Repellent efficacy of water-balm formulation against Aedes aegypti based on zedoary, Curcuma zedoaria.

Mosquitoes alone transmit diseases to around 700 million individuals annually, killing approximately 0.7 million people every year worldwide. Considering the potential health risks linked with synthetic repellents, it has become vital to identify eco-friendly, natural repellents for mosquito control as well as to understand the underlying mechanism for mosquito repellent activity. To address this, objectives were set to extract essential oils from Citrus macroptera peel and Homalomena aromatica (Spreng.) Schott. rhizomes, evaluate their mosquito repellent activity against Aedes aegypti, and further explore their mosquito odorant receptor inhibition potential. The oils were extracted using Clevenger's apparatus, and properties like specific gravity, refractive index, and boiling point were evaluated and characterised using Fourier transform infrared spectroscopy (FTIR) and gas chromatography-mass spectroscopy (GC-MS). Aedes aegypti mosquito eggs collected from the Indian Council of Medical Research (ICMR), Dibrugarh, were reared in the Department of Pharmaceutical Sciences, Research Laboratory, to obtain adult Aedes aegypti mosquitoes for the mosquito repellent activity evaluation of the essential oils using the Human Bait technique'. Molecular docking studies were performed for the oil components against mosquito odorant binding proteins. Further, toxicity studies of these two oils were evaluated against human dermal fibroblast adult (HDFa) cells. The results revealed the presence of limonene (86.76%) and linalool (52.35%), respectively, in Citrus macroptera and Homalomena aromatica oils. It was found that the combination of the oils in a ratio of 1:1 showed mosquito repellent activity for up to 6.33 ± 0.23 h. Molecular docking studies showed the presence of major oil components having mosquito odorant receptor blocking potential comparable to N, N-diethyl-meta-toluamide (DEET), indicating a rationale for extended mosquito repellent action. Further, both of these oils were found to be non-cytotoxic against HDFa cells after 24 h. The encouraging mosquito repellent activity of these two oils as compared to synthetic mosquito repellent DEET might pave the way for the development of novel herbal mosquito repellent formulations containing these essential oils.

Plant-based mosquito control offers a promising alternative to reduce the health and environmental risks associated with chemical insecticides. Citrus hystrix DC. (kaffir lime), a member of the Citrus genus, produces essential oils rich in bioactive compounds such as limonene, citronellal, and terpinolene, which are known for antimicrobial and insecticidal properties. This study focused on extracting essential oil from kaffir lime fruit, identifying its chemical constituents using gas chromatography–mass spectrometry (GC-MS), and evaluating the repellent efficacy of its spray formulation against Aedes aegypti. Essential oil was obtained through steam distillation and analyzed by GC-MS to determine its chemical profile. Repellent activity was assessed experimentally using 100 adult mosquitoes divided into five treatment groups, with spray formulations prepared at concentrations of 5%, 10%, and 15%. Data was analyzed using one-way ANOVA followed by post-hoc tests. GC-MS analysis revealed 90 compounds, with five major constituents: D-limonene (14.57%), limonene (13.92%), citronellal (6.66%), terpinolene (6.47%), and α-terpineol (5.74%). Repellent testing demonstrated that the 15% concentration provided the highest protection against mosquito landings. These findings confirm the potential of kaffir lime essential oil as an effective natural mosquito repellent and provide a scientific basis for developing eco-friendly, plant-derived vector control products. This research contributes to reducing dependence on synthetic insecticides and supports sustainable strategies for vector management that prioritize human health and environmental safety.

Chemical composition and repellent activity of native plants essential oils against dengue mosquito, Aedes aegypti

Synthetic mosquito repellents containing DEET (N, N-diethyl-3-methylbenzamide), DEPA (N, N-diethyl phenylacetamide), permethrin and deltamethrin as active components are known to be the most effective repellents. However, these types of repellents have contributed to numerous toxic effects on not only the environment, but also non-target organisms. The use of natural products such as essential oils is reported as a safe alternative. To date, the study on repellency activities against mosquitoes using Malaysian plants is rare. In the present study, essential oils from leaves and barks of Cinnamomum iners have been reported to show repellency activity, and the whole plant have been used by the local communities to repel mosquitoes and other blood-sucking insects. Repellency assay of the oils against Aedes aegypti was conducted using the percentage repellency bioassay method at three different concentrations: 1%, 5% and 10%. The results showed that the essential oils from barks had a significant percentage repellency (p<0.05) when compared to essential oils from leaves. Two main compounds were identified using the GC-MS: 1-isopropenyl-4-methyl-1,2-cyclohexanediol and 2-octen-1-ol,3,7-dimethyl (geraniol) from the bark and leaf essential oils, respectively. The essential oils demonstrated promising insect repellency activity which has the potential for further development into formulations that may serve as alternatives to DEET or be used as natural bioinsecticides to kill mosquitoes.

