Celery-based topical repellents as a potential natural alternative for personal protection against mosquitoes

Celery-based products were investigated for chemical composition, skin irritation, and mosquito repellency in comparison to commercial repellents and the standard chemical, N,N-diethyl-3-methylbenzamide (DEET), with a goal to develop a natural alternative to synthetic repellents for protection against mosquitoes. Chemical identification by gas chromatography coupled with mass spectrometry discovered that the major constituents of Apium graveolens hexane extract (AHE) were 3-n-butyl-tetrahydrophthalide (92.48%), followed by 5.10% β-selinene and 0.68% γ-selinene. Evaluation of skin irritation in 27 human volunteers revealed no irritant potential from 25% ethanolic AHE solution. Laboratory investigated repellent against female Aedes aegypti mosquitoes demonstrated that G10 formula, the best AHE-developed product, provided remarkable repellency with a median protection time of 4.5 h (4.5–5 h), which was greater than that of ethanolic DEET solution (25% DEET, 3.5 h) and comparable to that of the best commercial repellent, Insect Block 28 (28.5% DEET, 4.5 h). According to significantly promising results, including highly effective repellency and no potential skin irritation or other side effects, the G10 formula is a worthwhile product that has the promise of being developed for commercialized registration. This developed AHE product could be an acceptable and affordable alternative to conventional synthetic chemicals in preventing mosquito bites, and in turn, helping to interrupt mosquito-borne disease transmission.     

Enhanced repellency of binary mixtures of Zanthoxylum armatum seed oil, vanillin, and their aerosols to mosquitoes under laboratory and field conditions

The repellency of Zanthoxylum armatum seed oil (ZA-SO), alone or in combination with vanillin (VA), its six major constituents, and another four major previously known Zanthoxylum piperitum fruit oil constituents, as well as aerosol products containing 5 or 10% ZA-SO and 5% VA, was evaluated against female Aedes aegypti in laboratory and field studies. Results were then compared with those of N,N-diethyl-3-methylbenzamide (DEET) as a standard. Hand in cage laboratory tests showed that 0.2, 0.1, and 0.05 mg/cm2 ZA-SO resulted in > 92% protection through 30-min postexposure and was not significantly different than 0.05 mg/cm2 DEET. Skin treated with linalool and limonene (from Z. armatum) provided > 80% repellency to female Ae. aegypti at 10-min exposure, whereas cuminaldehyde, citronellal, geranyl acetate, and cuminyl alcohol (from Zanthoxylum piperitum) provided > 90% protection during this same time period. Only cuminaldehyde and citronellal provided complete protection comparable to DEET at 10-min postexposure. After that time, repellency of all plant constituents to mosquitoes was considerably decreased (< approximately 65%). An increase in repellency and duration of effectiveness was produced by a binary 1:4 mixture of ZA-SO and VA (0.05:0.2 mg/cm2) that was significantly more effective than 0.05 mg/cm2 DEET through 90 min. In field tests, an aerosol formulation containing 5 or 10% ZA-SO plus 5% VA gave 100% repellency at 60-min postexposure. Although these formulations were equal to the level of protection afforded by 10% DEET, repellency to the binary ZA-SO aerosol formulations at 90 min was significantly less effective than DEET. However, mixtures formulated from ZA-SO and VA merit further study as potential repellents for protection of humans and domestic animals from biting and nuisance caused by mosquitoes.     

Repellency of essential oils extracted from Thai native plants against Aedes aegypti (Linn.) and Culex quinquefasciatus (Say)

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.     

Field evaluation of G10, a celery (<Emphasis Type="Italic">Apium graveolens</Emphasis>)-based topical repellent,against mosquitoes (Diptera: Culicidae) in Chiang Mai province,northern Thailand

