Repellent activity of herbal essential oils against Aedes aegypti (Linn.) and Culex quinquefasciatus (Say.)

Objective

To determine the mosquito repellent activity of herbal essential oils against female Aedes aegypti and Culex quinquefasciatus.

Methods

On a volunteer''s forearm, 0.1 mL of each essential oil was applied to 3 cm×10 cm of exposed skin. The protection time was recorded for 3 min after every 30 min.

Results

Essential oil from clove oil in olive oil and in coconut oil gave the longest lasting period of 76.50 min and 96.00 min respectively against Aedes aegypti. The citronella grass oil in olive oil, citronella grass oil in coconut oil and lemongrass oil in coconut oil exhibited protection against Culex quinquefasciatus at 165.00, 105.00, and 112.50 min respectively.

Conclusions

The results clearly indicated that clove, citronella and lemongrass oil were the most promising for repellency against mosquito species. These oils could be used to develop a new formulation to control mosquitoes.     

Evaluation of Andrographis paniculata Burm.f. (Family:Acanthaceae) extracts against Culex quinquefasciatus (Say.) and Aedes aegypti (Linn.) (Diptera:Culicidae)

ObjectiveTo investigate the larvicidal and ovicidal efficacy of different extracts of Andrographis paniculata (A. paniculata) against Culex quinquefasciatus (Cx. quinquefasciatus) Say and Aedes aegypti (Ae. aegypti) L. (Diptera: Culicidae).MethodsLarvicidal efficacy of the crude leaf extracts of A. paniculata with five different solvents like benzene, hexane, ethyl acetate, methanol and chloroform was tested against the early third instar larvae of Cx. quinquefasciatus and Ae. aegypti. The ovicidal activity was determined against two mosquito species to various concentrations ranging from 50-300 ppm under the laboratory conditions.ResultsThe benzene, hexane, ethyl acetate, methanol and chloroform leaf extract of A. paniculata was found to be more effective against Cx. quinquefasciatus than Ae. aegypti. The LC₅₀ values were 112.19, 137.48, 118.67, 102.05, 91.20 ppm and 119.58, 146.34, 124.24, 110.12, 99.54 ppm respectively. Among five tested solvent, methanol and ethyl acetate crude extract was found to be most effective for ovicidal activity against two mosquito species. The extract of methanol and ethyl acetate exerted 100% mortality at 200 ppm against Cx. quinquefasciatus and at 250 ppm against Ae. aegypti.ConclusionsFrom the results it can be concluded the crude extract of A. paniculata was a potential for controlling Cx. quinquefasciatus and Ae. aegypti mosquitoes.     

Insect repellent activity of medicinal plant oils against Aedes aegypti (Linn.), Anopheles minimus (Theobald) and Culex quinquefasciatus Say based on protection time and biting rate

This study investigated insect bite protection and length of the protection with 30 repellents which were divided into 3 categories: plant oil, essential oil and essential oil with ethyl alcohol, tested against three mosquito species, Aedes aegypti, Anopheles minimus and Culex quinquefasciatus, under laboratory conditions. The plant oil group was comprised of Phlai (Zingiber cassumunar) and Sweet basil (Ocimum basilicum). Both substances were effective as repellents and feeding deterrents against An. minimus (205 minutes protection time and a biting rate of 0.9%), Cx. quinquefasciatus (165 minutes protection time and 0.9% biting rate) and Ae. aegypti (90 minutes protection time and 0.8% biting rate). Essential oil from citronella grass (Cymbopogon nardus) exhibited protection against biting from all 3 mosquito species: for An. minimus, Cx. quinquefasciatus and Ae. aegypti, the results were 130 minutes and 0.9%, 140 minutes and 0.8%, and 115 minutes and 0.8%, respectively. The period of protection time against Ae. aegypti for all repellent candidates tested was lower than the Thai Industrial Standards Institute (TISI) determined time of greater than 2 hours.     

