Insect Repellent Research Articles

The Effectiveness Test Atung Methanol Extract (Parinarium Glaberimum Hassk) as a Fly Repellent for Salted Skipjack Tuna

House flies (Musca domestica) and green flies (Calliphora vomitoria) are members of the Muscidae family which are commonly found in residential areas in Indonesia. The habit of houseflies and greenflies in searching for food in wet household waste has the potential to make them vectors of pathogens that cause dysentery , cholera, typhoid, diarrhea and worms . Atung ( Parinarium glaberimum Hassk) contains secondary metabolites, namely: alkaloids, flavonoids, terpenoids, phenol, saponins and tannins. The phytochemical compounds in Atung have the potential to act as a fly repellent (Repellent). The aim of this research was to determine the landing power of fly repellent on Atung methanol extract. This research was designed using a simple RAL experimental method with 4 treatments and 3 repetitions. Concentration variations 0% (control), 1%, 2%, from 4%. Data analysis used the Anova statistical test analysis version SPSS 24 at a significance level of 0.05. The results of the research showed that the higher the concentration of Atung methanol extract used in the fly repellent, the less the fly's ability to land on salted skipjack tuna. The protective ability of the repellent against house flies and green flies is 83% for a methanol extract concentration of 1%, 88% for a methanol extract concentration of 2%, and 100% for a methanol extract concentration of 4%. Atung methanol extract has the potential to be used as an active ingredient. Effective repellent against houseflies and greenflies.

A preliminary investigation of China Ginger and Kuching Local Ginger species: Oil extracts and synthesis towards potential greener insect repellent

Ginger essential oil (Zingiber officinale) is the volatile oil extracted from ginger rhizome. Compared to chemical synthetic repellent, green insect (in particular mosquito) repellent would be favoured by the public as it is environmentally friendly and does not cause harm to the human’s health. The focus of this study is on the comparison study between China Ginger and Kuching Local Ginger essential oil aim towards utilization as the greener mosquito repellent. In this study, the ginger essential oils are extracted greener method i.e. via hydro distillation process for 7 h. The percentage oil yield for China and Kuching Local Ginger are 0.158 wt% and 0.264 wt%, respectively. The extracted ginger essential oils are further subject to Fourier Transform Infrared Spectroscopy (FTIR) and Gas Chromatography- Mass spectrometry (GC-MS) analysis. Based on the FTIR spectrum graph generated, both types of ginger essential oils essentially having the similar function groups including phenolic compounds, alcohol primer, alkena methyl group, aromatic compound, carbonyl compound, carboxylic acid, hydroxyl group. From the GC-MS results it revealed that the most abundant chemical constituents presented in both China Gniger and Kuching Local Ginger essential are: α-Zingiberene (7.88% and 7.03%), α-Curcumene (6.04% and 6.49%), α-Citral or Genarial (3.81% and 7.86%), β-Bisabolene (3.06% and 4.62%), β-Sesquiphellandrene (5.83% and 5.95%), β-Sesquisabinene (0.07% and 0.51%), β-Selinenol (3.97% and 2.26%), Zingiberenol (5.16% and 1.64%), [6]-Shogaol (0.33% and 0.23%), trans-Sesquisabinene hydrate (1.72% and 2.87%), trans-Geranylgeraniol (3.51% and 2.81%), Camphene (1.17% and 0.56%), Eucalyptol (2.68% and 1.81%), Citronellol (1.76% and 1.55%), Neral (2.82% and 6.03%), and Geraniol (1.62% and 2.29%) respectively. Kuching Local Ginger essential oil is found marginally superior insect repellent characteristics due to its higher monoterpene compounds in the essential oil.

Optimal control applied to Zika virus epidemics in Colombia and Puerto Rico

Zika virus (ZIKV) is a mostly non-lethal disease in humans transmitted by mosquitoes or humans that can produce severe brain defects such as microcephaly in babies and Guillain-Barré syndrome in elderly adults. The use of optimal control strategies involving information campaigns about insect repellents and condoms alongside an available safe and effective vaccine can prevent the number of infected humans with ZIKV. A system of nonlinear ordinary differential equations is formulated for the transmission dynamics of ZIKV in the presence of three control strategies to evaluate the impact of various scenarios during a ZIKV epidemic. In addition, we estimate parameters using weekly incidence data from previous ZIKV outbreaks in Colombia and Puerto Rico to capture the dynamics of an epidemic in each country when control measures are available. The basic reproduction number, R0, of each country is calculated using estimated parameters (without the controls). The vector-borne transmission threshold (Rv) is dominant in both countries, but the sexual transmission threshold (Rd) in Colombia is considerably higher than in Puerto Rico. Numerical simulations for Colombia show that the most effective strategies are to use three controls since the start of the outbreak. However, for Puerto Rico only information campaigns about mosquito repellents and vaccination are the most effective ways to mitigate the epidemic.