The potential of G10, a celery (Apium graveolens)-based topical product, as a repellent against natural mosquito populations was evaluated in comparison to commercial (Insect Block 28) and standard (25% DEET) repellents in Chiang Mai province, northern Thailand. These repellent products afforded encouragingly excellent personal protection against a broad range of mosquito species belonging to various genera, including Aedes, Anopheles, Armigeres, Culex, and Mansonia. No mosquito bite was observed on the volunteers treated with G10 and Insect Block 28 throughout the field study, whereas two species, i.e., six A. barbirostris and two A. subalbatus, came to bite or land on 25% DEET-treated volunteers. Thus, it can be concluded that while G10 and Insect Block 28 exhibited similarly powerful repellent activities with complete (100%) protection, 25% DEET was effective in minimizing bites with 99.68% protection. G10 formula was also studied for physical properties and biological stability after being kept under two conditions; a heating and cooling cycle, and varying temperature and time storage. Most samples of stored G10 not only demonstrated a similarity in appearance and physical properties, but also provided comparable repellency to that of the fresh preparation. These findings encourage commercial development of G10 formula as an alternative to conventional synthetic repellents.     

Oviposition deterrent activity of three mosquito repellents diethyl phenyl acetamide (DEPA), diethyl m toluamide (DEET), and diethyl benzamide (DEB) on Aedes aegypti, Aedes albopictus, and Culex quinquefasciatus

Oviposition deterrent activity of three mosquito repellents namely diethyl phenyl acetamide (DEPA), diethyl benzamide (DEB) along with diethyl toluamide (DEET) was studied in the laboratory against Aedes aegypti, A. albopictus, and Culex quinquefasciatus mosquitoes. All the repellents evaluated at three log concentrations 0.1, 0.01, and 0.001 % in comparison with control by dual choice method. The oviposition response and oviposition activity index (OAI) was estimated by counting number of eggs laid in both the treatment and control. Mean OAI determined for A. aegypti was in the range of ?0.23 to +0.22, ?0.3 to +0.27, and +0.04 to +0.33 for DEPA, DEET, and DEB, respectively, whereas it was ?0.77 to ?0.035, ?0.92 to +0.001, and ?0.77 to ?0.07 for A. albopictus and ?0.927 to ?0.251, ?1 to ?0.41, and ?0.94 to ?0.17 for C. quinquefasciatus. The oviposition deterrent activity was observed in the order of DEET > DEPA > DEB. Similarly, the response of species toward the repellents as oviposition deterrent was in the trend of C. quinquefasciatus > A. albopictus > A. aegypti. The finding suggests potential role of mosquito repellents as oviposition deterrent.     

Repellency of essential oils to mosquitoes (Diptera: Culicidae).

The repellency of different concentrations (5, 10, 25, 50, 75, and 100%) and combinations of 5 essential oils (Bourbon geranium, cedarwood, clove, peppermint, and thyme) to Aedes aegypti (L.) and Anopheles albimanus Wiedemann when applied to human skin was determined in laboratory tests. Cedarwood oil failed to repel mosquitoes and only high concentrations of peppermint oil repelled Ae. aegypti. None of the oils tested prevented mosquito bite when used at the 5 or 10% concentration. Thyme and clove oils were the most effective mosquito repellents and provided 1 1/2 to 3 1/2 h of protection, depending on oil concentration. Clove oil (50%) combined with geranium oil (50%) or with thyme oil (50%) prevented biting by An. albimanus for 1 1/4 to 2 1/2 h. The potential for using essential oils as topical mosquito repellents may be limited by user acceptability; clove, thyme, and peppermint oils can be irritating to the skin, whereas both human subjects in this study judged the odor of clove and thyme oils unacceptable at concentrations > or = 25%.     

Repellency effect of forty-one essential oils against Aedes, Anopheles, and Culex mosquitoes

Since ancient times, plant products were used in various aspects. However, their use against pests decreased when chemical products became developed. Recently, concerns increased with respect to public health and environmental security requiring detection of natural products that may be used against insect pests. In this study, 41 plant extracts and 11 oil mixtures were evaluated against the yellow fever mosquito, Aedes aegypti (Linnaeus), the malaria vector, Anopheles stephensi (Liston), and the filariasis and encephalitis vector, Culex quinquefasciatus (Say) (Diptera: Culicidae) using the skin of human volunteers to find out the protection time and repellency. The five most effective oils were those of Litsea (Litsea cubeba), Cajeput (Melaleuca leucadendron), Niaouli (Melaleuca quinquenervia), Violet (Viola odorata), and Catnip (Nepeta cataria), which induced a protection time of 8 h at the maximum and a 100% repellency against all three species. This effect needs, however, a peculiar formulation to fix them on the human skin.     

