Toxicity Of Essential Oil Research Articles

Active Components of 16 Essential Oils and Their Fumigation Effects on Galleria mellonella (Lepidoptera: Pyralidae).

The greater wax moth (GWM, Galleria mellonella) is a prevalent pest of the honeybee and a significant risk to both honeybee populations and honeycomb storage. Research on the toxicity of essential oils (EOs) to GWM larvae has provided promising results, although their ovicidal effects and active ingredients require further study. Identifying effective plant compounds is essential for developing insecticides for GWM control. This study assessed the fumigation efficacy of 16 EOs on GWM eggs and fifth instar larvae and determined the effectiveness of these EOs and their primary components for fumigating fifth larvae. Wintergreen, star anise, and clove oils demonstrated significant insecticidal effects on GWM eggs and fifth instar larvae, resulting in a mortality rate exceeding 80% within 48 h. Gas chromatography-mass spectrometry analysis identified methyl salicylate (93.26%), trans-anethole (87.75%), and eugenol (77.75%) as the primary compounds in wintergreen, star anise, and clove oils, respectively. Further toxicity testing confirmed that these compounds were responsible for the observed insecticidal properties of the EOs. Notably, trans-anethole exhibited the lowest LC50 value (25.22 μL/L) against the fifth instar larvae of GWM and significant toxicity against GWM eggs and fifth instar larvae, suggesting its potential as a viable option for the future control of GWM populations.

Chemical Variability and Fumigant Toxicity of Essential Oils from Peels of Citrus reticulata L. Native to Nigeria

Cowpeas infested with Callosobruchus maculatus have lower protein quality compared to the uninfected cowpeas. The affected cowpeas are usually treated with synthetic insecticides that are expensive and hazardous to man. Essential oils were established to possess insecticidal properties without detrimental effects on the users. The properties are influenced by environmental conditions that changes with time in a day and as well determine the type of chemical compounds present in the oils. In this study, we investigated the chemical composition and fumigant toxicity of essential oils from rinds of Citrus reticulata collected at 7.00am and 2.00pm against C. maculatus. Hydrodistillation of the pulverized (500 g each) rinds from morning and afternoon harvests afforded 0.56±0.06 % and 0.38±0.03 %(w/w) of volatile oils. GC-MS was employed to analyze the oils and the results showed abundance of D-Limonene (55.7% and 61.1%), linalool (12.5% and 16.9%), terpinen-4-ol (7.7% and 5.4%), nerol (1.1% and 4.0%) and α-terpineol (3.3% and 4.5%). The insecticidal property of the oils was examined against bean weevils using fumigant toxicity bioassay. The activity of the oils differs significantly with LT50 of 1.967 hours and 1.297 hours for the oils from the rinds of fruits harvested at 7.00am and 2.00pm respectively. The oil from the 2.00pm harvest is therefore more potent and thereby recommended as a safer insecticide against stored product insect pest, C. maculatus.

Toxicity of Essential Oil from Artemisia herba-alba (Asso.) against Two Insect Pests of Stored Products

This study aimed to examine the insecticide properties of Artemisia herba-alba essential oil (EO) against two main insect pests of stored products Tribolium castaneum and Sitophilus zeamais. The toxicity of EO was tested using contact and fumigant bioassays. Repellent activity was also studied using the preference zone method on filter paper. Using GC/MS analysis, the major compounds were, respectively, camphor (23.61%), α-thujone (13.67%), chrysanthenone (11.21%), 1,8-cineole (10%) and β-thujone (7.65%). In both insects, the toxicity tests applied showed a significant increase in the percentage of mortality according to the doses tested (p ≤ 0.05). Moreover, the probit analysis exposed lower values of doses and lethal concentrations (LD50, LD90, LC50, and LC90), which justified the toxic effect of EO on the two insects. In addition, EO caused a significant repulsion after 1 h and 2 h of exposure. The results obtained suggest that A. herba-alba EO can be an excellent alternative to chemical insecticides in the conservation of stored products.

