Search Results (126)

Dengue is the most concerning mosquito-borne neglected tropical disease globally. The disease is caused by the dengue virus (DENV) and transmitted by the vector mosquito species belonging to the genus Aedes Meigen, 1818, particularly Aedes aegypti (Linnaeus, 1762) and Aedes albopictus (Skuse, 1895). In 2024, global cases of dengue exceeded 7.6 million, with India reporting 233,519 cases. These statistics underscore the ongoing challenge of managing dengue outbreaks worldwide. For generations, tribal communities across India have employed medicinal plant-based extracts as mosquito and other insect repellents. Plant-based phytochemicals are largely preferred over synthetic insecticides due to their perceived safety, non-toxicity to non-target organisms, and environmental sustainability. This review provides a comprehensive overview of various phytochemicals extracted from Indian medicinal plants for their larvicidal activity against Aedes mosquitoes. Furthermore, the article also reviews the mode of action of these phytochemicals, including neurotoxicity, mitochondrial dysfunction, sterol carrier protein-2 inhibition, midgut cytotoxicity, insect growth regulation disruption, and antifeedant activity, which aids in formulating dengue vector control strategies. Based on this review, Ecbolin B from Ecbolium viride, Alizarin from Rubia cordifolia, and Azadirachtin from Azadirachta indica exhibited better larval mortality rates against Ae. aegypti, with LC50 values recorded at 0.70, 1.31, and 1.7 ppm, respectively. Full article

Mosquito-borne diseases, including dengue fever, chikungunya, and Zika, continue to pose a substantial global public health challenge. This is largely attributable to the absence of effective vaccines and the expanding distribution of vectors such as Aedes albopictus (Ae. albopictus). Repellents, therefore, remain a critical component of prevention strategies for disease prevention. However, existing formulations have notable limitations. Synthetic repellents such as DEET provide broad-spectrum efficacy but may raise safety concerns, especially at high concentrations. In contrast, botanical repellents, such as citronella and camphor oils, offer more favorable safety profiles but are restricted by short protection durations due to their high volatility. To overcome these drawbacks, this research developed a composite mosquito repellent through the strategic combination of DEET (5–15%), citronella oil (10–20%), and camphor oil (5–15%). This formulation leverages interactions across multiple olfactory pathways to simultaneously enhance efficacy and reduce the DEET concentration. Orthogonal experimental optimization identified an optimized formulation, Mix-3 (consisting of 15% DEET, 15% citronella oil, and 10% camphor oil in 75% ethanol), which achieved a mean complete protection time of 9.45 h. Mix-3 provided longer protection than 7% DEET (mean difference = 5.50 h, p < 0.001), 4.5% IR3535 (2.83 h, p < 0.001), 10% citronella oil (3.58 h, p < 0.001), and 15% DEET (6.50 h, p < 0.001). Catnip oil did not contribute significantly to repellency (p = 0.895). This study demonstrates that the rational combination of synthetic and botanical repellents effectively overcomes the limitations of single-agent formulations, providing a long-lasting and scalable approach for vector control. Full article

R-limonene has been integrated into various pest control practices as a repellent or an insecticide. However, how limonene induces aversion or mortality remains largely unknown. To elucidate the underlying mechanisms, we conducted behavioral, toxicological, and electrophysiological assays in Aedes aegypti, a primary vector of human diseases. To investigate whether limonene acts on voltage-gated sodium channels and/or the Rdl (Resistance to dieldrin) receptor, two major targets of neuroactive insecticides, we characterized the effect of limonene on Ae. aegypti sodium and Rdl channels expressed in Xenopus oocytes. Limonene significantly potentiated GABA-induced chloride currents through Rdl in a concentration-dependent manner but had no effect on sodium channels. For repellency, limonene evoked spatial repellency in wild-type mosquitoes; however, the spatial repellency by limonene was significantly reduced in knockout mutants of Orco^−/− (odorant receptor co-receptor) and TRPA1^−/− (Transient Receptor Protein, subfamily A and member 1). These results indicate that limonene likely targets the Rdl receptor for insecticidal activity and limonene spatial repellency requires both Orco and TRPA1 channels. Our results reveal the involvement of multiple ion channels and receptors in the mosquito nervous system for limonene’s insecticidal and/or spatial repellency actions, highlighting limonene’s potential as a multi-target neuroactive agent for pest control. Full article