Kaempferia galanga Linn: A Systematic Review of Phytochemistry, Extraction Technique, and Pharmacological Activities

Kaempferia galanga Linn is an endangered medicinal plant that contains high value essentials. This plant belongs to the Zingiberaceae family and is used in pharmaceuticals and cosmetics, as well as food. This paper aims to review the research progress on K. galanga Linn, particularly on the phytochemistry and extraction process of this plant, including a new perspective on its pharmacological activities. Data and information on this aromatic ginger were collected and summarised from various resources, mainly from Science Direct and Web of Science. The main bioactive compounds extracted from its rhizome were ethyl cinnamate, ethyl p-methoxycinnamate, kaempferol, camphene, linoleoyl, borneol, and 1,8-cineole. These bioactive compounds have numerous nutraceutical properties, such as antioxidant, anti-inflammatory, anti-microbial, analgesic, anti-tuberculosis, anticancer, wound healing, and mosquito repellent. Furthermore, chemical characterisation, in vitro analysis, and in vivo biological studies have confirmed the traditional uses of this plant.

Identification of antioxidant compounds from the stem bark fraction of Strychnosinnocua Del.

Strychnos innocua is a shrub that is native to the tropic region of the world. It is used locally as food, medicine, fuel, and as an insect repellent. Extracts of this plant are used as an aphrodisiac and in the treatment of gonorrhoea, snakebite and dysentery. It has been proven to possess antioxidant and antimicrobial activities. There is little or no information on the identification and pharmacological activities of the chemical composition of the stem bark of this plant. The aim of this work is to identify the chemical compounds present in this plant and determine their antioxidant activities. The ethyl acetate extract of this plant was subjected to purification techniques which lead to the isolation of fraction SI1. The chemical composition of the fraction SI1 was then determined using gas chromatography–mass spectrometry (GCMS). Fractions SI1 was then analysed for its free radical scavenging potential using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and Ferric ion reducing antioxidant property (FRAP) assay. A total of thirty compounds were identified with the major compounds being Cyclohex-2-enone,3-)2H-tetrazol-5-yl amino) (15.83 %), N-hexadecanoic acid (38.21%), N-hexadecanoic acid (38.21%), Octadecanoic acid (13.41%), Cis-vaccenic acid (13.41 %). The DPPH radical scavenging potential of the fraction SI1 compares well with the standard, ascorbic acid with IC50 of 3.71 ± 0.31 μg/mL and 1.68 ± 1.27 μg/mL, respectively. At 500 μg/mL, the antioxidant potential of the standard ascorbic acid was 96.9% whereas the fraction SI1 had 62.1% free DPPH radical scavenging activity. The half-maximal inhibitory concentration (IC50) of SI1 observed is 0.0488 ± 0.01 nm, and 0.5375 ± 0.01 nm and for ascorbic acid. In conclusion, fraction SI1 can act as an antioxidant supplement for various applications in diverse fields of food, cosmetics, and medicine. Several compounds contained in the fraction SI1 may have contributed to the antioxidant properties of the fraction. The compounds identified could be useful precursors for the synthesis of therapeutic drugs associated with the treatment of human and animal diseases.

Risk Factors of Dengue Hemorrhagic Fever

The purpose of this study was to determine what risk factors caused the incidence of dengue hemorrhagic fever in Simpang Selayang Village, Kecamatan Medan Tuntungan in 2022. The method used in this study is a survey method with quantitative research conducted by distributing questionnaires and direct interviews with respondents using a case control approach. Data analysis used multiple logistic regression with a sample of 33 case respondents and 33 control respondents. The results showed that the influential variables were attitude, application of 3M Plus, habit of hanging clothes, and larva free rate on the incidence of dengue fever. The results showed that the influential variables were attitude (p = 0.046), the application of 3M Plus (p = 0.026), the habit of hanging clothes (p = 0.001), larvae-free rate (p = 0.037) on the incidence of dengue fever dengue in Simpang Selayang Village. Medan Tuntungan District in 2022 and the variables that had no effect were knowledge (p = 0.325) and use of mosquito repellent (p = 0.314). From the results of this study, it can be concluded that the most influential variable on the incidence of dengue fever is the habit of hanging clothes which has the greatest Exp.B value, which is 9.754 times greater.

