates and in each experiment twenty active workers of M. bellicosus were exposed. Repellency results were somewhat irregular and oil volume and exposure, time independent. Knockdown effect of 56.67 and 86.67 % were observed for C. odorata and U. chamae oils (0.15ml), respectively at the 60th minute. Contact toxicity test with 0.15 ml of the oils resulted in 100 % and 86.67 % mortalities for U. chamae and C. odorata, respectively. No knockdown or mortalities were observed in the controls. The difference between the repellency of both oils at 30 and 60 minutes was not significant (p>0.05; p= 0.842 and 0.212 respectively), whereas for knockdown and insecticidal effects of both oils the difference was significant Q3(p<0.05; p= 0.000 and 0.001 respectively).. Essential oils of C. odorata and U. chamae are potential agents for the control of M. bellicosus.

Oviposition-deterrent effect of linalool - a compound of citrus essential oils - on female Mediterranean fruit flies, Ceratitis capitata (Diptera: Tephritidae).

Linalool is a natural scent, found in essential oils (EOs) of several plants. It is widely used as a fragrant, also possessing toxic, oviposition-deterrent and repellent properties against many insect species. Ceratitis capitata (medfly) is one of the most notorious insect pests for international fresh fruit production. Despite the available information on the repellent effects of EOs on herbivorous insects, possible oviposition-deterrent effects of linalool against C. capitata remain unknown. We tested whether different linalool concentrations, application methods on fruit hosts and time since application elicited oviposition-deterrence on medfly, from bitter oranges, apples and nectarines, under constant laboratory conditions. We also tested possible repellent properties of linalool on adult medflies in field conditions. Females drilled fewer oviposition stings and deposited fewer eggs per fruit in all linalool-treated hosts. Spraying and topical-droplet application were the most efficient methods on bitter oranges, although spraying was the least effective method in apples. Bitter oranges and nectarines that were offered to females immediately post-exposure to linalool received more oviposition stings and eggs than those offered 3 days post-exposure to linalool solutions. Conversely, apples tested 3 days following linalool application received significantly more oviposition stings and eggs than those tested immediately and 1 day post-exposure. More adults in total, and more females, were captured in traps located on untreated-control than on linalool-treated trees, especially in citrus hosts. Linalool has a potential future use in environmentally friendly control strategies against C. capitata. © 2020 Society of Chemical Industry.

Effiiency of the Essential Oil of Porophyllum linaria (Asteraceae) a Mexican Endemic Plant Against Sitophilus zeamais (Coleoptera: Curculionidae).

The insecticidal and repellent effect of essential oil isolated from fresh leaves of Porophyllum linaria on maize weevil was evaluated, as well as the effect on the grain germination after treated. In total, 28 constituents were identified by gas chromatography coupled with mass spectrometry accounting for 99.86% of whole essential oil. The main majority compounds were β-myrcene (41.94%), D-limonene (20.29%), and estragole (20.03%). Contact toxicity significantly increased with dose and time after treatment. With the 800 ppm (highest concentration), the mortality (%) obtained for the tenth and fifteenth day was 43 and 82%, respectively, whereas with 50 ppm (lowest concentration) 30% mortality was obtained at the end of the experiment (fifteenth day). At 15 d (end of the experiment), the LC50 y LC90 were obtained with values of 329.01 ± 44.35 y 1058.86 ± 117.76 ppm, respectively. For a concentration of 800 ppm, a selection index of zero was obtained, indicating the preference of the pest to the untreated maize (control). The maize grains germination test showed a significant reduction both in the length of hypocotyl and radicle of maize grain. So, in the highest dose, the hypocotyl and radicle length was 1.40 ± 0.34 and 9.14 ± 0.55 cm, respectively, whereas the control group registered 3.28 ± 0.39 and 13.02 ± 0.97 cm, respectively. This finding is promising since as it could result in the identification of botanical substances capable of suppressing maize weevil, Sitophilus zeamais development.

Insecticidal and repellent effects of essential oils from leaves of Hyptis suaveolens and Ocimum canum against Tenebroides mauritanicus (L.) isolated from peanut in post-harvest

The present work aims to evaluate the insecticidal and repellent effects of essential oils from fresh leaves of Hyptis suaveolens and Ocimum canum against Tenebroides mauritanicus (L.) (Coleoptera: Tenebrionidaea) isolated from peanut in post-harvest in Benin. Chemical analysis of essential oils by GC and GC-MS indicated that, in the volatile extracts, different groups of terpene and terpenoid were present. The results of contact toxicity tests indicated that at a concentration of 0.5 µl of essential oil/g of peanut the mortality rate of Tenebroides mauritanicus (L.) is 100% after 24 h for the essential oil of Hyptis suaveolens, while it is still at 20% for the essential oil of Ocimum canum. Results also indicated that Hyptis suaveolens oil has a high repellent activity, when compared to the essential oil of Ocimum canum. This essential oil with high repellent and insecticidal properties represents a novel approach in the protection of grains against T. mauritanicus and the reduction of post-harvest losses.

