Essential oils for the development of eco-friendly mosquito larvicides: A review

Mosquitoes act as a vector for most of the life threatening diseases like malaria, yellow fever, dengue fever, chikungunya ferver, filariasis, encephalitis, West Nile Virus infection, etc. Under the Integrated Mosquito Management (IMM), emphasis was given on the application of alternative strategies in mosquito control. The continuous application of synthetic insecticides causes development of resistance in vector species, biological magnification of toxic substances through the food chain and adverse effects on environmental quality and non target organisms including human health. Application of active toxic agents from plant extracts as an alternative mosquito control strategy was available from ancient times. These are non-toxic, easily available at affordable prices, biodegradable and show broad-spectrum target-specific activities against different species of vector mosquitoes. In this article, the current state of knowledge on phytochemical sources and mosquitocidal activity, their mechanism of action on target population, variation of their larvicidal activity according to mosquito species, instar specificity, polarity of solvents used during extraction, nature of active ingredient and promising advances made in biological control of mosquitoes by plant derived secondary metabolites have been reviewed.

Plant extracts as potential mosquito larvicides

The aim of this study was to investigate the larvicidal potential of the hexane, chloroform, ethyl acetate, acetone, methanol, and aqueous leaf extracts of Nelumbo nucifera Gaertn. (Nymphaeaceae) and synthesized silver nanoparticles using aqueous leaf extract against fourth instar larvae of Anopheles subpictus Grassi and Culex quinquefasciatus Say (Diptera: Culicidae). Nanoparticles are being used in many commercial applications. It was found that aqueous silver ions can be reduced by aqueous extract of plant parts to generate extremely stable silver nanoparticles in water. The results recorded from UV–vis spectrum, scanning electron microscopy, X-ray diffraction, and Fourier transform infrared support the biosynthesis and characterization of silver nanoparticles. Larvae were exposed to varying concentrations of plant extracts and synthesized silver nanoparticles for 24 h. All extracts showed moderate larvicidal effects; however, the maximum efficacy was observed in crude methanol, aqueous, and synthesized silver nanoparticles against the larvae of A. subpictus (LC50 = 8.89, 11.82, and 0.69 ppm; LC90 = 28.65, 36.06, and 2.15 ppm) and against the larvae of C. quinquefasciatus (LC50 = 9.51, 13.65, and 1.10 ppm; LC90 = 28.13, 35.83, and 3.59 ppm), respectively. These results suggest that the leaf methanol, aqueous extracts of N. nucifera, and green synthesis of silver nanoparticles have the potential to be used as an ideal eco-friendly approach for the control of the A. subpictus and C. quinquefasciatus. This is the first report on the mosquito larvicidal activity of the plant extracts and synthesized nanoparticles.

Synthesis of silver nanoparticles using Nelumbo nucifera leaf extract and its larvicidal activity against malaria and filariasis vectors.

정유(Essential Oil)와 그 응용

This review aims to describe essential oils and their constituent compounds that exhibit bioactivity against Aedes aegypti L (Diptera: Culicidae) larvae, the immature stage of the primary vector of dengue This review is based on original articles obtained by searching on major databases Our literature review revealed that 361 essential oils from 269 plant species have been tested for their larvicidal activity More than 60 % of these essential oils were considered active (LC50<100 mg/L), and the majority of these active oils were derived from species belonging to Myrtaceae, Lamiaceae, and Rutaceae The most active essential oils exhibited effective concentrations comparable with the dosage recommended for the use of temephos in container breeding Approximately 27 % of the plants studied for their larvicidal activity against A aegypti were collected in Brazil Essential oils rich in phenylpropanoids, oxygenated sesquiterpenes, and monoterpene hydrocarbons were found to be the most active When the isolates were tested, phenylpropanoids and monoterpene hydrocarbons were the most active compound classes We describe the plant parts used and the major constituents of the essential oils In addition, we discuss factors affecting the activity (such as plant parts, age of the plant, chemotypes, larval source, and methods used), structure-activity relationships, and mechanisms of action of the essential oils and their compounds Essential oils have been widely investigated and show high larvicidal activity against A aegypti This review reveals that the essential oils are effective alternatives for the production of larvicides, which can be used in vector-borne disease control programmes

Essential oils and their compounds as Aedes aegypti L. (Diptera: Culicidae) larvicides: review

Objectives: The fatty acid methyl esters (FAME extract) from Sesuvium (S.) portulacastrum was studied for its fatty acid composition and antimicrobial activity against human pathogenic microorganisms. Materials and Methods and Results: The gas chromatographic analysis of FAME extract re- vealed the presence of palmitic acid with the highest relative percentage (31.18%), followed by oleic acid (21.15%), linolenic acid (14.18%) linoleic acid (10.63%), myristic acid (6.91%) and behenic acid (2.42%). The saturated fatty acids were high- er than the unsaturated fatty acids. FAME extract showed the highest antibacterial and anticandidal activities and moderate antifungal activity against the tested microorganisms. The highest mean zone of inhibition (16.3 mm) and the lowest MIC (0.25 mg/ml) and MBC (0.5 mg/ml) values were recorded against Bacillus subtilis. The lowest mean zone of inhibition (8.8 mm) and the highest MIC (8 mg/ml) and MFC (16 mg/ml) values were recorded against Aspergillus fumigatus and As- pergillus niger. Conclusions: The results of the present study justify the use of S. portulacastrum in traditional medicine and the FAME extract can be used as a potential antimicrobial agent against the tested human pathogenic microorganisms.

