Effective Mosquito Repellent Research Articles

Effective Mosquito Repellents: Myrcene- and Cymene-Loaded Nanohydrogels against Aedes aegypti.

Aedes mosquito-borne diseases remain a significant global health threat, necessitating effective control strategies. This study introduces monoterpenes-based nanohydrogels for potential use as repellents against Aedes aegypti, the primary dengue vector worldwide. We formulated hydrogels using cymene- and myrcene-based nanoemulsions with different polymers: chitosan, carboxymethylcellulose (CMC), and carbopol®. Our evaluations of rheological, texture, and bioadhesive properties identified CMC hydrogel as the most promising gelling agent for topical application, exhibiting sustained monoterpene release over 12 h with low skin permeation and high retention in the stratum corneum. Myrcene-loaded CMC hydrogel achieved a 57% feeding deterrence compared to 47% with cymene hydrogel in the mosquito membrane-feeding model. Molecular docking studies revealed interactions between myrcene and an essential amino acid (Ile116) in the Ae. aegypti odorant-binding protein 22 (AeOBP22), corroborating its higher repellent efficacy. These findings suggest that myrcene-loaded CMC hydrogels offer a promising, minimally invasive strategy for personal protection against Ae. aegypti and warrant further investigation to optimize monoterpene concentrations for vector control.

Efektivitas Biolarvasida Kombinasi Ekstrak Daun Sirsak (Annona muricata) dan Bunga Marigold (Tagetes erecta L.) sebagai Pembasmi Jentik Nyamuk

This research aims to determine the effectiveness of using a biolarvicide combination of soursop leaf extract and marigold flowers as an exterminator for mosquito larvae. This research included a laboratory experiment using a completely randomized 2 factorial design. The first factor is a combination of soursop leaf extract and marigold flowers, namely, a) 75%:25% (F1); b) 50%:50% (F2); c) 25%:75% (F3). The second factor is the treatment dose, namely, a) 1% (D1); b) 2% (D2); c) 2.5% (D3). Each factor was repeated 3 times. Data analysis uses a non-parametric test, namely Kruskal-Wallist. The results of the study showed that the soursop leaf and marigold flower extract formula 75%:25% was most effective against mosquito larvae mortality at a dose of 2.5% within an observation period of 6 hours. In conclusion, soursop leaf and marigold flower extracts are effective mosquito larva repellents. Keywords: Biolarvicide, Marigold Flowers, Soursop Leaves, Effectiveness, Mosquito Larvae

A critical review of current laboratory methods used to evaluate mosquito repellents.

Pathogens transmitted by mosquitoes threaten human health around the globe. The use of effective mosquito repellents can protect individuals from contracting mosquito-borne diseases. Collecting evidence to confirm and quantify the effectiveness of a mosquito repellent is crucial and requires thorough standardized testing. There are multitudes of methods to test repellents that each have their own strengths and weaknesses. Determining which type of test to conduct can be challenging and the collection of currently used and standardized methods has changed over time. Some of these methods can be powerful to rapidly screen numerous putative repellent treatments. Other methods can test mosquito responses to specific treatments and measure either spatial or contact repellency. A subset of these methods uses live animals or human volunteers to test the repellency of treatments. Assays can greatly vary in their affordability and accessibility for researchers and/or may require additional methods to confirm results. Here I present a critical review that covers some of the most frequently used laboratory assays from the last two decades. I discuss the experimental designs and highlight some of the strengths and weaknesses of each type of method covered.