Phloroglucinol/activated carbon composite/multiwalled carbon nanotubes modified glassy carbon electrode for electrochemical quantification of caffeic acid

Waste-derived carbon materials and their composites have recently been utilized in electrochemical sensing of biologically important analytes due to their distinctive properties. Here, we present the electrochemical sensing of caffeic acid (CA) based on a phloroglucinol/ activated carbon composite (derived from mosquito repellent carbon rod)/multiwalled carbon nanotubes modified glassy carbon electrode (PL/AC/MWCNT/GCE). The hydrothermal process was employed to prepare activated carbon composite from waste carbon rods used in mosquito repellents. Thus obtained activated carbon composite was combined with multiwalled carbon nanotubes and electrochemically modified with phloroglucinol. Further, the prepared sensor was used effectively for electrochemical analysis of CA. The prepared electrodes are characterized using Field emission scanning electron microscope (FESEM), Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD) and voltammetric methods. The PL/AC/MWCNT/GCE gives an enhanced electrochemical signal for CA in contrast to the lowest modified electrodes. Electrochemical studies such as impact of scan rate, pH, catalyst loading, coating cycles and concentration were performed using cyclic voltammetric (CV) technique. Under the optimized electrochemical conditions, the PL/AC/MWCNT/GCE was used to plot the calibration curve for CA using amperometry and square wave voltammetry (SWV) techniques in the analyte concentration ranging from 0.02 to 0.2 µM and 0.01 to 0.1 µM, which resulted in lesser Limit of detection (LOD) of 36.4 nM and 4.490 nM, respectively. Finally, the prepared sensor was applied for electrochemical quantification of CA in real-time analysis using commercially available coffee and wine samples with exceptional results.

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.

First serological prevalence of dengue virus IgG antibody among pregnant women in Port Harcourt, Nigeria

Dengue is a viral disease transmitted by Aedes mosquitoes and is considered a public health problem worldwide. Pregnant women and infants are at risk of developing severe dengue, which has been linked to poor outcomes. This study sought to determine the prevalence of Dengue Virus IgG antibodies among pregnant women attending antenatal care at the University of Port Harcourt Teaching Hospital, Rivers State, Nigeria. In this cross-sectional study, a total of 94 pregnant women were enlisted, and after gaining consent, approximately 5 ml of whole blood was taken. Enzyme-Linked Immunosorbent Assay (ELISA) was used to detect the presence of IgG antibodies to the dengue fever virus. IgG antibodies prevalence to the dengue fever virus was found to be 2.1%. Women who were within 16 to 20 years (6.7%), single (2.6%), employed (3.8%), had primary education (5.3%) and resided in urban areas (4.8%) all had higher incidence rates. Although this study reported a low prevalence of dengue virus among pregnant women, intensive enlightenment on the preventive measures which include the use of insect repellant and wearing of long-sleeved shirts, among others, should be sustained.

Optimization and Development of Herbal Incense Cones for Air Purification and Mosquito Repellent Trash into Treasure: Novel Low Cost Environmental Friendly Polyherbal Mosquito Repellants and Air Purifier Incense Cones

The atmosphere has been a foremost concern in today’s era. The constant pollution all around has gathered the attention of many people. Disease causing pathogens spread from an infected person and mosquitoes also spread diseases like malaria. Microbial burden of the air causes several airborne illnesses[1]. Synthetic mosquito repellent and air purifiers used to control the vectors are causing irreversible damage to ecosystem and also chemicals are carcinogenic in nature. Poly herbal incense cones are free from cancer-causing chemicals. Incense is known to impart antimicrobial activity. The objective of the current work is to formulate low cost environmental friendly polyherbal mosquito repellants and air purifier incense cones and to evaluate its activity. Public survey was also done to study safety and efficacy of the formulation. Dried powdered leaves of Piper bettle, flowers of Nyctanthes arbortristis, Artemisia pallens, Rosa rubiginosa, Tagetsarecta, Nelumbonucifera, and plant extrudes of Spyrax benzoin were mixed with Azadirechta indica oil. Linumusit atissimum and Apismellifera used as binders. Saw dust and cow dung are used for ignition. The powdered blend additional to enhance worth, it was later fragranced 1with volatile oil like Jasminum officinale and dehydrated [2]. Results shows that they have the mosquito repellant and air purifying activity. The prepared herbal mosquito incense cones are effective, safe with more duration of time and less cost.