Toxicity of botanical insecticides on different species of lace bugs

This study aimed to evaluate the toxicity of essential oils (EO) from Allium sativum (Amaryllidaceae) and Eucalyptus citriodora (Myrtaceae), commercial oil (CO) from Azadirachta indica (Meliaceae), and ethanolic extracts (EE) of Eugenia caryophyllata (Myrtaceae) and Piper nigrum (Piperaceae) on lace bugs (Hemiptera: Tingidae). The study also investigated the effects of exposure method, surfactant addition, and lace bug species on insecticide toxicity. The results indicated that assessing lace bug toxicity via contact with contaminated filter paper is a more effective method. Adding 5% detergent to E. citriodora EO 1% increased the mean mortality rates of the lace bug Gargaphia lunulata and Corythaica passiflorae from 34.11% to 94.00%. A. sativum EO 10%, E. citriodora EO 1%, and A. indica CO 1%, when combined with 5% detergent, caused high mortality rates in G. lunulata (76.00%, 77.67%, and 80.73%, respectively). However, these insecticides without detergent caused lower mortality in C. passiflorae (15.44%, 20.09%, and 11.15%, respectively), highlighting the significant impact of surfactant addition on the toxicity of essential and commercial oils. Piper nigrum EE 10% was toxic to all lace bug species. Conversely, the toxicity of Eugenia caryophyllata EE 10% varied among species, with mortality rates of 40% in G. lunulata, an average of 76.00% in Ulotingis sp. and Vartiga illudens, and 95.48% in C. passiflorae. In conclusion, despite variations in toxicity due to exposure method, surfactant addition, and lace bug species in laboratory bioassays, the botanical insecticides studied show promise for lace bug control.

Knockdown and Toxicity of Essential Oils from the Rhizome of Zingiber officinale (L) and the Bud of Syzygium aromaticum (L) to Periplaneta americana (L)

The American cockroach (Periplanata americana) is an important peridomestic pest that is responsible for the mechanical transmission of several disease pathogens. This study aimed to evaluate the knockdown and toxicity effects of ginger (Zingiber officinale) and cloves (Syzygium aromaticum) essential oils against Periplanata americana. Oils were extracted from the rhizomes and buds of ginger and cloves plants respectively. The oils were extracted using the hydrodistillation method and were serially diluted in 20% tween 80 solution to obtain seven concentrations (5, 10, 25, 50, 100, 200 and 400μl/ml). Whatman No.1 filter paper was smeared with 1ml of each concentration of the oil and allowed to dry. Adult P. americana were exposed to the treated filter paper in a glass jar. Each experimental set up and the control had 20 adult cockroaches each. The control experiment had the cockroaches exposed to 1ml of 20% tween 80 solution. Each experiment was replicated 4 times. The knockdown effect was observed at 10 minutes intervals for 60 minutes while the mortality count was recorded after 24 and 48 hours. After 20 minutes of exposure to cloves oil, 100% knockdown was observed in the highest concentration (400μl/ml). For ginger oil, complete knockdown was observed in the highest concentration (400μl/ml) after 30 minutes of exposure. Both ginger and clove oil showed increased mortality as the concentration increased. After 48 hours of exposure, 100% mortality of adult P. americana were recorded in both oils at the highest concentration of 400μl/ml. While 25% and 40% mortality recorded at the lowest concentration of 5μl/ml for ginger and clove oil respectively at 48 hours. There was no mortality recorded in the control. Clove oil was more potent than ginger oil, this was judged by the 48 hours LC50 value of 7.344μl/ml while the 48 hour LC50 value for ginger oil was 56.564μl/ml. It was concluded from the study that both ginger and clove oils exhibited significant knockdown and toxicity activity against P. americana. Thus, it is recommended that the essential oils from these plants should be incorporated in the production of botanical pesticides for the management of P. americana, which is a well-known mechanical vector and common household’s pest.

Research Progress in Essential Oil Nanodelivery Systems

Essential Oil (EO) is widely usedin medicine because of its antioxidant, antiinflammatory, antibacterial, antimicrobial, and antiviral properties. However, the hydrophobicity, volatility, instability, and potential toxicity of EO make it difficult to achieve efficient delivery in vivo, which limits its application. In recent years, nano drug delivery systems have been gradually applied to encapsulate EO to improve their physical and chemical properties. In order to further improve the delivery efficiency of EOs, this review summarized the commonly used nano delivery systems for EOs, analyzed their preparation principles, and listed the factors affecting the delivery efficiency of essential oils. Moreover, the challenges faced by the EO delivery system are sorted out, and the corresponding solutions are proposed, with the hope of indicating the development direction for expanding the application of the nano drug delivery system in EO.

Antimicrobial Activity of Essential-Oil-Based Nanostructured Lipid Carriers against Campylobacter Spp. Isolated from Chicken Carcasses.