Chemical composition of four essential oils and their adulticidal, repellence, and field oviposition deterrence activities against Culex pipiens L. (Diptera: Culicidae)

Effective mosquito repellents can limit the transmission of vector-borne diseases to humans. Consequently, there is an urgent need to develop mosquito control strategies that prioritize eco-friendly and cost-effective repellents. Essential oils (EOs) have enormous potential for mosquito repellency. Here, cinnamon, basil, eucalyptus, and peppermint EOs were investigated for adulticide and repellency properties against Culex pipiens as well on the oviposition behavior of gravid females from laboratory (lab test) and field (field test) populations. Cinnamon oil was an effective oviposition deterrent regardless of the population and had high adulticidal activity with toxicity index of 75.00% at 24 h of exposure, relative to deltamethrin. In addition, it exhibited effective repellency at 98.01% and 71.22% at 6.67 and 1.71 µl/cm2, respectively. Peppermint oil had the least adulticidal activity with toxicity index of 6.2% at 24 h, and it resulted in low repellency at 70.90% and 50.64% at 6.67 and 1.71 µl/cm2, respectively. On average, basil and eucalyptus oils showed some adulticidal efficiency, repellency, and oviposition deterrent activity. For all treatments, the oviposition deterrent index values of gravid females from natural populations (field test) were lower than those from lab-reared (lab test) females. Different ratios of monoterpenoids, phenylpropanoids, and fatty acids in the EOs tested likely account for the activity variations observed. Our results suggest cinnamon, basil, eucalyptus, and peppermint EOs, which are widely available, economical, and eco-friendly, with good potential for mosquito control strategies.

Interesting Nuclear Magnetic Resonance studies of some N, N-bis(2-methoxyethyl) substituted Benzamides

DEET (N, N Diethyl m-toluamide) and DEPA (Diethyl phenyl acetamide) are synthetic compounds and proven potent insecticide and repellent respectively. In the search of effective mosquito repellent, different derivatives of DEPA or substituted benzamides were synthesized and their NMR analysis was carried out at low temperature. Sterically Crowded Bis (2-methoxyethyl) substituted Benzamides possess low rotational barrier and are floppy at room temperature. Alkyl arms attached to nitrogen become magnetically nonequivalent even at low temperature. Di ortho Substitution in benzamides enhanced hindered internal rotation and resulted splitting in methylene proton signals. The effect of substitution in benzene ring, on the splitting of methylene proton NMR is very well explained and the complete NMR data of substituted benzamides is described in this study for reference purpose.

Topical Mosquito Repellent Formulations for Enhanced Repellency Time and Reduced Toxicity.

Mosquito-borne diseases such as dengue, malaria, yellow fever, chikungunya and Zika virus affect millions of people worldwide each year. Vector control and personal protection are very important to minimize the spread of diseases, and the use of repellent is an economic practice to prevent them. The application of repellent, which acts on the skin to form a vapor layer with a repellent odor to mosquitos, is recommended as an economic prevention and practice. The natural botanical product Citronella is an effective mosquito repellent due to the high concentrations of active chemical constituents present, notably terpenic alcohols. However, citronella tends to evaporate quickly from the skin surface, resulting in a rapid loss of activity. Strategies to increase repellency time, while at the same time minimizing toxicity, are major focuses of research and development in natural repellent products. Here we highlight the role of extended-release systems (ERS) of citronella oil in this approach.

Biomonitoring Equivalents for N,N-Diethyl-meta-toluamide (DEET)

N,N-Diethyl-meta-toluamide (DEET) is widely used as an effective mosquito and tick repellent. DEET is absorbed systemically after applications to skin. Once absorbed, DEET is rapidly metabolized with the predominant metabolite being m-dimethylaminocarbonyl benzoic acid (DBA). DEET and metabolites are predominantly excreted in urine after being absorbed systemically. Exposures to DEET are typically biomonitored via measures of DEET and DBA in urine. In this evaluation, we review available health-based risk assessments and toxicological reference values (TRVs) for DEET and derive Biomonitoring Equivalent (BE) values for interpretation of population biomonitoring data. BEs were derived based on existing TRVs derived by Health Canada, yielding 38 and 23 mg/L DBA in urine for adults and 57 and 34 mg/L DBA in urine in children for the acute oral and intermediate dermal TRVs, respectively. The BEs for unchanged DEET in urine are 21 and 12 mg/L in adults and 4.5 and 2.7 mg/L in children for the acute oral and intermediate dermal TRVs. The BE values derived in this manuscript can serve as a guide to help public health officials and regulators interpret population based DEET biomonitoring data in a public health risk context.