N,N-diethyl phenylacetamide (DEPA): A safe and effective repellent for personal protection against hematophagous arthropods

Repellents play an important role in protecting humans from the bites of insect pests. An effective and safe repellent will be useful in reducing human-vector contact and thereby help in the interruption of vector borne disease transmission. Because of the unavailability of m-toluic acid in India for the manufacture of N,N-diethyl m-toluamide (DEET), there is a need to develop an alternate effective and safe insect repellent. In total, 120 substituted amides were synthesized and tested for repellency at 1.0 mg/cm2 under laboratory conditions. Among these amides, N,N-diethyl phenylacetamide (DEPA), applied at 1.0 mg/cm2 in different oil bases, was found to exhibit promising repellency (6-8 h) in the laboratory when tested against Aedes aegypti (L.) The repellent DEPA was evaluated on army personnel in comparison with dimethylphthalate (DMP) and DEET against mosquitoes, black flies, and land leeches under field condition in the North-East Frontier area of India. Both DEPA and DEET displayed broad-spectrum repellency. DEPA was more effective than DMP against all test organisms. However, no significant difference was noticed between DEPA and DEET for repellency at 0.25 and 0.5 mg/cm2 against black flies and mosquitoes. DMP was the least effective among the three compounds in the field studies. The relative potency of DEPA in comparison with DEET and DMP for repellency against Phlebotomine sand flies also was determined. At 0.1 mg/cm2, both DEPA and DEET were found to be equally effective with a protection time from 4.37 +/- 0.08 to 4.45 +/- 0.15 h. Both compounds were significantly more effective than DMP. At 0.2 mg/cm2, DEPA and DEET provided protection times of 6.52 +/- 0.08 and 7.15 +/- 0.15 h, respectively. DEPA was formulated into a vanishing cream, a pharmacologically safe polymer-based liquid, and a liposphere lotion. The vanishing cream and the two-polymer liquid formulations enhanced protection times from 4.4 to 6.5 and 7.13 h, respectively, compared with an alcohol solution applied at 0.5 mg/cm2 on the forearm of human volunteers. Formulations of DEPA and DEET applied at 0.5 mg/cm2 on rabbits exposed to Ae. aegypti enhanced protection times compared with an alcohol solution and the liposphere lotion from 4.0 to 6.0 h and 4.0 to 5.0 h, respectively. Comparison of mean protection times of DEET and DEPA applied at a rate of 0.3 mg/cm2 to human volunteers exposed to Cx. quinque-fasciatus under field conditions indicated that the lotion formulations of DEET and DEPA provided significantly (Duncan's multiple-range test, P < 0.05) higher protection times than did alcohol solutions. Toxicological studies revealed that DEPA is safe.     

Knockdown and repellent effect of permethrin-impregnated army uniform cloth against Aedes aegypti after different cycles of washings

Personnel protection is one of the methods for protection from bites of mosquitoes and other arthropod vectors transmitting many dreadful diseases. Insect repellents and other plant products are normally used to ward off mosquitoes. Application of synthetic pyrethroid permethrin on cloth is adopted for repelling arthropod vectors in many countries for military and civil purposes. In the present study, attempt has been made to impregnate permethrin in the army uniform cloth and to evaluate for its knockdown and repellency against unfed female Aedes aegypti mosquitoes in laboratory condition. WHO protocols were adopted for impregnation of permethrin on cloth and evaluation for its knockdown and repellency after different cycles of washing. Results showed that 93.33 % of mosquitoes were knocked down within 1 h after the first washing while its efficacy reduced gradually till the fifty-fifth washing. Landing of mosquitoes on the permethrin-treated cloth was found to increase with respect to number of washings as compared to the untreated cloth. Within 24 h, 100 % mortality of all the mosquitoes exposed to permethrin-impregnated cloth was observed. SEM-EDX studies on the texture of untreated cloth and permethrin-treated cloth after different cycles of washing also revealed presence of permethrin on treated cloth.     