Chimpanzees select comfortable nesting tree species

Every evening, chimpanzees build sleeping “nests” in trees. In some studied communities, individuals appear to be selective about the tree species used, which has led researchers to hypothesize whether chimpanzees prefer trees that repel troublesome insects or/and that provide comfortable and stable structures. We investigate these hypotheses, or a trade-off between both, though study of tree species preference based on their biomechanical and/or biochemical properties in the Sebitoli chimpanzee community in Kibale National Park, Uganda. The ten tree species most frequently used for nesting were compared with ten abundant in their environment but not preferred for nesting. For these 20 tree species, we determined their biomechanical and morphological characteristics such as foliar density, foliar units form (shape and size) and branch rigidity. Their spatial repellent activity, previously tested against Anopheles gambiae was incorporated into the analysis. Chimpanzees chose tree species with medium-sized and elongated foliar units, high foliar density and branch with stiffer wood. In addition, most tree species with such mechanical and morphological properties also have mosquito repellent activity. These tree properties may provide a comfortable sleeping environment enhancing sleep quality. Finally, a comparison across chimpanzee communities would be relevant to understand whether these choices are not only ecological but also cultural.

Ronald Ross- Mosquito, Malaria and Much More

Malaria has been, and still is, a major cause of not only human suffering and death and infant mortality, but also an economic burden on the society. According to the WHO Report of 2022, in 2021 alone 247 m people were affected by malaria. Apart from the use of antimalaria drugs, the importance of different preventive measures including the use of mosquito nets and insect repellents in managing malaria cannot be gainsaid. It should be underscored that the determined research efforts by medical personnel such as Ronald Ross, Patrick Manson, Charles Louis Alphonse Laveran, Giovanni Battista Grassi, and a few others, despite several hardships they faced in pinning the mosquito as the transmitter of malaria was epoch-making. Obviously, this finding has played a key role in reducing the global impact of malaria. In this communication, I outline the efforts of Ronald Ross and the travails he went through while pursuing it, as well as his attitude in denying his co-workers their due credit, and the extroversion rooted in him which eventually made him turn hostile to his collaborators and to his mentor, Patrick Manson.

Poly(oxyethylene)/Poly(oxypropylene) butyl ether prolongs the repellent effect of N,N-diethyl-3-toluamide on the skin.

N,N-diethyl-meta-toluamide (DEET) is a widely used insect repellent, with minimal skin permeation and sustained repellent activity in the superficial layers of the skin. In this study, we prepared a 10% DEET formulation consisting of 40% ethanol with or without 2% poly(oxyethylene)/poly(oxypropylene) butyl ether (POE-POP), an amphiphilic random copolymer. Further, we demonstrated the effects of POE-POP on tensile stress (stickiness), hydrophobicity, skin retention, permeation, and repellent activity of DEET. Stickiness was measured in male ICR mice (7-week old), and skin retention and permeation were evaluated in male Wistar rats (7-week old). In addition, female Aedes albopictus were used to measure the repellent action of DEET. The addition of POE-POP did not affect stickiness, volatility, and degradability but decreased logP and increased viscosity of DEET. Next, we demonstrated the behavior of DEET formulations in the rat skin. POE-POP prolonged the retention of DEET in the superficial layers of the rat skin (skin surface and stratum corneum) and decreased the penetration of DEET into rat skin tissues (epithelium and dermis). The repellent effect of DEET was also enhanced by the addition of POE-POP. However, severe skin damage was not observed after repetitive treatment with DEET formulations containing POE-POP for one month (twice a day). In conclusion, we demonstrated that a 10% DEET formulation consisting of 40% ethanol and 2% POE-POP attenuated the skin penetration and prolonged the repellent action of DEET without causing stickiness and skin damage. We conclude that the combination of ethanol and POE-POP is useful as a safe and effective delivery system for the development of insect repellent formulations containing DEET.

Nonlinear SAR Modelling of Mosquito Repellents for Skin Application.