Campylobacter is a virulent Gram-negative bacterial genus mainly found in the intestines of poultry. The indiscriminate use of traditional antibiotics has led to drug resistance in these pathogens, necessitating the development of more efficient and less toxic therapies. Despite their complex biologically active structures, the clinical applications of essential oils (EOs) remain limited. Therefore, this study aimed to increase the bioavailability, stability, and biocompatibility and decrease the photodegradation and toxicity of EO using nanotechnology. The diffusion disk test revealed the potent anti-Campylobacter activity of cinnamon, lemongrass, clove, geranium, and oregano EOs (>50 mm). These were subsequently used to prepare nanostructured lipid carriers (NLCs). Formulations containing these EOs inhibited Campylobacter spp. growth at low concentrations (0.2 mg/mL). The particle size, polydispersity index, and zeta potential of these systems were monitored, confirming its physicochemical stability for 210 days at 25 °C. FTIR-ATR and DSC analyses confirmed excellent miscibility among the excipients, and FE-SEM elucidated a spherical shape with well-delimited contours of nanoparticles. The best NLCs were tested regarding nanotoxicity in a chicken embryo model. These results indicate that the NLC-based geranium EO is the most promising and safe system for the control and treatment of multidrug-resistant strains of Campylobacter spp.

Effects of Essential Oils on Biological Characteristics and Potential Molecular Targets in Spodoptera frugiperda.

Spodoptera frugiperda control methods have proved to be inefficient, which justifies the search for new control measures. In this search for botanical insecticides for controlling S. frugiperda, the following were evaluated: (i) the toxicity of essential oils (EOs) from Cinnamodendron dinisii, Eugenia uniflora, and Melaleuca armillaris; (ii) the effect of EOs on life table parameters against S. frugiperda; (iii) the chemical characterization of EOs; and (iv) the in silico interaction of the chemical constituents present in the three EOs with the molecular targets of S. frugiperda. The EO from E. uniflora had the lowest LD50 (1.19 µg of EO/caterpillar). The major compounds bicyclogermacrene (18.64%) in C. dinisii and terpinolene (57.75%) in M. armillaris are highly predicted to interact with the octopamine receptor (OctpR). The compound 1,8-cineole (21.81%) in M. armillaris interacts mainly with a tolerant methoprene receptor (MET) and curzerene (41.22%) in E. uniflora, which acts on the OctpR receptor. Minor compounds, such as nerolidol in C. dinisii and β-elemene in E. uniflora, are highly ranked for multiple targets: AChE, MET, OctpR, and 5-HT1. It was concluded that the EO from E. uniflora negatively affects several biological parameters of S. frugiperda development and is promising as an active ingredient in formulations for controlling this insect pest.

Syzygium aromaticum essential oil and its major constituents: Assessment of activity against Candida spp. and toxicity.

Syzigium aromaticum essential oil (EO), eugenol, and β-caryophyllene were evaluated regarding antifungal, antibiofilm, and in vitro toxicity. Additionally, in vivo toxicity of EO was observed. Anti-Candida activity was assessed through broth microdilution assay for all compounds. Time-kill assay (0, 1, 10, 30 min, 1, 2, and 4 h) was used to determine the influence of EO and eugenol on Candida Growth kinetics. Thereafter, both compounds were evaluated regarding their capacity to act on a biofilm formation and on mature biofilm, based on CFU/ml/g of dry weight. Cell Titer Blue Viability Assay was used for in vitro cytotoxicity, using oral epithelial cells (TR146) and human monocytes (THP-1). Lastly, Galleria mellonella model defined the EO in vivo acute toxicity. All compounds, except β-cariofilene (MIC > 8000 μg/ml), presented antifungal activity against Candida strains (MIC 500-1000 μg/ml). The growth kinetics of Candida was affected by the EO (5xMIC 30 min onward; 10xMIC 10 min onward) and eugenol (5xMIC 10 min onward; 10xMIC 1 min onward). Fungal viability was also affected by 5xMIC and 10xMIC of both compounds during biofilm formation and upon mature biofilms. LD50 was defined for TR146 and THP1 cells at, respectively, 59.37 and 79.54 μg/ml for the EO and 55.35 and 84.16 μg/ml for eugenol. No sign of toxicity was seen in vivo up to 10mg/ml (20 x MIC) for the EO. S. aromaticum and eugenol presented antifungal and antibiofilm activity, with action on cell growth kinetics. In vivo acute toxicity showed a safe parameter for the EO up to 10 mg/ml.

