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Efficacy of Thai herbal essential oils as green repellent against mosquito vectors

Coticotropine-Releasing Hormone receptor 1 (CRHR1) signalling interferes with steroid biosynthesis of ovarian granulosa cells

Comparative mosquito repellency of essential oils against Aedes aegypti (Linn.), Anopheles dirus (Peyton and Harrison) and Culex quinquefasciatus (Say)

Plant-based essential oils have gained attention as a natural alternative for controlling mosquitoes due to their repellent, larvicidal and oviposition deterrent properties. We tested repellent, larvicidal, and oviposition deterrent effects of essential oils (EOs) of Mentha spicata (L.), Ocimum basilicum (L.), and Abutilon indicum (L.) against three mosquito species (Diptera: Culicidae) including Aedes aegypti (L.), Anopheles gambiae s. l. Giles, and Culex quinquefasciatus Say by using contact-based technique. In screening bioassays, M. spicata I, M. spicata II, O. basilicum I, O. basilicum II, and A. indicum EOs showed higher repellency against Cx. quinquefasciatus as compared to Ae. aegypti and An. gambiae when tested at 33.3 μg/cm2. In time-span bioassays performed at 33.3 μg/cm2, EO of M. spicata I exhibited 100% repellence up to 45, 30, and 75 min against Ae. aegypti, An. gambiae, and Cx. quinquefasciatus, respectively. Interestingly, at this tested dose, M. spicata I and M. spicata II showed higher repellence compared to DEET against Ae. aegypti and Cx. quinquefasciatus after 45 and 75 min, respectively. Their repellency was observed up to 150 and 210 min against Ae. aegypti and Cx. quinquefasciatus, respectively. In larvicidal bioassays, M. spicata I EO proved more toxic against 2nd instar larvae of Ae. aegypti, An. gambiae, and Cx. quinquefasciatus (LC50 = 11.0, 42.9, and 12.6 mg/L, respectively) compared to other tested EOs. In oviposition bioassays, M. spicata I exhibited the highest activity, showing 60%, 46%, and 79% oviposition deterrence against Ae. aegypti, An. gambiae, and Cx. quinquefasciatus, respectively, tested at a dose of 600 µg/cm2. Major compounds of M. spicata I, M. spicata II, O. basilicum I, and O. basilicum II EOs were piperitenone oxide (38.8%), piperitone oxide (35.4%), estragole (55.3%), and linalool (43.8%), respectively. In conclusion, M. spicata EO could be used to control mosquitoes and their bites.

Repellent activity of essential oils derived from 10 Thai native plants, belonging to three families were evaluated against female Aedes aegypti and Culex quinquefasciatus and to compare them with a commercial chemical repellents (DEET; N,N-diethyl-3-methylbenzamide 20% w/w; Sketolene Shield). Each test repellent was applied at 1, 5, and 10% concentrations for testing by arm in cage method. The results showed significant differences in repellency among the repellents by mosquito species. The protection time of the essential oils against Ae. aegypti ranged from 3 to 30 min. According to the Culex mosquito, it showed the protection time ranged from 3 to 260 min. 10 % Boesenbergia rotunda essential oil provided the best efficiency, in which protection time was 4.3 h as equal as DEET. The essential oils which exhibited protection time more than 2 h were those of 10% Zingiber zerumbet, Litsea petiolata, Curcuma zedoaria, and Zingiber cassumunar essential oils (3.1, 2.8, 2.6, and 2.3 h, respectively). The biting percentage ranged from 0.9 to 18.0% and 0.8 to 3.6% against Ae. aegypti and Cx. quinquefasciatus, respectively. The results revealed that the potential of essential oil extracted from B. rotunda, Z. zerumbet, L. petiolata, C. zedoaria, and Z. cassumunar had attributes of good repellent and deterred biting. We recommend the five essential oils for further study to develop as commercial repellents.

Insecticidal, repellent and oviposition-deterrent activity of selected essential oils against Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus

Evaluation of herbal essential oil as repellents against Aedes aegypti (L.) and Anopheles dirus Peyton & Harrion