Finding new marketable mosquito repellents is a complex and time-consuming process that can be optimized via modelling. In this context, a SAR (Structure-Activity Relationship) model was designed from a set of 2171 molecules whose actual repellent activity against Aedes aegypti was available. Information-rich descriptors were used as input neurons of a three-layer perceptron (TLP) to compute the models. The most interesting classification model was a 20/6/2 TLP showing 94% and 89% accuracy on the training set and test set, respectively. A total of 57 other artificial neural network models based on the same architecture were also computed. This allowed us to consider all chemicals both as training and test set members in order to better interpret the results obtained with the selected model. Most of the wrong predictions were explainable. The 20/6/2 TLP model was then used for predicting the potential repellent activity of new molecules. Among them, two were successfully evaluated in vivo.

Blue and UV light-emitting diodes (LEDs) disturb the greenhouse whitefly (Trialeurodes vaporariorum) from its host

Push–pull strategy is a well-known and widely used technique for integrated pest management, leading to the reduction of insecticides. This strategy involves the use of mostly visual and chemical stimuli to repel pests from a valuable crop (push) and attract them to an appealing target, e.g., a trap, (pull). Based on former results, this study explored the effect of light-emitting diodes (LEDs) as repelling factors of whiteflies (push). Wavelengths of blue and ultraviolet (UV) were investigated in different light intensities and exposure times in no-choice experiments, under controlled conditions. Whiteflies were exposed directly to LEDs on the underside of tomato leaves and number of repelled insects was counted. The results showed that light intensity and insect repellency were positively related. Insect repellency increased up to tenfold with longer light exposure period. Wavelength of blue and combination of blue + UV repelled more than 87% of whiteflies in light conditions. In darkness, results were only slightly different. The results reveal the property of blue light to repel whiteflies from its host and that addition of UV to blue enhances this effect. They further demonstrate that whitefly vision is dependent on wavelength, light intensity and exposure period. The contribution of the results on understanding the visual behavior of whiteflies and their possible implementation on pest control strategies is discussed.

Urinary Glyphosate, 2,4-D and DEET Biomarkers in Relation to Neurobehavioral Performance in Ecuadorian Adolescents in the ESPINA Cohort.

Herbicides are the most used class of pesticides worldwide, and insect repellents are widely used globally. Yet, there is a dearth of studies characterizing the associations between these chemical groups and human neurobehavior. Experimental studies suggest that glyphosate and 2,4-dichlorophenoxyacetic acid (2,4-D) herbicides can affect neurobehavior and the cholinergic and glutamatergic pathways in the brain. We aim to assess whether herbicides and insect repellents are associated with neurobehavioral performance in adolescents. We assessed 519 participants (11-17 years of age) living in agricultural communities in Ecuador. We quantified urinary concentrations of glyphosate, 2,4-D, and two N,N-diethyl-meta-toluamide (DEET) insect repellent metabolites [3-(diethylcarbamoyl)benzoic acid (DCBA) and 3-(ethylcarbamoyl)benzoic acid (ECBA)] using isotope-dilution mass spectrometry. We assessed neurobehavioral performance using 9 subtests across 5 domains (attention/inhibitory control, memory/learning, language, visuospatial processing, and social perception). We characterized the associations using generalized estimating equations and multiple imputation for metabolites below detection limits. Models were adjusted for demographic and anthropometric characteristics, urinary creatinine, and sexual maturation. Mediation by salivary cortisol, dehydroepiandrosterone, , and testosterone was assessed using structural equation modeling. The mean of each neurobehavioral domain score was between 7.0 and 8.7 [standard deviation (SD) range: 2.0-2.3]. Glyphosate was detected in 98.3% of participants, 2,4-D in 66.2%, DCBA in 63.3%, and ECBA in 33.4%. 2,4-D was negatively associated with all neurobehavioral domains, but statistically significant associations were observed with attention/inhibition [score difference per 50% higher metabolite concentration 95% confidence interval (CI): , ], language [ (95% CI: , )], and memory/learning [ (95% CI: , 0.01)]. Glyphosate had a statistically significant negative association only with social perception [ (95% CI: , )]. DEET metabolites were not associated with neurobehavioral performance. Mediation by gender and adrenal hormones was not observed. This study describes worse neurobehavioral performance associated with herbicide exposures in adolescents, particularly with 2,4-D. Replication of these findings among other pediatric and adult populations is needed. https://doi.org/10.1289/EHP11383.

Comprehensive Case-Control Study of Protective and Risk Factors for Buruli Ulcer, Southeastern Australia.