Background: Recently, the use of volatile compounds as spatial repellents have received special attention as a promising strategy for adult An. gambiae s.l control. Anopheles gambiae s.l is a primary vector of malaria, an arthropod-borne disease of global significance. Current strategies for controlling mosquitoes heavily rely on vector control methods. Understanding the responses of these vectors to volatile compounds will be helpful in the formulation of repellants or attractants for control vector populations. This study was conducted in Nwoya district, Uganda, one of the high-malaria-transmission areas in the northern part of Uganda, as one of the ways of reducing contact between the parasite, vector, and malaria outbreak. Materials and Methods: In this study, a laboratory-reared female An. gambiae Kisumu strain from Uganda Virus Research Institute (UVRI) insectaries were used to examine spatial behavior responses of An. gambiae to selected EOs of Eucalyptus grandis and Cymbopogon citratus. Spatial activity responses were measured using a Y-tube olfactometer under controlled conditions using three replicates in various concentrations of the tested EOs. These oils were extracted by steam distillation and the main constituents identified using gas chromatography–mass spectrometry. Results: Mosquito response curves indicating effective repellency concentrations are reported, as well as the gas chromatography–mass spectrophotometry analysis results. For Eucalyptus grandis, the two components with the highest composition were L-α terpineol and Eucalyptol, while those for Cymbopogon citratus were Lavandulol, methyl ether, and citral. Other components had a percentage composition less than five but they might play a big role in repellent activity against mosquito species. Conclusions: The mosquito repellency results in this study indicate that Eucalyptus grandis and Cymbopogon citratus EOs could be used as mosquito repellents, providing more evidence that natural products have promising lead compounds for further development of botanical spatial repellents. Further characterization of EOs and testing on mosquito behavior related to the prevention of malaria and other vector-borne diseases will promote innovation in vector control and provide new vector control tools that are needed in this era of insecticide resistance. Full article

This study explores the sustainable extraction and application of natural dyes from figs (Ficus carica) and Eucalyptus leaves using an aqueous alkaline medium. The dyeing process was optimized for cotton fabric using the exhaust-dyeing method. Fabrics dyed with Ficus carica extract and its blend with Eucalyptus exhibited enhanced color strength, excellent crocking fastness (rated 4–5), and good washing fastness (rated 3–4 on the gray scale). The use of Aloe barbadensis Miller as a bio-mordant significantly improved dye fixation, resulting in deeper, earthy shades, such as green, yellow–green, and yellowish brown. The highest K/S value (5.85) was recorded in samples treated with a mordant, sodium chloride (NaCl), and the combined dye extracts, indicating a synergistic effect among the components. Mosquito repellency tests revealed that treated fabrics exhibited up to 70% repellency, compared to just 20% in undyed samples. Antibacterial testing against E. coli showed that dyed fabrics achieved over 80% bacterial reduction after 24 h, indicating promising antimicrobial functionality. Air permeability slightly decreased post-dyeing due to the potential shrinkage in cotton fabrics. Furthermore, adsorption studies showed a removal efficiency of 57% for Ficus carica dye on graphene oxide (GO) under ultrasonication. These findings confirm the potential of GO as an effective adsorbent material for treating wastewater from natural textile dyes. Overall, the study highlights the environmental safety, functional performance, and multifunctional advantages of plant-based dyeing systems in sustainable textile applications. Full article

Aedes aegypti, also known as the yellow fever mosquito, presents a major public health challenge, highlighting the need for effective biorational agents for mosquito control. Here, we investigated the synergistic effects of essential oil mixtures derived from Hypenia irregularis that is a mint-family shrub native to Brazil’s Cerrado biome, known as “alecrim do Cerrado”, in combination with essential oils from noni (Morinda citrifolia), Brazilian mint (“salva-do-Marajó”, Hyptis crenata), and lemongrass (Cymbopogon citratus) against Ae. aegypti. We conducted phytochemical analyses and assessed larvicidal, repellent, and oviposition deterrent activities. Using in silico methods, we predicted molecular interactions between key essential oil components and physiological targets involved in repellent action (odorant-binding protein AeagOBP1 and olfactory receptor Or31) and larvicidal activity (GABA and octopamine receptors, TRP channels, and acetylcholinesterase [AChE]). Major compounds identified included octanoic acid (23%; Hipe. irregularis × M. citrifolia), 2,5-dimethoxy-p-cymene (21.9%; Hipe. irregularis × Hypt. crenata), and citral (23.0%; Hipe. irregularis × C. citratus). Although individual oils showed strong larvicidal activity (Hipe. irregularis LC₅₀ = 2.35 µL/mL; Hypt. crenata = 2.37 µL/mL; M. citrifolia and C. citratus = 2.71 µL/mL), their mixtures did not display synergistic effects. Similarly, repellency and oviposition deterrence were comparable to DEET for individual oils but were not enhanced in mixtures. Notably, the Hipe. irregularis × C. citratus essential oil blend reduced oviposition deterrence. Molecular docking confirmed strong binding of major oil components to AeagOBP1 and Or31, supporting their role in repellency. For larvicidal effects, AChE showed the highest predicted binding affinity. Overall, our findings suggest that H. irregularis, Hypt. crenata, C. citratus, and M. citrifolia (alone or in 1:1 mixture) are promising, sustainable agents for A. aegypti control. Full article