THE COMPONENT COMPOSITION AND FUMIGANTN ACTIVITY OF ESSENTIAL OILS OF SPECIES OF GENUS ARTEMISIA L.

The article presents data on the study of fumigantn activity of 12 species (A. fragrans Willd., A szowitziana (Bess.) Grossh., A. spicigera Koch., A. santonica L., A. kobstanica Rzazade, A. scoparia W.et. K., A. scoparioides Grossh., A. annua L., A. maritima L., A. marschalliana Spreng., A. pausiflora Web.ex Stechm., A. tournefortiana Rchb., A. hanseniana Grossh. genus Artemisia L. It is revealed repellent effects of essential oils for 3–8 hours.Duration of repellent action depends on the major component of essential oils. Maximum duration (8 hours.) was observed in action of essential oils Artemisia fragrans Willd, A.santonica, A szowitziana and A.spicigera. Duration repellent action also depends on the ambient temperature. Essential oils of the studied species are repellents and can be used in the prevention of malaria, Zeke disease and other illnesses. Repellent effect of essential oils is associated with majore various components of essential oils; A.fragrans 1,8-cineole (3,6%) and λ-thujone (28%); A.szowitziana β-thujone, 75% and λ-tuyon (9%); A. spicigera camphor (48%) and 1,8-cineole (46%); A.santonica β-citral (34%) and λ-citral (33%).

Repellent Effects of Essential Oils on AdultBagrada hilarisby Using an Olfactometer

Abstract. Bagrada hilaris (Burmeister) (Hemiptera: Pentatomidae) is a serious invasive stink bug species in the central coast region of California. Although B. hilaris can be effectively managed using synthetic insecticides, organic growers have limited effective tools to manage this pest. Little is known about repellent effects of essential oils on adult B. hilaris; thus, repellent effect of citronellal, lemongrass oil, geraniol, peppermint oil, thyme oil, rosemary oil, pine needle oil, and vetiver acetate was examined using olfactormeter. In the choice assay, most of the essential oils did not elicit repellency to both female and male adult B. hilaris except geraniol because significantly more B. hilaris chose the empty arm of the olfactometer than the arm with geraniol. Implications of essential oils on B. hilaris management are discussed.

Fumigation and repellency of essential oils against Callosobruchus maculatus (Coleoptera: Chrysomelidae: Bruchinae) in cowpea

Abstract: The objective of this work was to assess the fumigant and repellent effects of essential oils on adults of Callosobruchus maculatus and to identify the chemical composition of two of the tested essential oils. For the fumigation test, the oils of Schinus terebinthifolius, Piper aduncum, Syzygium aromaticum, Piper hispidinervum, Cymbopogon citratus, Cinnamomum zeylanicum, and the eugenol compound were tested at different concentrations on C. maculatus adults. For the repellency test, the oils of S. terebinthifolius, P. aduncum, P. hispidinervum, S. aromaticum, Jatropha curcas, and Ricinus communis were evaluated. In the fumigation test, it was observed that P. aduncum and eugenol showed the highest and lowest LC50s, of 169.50 and 0.28 μL L-1 air, respectively. In the repellency test, the oils of S. aromaticum and P. hispidinervum were repellent to C. maculatus. Gas chromatography coupled to mass spectrometry (GC-MS) analysis of these two oils identified 42 compounds, of which safrole was the main component of P. hispidinervum and eugenol of S. aromaticum. The essential oils of S. aromaticum, C. zeylanicum, and the eugenol compound are the most promising to control C. maculatus, via fumigation.

Toxicity and repellent effect of essential oils and a major component against Lipaphis erysimi

Toxicity and repellent effect of essential oils and a major component against Lipaphis erysimi

Chemical Composition and Insecticidal and Repellent Effect of Essential Oils of Two Premna Species against Sitotroga cerealella

This work aims to study for the first time the chemical composition and evaluate insecticidal and repellent effects of essential oils of Premna angolensis and Premna quadrifolia leaves, against Sitotroga cerealella, an insect pest of rice stocks as alternatives to synthetic pesticides. The GC-MS analysis showed that essential oil of P. angolensis contains 29 compounds representing 96.1% of the oil and 42 compounds corresponding to 91% for the essential oil of P. quadrifolia. The main constituents regardless of the species were β-caryophyllene (13.1%), (E)-β-caryophyllene (13.5%), octen-3-ol (3.2%–28%), phytol (3.7%–4.9%), β-elemene (1.4%–21%), globulol (11.2%), germacrene-D (8.9%), α-humulene (2.9%–6.4%), α-pinene (5%), sabinene (3.7%), δ-cadinene (0.4%–3.3%), and linalool (3.3%). The results of laboratory tests showed that both essential oils have insecticidal and repellent effects on S. cerealella. Presenting the results, the damage caused by the adults and larvae of S. cerealella was evaluated by calculating the percentage of grains attacked and weight loss thereof. The results suggest that volatile extracts of P. angolensis and P. quadrifolia can be used as alternatives to synthetic chemicals in paddy protection against S. cerealella.