Efficacies of essential oils (EOs) of Vetiveria zizanioides (L.) Nash. (Poales: Poaceae) (VZ EO), Cananga odorata (Lam) Hook. F. & Thomson (Magnoliales: Annonaceae) (CO EO), and crude extract (CE) of Andrographis paniculata (Burm.F.) Wall ex. Nees (Lamiales: Acanthaceae) (AP CE), against laboratory (lab) and field strains of Culex quinquefasciatus Say were investigated. Irritant and repellent activities of individual and binary mixtures of plant extracts were compared with N,N-diethyl-m-toluamide (DEET) using an excito-repellency system. The irritant activity (direct tarsal contact), the mean percent escape response of VZ EO (91.67%, 83.33%), and CO EO (80%, 88.33%) were not significantly different compared with DEET (88.33%, 95%) against lab and field strains, respectively. Similarly, irritant responses in combinations (1:1 and 1:2, v:v) of either VZ EO or CO EO with AP CE were not significantly different from DEET against both strains (P > 0.001). The repellent activity (no tarsal contact), the mean percent escape response of VZ EO (68.33%), CO EO (61.67%), and VZ EO+AP CE (1:1, v:v) (81.67%) against lab strain and CO EO (85%) against field strain were not significantly different from that of DEET (P > 0.001). Interestingly, the greatest contact irritancy of VZ EO+AP CE (1:1, v:v) (96.67%) (P = 0.0026) and a stronger repellency response of CO EO (85%) (P = 0.0055) produced significantly different patterns of escape response compared with DEET against both lab and field strains, respectively. The EOs of VZ EO and CO EO or their mixture with AP CE showed potential as plant-based active ingredients for mosquito repellents. In addition, the major chemical constituents of VZ EO were β-vetivone (6.4%), khusimol (2.96%), and α-vetivone (2.94%) by gas chromatograpy-mass spectrometry.

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.

The behavioral effects of four essential oils extracted from orange peel (Citrus aurantium L.), cinnamon leaf (Cinnamomum verum J. Presl), citronella grass (Cymbopogonwinterianus Jowitt), and clove flower [Syzygium aromaticum (L.) Merrill & Perry] were evaluated against two medically important species of mosquitoes, Aedes aegypti (L.) and Culex quinquefasciatus Say, using an excito-repellency test system. Ae. aegypti was collected from a small village in Kanchanaburi Province and Culex quinquefasciatus was captured from an urban area of Bangkok. Mosquitoes from the F1–F3 generations were tested in the excito-repellency test chamber for contact excitation and non-contact spatial repellency. Results showed that both species demonstrated varying levels of behavioral escape responses to different essential oils, showing a clear dose response depending on percent w/v concentration used. Orange oil produced the least response in both mosquito species, while citronella and clove the greatest. In general, Cx. quinquefasciatus exhibited much stronger behavioral responses to all four essential oils than Ae. aegypti. From this study, we conclude that the essential oils from various botanical sources should continue to be screened for protective properties against mosquitoes and other biting arthropods.

Simple SummaryThe repellent efficacy of ten essential oils was measured against all three-mosquito species using the arm-in-cage approach to determine the duration of protection. All essential oils showed high complete-protection time against Culex quinquefasciatus, ranging from 120 to 360 min. Petitgrain oil showed the highest complete-protection time from bites of Aedes aegypti for 270 min. Peppermint oil also exhibited complete-protection time from bites of Anopheles dirus for 180 min. When two highly effective essential oils were combined to potentially prolong mosquito bite protection, the binary combinations of petitgrain with other essential oils (basil and coriander) exhibited antagonistic effects and provided complete protection against A. aegypti bite for 150 min. On the other hand, the sage and patchouli oil combination showed more repellent activity from A. dirus bite for 270 min than an individual oil. The binary combination efficiently increased or decreased protection time.Mosquito repellents reduce human-vector contact of vector-borne diseases. We compared the repellent activity of 10 undiluted essential oils (anise, basil, bergamot, coriander, patchouli, peppermint, petitgrain, rosemary, sage and vetiver) against A. aegypti, A. dirus and C. quinquefasciatus using the arm-in-cage method. Petitgrain oil was the most effective against A. aegypti (270 min). Peppermint oil was the most effective against A. dirus (180 min). Interestingly, all single oils had attributes of repellency against C. quinquefasciatus (ranged, 120–360 min). Moreover, we integrated their binary combinations of highly effective essential oils against A. aegypti and A. dirus to potentially increase the protection time. A 1:1 combination of petitgrain/basil, petitgrain/coriander, basil/coriander and basil/sage reduced the median complete-protection time of 150 min for A. aegypti; a combination of sage and patchouli oils prolonged the median complete-protection time of 270 min for A. dirus. Combining essential oils effect protection time from these two mosquito species.

Abstract. Arpiwi NL, Muksin IK, Kartini NL. 2020. Essential oil from Cymbopogon nardus and repellant activity against Aedes aegypti. Biodiversitas 21: 3873-3878. Cymbopogon nardus (L.) Rendle is an aromatic grass from the Poaceae family that produces essential oil mainly in the leaves. The essential oil from C. nardus is known as citronella oil has repellent activity. This research aimed to quantify the oil content of C. nardus leaves, to analyze the essential oil quality, to analyze the repellent activity of lotion with different concentrations of citronella oil against Aedes aegypti, and to examine the quality of formulated lotions. The oil was extracted from leaves using steam distillation, and the quality was examined according to the Indonesian National Standard. The citronella oil was formulated into a lotion with five concentrations (0, 2, 3, 4, 5% w/w). Repellent activity of the lotions against Ae. aegypti was tested using screened cage test method under laboratory conditions. Lotion quality was analyzed for pH, viscosity, homogeneity, and sensorial assessments. The result showed that the oil yield of C. nardus leaves was 0.9% w/w. The color of the oil was pale yellow, specific weight was 0.8819, the refraction index was 1.464, total geraniol was 72.71%, citronellal content was 49.14%, and solubility in 80% alcohol 1:2 was clear. The repellent activity of lotions with citronella oil was concentration-dependent, where a concentration of 5% gave the highest protection. The quality of formulated lotions met the standard and the lotions were nonirritant.