Simple SummaryDue to the environment and human health concerns of synthetic repellents, essential oils (EOs) as natural alternatives have received increased attention. In this study, the repellent activity of 60 commercial EOs against Aedes albopictus was evaluated. In the initial screening, 8 active EOs including cinnamon, marjoram, lemongrass, bay, chamomile, jasmine, peppermint2, and thyme were selected. Twenty-one major constituents (>5% relative area) in the 8 active EOs were identified via gas chromatography-mass spectrometry (GC-MS) analysis. Cinnamaldehyde, citral and terpinene-4-ol displayed the highest repellent activity with more than 60% RR, which were more active than N,N-diethyl-3-methyl benzoyl amide (DEET). Next, their nanoemulsions were prepared and characterized. In the arm-in-cage assay, cinnamaldehyde- and citral-based nanoemulsions have prolonged mosquito protection time compared with their normal solutions.Mosquitoes are one of the most important disease vectors from a medical viewpoint in that they transmit several diseases such as malaria, filariasis, yellow and Dengue fever. Mosquito vector control and personal protection from mosquito bites are currently the most efficient ways to prevent these diseases. Several synthetic repellents such as DEET, ethyl butylacetylaminopropionate (IR3535) and 1-(1-methylpropoxycarbonyl)-2-(2-hydroxyethyl)piperidine) (Picaridin), have been widely used to prevent humans from receiving mosquito bites. However, the use of synthetic repellents has raised several environment and health concerns. Therefore, essential oils (EOs) as natural alternatives receive our attention. In order to discover highly effective mosquito repellents from natural sources, the repellent activity of 60 commercial EOs against Ae. albopictus was screened in this study. Eight EOs including cinnamon, marjoram, lemongrass, bay, chamomile, jasmine, peppermint2, and thyme, showed a suitable repellent rate (>40%) at the tested dose of 10 μg/cm2. Then, their main constituents were analyzed by GC-MS, and the active constituents were identified. The most active compounds including cinnamaldehyde, citral and terpinen-4-ol, exhibited an 82%, 65% and 60% repellent rate, respectively. Moreover, the nanoemulsions of the three active compounds were prepared and characterized. In the arm-in-cage assay, the protection times of the nanoemulsions of cinnamaldehyde and citral were significantly extended compared with their normal solutions. This study provides several lead compounds to develop new mosquito repellents, and it suggests that nanoemulsification is an effective method for improving the duration of the activity of natural repellents.

Vector-borne diseases, such as Malaria and Dengue, transmitted by mosquitoes like Anopheles stephensi and Aedes aegypti, are major public health concerns. Although synthetic repellents, particularly DEET (N, N-diethyl-m-toluamide), are commonly used to prevent mosquito bites. However, growing concerns regarding their safety and environmental impact have increased the interest in natural alternatives. This study investigates the mosquito-repellent activity of a cream formulated with essential oil and methanolic extract of Artemisia absinthium L. The repellent activity of the cream was evaluated using an Artificial Membrane Feeding System simulating human skin. Non-blood-fed female mosquitoes (5-7 days old) from Anopheles and Aedes species, starved for 12 hours, were used. The cream was applied at various concentrations on the membrane, and its efficacy was assessed and compared with DEET. The complete protection time was analysed using the Kaplan-Meier method. The test cream showed a dose-dependent repellent activity against both Anopheles stephensi and Aedes aegypti. At a concentration of 12 mg/cm², the cream provided 100% protection for 105 minutes against both species. Whereas DEET, at the same concentration, provided complete protection for 105 minutes against Aedes aegypti and 97.5% protection for 105 minutes against Anopheles stephensi. The Artemisia absinthium-based cream effectively repels both Anopheles stephensi and Aedes aegypti mosquitoes, indicating its potential as a natural alternative to synthetic repellents. However, further studies are needed to evaluate its efficacy and safety on human skin under natural conditions. Anopheles stephensi, Aedes aegypti, Unani Medicine, Mosquito repellent, Artemisia absinthium.