Mosquito Repellent Bioactivity Combination Extract Of Nutmeg Leaf (Myrisctica fragrans Houtt), Lemongrass (Cymbopogon nardus L.) and Apis dorsata Binghami Nests

Nutmeg leaf, lemongrass, and bee nests contain bioactive compounds that have potential as mosquito repellents. The purpose of this study was to learn about the bioactivity of a combination extract of nutmeg leaf, lemongrass, and bee nests, as well as to determine the efficient mosquito repellent lotion recipe from a combination of nutmeg leaf, lemongrass, and bee nests extract. The maceration process was used for extraction. Total flavonoid content was estimated by comparing it to the flavonoid quercetin. The absorbance value was measured with a UV-Vis spectrophotometer. The concentration of the extract combination in the lotion used was 0%, 2.5%, 5% and 10%. The total flavonoid concentration was found to be 16.67 mgQE/g. The 2.5% formula lotion has a protective power of 22%, the 5% formula lotion has a power of 62.96%, and the 10% formula lotion has a power of 82.41%. From these results, it can be seen that a formula with a concentration of nutmeg leaf, lemongrass, and bee nests as much as 10% can be the most effective mosquito repellent. The outcomes of this study are expected to help the community select environmentally friendly and safe insect repellents.

Herbal, Safe and effective Mosquito repellents: Recent Development and Opportunity

Most of today's rapidly spreading infectious diseases are arthropod-borne, and vaccinations are powerless to prevent them. Because insect repellents are effective topical barriers to the spread of arthropod-borne infectious illnesses. Plant-based (natural) and chemical-based products are both used (synthetic) as a mosquito repellents, which come in a variety of forms such as mosquito repeller coils, mosquito repeller oil, and so on, are becoming more popular around the world as vector-borne viral diseases such as Dengue, Chikungunya, and Malaria become more prevalent. The best alternative to the optimal formulation is determined by a number of elements, including the type of repellent (natural or synthetic), medicinal forms (spray, lotion, cream, gel), duration of action (short or long), exposure environment, and user (adult, pregnant women, children, newborn). DEET, IPicaridin, and essential oils are the most commonly utilised repellents, each with its own set of benefits and drawbacks. DEET is not suggested for children under the age of six months or pregnant women because of its toxicity. The current tendency is to employ pant-based repellent active compounds like essential oils, which have minimal toxicity, are environmentally friendly, but have a shorter repellent action period due to quick evaporation after skin contact. Repellents could be a visible option for people to reduce the risk of interaction with rare mosquito-borne diseases for mosquito borne diseases. The review highlights a summary of mosquito repellents, its novel discoveries, and areaof technicalstudies such as the novel and unique repellent formulations and their potentialfuture.

Formulation and evaluation of Herbal Mosquito Repellent in two forms used in folklore practise

Mosquito borne diseases including malaria, dengue, filariasis, and chikungunya cause serious health hazards across the world. Several mosquito repellents are currently in the market; however, most of these are not efficacious and eco-friendly. Recently, considerable research progress has been made to develop more pleasant, effective, and non-toxic to other species using herbal oils and formulations. Also, these herbal compositions are easily available and economic. Although, this existing herbal composition has been demonstrated to be effective and non-toxic to humans, they are more volatile and short lifespan of these compounds has necessitated further development of plant originated pesticides as alternative to chemical pesticides. In the current study, we have developed the various herbal formulations and showed that these formulations are effective mosquito repellents. The survey further showed that these repellents are pleasant with minimum allergic reactions.