Insecticidal, acaricidal and repellent effects of DEET- and IR3535-impregnated bed nets using a novel long-lasting polymer-coating technique

A novel long-lasting repellent-treated net (LLRTN) has been designed by binding the skin repellents N,N-diethyl-m-toluamide (DEET), or IR3535, onto the fibres of bed net fabric using a new polymer-coating technique. The repellent toxicological effectiveness and residual activity of a factory-based repellent-impregnated fabric has been evaluated by laboratory testing against adult Aedes aegypti mosquitoes and nymphal Ixodes ricinus ticks. By using this repellent-embedding impregnation technique, concentrations exceeding 10 g/m² could be achieved with one single polymer layer. Both DEET- and IR3535-impregnated fabrics revealed a dose-dependent insecticidal as well as acaricidal activity. One hundred percent knockdown times of DEET-treated bed nets ranged from 187.5 ± 31.8 to 27.5 ± 3.5 min against A. aegypti, and between 214 ± 47 and 22.6 ± 5 min against nymphal I. ricinus, linked to a DEET concentration of 1.08 and 10.58 g/m², respectively. With IR3535, A. aegypti produced dose-dependent 100% knockdown times varying from 87.5 ± 10.6 to 57.5 ± 3.5 min and between 131.4 ± 6.5 and 33.8 ± 5 min against nymphal I. ricinus, respectively, linked to concentrations between 1.59 and 10.02 g/m². One hundred percent repellency measured by complete landing and biting protection of impregnated fabric by using the arm-in-cage test could be achieved at DEET concentrations exceeding 3.7 to 3.9 g/m², and for IR3535 concentrations over 10 g/m². One hundred percent landing and biting protection could be preserved with DEET-treated fabrics for 29 weeks at an initial concentration of 4.66 g/m², 54 weeks at 8.8 g/m², 58 weeks at 9.96 g/m² and 61 weeks at 10.48 g/m² for DEET, and 23 weeks for IR3535-treated fabric at a concentration of 10.02 g/m². Unlike repellent-treated fabric, a brand of a commercially available long-lasting insecticide-treated net tested containing 500 mg permethrin/m² did not protect from mosquito bites. First results on bioactivity and long-lasting efficacy show that the new LLRTN technique is highly promising as a potential candidate for future malaria control strategies, especially in areas where pyrethroid resistance occurs.     

Evaluation of the repellent effects of Nepeta parnassica extract,essential oil,and its major nepetalactone metabolite against mosquitoes

The dichloromethane-methanol extract, the essential oil obtained by hydrodistillation from Nepeta parnassica, and the isolated 4aα,7α,7aβ-nepetalactone were evaluated for their repellent effect against the mosquitoes Aedes (Stegomyia) cretinus Edwards and Culex pipiens pipiens biotype molestus Forskål. The chemical analysis of N. parnassica essential oil, dominated by oxygenated monoterpenes (87 %), revealed 4aα,7α,7aβ-nepetalactone (36.8 %), 1,8-cineole (25.5 %), and 4aα,7β,7aβ-nepetalactone (11.1 %) as the major constituents. The results of the insect bioassays showed that the essential oil and the dichloromethane-methanol extract of N. parnassica were very active against Aedes cretinus for up to 3 h and against Culex pipiens for up to 2 h post application. The isolated 4aα,7α,7aβ-nepetalactone showed very high mosquito repellency for periods of at least 2 h against both species.     

Toxicity and synergic repellency of plant essential oil mixtures with vanillin against Aedes aegypti (Diptera: Culicidae)