Mosquito repellent properties of Delonix elata (L.) gamble (Family: Fabaceae) against filariasis vector,Culex quinquefasciatus Say. (Diptera: Culicidae)

ObjectiveTo determine the repellent activity of hexane, ethyl acetate, benzene, chloroform and methanol extract of Delonix elata (D. elata) leaf and seed against Culex quinquefasciatus (Cx. quinquefasciatus).MethodsEvaluation was carried out in a net cage (45 cm×30 cm×25 cm) containing 100 blood starved female mosquitoes of Cx. quinquefasciatus. Repellent activity was carried out in the laboratory conditions according to the WHO 2009 protocol. Plant crude extracts of D. elata were applied at 1.0, 2.5, and 5.0 mg/cm² separately in the exposed fore arm of study subjects. Ethanol was used as the sole control.ResultsIn this study, the applied plant crude extracts were observed to protect against mosquito bites. There were no allergic reactions experienced by the study subjects. The repellent activity of the extract was dependent on the strength of the extract. Among the tested solvents, the leaf and seed methanol extract showed the maximum efficacy. The highest concentration of 5.0 mg/cm² provided over 150 min and 120 min protection, respectively.ConclusionsCrude extracts of D. elata exhibit the potential for controlling Cx. quinquefasciatus, the mosquito vector of filariasis.     

Larvicidal activity of Wrightia tinctoria R. BR. (Apocynaceae) fruit and leaf extracts against the filarial vector Culex quinquefasciatus Say (Diptera: Culicidae)

ObjectiveTo determine the larvicidal activity of crude aqueous and petroleum ether extracts of Wrightia tinctoria fruits and leaves against the filarial vector, Culex quinquefasciatus.MethodsThe larvicidal activity was evaluated at concentrations of 0.06%, 0.12%, 0.25%, 0.50% and 1.00%. Larval mortality was observed for 24 and 48 h.ResultsAmong the plant parts tested, aqueous fruit extract exhibited highest larvicidal activity followed by aqueous leaf extract with LC₅₀ values of 0.17% and 0.09%; 0.21% and 0.11% after 24 and 48 h respectively.ConclusionsFurther investigations are needed to elucidate this activity against a wide range of all stages of mosquito species and also the active ingredient(s) of the extract responsible for larvicidal activity should be identified.     

Repellent activity of Ageratum houstonianum Mill. (Asteraceae) leaf extracts against Anopheles stephensi,Aedes aegypti and Culex quinquefasciatus (Diptera: Culicidae)

ObjectiveTo determine the repellent activity of hexane, ethyl acetate and methanol crude extracts of Ageratum houstonianum(A. houstonianum) leaves against adult Anopheles stephensi (An. stephensi), Aedes aegypti (Ae. aegypti) and Culex quinquefasciatus (Cx. quinquefasciatus) mosquitoes.MethodsBioassay on laboratory reared Swiss albino mice by topical application at a fixed concentration of 0.01 per cent with coconut oil as a base.ResultsCrude leaf extracts of A. houstonianum in combination with coconut oil repelled vector mosquitoes. Maximum protection for a period of 11.30 h was obtained against Cx. quinquefasciatus and An. stephensi when treated with methanol and hexane extracts followed by 8.30 h against Ae. aegypti in methanol extract. Amongst the three extracts, methanol extract gave the maximum protection of 95.0% against Cx. quinquefasciatus. Hexane and ethyl acetate extracts gave a maximum of 93.4% protection against An. stephensi.ConclusionsThe crude extracts of A. houstonianum leaves in combination with coconut oil showed repellent activity with repellent quotient ranging from 0.6 to 0.9.     

Vector competence of Aedes aegypti (L.) and Culex quinquefasciatus (Say) for Dirofilaria immitis (Leidy)