Transfluthrin enhances odorant receptor-mediated spatial repellency in Aedes aegypti

Mosquito-borne diseases are an increasing global health challenge and vector-based interventions remain the most important methods for reducing the public health burden of most mosquito-borne diseases. Transfluthrin, a volatile pyrethroid insecticide, is used widely and effectively as an insecticide and as a repellent. In a recent study, we showed that at very low concentrations transfluthrin repels Aedes aegypti mosquitoes in a hand-in-cage assay without detectable stimulation of antennal olfactory responses. Furthermore, activation of sodium channels by transfluthrin enhances repellency by DEET, which has been reported to repel mosquitoes via odorant receptor (Or)-dependent and Or-independent mechanisms. However, whether activation of sodium channels by transfluthrin can serve as a general mechanism for synergizing the activities of other repellents remain unknown. In this study, we found that, in hand-in-cage assay, transfluthrin enhanced repellency by geranyl acetate and (E)-β-farnesene, which activate AaOr31. Such enhancement was not observed in AaOr31-knockout mosquitoes and dampened in a pyrethroid-resistant strain carrying two sodium channel mutations, which reduce the action of transfluthrin on sodium channels. In addition, transfluthrin also enhanced repellency by (−)-borneol, (±)-citronellal, camphor, and eucalyptol, which activate Or-mediated repellency. Our study has uncovered the ability of transfluthrin to enhance the repellency to a variety of mosquito repellents, beyond DEET, and provided experimental support for the emerging paradigm of synergistic interactions between repellency mediated by sodium channel activation and Or activation. These findings have potential implications in the development of more effective mosquito repellent mixtures.

Natural repellents a topic not to be neglected in a quest for new effective mosquito repellent: A review on Azardirachta indica (neem) and Citrus sinensis (sweet orange)

The current rise in insecticide resistance of mosquitoes to synthetic compounds that used to be very effective is of great concern to malaria control. Several bio-compounds from plants and essential oils have insecticidal or repellent potencies. However, lack of harmonization and complete research on insecticides from plant origin have obscured the breakthrough of discovering an alternative plant-based mosquito repellent to the synthetic DEET-based repellents. This review seeks to provoke the drive for finding an alternative and effective mosquito repellent from plants or essential oil sources with focus on Azadirachta indica and Citrus sinensis.

Natural repellents a topic not to be neglected in a quest for new effective mosquito repellent: A review on Azardirachta indica (neem) and Citrus sinensis (sweet orange)

Natural repellents a topic not to be neglected in a quest for new effective mosquito repellent: A review on Azardirachta indica (neem) and Citrus sinensis (sweet orange)

Study of the Repellent Activity of 60 Essential Oils and Their Main Constituents against Aedes albopictus, and Nano-Formulation Development.

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.

Lymphatic Filariasis Control: School-based One Health Initiative on The Usage of Local Plants as Alternative Mosquito Repellants in Timor Tengah Selatan, Nusa Tenggara Timur

Lymphatic filariasis is a mosquito-borne disease that poses a serious public health concern. The disease has spread to 28 Indonesian provinces, with NTT province being one of the 10 provinces with the highest incidence. Aside from being a major supporter of the annual mass drug administration program, the mosquito control initiative is also critical to the disease's eradication. However, today's mosquito control approaches depend primarily on synthetic moieties, which, unfortunately, have resulted in environmental problems and also resistance in important mosquito species. Consequently, developing alternative mosquito control strategies based on herbal components that are environmentally friendly, safe, and long-lasting is necessary. This one-health program aims to educate and raise public awareness of the importance of mosquito control and to inspire the community to utilize local plants as alternative mosquito repellents. This program is targeted high school students from the Timor Tengah Selatan regency. This regency is one of the NTT regencies with the highest risk of lymphatic filariasis. The approach method employed in this program was a series of presentations, discussions, and a demonstration of lymphatic filariasis and the selection of local plants that can be used as herbal repellents. Based on discussions with the students, it was discovered that after engaging in this activity, the participants had learned and recognized the dual function of various indigenous plants in their area as effective and cost-effective mosquito repellents. Furthermore, the students became more excited to learn and develop knowledge about the function of other local plants as efficient mosquito repellents.