The essential oil of Cananga odorata flowers was evaluated for oviposition-deterrent, ovicidal, insecticidal, and repellent activities toward three mosquito species: Aedes aegypti, Anopheles dirus, and Culex quinquefasciatus. Oviposition deterrence of the oil was evaluated on gravid females using oviposition deterrence bioassay. The results showed that 10% Ca. odorata exhibited high percent effective repellency against oviposition at 99.4% to Ae. aegypti, 97.1% to An. dirus, and 100% to Cx. quinquefasciatus. Ca. odorata oil was tested for ovicidal activity. Regression equations revealed that the ovicidal rates were positively correlated with the concentrations of the essential oil. As the concentration of essential oil increased from 1, 5, and up to 10% concentration, the ovicidal rate increased accordingly. Larvicidal activity of the oils was used on immature stages (third and fourth instar lavae and pupae). The maximum larval mortality was found with 10% Ca. odorata against immature stages, and there were LC50 values ranged from 10.4 to 10.5% (for Ae. aegypti), <1% (for An. dirus), and <1% (for Cx. quinquefasciatus). Adulticidal properties were evaluated with unfed females. Ten percent Ca. odorata oil had high knockdown rates against the three mosquito species at 96% (for Ae. aegypti), 98.4% (for An. dirus), and 100% (for Cx. quinquefasciatus), with EC50 values of 6.2, 4.7, and 5.4%, respectively. It gave moderate mortality rates after 24 and 48h of exposure. Ca. odorata oil was assessed for repellency to females by using the modified K&D module. Ten percent Ca. odorata oil gave the strongest value against Ae. aegypti, An. dirus, and Cx. quinquefasciatus, with percentage repellency of 66, 92, and 90%, respectively. This study demonstrates the potential for the essential oil of Ca. odorata essential oil to be used as a botanical insecticide against three mosquito species.

BackgroundBeing a low-risk insecticide, plant essential oils emerge as competent mosquitocidal and repellent candidates. However, essential oil may act differently in different mosquito species and different developmental stages of same mosquito species. In the current investigation, we evaluated the ovicidal, larvicidal, adulticidal and repellent activities of essential oil extracted from the leaves of Lippia alba against two medically important mosquito species, Aedes aegypti and Culex quinquefasciatus. The efficacy of the oil was assessed under laboratory conditions against different developmental stages of the selected species.ResultsFrom the findings, it can be inferred that L. alba oil is more effective as a repellent against both the targeted mosquito species. Results also demonstrated that ovicidal, larvicidal and repellent properties of the essential oil were higher against Culex quinquefasciatus than Aedes aegypti. GC-MS analysis of the oil showed the presence of aromadendrene oxide, caryophyllene oxide, etc. as major constituent compounds.ConclusionThe outcomes of this study clearly indicated that the essential oil of L. alba has the potentiality to act more effectively as a repellent, followed by a larvicidal agent against mosquito and at the same time the results revealed differential vulnerability of different mosquito species and their life stages against a particular plant essential oil.

Description. Les huiles essentielles de Cymbopogon nardus (L.) Rendle, Cymbopogon winterianus Jowitt, Cymbopogon flexuosus (Nees ex Steud.) Wats et Cymbopogon citratus L. (DC.) Stapf (lemongrass) sont constituées à plus de 80 % de citronellal, géraniol, citral, citronellol, acétate de géranyle et limonène. Elles ne se distinguent les unes des autres que par les proportions relatives de ces différents constituants. Il est donc important de connaitre la composition chimique exacte des huiles essentielles produites. Objectifs. Évaluer le chémotype de C. nardus acclimaté sur le Plateau des Cataractes. Méthode. Les huiles essentielles de C. nardus acclimatées sur le Plateau des Cataractes ont été extraites par hydrodistillation et analysées par chromatographie (GC et CG/MS) pendant plus d’une décennie. Résultats. Avec un profil caractérisé par la composition suivante : citronellal (40-48 %), géraniol (10-22 %), citronellol (10-12 %), limonène (2-3 %), acétate de géranyle (1-2 %), linalol (1 %), cette espèce produit une huile essentielle de citronella type Java. Ceci tient au fait que la différence entre les types Java et Ceylan de citronella repose uniquement sur les teneurs individuelles de leurs trois principaux constituants : citronellal, géraniol et citronellol. Cymbopogon nardus est connu pour sa variabilité élevée, avec deux variétés et sept sous-variétés. Conclusions. Le citronella diffusé en Afrique de l’Ouest et du Centre sous le nom de Cymbopogon nardus type Java serait plutôt proche de Cymbopogon winterianus Jowitt par sa composition chimique.