In all triplicate tests of six plant essential oils and of vanillin mixtures, we corroborated strong insecticidal and repellent activities against adult Aedes aegypti (L.). Essential oils with potent toxic fumigant activities also exhibited repellency. Compared with N, N-diethyl-3-methylbenzamide, 5% of the essential oil concentrations of cassia, lemongrass, lemon eucalyptus, and xanthoxylum oils did not show repellent effects. However, a composition oflemongrass oil, xanthoxylum oil, and vanillin (1:3:1, vol:vol:wt) provided 270 min of complete protection time (CPT) compared with 247.5 min CPT with 15% N, N-diethyl-3-methylbenzamide. The CPT depended on concentration, presence ofvanillin, or on both factors. When we applied a mixture of lemongrass oil: xanthoxylum oil: vanillin (1:1:1, vol:vol:wt) to the Viscopearl formulation, or porous cellulose beads, it provided gradual release of volatile compounds, thus showing >90% of repellency for 2 h. The behavioral and electrophysiological approaches we drew upon in our current study demonstrated that plant essential oil mixtures combined with vanillin showed strong and durable repellency to the mosquito. We claim that such combinations of plant essential oils and vanillin found in current study propose a viable commercial product suitable for future application in protecting a person from mosquito bites.     

In vitro repellency of N,N-diethyl-3-methylbenzamide and N,N-diethylphenylacetamide analogs against Aedes aegypti and Anopheles stephensi (Diptera: Culicidae)

Seventeen analogs of the repellent compounds N,N-diethyl-3-methylbenzamide (DEET) and N,N-diethylphenylacetamide (DEPA) were evaluated in vitro for repellency against laboratory-reared Aedes aegypti (L.) and Anopheles stephensi Liston mosquitoes by using a modified membrane blood feeding test system. The system was a valuable tool for comparing the effective concentrations of the repellent analogs. Additionally, this method used easily controlled test conditions, allowing completion of the many test replications necessary to evaluate all of the repellent analogs over a period of several years. One compound, N,N-diethyl-2-[3-(triflouromethyl)phenyl] acetamide, provided significantly better repellency than DEET against Ae. aegypti and slightly improved efficacy against An. stephensi. Eight of the analogs were as effective as or slightly more repellent than DEET against both species. Seven analogs were less effective than DEET and one compound, N,N-diethyl-3-hydroxybenzamide, was as a poor repellent. Overall, two DEPA analogs and a single DEET analog provided better repellency than DEET against both mosquito species and warrant future laboratory and field evaluation.     

An olfactometer for discriminating between attraction, inhibition, and repellency in mosquitoes (Diptera: Culicidae)

We constructed an olfactometer that differentiates and quantifies attraction, inhibition, and repellency to mosquitoes. Using this device, 22 formulations of various chemicals on gauze pads and 8 dilutions of DEET on skin were tested. Four novel formulations were discovered acting as true repellents, whereas DEET did not act as a true repellent but as an inhibitor.     

Larvicidal, oviposition, and ovicidal effects of Artemisia annua (Asterales: Asteraceae) against Aedes aegypti, Anopheles sinensis, and Culex quinquefasciatus (Diptera: Culicidae)

This study focuses on the larvicidal, oviposition, and ovicidal effects of a crude extract of Artemisia annua against Aedes aegypti, Anopheles sinensis, and Culex quinquefasciatus. Dried cells of Artemisia annua from cell suspension cultures were extracted using hexane. The extract showed moderate larvicidal effects against mosquitoes. At 24-h post treatment, the LC₅₀ values for Anopheles sinensis, Aedes aegypti, and Culex quinquefasciatus were recorded as 244.55, 276.14, and 374.99 ppm, respectively. The percentage mortality of larvae was directly proportional to the tested concentration. Anopheles sinensis was found to be the most susceptible species, whereas Culex quinquefasciatus was the most tolerant to the Artemisia annua extract. The results indicated that the Artemisia annua extract showed concentration-dependent oviposition deterrent activity and had a strong deterrent effect. At 500 ppm, the percentage effective repellency was more than 85 % compared with the control group for all the species, with oviposition activity index values of ?0.94, ?0.95, and ?0.78 for Aedes aegypti, Anopheles sinensis, and Culex quinquefasciatus, respectively. In the ovicidal assay, the percentage hatchability of eggs after treatment with 500 ppm of Artemisia annua extract was significantly lower than the control, with values of 48.84?±?4.08, 38.42?±?3.67, and 79.35?±?2.09 % for Aedes aegypti, Anopheles sinensis, and Culex quinquefasciatus, respectively. Artemisia annua was found to be more effective against Aedes aegypti and Anopheles sinensis compared with Culex quinquefasciatus. This study indicated that crude extract of A. annua could be a potential alternative for use in vector management programs.     