Chemical variability and insect repellent effects of lemon catnip essential oil and related phytochemicals against Cimex lectularius L

Indian Journal of Natural Products,2022,36,1,2-16.DOI:10.5530/ijnp.2022.1.2Published:February 2023Type:Review ArticleAuthors:Disha Sharma, Vandana Singh, Manoj Kumar Yadav, Umesh Kumar Patil, Vinod Kumar Dixit, and Narayan Prasad Yadav Author(s) affiliations:Disha Sharma1, Vandana Singh1, Manoj Kumar Yadav1, Umesh Kumar Patil2, Vinod Kumar Dixit2, Narayan Prasad Yadav1,* 1Bioprospection and Product Development, CSIR-Central Institute of Medicinal and Aromatic Plants, Lucknow, Uttar Pradesh, INDIA. 2Department of Pharmaceutical Sciences, Dr. Harisingh Gour Vishwavidyalaya (A Central University), Sagar, Madhya Pradesh, INDIA. Abstract:Mosquitoes are majorly responsible for causing vector-borne diseases such as malaria, filariasis, chikungunya, dengue, zika, yellow fever, west nile etc. Aedes, Anopheles, Culex are the main genera among other mosquitoes’ species, that are affecting human beings with such dreadful diseases worldwide. To control the transmission of diseases by mosquitoes generally mosquito nets, ITNs and LLINs, DDT, DEET, IR3535 are being used. Prolong use of these harmful chemicals not only cause development of resistance in mosquitoes but also have shown adverse effects on humans as well as on environment. So, there is a growing urge/ need of finding a suitable mosquito repellent from natural origin, that have potential to prevent such vector-borne diseases with least side- effects on humans as well as on environment. In this review, we have enlisted various Essential oils (EO) that are having mosquito repellent properties and some of them such as Cymbopogon nardus, Eucalyptus maculata, Cymbopogon excavatus, Mentha piperita, Azadirachta indica are already used in various mosquito repellent formulations that are being marketed presently. EO of particular plant can be extracted from respective parts of it such as seeds, roots, rhizomes, stems, leaves, bracts, fruits, bark and inflorescences mainly by hydrodistillation, steam distillation, maceration, absorption and supercritical extraction, as well as a mechanical process at room temperature. Gas chromatography coupled to mass spectrometry (GC-MS) is the identification technique used for identification of EO constituents. In addition, the combinations of potent EOs are also found to be the best effective way to be used as mosquito repellent so that repellent potential enhanced due to synergism as well as negates the harmful effects of individual oils. The efficiency of essential oils as well as its protection time can also be enhanced by using vanillin and formulation techniques like microencapsulation and nanoemulsion. Based on market coverage as well as economical cost, synthetic repellents are frequently marketed than essential oils but these EOs, extracts or natural products have the potential to provide efficient and safer repellents for humans as well as the environment. Keywords:Aedes aegypti, Anopheles stephensi, Dengue, Essential oils combinations, Herbal mosquito repellent, Malaria., Natural productsView:PDF (477.03 KB)

The necessity of developing insect repellents with highly effective sustained release properties has attracted more attention due to the vast spread of arthropod-borne diseases such as dengue and malaria, which must be controlled with proper measures, and also due to the devastating damage caused by severe infestation of insect pests on crops and stored food. Natural and synthetic insect repellents are used against insect vectors and insect pests. Topical insect repellent formulations should be less toxic, less irritant, and less skin permeable. Irrespective of the type and form of the repellent, the mechanism of action depends on the formation of a vapour barrier/ odour barrier, that would deviate the insect from reaching the host. Synthetic insect repellents are highly efficient but due to their high toxicity, degradation resistance, and bio accumulation, they raise environmental and ecological issues. Due to the adverse effects caused by synthetic insect repellents, more attention is given to insect repellents consisting of natural products.Essential oils are among the widely used natural insect repellents available due to their biocompatibility and non-toxicity. High volatility of essential oils is the major problem that hampers the application of essential oils as insect repellent agents. The high volatility that reduces the length of application, and its activity can be successfully addressed by the formulation of slow-release insect repellent composites by incorporating essential oils into adsorbing or encapsulating matrices. Zeolites, montmorillonite, β-cyclodextrin, polymeric materials, and electrospun nanomaterials are commonly used to develop slow-release formulations with essential oils. Among these, polymeric microcapsules are the most extensively studied and developed slow-release insect repellent systems that are based on natural and synthetic active compounds.&#x0D; Key words: Formulation, Insects, Microcapsules, Repellents, Zeolite