To examine protective and risk factors for Buruli ulcer (BU), we conducted a case-control study of 245 adult BU cases and 481 postcode-matched controls across BU-endemic areas of Victoria, Australia. We calculated age- and sex-adjusted odds ratios for socio-environmental, host, and behavioral factors associated with BU by using conditional logistic regression. Odds of BU were >2-fold for persons with diabetes mellitus and persons working outdoors who had soil contact in BU-endemic areas (compared with indoor work) but were lower among persons who had bacillus Calmette-Guérin vaccinations. BU was associated with increasing numbers of possums and with ponds and bore water use at residences. Using insect repellent, covering arms and legs outdoors, and immediately washing wounds were protective; undertaking multiple protective behaviors was associated with the lowest odds of BU. Skin hygiene/protection behaviors and previous bacillus Calmette-Guérin vaccination might provide protection against BU in BU-endemic areas.

Sensitivity of patchouli oil refining business (Case study: Patchouli Oil Agro, Tompira, North Morowali)

Patchouli oil is an essential oil obtained by distilling all parts of the patchouli plant. This oil has good prospects in several industries, such as perfume, cosmetics, and insect repellent. Although this commodity has potential opportunities in foreign markets, several problems were found in oil refinings, such as unstable raw material prices and transportation costs. This research was conducted at the Agro Patchouli Oil Refining Business in Tompira, Petasia Timur District, North Morowali Regency. The determination of refining business was done purposively. There were two data used in this study, primary data and secondary data. The analysis used to determine the objectives to be achieved in this study is Sensitivity Analysis taking into account Net Present Value (NPV), Internal Rate of Return (IRR), and Net Benefit Cost Ratio (Net B/C). The result of calculating the positive NPV value was IDR 31,450,688; the IRR value was 25.80%; and the Net B/C value was 1.28. Sensitivity analysis shows that the Agro Patchouli Oil Refining Business is still profitable even though transportation costs have increased by 33% or the greatest change in patchouli raw material prices is 5%.

How often are male mosquitoes attracted to humans?

Many mosquito species live close to humans where females feed on human blood. While male mosquitoes do not feed on blood, it has long been recognized that males of some species can be attracted to human hosts. To investigate the frequency of male mosquito attraction to humans, we conducted a literature review and human-baited field trials, as well as laboratory experiments involving males and females of three common Aedes species. Our literature review indicated that male attraction to humans is limited to a small number of species, including Ae. aegypti and Ae. albopictus. In our human-baited field collections, only 4 out of 13 species captured included males. In laboratory experiments, we found that male Ae. notoscriptus and Ae. vigilax showed no attraction to humans, while male Ae. aegypti exhibited persistent attraction for up to 30 min. Both male and female Ae. aegypti displayed similar preferences for different human subjects, suggesting that male Ae. aegypti respond to similar cues as females. Additionally, we found that mosquito repellents applied to human skin effectively repelled male mosquitoes. These findings shed light on mosquito behaviour and have implications for mosquito control programmes, particularly those involving the release or monitoring of the male mosquito population.

Study of Antioxidant and Larvicidal Properties of Selected Medicinal Plants of Fringe Villages of Manas National Park, Assam, India

Background: Mosquito-borne diseases are among the major ailments of world affecting billions of people living in economically poor and developing countries. The development of insecticide resistance in mosquito vectors has forced the global community to look into alternative sources of medicines with better efficacy and less side effects. Plants with rich sources of metabolites have been explored extensively for mosquitocidal activity. The present study explored the antioxidant and larvicidal activities of five important plants traditionally used as mosquito repellent by tribal communities of fringe villages of Manas National Park of Assam. Methods: Methanolic crude extracts were prepared for all the plants following standard protocols. Phytochemical and antioxidant study was performed following the protocol published in recent publications. Larvicidal bioassay was carried out as per WHO protocol. Results: The study observed considerable phytochemical and antioxidant activity. Phenolics, flavonoid and antioxidant activity, were found to be highest in Cinnamomum tamala. The phenolic and flavonoid value ranged from 9.89 to 147.15µgGAE/mg and 4.32 to 28.43µgQE/mg plant extract, respectively. The IC50 for various antioxidant activities ranged from 27.94 to 114.15µg/mL (DPPH), 15.05 to 707.74µg/mL and 40.23 to 338.91µg/mL (TBARS). Similarly, C. tamala showed the strongest larvicidal activity with LC50 value of 3.11mg/mL in Aedes aegypti larvae. Conclusion: The present study observed that C. tamala leaves could be a good source of phytochemicals and antioxidant and larvicidal activity.