Field trials on the efficacy of DEET-impregnated anklets,wristbands, shoulder,and pocket strips against mosquito vectors of disease

A field trial was undertaken in order to determine the efficacy of DEET (N,N-diethyl-m-toluamide) impregnated anklets, wristbands, shoulder and pocket fabric strips against mosquito vectors of disease. The present study was conducted in the urban locality of Pondicherry, India. Human test subjects were exposed to natural populations of mosquitoes for a 12 h (18.00–06.00) night time period. The fabric strips (anklets, wristbands, shoulder, and pocket strips) were impregnated with DEET at two different concentrations of 1.5 mg/cm² and 2.0 mg/cm². The results clearly revealed that DEET-impregnated anklets, wristbands, shoulder and pocket fabric strips were found more effective against mosquitoes remarkably. The DEET-impregnated anklets, wristbands, shoulder and pocket fabric strips at a concentration of 2 mg/cm² provided 5 h complete protection against mosquitoes bites and the reduction of man-landing rate varied between 65.85 and 100%. However, DEET-impregnated fabric strips at a concentration of 1.5 mg/cm² provided 4 h complete protection against mosquito bites and the reduction of man-landing rate varied between 51.21 and 100%. The final results clearly demonstrate that repellent activity of DEET-impregnated anklets, wristbands, shoulder, and pocket strips were dose-dependent. Certainly, the DEET-impregnated fabric strips can be used as an effective potential personal protection measure in order to avoid those insects/mosquitoes that prefer to feed outdoors or those that feed in the early evening.     

Mosquito larvicidal, ovicidal, and repellent properties of botanical extracts against Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus (Diptera: Culicidae)

Mosquito-borne diseases have an economic impact, including loss in commercial and labor outputs, particularly in countries with tropical and subtropical climates; however, no part of the world is free from vector-borne diseases. In mosquito control programs, botanical origin may have the potential to be used successfully as eggs, larvae, and adult. The larvicidal, ovicidal, and repellent activities of crude benzene and ethyl acetate extracts of leaf of Ervatamia coronaria and Caesalpinia pulcherrima were assayed for their toxicity against three important vector mosquitoes, viz., Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus (Diptera: Culicidae). The larval mortality was observed after 24 h of exposure. All extracts showed moderate larvicidal effects; however, the highest larval mortality was found in benzene extract of E. coronaria against the larvae of Anopheles Stephensi, Aedes aegypti, and Culex quinquefasciatus with the LC₅₀ and LC₉₀ values were 79.08, 89.59, and 96.15 ppm and 150.47, 166.04, and 174.10 ppm, respectively. Mean percent hatchability of the ovicidal activity was observed 48 h posttreatment. The percent hatchability was inversely proportional to the concentration of extract and directly proportional to the eggs. The leaf extract of E. coronaria was found to be most effective than Caesalpinia pulcherrima against eggs/egg rafts of three vector mosquitoes. For E. coronaria, the benzene extract exerted 300, 250, and 200 ppm against Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus, respectively. The results of the repellent activity of benzene and ethyl acetate extract of E. coronaria and Caesalpinia pulcherrima plants at three different concentrations of 1.0, 2.5, and 5.0 mg/cm² were applied on skin of fore arm in man and exposed against adult female mosquitoes. In this observation, these two plant crude extracts gave protection against mosquito bites without any allergic reaction to the test person, and also, the repellent activity is dependent on the strength of the plant extracts. These results suggest that the leaf solvent plant extracts have the potential to be used as an ideal ecofriendly approach for the control of mosquitoes. This is the first report on the mosquito larvicidal, ovicidal, and repellent activities of the reported E. coronaria and Caesalpinia pulcherrima plants.     