What routes makes Essential Oils effective in Aromatherapy? A current perspective study

Aromatherapy, the therapeutic application of essential oils extracted from plants, has emerged as a prominent practice in complementary and alternative medicine. Essential oils, renowned for their aromatic compounds, are utilized in a variety of therapeutic modalities to enhance physical, emotional, and mental health. Understanding the administration routes of essential oils is crucial for maximizing their therapeutic potential and ensuring safety. The method of administration—whether inhalation, topical application, or ingestion—significantly influences the absorption, distribution, and efficacy of the bioactive compounds in essential oils. For instance, inhalation directly interacts with the olfactory system, potentially impacting mood and stress levels, while topical application facilitates localized effects and transdermal absorption, providing targeted therapeutic benefits. Ingestion, though less common, requires careful consideration due to the potent nature and potential toxicity of essential oils. This paper emphasizes the importance of selecting the appropriate administration route based on desired outcomes and safety considerations. It also explores the concept of synergy, where the interaction of multiple essential oil constituents can enhance therapeutic effects, exemplified by the compounds in lavender and eucalyptus oils. This study highlights the challenges in aromatherapy research, including the need for standardization, quality assurance, and rigorous methodological approaches to validate the therapeutic efficacy of essential oils.

Toxicity of Essential Oil of Cnidium monnieri 1 Fruit against Adults of Lasioderma serricorne 2

Toxicity of Essential Oil of Cnidium monnieri 1 Fruit against Adults of Lasioderma serricorne 2

Serbian Artemisia species – chemical composition, acute toxicity and larvicidal activity of the essential oils

The chemical composition and biological activities of the essential oils obtained from Serbian Artemisia species (A. alba, A. absinthium, A. annua, A. vulgaris, and A. scoparia) were analysed. The essential oil was obtained by merging several samples (same plant species, different localities) and the chemical composition was compared with pre-merging results. In the merged A. scoparia sample four components were not found in any pre-merging sample and one of those is present in the highest percentage (capillin 35.7%). The least toxic essential oil in Artemia salina test was A. annua, followed by A. alba (both showing medium toxicity), while A. absinthium, A. vulgaris, and A. scoparia showed strong toxicity. All tested samples showed activity against Drosophila melanogaster larvae in descending order ΣAS > ΣAN > ΣAV > ΣAB > ΣAA. The essential oil of A. scoparia has exceptional larvicidal activity (in concentrations of 2% and 1% causes complete mortality).

Efficacy of fumigant compounds from essential oil of feverfew (Chrysanthemum parthenium L.) against maize weevil (Sitophilus zeamais Mots.): Fumigant toxicity test and in-silico study

Post-harvest insects are among the significant problems in the agricultural sector. The most accessible tools available for managing post-harvest arthropod-pests are fumigants because of the convenience of their applications and fast action in disinfecting. This study aimed to examine the fumigant toxicity of essential oil (EO) against maize weevil and identify the specific fumigants among the major components. The EO was extracted from aerial part of Chrysanthemum parthenium L. using Clevenger apparatus and was tested for fumigant toxicity. GC-MS was used to determine the chemical composition of EO. The major components were identified and screened virtually using Auto dock vina 1.2. in PyRx 0.8 platform. Dm AChE PDB ID: 6XYY was used as a target for molecular docking and malathion and pirimiphusmethyl were used as a reference for comparison. From the results of binding affinities, most of the major EO components showed better fumigant activity than the reference fumigants. More specifically 1,6-dioxaspiro[4,4]non-ene, b-farensen, bornyl-tiglate, g-terpinene, p-cymene, bornyl-acetate, bornyl-isovalerate, terpinen-4-ol, trans-chrysanthenyl-acetate and a-phellandrene were found to be effective fumigants against maize weevil. The above findings suggest that the EO of the aerial part of C. parthenium can be a potential candidate for the development of novel natural fumigants for stored products.
 KEY WORDS: Essential oil, Fumigants, Insecticides, Binding affinity, Maize weevil
 Bull. Chem. Soc. Ethiop. 2024, 38(2), 457-472. 
 DOI: https://dx.doi.org/10.4314/bcse.v38i2.13

Chemical profile and biological potential of essential oil of Psidium bahianum Landrum & Funch (Myrtaceae).