This study was performed to examine the vector competence of Aedes aegypti and Culex quinquefasciatus for Dirofilaria immitis. Eleven individual experiments were conducted in this study. Nonthaburi and Udon Thani strains of Ae. aegypti were allowed to feed on infected dogs that had 5,750 and 4,600 microfilariae (mW) per ml of blood, respectively. Three groups of Bangkok-strain Cx. quinquefasciatus were allowed to feed on dogs that had 4,800, 5,200, and 5,850 mf per ml of blood. Six groups of Liverpool-strain Ae. aegypti were allowed to feed on dogs with 1,650, 1,950, 3,350, 9,000, 9,250, and 11,550 mf per ml of blood. Three to 4% of Nonthaburi-strain, and 0-6% of Udon Thani-strain Ae. aegypti became infected and had infective-stage larvae (L3) of D. immitis in their probosces. Zero to 1 and 7% of Bangkok-strain Cx. quinquefasciatus had L3 in their probosces after taking blood meals with 4,800 and 5,850 mf per ml of blood, respectively. The percent-infected Liverpool-strain Ae. aegypti with L3 in their probosces were 3-12, 0-12, 10, 16, 7-19, and 0-21 after taking blood meals with 1,650, 1,950, 3,350, 9,000, 9,250, and 11,550 mf per ml of blood, respectively, when tested at different post-blood-feeding days. This study showed both Ae. aegypti and Cx. quinquefasciatus from Thailand can become vectors for D. immitis; however, Liverpool-strain Ae. aegypti are more likely to be competent vectors for D. immitis than Ae. aegypti and Cx. quinquefasciatus from Thailand. The percent infection rates of Ae. aegypti and Cx. quinquefasciatus with D. immitis in the field in Thailand need to be investigated, to confirm the role of these mosquitoes in the life cycle of D. immitis in nature.     

Evaluation of repellent action of neem oil against the filarial vector, Culex quinquefasciatus (Diptera: Culicidae)

Studies were carried out to evaluate the repellent action of neem oil against Culex quinquefasciatus. Application of 2 and 5 per cent neem oil @ 5 ml/person/night gave 50 and 40.9 per cent protection in indoor collections and 17.4 and 5.6 per cent in outdoor collections as compared with that of untreated control respectively. The protection time ranged from 0100 to 0300 hrs and 0100 to 0600 hrs in indoor and outdoor collections respectively. Results of repellent action of Autan, a synthetic mosquito repellent studied concurrently showed a relatively higher protection rate from the bites of Cx. quinquefasciatus.     

Studies on effects of Andrographis paniculata (Burm.f.) and Andrographis lineata nees (Family: Acanthaceae) extracts against two mosquitoes Culex quinquefasciatus (Say.) and Aedes aegypti (Linn.)

ObjectiveTo investigate the studies on effects of Andrographis paniculata (A. paniculata) (Burm.f.) and Andrographis lineata (A. lineata) nees (Family: Acanthaceae) extracts against two mosquitoes Culex quinquefasciatus (Cx. quinquefasciatus) (Say.) and Aedes aegypti (Ae. aegypti) (Linn.).MethodsThe aqueous and petroleum ether extracts of two plant species, A. paniculata and A. lineate were examined against the larvae of A. aegypti (L.) and Cx. quinquefasciatus with gradually increasing concentration ie. from 50 to 200 ppm of solvent extracts and to test their activity in combination with each other.ResultsIn a 24 h bioassay experiment with plant extracts, highest mortalities were recorded at 200 ppm of concentrations for leaves of A. lineta and A. paniculata individually. For combination effect, only 150 ppm of the mixture of solvent extracts of petroleum ether: aqueous (1:1) extracts showed 100% mortality after 24 h of exposure.ConclusionsThe results show that, insecticides of plant combination is ecofriend and has better larvicidal activity compared to individual extracts.     

Larvicidal and repellent properties of some essential oils against Culex tritaeniorhynchus Giles and Anopheles subpictus Grassi (Diptera: Culicidae)