Preparation of mosquito repellent, antibacterial and UV protective cotton using a novel, chitosan-based polymeric dye

With the increasing population of mosquitoes due to urbanisation, requirement for effective mosquito repellent gadgets is rising. To guarantee the security from mosquitoes, dire need is felt to build productive innovations. In the current work, a carbohydrate-based textile fibre was functionalised for imparting colour, mosquito repellency, antibacterial activity and UV protection using a novel polymeric dye. Mosquito repellent 4-amino N,N-diethyl-meta-toluamide (DEET-NH2) was diazotised and reacted with chitosan for the in-situ preparation of azo polymeric dye. The separately prepared polymeric dye was characterised using FTIR (Fourier Transform Infrared Spectroscopy) analysis. In-situ dyed fabric was thoroughly characterised and evaluated for colouration, mechanical and functional properties. The dyed cotton showed an outstanding mosquito repellency (100%) with good durability. Moreover, antibacterial activity (>78%) and UV protection (good to very good) were also displayed by the dyed cotton. An innovative technique to develop multifunctional carbohydrate-based fibre is developed.

Repellent Efficacy of Eucalyptus globulus and Syzygium aromaticum Essential Oils against Malaria Vector, Anopheles stephensi (Diptera: Culicidae).

Background:Mosquito species are highly considering as disease transmission as well as nuisance insects. One of the principal strategy to protect human from the mosquito bites is repellent agents. This study aimed to assess repellency of two organic essential oils, Eucalyptus globulus and Syzygium aromaticum from bites of malaria vector, Anopheles stephensi.Methods:The study was conducted in 2019–2020. The components of essential oils of E. globulus and S. aromaticum was determined using gas chromatography/mass spectrometry. The unfed female mosquitoes aged 2–5 d old were used in all experiments. In vivo Klun and Debboun module bioassays were utilized on human-volunteer skin. The essential oils at serial concentrations were used to find repellent efficacy against Anopheles landings and bites. To find the synergistic effect, four combinations of the essential oils were tested.Results:The main composition of E. globulus essential oil was 1,8-Cineol (78.20%), whereas that of S. aromaticum essential oil was 2-methoxy-3-(2-propenyl) (77.04%). Based on minimum effective dose (≤1% biting), 10% (v/v) of E. globulus showed high landing repellency (77.78%), whereas minimum effective dose of S. aromaticum at concentration of 1% had high landing repellency (88.89%). Among four combinations, the ratio of 1:1 of E. globulus (10%):S. aromaticum (1%) showed the most landing repellency (94.44%).Conclusion:The combinations of two essential oils had the most potential repellency effect against landing of mosquitoes. As essential oils are eco-friendly with less irritation for human skin, E. globulus and S. aromaticum essential oils are recommended as effective and safe mosquito repellents.

Pyrethrins elicit olfactory response and spatial repellency in Aedes albopictus.

Pyrethrum from dry flowers of Chrysanthemum is a well-known botanical insecticide and repellent. Its insecticidal activity attributes to its six insecticidal esters, collectively known as pyrethrins. Pyrethrins and its synthetic analogs pyrethroids exert their toxic action by modifying the function of voltage-gated sodium channels. Aside from insecticidal activity, pyrethrum has also been used to repel mosquitoes for centuries. Today, pyrethrum continues to be used as an active ingredient in mosquito coils and other mosquito-repellent devices globally. However, the mechanism of pyrethrum repellency remains largely unknown. Here we report that pyrethrum vapor induced spatial (non-contact) repellency in Aedes albopictus, a major vector of dengue and West Nile viruses. Using electroantennogram (EAG) recordings from adult antennae, we found that pyrethrum elicited EAG response in a dose-dependent manner. We then isolated the six insecticidal esters, pyrethrins I and II, cinerins I and II, jasmolins I and II from pyrethrum extract and discovered that five of the six esters, except jasmolin I, all elicited EAG responses. Furthermore, pyrethrins I and II, cinerin II and jasmolin II induced repellency, whereas cinerin I and jasmolin I did not. Of the six pyrethrins, four of them, pyrethrins I and II, cinerin II and jasmolin II, activate olfactory-receptor neurons and elicit spatial repellency in Ae. albopictus. Our study provided a foundation for future structure-function studies of pyrethrins, their cognate olfactory receptors and efficacies of repellency and for the development of new and more effective mosquito repellents for controlling vector-borne human diseases. © 2021 Society of Chemical Industry.