Aedes aegypti is a vector for Dengue. The use of synthetic repellent cause several health issue. Zingiber officinale Roxb. “Cochin Ginger” essential oil (A) and Zingiber officinale Roxb. var rubrum essential oil (B) was used as a repellent for Aedes aegypti. Increasing of repellent activity was strived by formulating A and B with sesame oil and coconut oil as a base. The aim of this study was to compare repellent activity between A and B, to know the influence of oily base to repellent activity of A and B, to know the effective concentration of essential oil in oily base as a repellent.Isolation of essential oil was done by water and steam destilation. Quantitative and qualitative assays by GS-MS. Repellent activity was tested by three steps: initiation, effective consentration assay, and effective concentration of repellent activity. Essential oil on certain concentration (100%, 50% in the base, the effective concentration of SLD) and Lemon grass essential oil was applied on the surface of palm hand. The hand was put into 20x20x20 cm 3 cage containing 25 female Aedes aegypti. The number of Aedes aegypti lied on the hand was noted to count protective capacity. First bite was counted as protective time. Analyse was done by One-way ANOVA and Post Hoc Test Tukey HSD (Homogeneous subsets) or Kruskal-Wallis and Mann-Whitney Test. The result showed that A and B contain camphene, mirsene, 1,8-sineol, l-linalool, l-borneol, neral, geraniol, sitral, and α-kurkumen (only A) that quantitatively different. Statistic result showed that B has a greater repellent activity than A. Sesame oil base give a better effect on repellent activity of sesame oil compare than coconut oil. The effective concentration of Zingiber officinale Roxb. “Cochin Ginger” essential oil and Zingiber officinale Roxb. var rubrum essential oil in sesame oil and coconut oil was 75, 85, 85 and 90%, respectively.

Insecticidal and mosquito repellent efficacy of the essential oils from stem bark and wood of Hazomalania voyronii.

Mosquito-borne diseases such as malaria, encephalitis, and Yellow, Dengue, and Rift Valley fevers are diseases that result in significant morbidity and mortality in humans and livestock globally. Currently, the development of natural product-based insecticides and repellents are under exploration to increase and improve our ability to protect humans from mosquito bites, and ultimately to reduce the incidence of mosquito-borne illnesses [1]. We have undertaken a collaborative research project to discover new natural compounds for personal protection and control of mosquitoes. Artemisia abrotanum L. leaves have reportedly been used as a moth and insect repellent. Therefore, we evaluated Artemisia abrotanum and A. pontica L. essential oils for mosquito repellent activity against Aedes aegypti L. Artemisia oils obtained by hydrodistillation of aerial parts were analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The main Artemisia oil constituents were as follows: A. abrotanum: 32.6% 1,8-cineole, 13.5% borneol, 10.2% presilphiperfolan-9α-ol and 8.0% p-cymene; A. pontica: 35.6% artemisia ketone, 30.1% α-thujone, 22.3% 1,8-cineole and 3.7% β-thujone. Artemisia abrotanum oil showed repellent activity down to a minimum effective dosage of 0.219mg/cm2 (±0.143) using cloth patch assay. Whereas A. pontica oil exhibited no repellent activity at the highest concentration tested, 0.375mg/cm2. Our research into exploring the repellency of specific compounds in the A. abrotanum oil will continue and be expanded to include other mosquito vectors and pesticide resistant mosquito strains.