ObjectiveTo investigate the larvicidal and repellent properties of essential oils from various parts of four plant species Cymbopogan citrates, Cinnamomum zeylanicum, Rosmarinus officinalis and Zingiber officinale against Culex tritaeniorhynchus (Cx. tritaeniorhynchus) and Anopheles subpictus (An. subpictus).MethodsEssential oils were obtained by hydro-distillation method. The mosquitoes were reared in the vector control laboratory and twenty five late third instar larvae of Cx. tritaeniorhynchus and An. subpictus were exposed to based on the wide range and narrow range test, essential oil tested at various concentrations ranging from 25 to 250 ppm. The larval mortality was observed after 24 h under the laboratory conditions. The repellent efficacy was determined against two mosquito species at three concentrations viz., 1.0, 2.5 and 5.0 mg/cm² under laboratory conditions.ResultsResults showed all the four plant essential oil produced significant larval mortality against two mosquito species. However, the highest larvicidal activity was observed in the essential oil from Zingiber officinale against Cx. tritaeniorhynchus and An. subpictus with the LC₅₀ and LC₉₀ values as 98.83, 57.98 ppm and 186.55, 104.23 ppm, respectively. All the four essential oil shows significant repellency against Cx. tritaeniorhynchus than An. subpictus. Among four essential oil tested the highest repellency was observed in Zingiber officinale, a higher concentration of 5.0 mg/cm² provided 100% protection up to 150 and180 min against Cx. tritaeniorhynchus and An. subpictus, respectively.ConclusionsIn this work, it can be concluded that four essential oils which were distilled from Cymbopogan citrates, Cinnamomum zeylanicum, Rosmarinus officinalis and Zingiber officinale showed promising larvicidal and repellent agent against Cx. tritaeniorhynchus and An. subpictus.     

Larvicidal potential of Acorus calamus L. essential oil against filarial vector mosquito Culex quinquefasciatus (Diptera: Culicidae)

ObjectiveTo identify the chemical composition and larvicidal activity of Acorus calamus (A. calamus) rhizome essential oil against the filarial vector mosquito, Culex quinquefasciatus (Cx. quinquefasciatus).MethodsEssential oil was isolated by hydro-distillation and the chemical composition of the oil was analysed by gas chromatography and gas chromatography mass spectroscopy analysis. The larvicidal activity of the essential oil was analysed at different concentrations, viz., 12.5, 25.0, 50.0, 100.0 and 200.0 mL/L. Early 4th instar larvae were used for the larvicidal assay. The larval mortality was calculated after 24 h of the exposure.ResultsThe gas chromatography and gas chromatography mass spectroscopy analysis showed that the essential oil extracted from the rhizome of A. calamus contained 20 chemical compounds representing about 99.99% of the total oil. Beta-asarone (33.36%), cis-beta-terpineol (23.44%), limonene (13.08%), carvone (5.64%) and amyl isovalerate (4.92%) were identified as the major chemical compounds. The essential oil had promising larvicidal effect against the early 4th instar larvae of Cx. quinquefasciatus with LC₅₀ value of 63.43 mL/L and LC₉₀ value of 145.95 mL/L.ConclusionThe essential oil of A. calamus rhizome can be used as a natural larvicidal agent against the larvae of filarial vector mosquito, Cx. quinquefasciatus.     

Larvicidal effect of Verticillium lecanii metabolites on Culex quinquefasciatus and Aedes aegypti larvae

ObjectiveTo investigate the efficacy of Verticillium lecanii metabolites after filtration and purification through the chromatographic techniques against the larvae of Culex quinquefasciatus (Cx. quinquefasciatus) and Aedes aegypti (Ae. aegypti).MethodsThis fungus was cultured on potato dextrose broth in the laboratory at 25 °C, while the relative humidity was maintained at (75±5)% for 15 d. Filtration process of metabolites was done using whatman-1 filter paper, column chromatography and flash chromatography. Larvicidal efficacy was performed at six different concentrations with different effective volume ratios (ethanol/metabolites: 9:1, 8:2, 7:3, 6:4, 5:5, 4:6, 3:7, 2:8 and 1:9) for a period of 24, 48 and 72 h, respectively.ResultsAmong all ratios, the 4:6 ratio was found effective against the larvae of Cx. quinquefasciatus and 1:9 ratio was found effective against the larvae of Ae. aegypti. The first, second, and third instars of Cx. quinquefasciatus were found more susceptible to the metabolites than the fourth instars. However, the first instars of Ae. aegypti were found more susceptible than the other instars.ConclusionsLarvicidal efficacy has been pioneered by us for the first time and performed against all instars of Cx. quinquefasciatus and Ae. aegypti. The filtration and purification made metabolites more effective than the crude metabolites. The metabolites of Verticillium lecanii could be an environmentally safer larvicide source for the control of mosquito larvae.     