Synergistic insecticidal and repellent effects of combined pyrethroid and repellent-impregnated bed nets using a novel long-lasting polymer-coating multi-layer technique

New and improved strategies for malaria control and prevention are urgently needed. As a contribution to an optimized personal protection strategy, a novel long-lasting insecticide and repellent-treated net (LLIRN) has been designed by binding combinations of permethrin plus N,N-diethyl-m-toluamide (DEET), or insect repellent 3535 (IR3535), and etofenprox plus DEET, onto fibres of bed net fabric employing a new multi-layer polymer-coating technique. Protective repellent efficacy, toxicological effectiveness and residual activity of 12 LLIRN types have been evaluated by laboratory testing against adult Aedes aegypti. The novel multi-layer LLIRN design allowed simultaneous embedding at concentrations up to 5,930 mg/m(2) for DEET, 3,408 mg/m(2) for IR3535, 2,296 mg/m(2) for permethrin and 2,349 mg/m(2) for etofenprox, respectively. IR3535 layers prevented co-binding of additional pyrethroid-containing polymer layers, thus making pyrethroids plus DEET LLIRNs an ideal combination. All LLIRNs revealed synergistic insecticidal effects which, when measured against concentration controls of the isolated compounds, were significant in all LLIRN types designed. DEET in DEET plus permethrin LLIRNs significantly (p?相似文献   

Laboratory evaluation of mosquito repellents against Aedes albopictus, Culex nigripalpus, and Ochierotatus triseriatus (Diptera: Culicidae)

Four synthetic mosquito repellents (Autan [10% KBR3023], IR3535 [7.5%], Off! [15% deet], Skinsations [7% deet]) and eight natural (primarily plant extracts and/or essential oils) product-based repellents (Bite Blocker [2% soybean oil], ByGone, GonE!, Natrapel [10% citronella], Neem Aura, Sunswat, MosquitoSafe [25% geraniol], and Repel [26% p-menthane-3,8-diol]) were tested in the laboratory against Aedes albopictus Skuse, Culex nigripalpus Theobald, and Ochlerotatus triseriatus (Say). When estimated mean protection time (eMPT) responses for each repellent were averaged for all three mosquito species, Autan, Bite Blocker, Off!, and Repel prevented biting for > or =7.2 h; IR3535, MosquitoSafe, and Skinsations for 3.2-4.8 h; and ByGone, Natrapel, GonE, NeemAura, and SunSwat for 0.9-2.3 h. Against Ae. albopictus, the eMPT for Off! and Repel exceeded 7.0 h and ranged from 5.0 to 5.7 h for Autan, Bite Blocker, and Skinsations. Bygone, GonE, NeemAura, and SunSwat provided 0.2 h protection against Ae. albopictus and Oc. triseriatus, whereas Autan, Bite Blocker, Off., and Repel prevented bites by Oc. triseriatus for > or =7.3 h. All 12 repellents provided an eMPT > or =2.8 h against Cx. nigripalpus (maximum: 8.5 h for Bite Blocker). When the average eMPT for each repellent (for all species) was divided by the eMPT for 7% deet (Skinsations), the order of repellent effectiveness and the corresponding repellency index (R,) was Repel (1.7) > Bite Blocker (1.5) = Autan (1.5) = Off! (1.5) > Skinsations (1.0) > IR3535 (0.8) > MosquitoSafe (0.6) > Natrapel (0.5) > Neem Aura (0.3) = SunSwat (0.3) = Bygone (0.3) > GonE (0.2).     

Repellence of essential oils of aromatic plants growing in Argentina against Aedes aegypti (Diptera: Culicidae)

Mosquitoes are vectors of pathogens to humans and domestic animals and may also have economical impacts. One approach to prevent mosquito-borne diseases is bite deterrence through the application of repellents. Currently, there is an interest to search for alternative bioactive products to the synthetic active ingredients most widely used in insect repellents. Repellence against Aedes aegypti of essential oils extracted from Acantholippia salsoloides, Aloysia catamarcensis, Aloysia polystachya, Lippia integrifolia, Lippia junelliana (Verbenaceae), Baccharis salicifolia, Euphatorium buniifolium, and Tagetes filifolia (Asteraceae) were assessed. Tests were conducted by alternatively exposing untreated and treated forehand to the mosquitoes and counting probing attempts. All essential oils tested were significantly repellent against A. aegypti when compared to untreated controls; L. junelliana was the most repellent and T. filifolia was the least based on the response of the mosquitoes to different concentrations of the essential oils (EO). Repellence may be attributed to the respective main components of each EO.