Since 1968, dengue fever cases in Indonesia have persisted despite various vector control efforts. One of the most common and accessible methods of personal protection is the use of mosquito repellents. This study evaluated public perceptions of mosquitoes and repellents, their willingness to pay (WTP) for these products, and the efficacy of synthetic and natural-based repellents against Aedes aegypti, considering variations in mosquito strain and age. A Knowledge, Attitude, and Practices (KAP) analysis was conducted to assess public understanding and behaviors, utilizing the Analytical Hierarchy Process (AHP) and SWOT-AHP. Repellent efficacy was tested using the arm-in-cage method based on WHO guidelines, involving four mosquito strains (BORA, BDG, TSK, TGR) and three age groups (5, 10, 15 days). The KAP analysis revealed high public awareness but limited translation into effective practices due to differing perceptions and low personal responsibility for dengue prevention. Natural-based repellents were preferred, scoring 3.40 out of 5, with WTP ranging from IDR 20,000–40,000. However, only synthetic repellents containing DEET provided 90% protection for six hours, while natural-based repellents offered less than 60% protection in the first hour. Strain variation significantly affected repellency, with TSK showing the highest repellency, while BORA and BDG exhibited similar trends. Although 10-day-old mosquitoes were more sensitive to repellents, age variation did not consistently influence repellency. These findings highlight the need for improved education campaigns, tailored repellent formulations, and localized testing to enhance public protection against mosquito bites and dengue transmission.

Essential oils of basil leaves that have spesific aroma can be used as a mosquito repellent. Lotions are more practical, easy to apply, easy to pour, and more efficient so repellent made in dosage form of lotion. The purpose of this study was to determine the repellent activity of volatile oil of basil leaf (Ocimum basilicum (L.) f. Citratum Back) against Aedes aegypti in lotion. Basil leaves are air-dried, then distilled by water and steam distillation for ± 6 hours. Essential oils with some concentrations(15% v / v, 25% v / v, and 35% v / v in 95% ethanol)are formulated in lotion. Physical properties (homogeneity, viscosity, dispersive power, and adhesion power) and repellent activity of lotions are tested. The data obtained are analyzed using the Kolmogorov-Smirnov test analysis, 2-way ANOVA test, and Turkey HSD test. The repellent activity is analyzed using One-Way ANOVA and Turkey test in level of 95%. The results showed that lotions with increasedessential oil concentration (15% v / v, 25% v / v, 35% v / v in 95% ethanol) are homogeneous and easily poured. Lotion with that increased concentration of essential oils of basil leaves (15% v / v, 25% v / v, 35% v / v in 95% ethanol) showed repellent activity with time protection of 3522, 4611, and 5435 seconds.

Vector-borne diseases caused by Aedes aegypti and other mosquitoes have become a global health problem. Zanthoxylum limonella essential oils, one of the rich sources of limonene, have a potential mosquito repellent effect. In this current study, the essential oils were successfully extracted from clusters of dried fruits by steam distillation method. The percentage yield of the essential oils was 6 %v/w. GC-MS results suggested that the essential oils composed mainly of five peaks where limonene was found as a major volatile constituent. GC-FID result showed that the concentration of limonene was 71.07 %w/w. The essential oils were prepared as microcapsules using the extrusion method involving emulsification and crosslinking processes where sodium alginate was employed as polymer matrix and calcium alginate as a crosslinking agent. The calcium alginate microcapsules of essential oils were obtained by employing sodium alginate (1.5%), Span 20 (3%) and essential oils (20%). The microcapsules obtained were ≤200 μm in diameter. The percentage yield and percentage entrapment efficiency of alginate microcapsules were 67.29±2.5 %w/w and 29.96±1.65 %w/w, respectively. The microcapsules of essential oils and free essential oils were separately prepared in the emulgels. The emulgels containing microcapsules of essential oils or free essential oils, jojoba oil, cremophorRH 40 and carbopol 940 were whitish milky cream with lemon-like odor. 5% vanillin was also added into the emulgels as a fixative. The emulgels were found as stable under centrifugation at 6000 rpm for 8 cycles with no phase separation. There were no changes in appearance, color, odor, pH and viscosity after emulgels were subjected to 6 cycles of heating-cooling cycle. Moreover, the emulgels showed pseudoplastic behavior throughout the heating-cooling cycle test. The physically stable emulgel preparations were subjected to mosquito repellency test on human volunteers. The emulgel preparations containing essential oils (18%) and vanillin (5%) showed 3.1-3.4 hours of protection against Ae. aegypti. The emulgel was stored at 30˚C, 75% RH and 40˚C, 75% RH for 12 weeks and determined the amount of limonene and vanillin. The results showed that limonene and vanillin were stable for 8 weeks at 30˚C. Therefore, emulgel containing Zanthoxylum limonella essential oils was a potential mosquito repellent for general public use.