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Antibacterial and antifungal efficacy of fatty acid methyl esters from the leaves of Sesuvium portulacastrum L.

The early fourth instar larvae of Culex quinquefasciatus, reared in the laboratory were used for larvicidal assay with leaf extracts of Vitex negundo, Vitex trifolia, Vitex peduncularis and Vitex altissima. The methanol extracts of the four species possessed varying levels of larvicidal nature. The highest larvicidal activity was found with the extract of V. trifolia (LC50 = 41.41 ppm) followed by V. peduncularis (LC50 = 76.28 ppm), V. altissima (LC50 = 128.04 ppm) and V. negundo (LC50 = 212.57 ppm).

Differential larvicidal efficacy of four species of Vitex against Culex quinquefasciatus larvae.

The essential oil from the leaves of Blumea mollis was extracted and the chemical constituents and the larvicidal against Culex quinquefasciatus effects studied. The analyses of gas chromatography (GC) and GC–mass spectroscopy (GC–MS) revealed that the leaf essential oil of B. mollis contained 39 compounds, and the major chemical compounds identified were linalool (19.43%), γ-elemene (12.19%), copaene (10.93%), estragole (10.81%), Allo-ocimene (10.03%), γ-terpinene (8.28%) and Allo-aromadendrene (7.44%). The essential oil had significant toxic effect against early fourth-instar larvae of C. quinquefasciatus with LC50 = 71.71 and LC90 = 143.41 ppm. The results could be useful in search of newer, safer and more effective natural larvicidal agent against C. quinquefasciatus.

Chemical constituents and larvicidal property of the essential oil of Blumea mollis (D. Don) Merr. against Culex quinquefasciatus.

Essential oil of Plectranthus amboinicus was studied for its chemical composition and larvicidal potential against the malarial vector mosquito Anopheles stephensi. Totally 26 compounds were identified by GC and GC-MS. The major chemical compounds were carvacrol (28.65%) followed by thymol (21.66%), α-humulene (9.67%), undecanal (8.29%), γ-terpinene (7.76%), ρ-cymene (6.46%), caryophyllene oxide (5.85%), α-terpineol (3.28%) and β-selinene (2.01%). The larvicidal assay was conducted to record the LC50 and LC90 values and the larval mortality was observed after 12 and 24 h of exposure period. The LC50 values of the oil were 33.54 (after 12 h) and 28.37 ppm (after 24 h). The LC90 values of the oil were 70.27 (after 12 h) and 59.38 ppm (after 24 h). The results of the present study showed that the essential oil of P. amboinicus is one of the inexpensive and eco-friendly sources of natural mosquito larvicidal agent to control/reduce the population of malarial vector mosquito.

Chemical composition and larvicidal activity of the essential oil of Plectranthus amboinicus (Lour.) Spreng against Anopheles stephensi: a malarial vector mosquito.

The larvicidal activity of fatty acid methyl ester (FAME) extracts of Vitex altissima, Vitex negundo and Vitex trifolia was studied against early fourth-instar larvae of Culex quinquefasciatus. The fatty composition was analysed by gas chromatography. The highest percentage of lauric acid, palmitic acid, stearic acid, oleic acid and linolenic acid were recorded in V. negundo. The highest percentage of linolenic acid was recorded in V. trifolia. The FAME extract of V. trifolia showed the highest larvicidal activity with an LC50 value of 9.25 ppm followed by V. altissima (14.82 ppm) and V. negundo (18.64 ppm).

A. Senthilkumar

Papers

Antibacterial and antifungal efficacy of fatty acid methyl esters from the leaves of Sesuvium portulacastrum L.

Differential larvicidal efficacy of four species of Vitex against Culex quinquefasciatus larvae.

Chemical constituents and larvicidal property of the essential oil of Blumea mollis (D. Don) Merr. against Culex quinquefasciatus.

Chemical composition and larvicidal activity of the essential oil of Plectranthus amboinicus (Lour.) Spreng against Anopheles stephensi: a malarial vector mosquito.

Larvicidal activity of fatty acid methyl esters of Vitex species against Culex quinquefasciatus.