CDI Cross-linked Nanosponges of Citronella Oil for Controlled Mosquito-repellent Activity

Background: Citronella oil is considered one of the effective mosquito- repellent oil and in cooperation of oil into nanosponges will help to prevent its evaporation and enhance its effect. Objective: The objective of the current research was to formulate and characterize CDI cross-linked nanosponges of citronella oil for controlled mosquito-repellent activity. Method: β-cyclodextrin-based nanosponges were prepared by polymer condensation method and encapsulated with citronella oil by the sonication method. A topical cream containing citronella oil-based nanosponges was formulated by the phase inversion temperature method. Particle size, zeta potential, encapsulation efficiency, stability, in vitro release, FTIR and DSC studies were used as characterization parameters. Results: The particle size of citronella oil encapsulated β-cyclodextrin-based nanosponges was 23.05±3.88 nm. The zeta potential of nanosponges was sufficiently high to prevent aggregation. In vitro studies revealed the controlled release of citronella oil from the nanosponges for 24 h. FTIR and DSC confirmed the interaction of the citronella oil with the nanosponges. Conclusion: Citronella oil encapsulated nanosponges in the topical formulation is an alternative to synthetic marketed creams for controlled mosquito-repellent activity.

Inverse association between dengue, chikungunya, and Zika virus infection and indicators of household air pollution in Santa Rosa, Guatemala: A case-control study, 2011-2018.

BackgroundDengue, chikungunya, and Zika viruses are increasingly important public health problems. Burning vegetation, leaves, and other plant products have been shown to be effective mosquito repellents for their vector, Aedes spp., but there has been scant research on whether firewood cooking smoke in households influences mosquito populations or mosquito-borne diseases. About 2.9 billion people worldwide use biomass fuel for household cooking and heating, resulting in an estimated 1.6 million deaths annually from household air pollution (HAP)-related diseases. Global health agencies now encourage households to transition from biomass to clean fuels, but it is unclear whether such interventions may actually increase risk for mosquito-borne diseases. This retrospective case-control study evaluated associations between arboviral infections and cooking with firewood in Santa Rosa, Guatemala.MethodVigilancia Integrada Comunitaria (VICo) was a prospective public health surveillance system for bacterial, parasitic, and viral causes of diarrheal, neurological, respiratory, and febrile illnesses in hospitals and clinics in the department of Santa Rosa, Guatemala. Enrolled VICo in-patients and out-patients during 2011–2018 were interviewed using standardized questionnaires on demographics and household characteristics. Blood and stool specimens were collected and tested to identify the etiologies presenting symptoms. Cases were defined as laboratory-positive for dengue, chikungunya, or Zika virus infections. Controls were laboratory-positive for bacterial and viral diarrheal illnesses (e.g., Salmonella, Shigella, Campylobacter, Escherichia coli, rotavirus, norovirus, sapovirus, or astrovirus). Cooking with firewood, kitchen location, stove type, and firewood cooking frequency were the independent exposure variables. Logistic regression models were used to analyze unadjusted and adjusted associations between arboviral infections and exposures of interest.ResultThere were 311 arboviral cases and 1,239 diarrheal controls. Arboviral infections were inversely associated with cooking with firewood in the main house (AOR: 0.22; 95% CI: 0.08–0.57), cooking with firewood on an open hearth (AOR: 0.50; 95% CI: 0.33–0.78), and cooking with firewood ≥5 times per week (AOR: 0.54; 95% CI: 0.36–0.81), adjusting for age, sex, ethnicity, socioeconomic status index, number of people per household, community population density, community elevation, recruitment location, season, and admission year.ConclusionSeveral primary determinants of HAP exposure were inversely associated with arboviral infections. Additional studies are needed to understand whether interventions to reduce HAP might actually increase risk for mosquito-borne infectious diseases, which would warrant improved education and mosquito control efforts in conjunction with fuel interventions.