Effects of cyromazin and methoprene on the developmental stages of Anopheles dirus, Aedes aegypti and Culex quinquefasciatus (Diptera : Culicidae)

The effects of two chemical compounds, cyromazin and methoprene, on the developmental stages of Anopheles dirus, Aedes aegypti and Culex quinquefasciatus were investigated under laboratory conditions, with the mean temperature of 24 degrees +/- 1 degree C and the relative humidity at 65-75%. Both compounds were tested against the second, third and fourth instar larvae. The concentrations of cyromazin used for An. dirus and Cx. quinquefasciatus ranged from 0.0008 to 0.5 mg/l; and for Ae. aegypti from 0.004 to 2.5 mg/l. The concentrations of methoprene used for An. dirus, Ae. aegypti and Cx. quinquefasciatus ranged from 0.00016 to 0.1 mg/l. The mortality rates were found to be relatively high in larval and pupal stages when treated with cyromazin and methoprene. The primary toxic effects of cyromazin were on the second stage larvae. The LC50 values for cyromazin on the second, third and fourth stage larvae were, respectively, 0.0027, 0.0042 and 0.0114 mg/l for An. dirus, and 0.1662, 0.2307 and 0.3005 mg/l for Ae. aegypti. Cx. quinquefasciatus was the most sensitive species to cyromazin with LC50 values for second, third and fourth stage larvae of 0.0015, 0.0068 and 0.0130 mg/l, respectively. The primary toxic effects of methoprene were in the fourth stage larvae. The LC50 values for methoprene on the second, third and fourth stage larvae were, respectively, 0.0110, 0.0041 and 0.0022 mg/l for An. dirus, and 0.0077, 0.0034 and 0.0025 mg/l for Ae. aegypti. Cx. quinquefasciatus was the most sensitive species to methoprene, with LC50 values for second, third and fourth stage larvae of 0.0013, 0.0008 and 0.0006 mg/l, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Diterpenoids from Copaifera reticulata Ducke with larvicidal activity against Aedes aegypti (L.) (Diptera, Culicidae)

The objective of this study was to evaluate the larvicidal activity of diterpenoids obtained from the oil-resin of Copaifera reticulata against Aedes aegypti larvae, the principal vector of dengue and urban yellow fever. Four diterpenes were obtained from oil-resin extraction with organic solvents and subsequent chromatographic and spectroscopic procedures allowed to isolation and identification of these compounds as 3-beta-acetoxylabdan-8(17)-13-dien-15-oic acid (1), alepterolic acid (2), 3-beta-hidroxylabdan-8(17)-en-15-oic acid (3), and ent-agatic acid (4). Each compound was previously dissolved in dimethylsulphoxide, and distilled water was added to obtain the desired concentrations. Twenty larvae of third instars were placed into plastic beckers, containing the solution test (25 mL), in a five repetitions scheme, and their mortality, indicated by torpor and darkening of the cephalic capsule, was recorded after 48 h. Probit analyses were used to determine lethal concentrations (LC50 and LC90) and their respective 95% confidence intervals. This study showed that only diterpenoids 1 and 2 exhibited larvicidal properties with LC50 of 0.8 ppm and 87.3 ppm, respectively, revealing the former as the most toxic compound against third instars of Ae. aegypti. Therefore, this compound seems to be an interesting source for new metabolite to be exploited.     

Adulticidal activity of Pithecellobium dulce (Roxb.) Benth. against Culex quinquefasciatus (Say)

ObjectiveTo determine the adulticidal efficacy of different solvent leaf and seed extracts of Pithecellobium dulce (P. dulce) against Culex quinquefasciatus (Cx. quinquefasciatus).MethodsSucrose-fed and blood starved mosquitoes were released into the tube, and the mortality effects of the extracts were observed every 10 min for 3 h exposure period. At the end of 1, 2, and 3 h exposure periods, the mosquitoes were placed in the holding tube. Cotton pads soaked in 10% sugar solution with vitamin B complex were placed in the tube during the holding period of 24 h. Mortality of the mosquitoes was recorded after 24 h.ResultsAmong five solvent extracts tested, the maximum efficacy was observed in the methanol extract of leaves of P. dulce. The LC₅₀ and LC₉₀ values of P. dulce leaves and seeds against Cx. quinquefasciatus were 234.97, 309.24 ppm and 464.86, 570.80 ppm, respectively. No mortality was observed in controls. The Chi-square values were significant at P<0.05 level.ConclusionsFrom the results it can be concluded that the crude extract of P. dulce has excellent potential for controlling filariasis vector mosquito, Cx. quinquefasciatus. This is the first report on the mosquito adulticidal activity of the reported P. dulce plant.     