The genus Psidium, belonging to the family Myrtaceae, encompasses several plant species rich in essential oils. Several studies involving different research areas have shown promising results for essential oils, which has attracted interest from diverse sectors, including pharmaceutical, food, and cosmetic industries. Thus, the objective of this study was to evaluate the biological activity of the essential oil extracted from Psidium bahianum leaves (EOPb) collected in an Atlantic Forest remnant in the northern coast of the state of Bahia, Brazil. EOPb was extracted by steam distillation and analyzed through proton nuclear magnetic resonance (1H-NMR). The free radical scavenging activity was assessed using the DPPH methodology (analyzing the scavenging of the stable free radical 1,1-diphenyl-2-picrylhydrazyl). Antimicrobial disk diffusion assays were conducted; toxicity was determined through assays on sheep erythrocytes and Artemia salina. 1H-NMR evaluation showed the presence mainly of monoterpenes and sesquisterpenes. The percentage of antioxidant activity was 18.03±2.53 53 for 125 125 µg mL-1. Antimicrobial assays showed that the essential oil at a concentration of 10 mg mL-1 inhibited the growth of the microorganisms Staphylococcus aureus, Bacillus subtilis, B. cereus, Micrococcus luteus, Escherichia coli, Aspergillus niger, Candida albicans, and C. glabrata. The toxicity results indicated that concentrations of EOPb at 10, 100, 250, and 500 µg mL-1 were not toxic to sheep erythrocytes. The toxicity assay on A. salina showed that the lethal concentration for 50% of individuals (LC50) within 24 and 48 hours were 371.48 and 302 µg mL-1 of EOPb, respectively, which were considered moderately toxic, whereas the LC50 within 72 horas was 33.11 µg mL-1, considered highly toxic. These findings are promising, as the essential oil from P. bahianum leaves showed antimicrobial activity against both Gram-positive and Gram-negative bacteria and fungi. The data obtained for the essential oil toxicity in A. salina could be tested on different tumor cell lines.

Evaluation of Phytochemical Compounds, In-vitro Antioxidant Properties, and Toxicity of Essential Oil from Myristica fragrans Houtt (Nutmeg) Using Danio rerio (Zebrafish)

Evaluation of Phytochemical Compounds, In-vitro Antioxidant Properties, and Toxicity of Essential Oil from Myristica fragrans Houtt (Nutmeg) Using Danio rerio (Zebrafish)

Drosophila melanogaster as a model for studies related to the toxicity of lavender, ginger and copaiba essential oils.

This study addresses the current trend of essential oils in alternative medicine using the non-chordate model Drosophila melanogaster. Following the three R's principles, it proposes non-chordate models to fill knowledge gaps on essential oil toxicity. Copaiba, lavender, and ginger essential oils are evaluated for effects on D. melanogaster lifespan, climbing ability, and brain structure, while their anti-inflammatory properties are also analyzed. Results show dose-related differences: higher concentrations (0.25% v/v) cause brain deterioration and impaired climbing, while lower concentrations (0.0625% v/v for copaiba and ginger; 0.125% for lavender) have no effect on climbing or brain structure. Lavender oil significantly extends lifespan and maintains anti-inflammatory activity when ingested, underscoring its therapeutic potential. These findings highlight the importance of D. melanogaster as a model for studying essential oil properties, potentially replacing chordate models. In addition, this research advances alternative remedies for currently incurable diseases, with lavender oil emerging as a promising candidate for drug discovery.

Effects of Rosmarinus officinalis L. (Laminaceae) essential oil on adult and larvae of Drosophila melanogaster.

Rosmarinus officinalis (Lamiaceae family), also known as "alecrim," is a perennial herb, typical of the Mediterranean region and widely distributed in Brazilian territory. Despite having demonstrated several properties of human interest, insecticide/larvicidal effect of essential oil from R. officinalis on insects remains unclear. In this study, we tested the effects of R. officinalis essential oil on biomarkers of oxidative damage in Drosophila melanogaster. Exposure to R. officinalis essential oil increased adult mortality and decreased geotaxis behavior in adult fruit flies. In addition, essential oil increased of larval mortality and impaired the developmental success in D. melanogaster. R. officinalis essential oil showed a significant repellent effect, with duration time of about 6h. To understand the mechanism underlying the toxicity of essential oil both pro-oxidant effects and biomarkers of oxidative damage were evaluated in exposed flies. Exposure to essential oil caused a significant redox imbalance with impairment of both enzymatic and non-enzymatic antioxidant system and increased the lipid peroxidation levels. These results suggest that R. officinalis essential oil can be used as a bioinsecticide and/or larvicide as well as an alternative insect repellent.

Pistacia lentiscus essential oil and its pure active components as acaricides to control Dermanyssus gallinae (Acari: Mesostigmata)

The goal of this work was to assess the in vitro acaricidal effects of Pistacia lentiscus essential oil and its pure active components against red poultry mites Dermanyssus gallinae as an alternative to chemical acaricide (formamidines). Essential oil was obtained using hydrodistillation and then analyzed using GC-MS. The following major components were identified: α-pinene (20.58 %), D-Limonene (18.16 %), β-Myrcène (15.06 %), 4-Terpineol (7.68 %), caryophyllene (5.45 %) and γ-terpinene (5.21 %). The toxicity of essential oil and its six monoterpenes were tested at concentrations ranging from 0.43 to 3.50 mg/cm2, using contact and spraying bioassays. Toxicity was expressed as a lethal concentration (LC50 or LC90). The experiment results revealed that activity was method and concentration dependent, and the spraying method was more effective than the contact bioassay for acaricidal activity. In this bioassay, the highest mortality was observed with 4-Terpineol. The LC50 was estimated to be 0.184 mg/cm2 for this substance, followed by α-pinene, the LC50 of which was estimated to be 0.203 mg/cm2. Caryophyllene and γ-terpinene were found less effective in controlling D. gallinae. P. lentiscus oil and its major compounds were also evaluated for anti-acetylcholinesterase (AChE) effects; 4-Terpineol was found to be the most effective AChE inhibitor with IC50 values reaching 18.73 ± 2.83 µg/mL. This framework pointed out the importance of the traditional use of P. lentiscus as an ecofriendly alternative against ectoparasite of veterinary importance; D. gallinae. In vivo trials should also be conducted to assure the safe use of essential oils or individual compounds and to achieve efficient acaricidal property.

Aromatherapy in practice: The viewpoint of healthcare professionals

This article presents the results of a study conducted to explore the role of aromatherapy in therapeutic practices in Algeria. The study used a targeted survey method involving health professionals and auxiliaries. The questionnaire used in the study was based on a review of the literature on aromatherapy, essential oils, therapeutic practices, alternative medicine, the toxicity of essential oils, regulations and the essential oils market. The questionnaire was distributed physically in the Algiers region and also shared online via Google Docs and social media platforms. The data collected was initially processed and analysed using Microsoft Excel 2019. The study was conducted over a one-month period, from 25 April to 25 May 2023, and included healthcare professionals and related persons residing and practising in Algeria. Inclusion criteria required individuals to meet at least one of the two conditions, while incomplete or incorrectly completed forms were excluded. The results of the study showed that a total of 170 responses were collected from healthcare professionals. The study focused on the awareness and use of herbal products, particularly essential oils, among survey participants. The study also examined the length of time essential oils were used, the indications for which they were used, and the side effects and adverse reactions reported. The results highlight the need to improve the scientific literature and remedy the shortage of experts in this field, which can have an impact on the validity and credibility of aromatherapy practices. The study also highlights the importance of education, training and regulation to ensure the safe and effective use of essential oils in a therapeutic context.

Toxicological interactions between spinosad and essential oils in the Mediterranean fruit fly, Ceratitis capitata

AbstractIn recent decades, the use of biopesticides for pest management has increased, especially in modern and organic agriculture. Spinosad is a biopesticide approved in many countries for its use against Ceratitis capitata. However, an increasing amount of pest resistance against spinosad had been found in different pest species. In the present study, we propose the use of a combination between essential oils (EOs) and spinosad as a way to contribute to the development of sustainable alternatives, integrating natural substances with anti‐insect properties and reducing the amount of commercial active ingredients by synergistic effects. Our primary objective was to investigate the synergistic potential of EOs and spinosad in order to enhance the insecticidal efficacy against C. capitata adults. We evaluate the toxic effect of the EOs of Baccharis spartioides (Hook), Eucalyptus cinerea (F. Muell. ex Benth) and Schinus areira (Linneo), the bioinsecticide spinosad and their combinations. We evaluated the combined toxicities of EOs from B. spartioides, E. cinerea and S. areira with spinosad and characterized the LD50 of each mixture and each substance administered topically alone on male and female individuals of C. capitata. A synergistic effect was observed for the B. spartioides–spinosad mixture in females and the S. areira–spinosad mixture in both sexes, and an antagonistic effect was found for the B. spartioides–spinosad mixture and the E. cinerea–spinosad mixture in males. Considering these results, we suggest the use of the EO from S. areira combined with spinosad as an alternative way of controlling C. capitata.