Larvicidal activity of the fungus Aphanomyces (oomycetes : Saprolegniales) against Culex quinquefasciatus

Several species of fungi are currently being considered for operational use in the microbial control of mosquito larvae. The oomycetous fungi are the prominent ones amongst them because of their ability to complete life cycle in water. During our studies on zoosporic fungi from riverine waters of Mula and Mutha flowing through Pune City, Maharashtra, India, Aphanomyces laevis de Bary (Oomycetes: Saprolegniales) was isolated from polluted waters. After critical observations it was found to be mosquito larvicidal. Sporulating hemp seed cultures when inoculated under laboratory conditions revealed that it causes 80%/ mortality after seven days to Culex quinquefasciatus larvae. Laboratory assays were conducted to determine the effects of water quality on the ability of the isolate to infect mosquito larvae in varying degrees of pollution levels. In all the experiments, a non sexual strain of Aphanomyces (zoospores) was found to be the pathogenic agent for the Culex larvae.     

Adulticidal properties of Pithecellobium dulce (Roxb.) Benth. (Family: Fabaceae) against dengue vector,Aedes aegypti (Linn.) (Diptera: Culicidae)

To examine the toxicity of mosquito adulticidal activity of different solvent leaf and seed extracts of Pithecellobium dulce (P. dulce) against dengue vector, Aedes aegypti (Ae. aegypti).MethodsAdulticidal efficacy of the crude leaf and seed extracts of P. dulce with five different solvents like benzene, hexane, ethyl acetate, methanol and chloroform was tested against the five to six day old adult female mosquitoes of Ae. aegypti. The adult mortality was observed after 24 h under the laboratory conditions.ResultsAmong the tested solvents the maximum efficacy was observed in the leaf and seed methanol extract. The LC₅₀ and LC₉₀ values of P. dulce leaf and seed extract against adults of Ae. aegypti were 218.64, 257.99 mg/L and 426.05, 507.73 mg/L, respectively. No mortality was observed in controls. The Chi-square values were significant at P<0.05 level.ConclusionsFrom the results it can be concluded the crude extract of P. dulce leaf and seed was an excellent potential for controlling dengue vector mosquito, Ae. aegypti.     

Mosquito larvicidal and ovicidal properties of Eclipta alba (L.) Hassk (Asteraceae) against chikungunya vector, Aedes aegypti (Linn.) (Diptera: Culicidae)

ObjectiveThe present study deals with the investigation of larvicidal and ovicidal activities of benzene, hexane, ethyl acetate, methanol and chloroform leaf extract of Eclipta alba (E. alba) against dengue vector, Aedes aegypti (Ae. Aegypti).MethodsTwenty five early III instar larvae of Ae. aegypti was exposed to various concentrations (50–300 ppm) and was assayed in the laboratory by using the protocol of WHO 2005; the 24 h LC₅₀ values of the E. alba leaf extract was determined by Probit analysis. For ovicidal activity, slightly modified method of Su and Mulla was performed. The ovicidal activity was determined against Ae. aegypti to various concentrations ranging from 100–350 ppm under the laboratory conditions. The egg hatch rates were assessed 48 h post treatment.ResultsThe LC₅₀ values of benzene, hexane, ethyl acetate, methanol and chloroform extract of E. alba against early third instar larvae of Ae. aegypti were 151.38, 165.10, 154.88, 127.64 and 146.28 ppm, respectively. Maximum larvicidal activity was observed in the methanol extract followed by chloroform, benzene, ethyl acetate and hexane extract. No mortality was observed in control. Among five solvent tested the methanol extract was found to be most effective for ovicidal activity against Ae. aegypti. The methanol extracts exerted 100% mortality (zero hatchability) at 300 ppm.ConclusionsFrom the results it can be concluded the crude extract of E. alba was an excellent potential for controlling Ae. aegypti mosquito.