Dengue virus infection (DVI), a mosquito-borne arboviral infection, is prevalent in tropical and subtropical regions, including Bangladesh, where incidence has surged over the past three decades—particularly in urban and peri-urban areas. This study investigates the factors influencing DVI seropositivity among clinically suspected patients admitted to the selected hospitals of Savar, Dhaka, and Chattogram. Data were collected from 850 clinically suspected patients admitted to two hospitals in Savar, Dhaka, and two in Chattogram during 2019. Questionnaire responses and laboratory test results (NS1, IgM, and IgG) were analyzed using descriptive statistics, chi-square tests, and logistic regression. Out of 450 admissions in Savar, 330 tested positive, while Chattogram reported 145 positives from 400 cases. No significant differences were observed between regions in relation to hospital type, season, gender, or household preventive measures. In Savar, DVI status was significantly associated with season, mosquito net use, and patient contact. In Chattogram, household repellent use and patient contact were key factors. Diagnostic tests varied in detection capability. These findings can inform targeted intervention strategies and public health messaging, such as promoting personal protection measures and community awareness campaigns, particularly in high-incidence urban settings. However, further research across diverse geographic and socio-ecological contexts is needed to enhance the generalizability and policy relevance of these results. Full article

Personal protection from mosquitos is dominated by topically applied aerosol sprays or lotions, which demonstrate efficacy durations of no longer than 10 h, thus encouraging the research and development of long-term insect-repelling devices. Repellent-loaded polymeric matrices have driven the development of insect-repelling apparel fabrics; however, most efforts either fail to offer the tensile properties demanded from apparel applications or only demonstrate repellency durations for multiple days. This study utilizes poly-D,L-lactic acid (PDLLA) as a compatibilizer between Nylon 12 and nootkatone for enhanced nootkatone retention throughout fabric manufacturing processes. Nootkatone-infused Nylon 12/PDLLA composites demonstrate up to a 14% increase in nootkatone retention throughout fabric manufacturing compared to pure Nylon 12, underscoring the importance of polymer/substrate miscibility on substrate retention. Moreover, while nootkatone-infused Nylon 12 filaments demonstrate decreasing tensile stress at breaks with increasing nootkatone content, Nylon 12/PDLLA filaments exhibit similar tensile properties regardless of nootkatone content. The PDLLA domains are suspected to behave as reservoirs for excess nootkatone to prevent its role as a defect within the Nylon 12 matrix. The resulting knits exhibit significant mosquito repellencies over 24 h dependent on the nootkatone concentration, thus demonstrating potential to embed insect repellent within high-performance polymeric filaments with effective mosquito repellencies. Therefore, the incorporation of PDLLA as a compatibilizer holds significant potential for enhanced nootkatone retention during Nylon 12 fabric manufacturing. Full article

Background: Coleus amboinicus (Lour.) (syn Plectranthus amboinicus) from the Lamiaceae family—a large family of aromatic herbs with many medicinally important species—is a frequently cited species within the Plectranthus genus, renowned for its traditional uses, phytochemical composition, biological activities, and applications in skin care. Methods: A systematic review was conducted following PRISMA guidelines to provide an in-depth understanding of P. amboinicus’ phytochemical composition and biological activity, particularly in dermatological contexts, underscoring its significance in traditional medicine and modern phytochemical research. Results: P. amboinicus extracts and essential oils exhibit significant antimicrobial activity against both Gram-positive and Gram-negative bacteria, and notable antifungal properties, particularly against dermatophytes. Additionally, the species demonstrates remarkable mosquito repellent and anti-parasitic effects, comparable to DEET, and potent anti-inflammatory properties by inhibiting pro-inflammatory cytokines. The plant’s rich polyphenolic content contributes to its significant antioxidant properties, preventing conditions like hyperpigmentation and premature aging. P. amboinicus also exhibits cytotoxic activity against various cancer cell lines and promotes wound healing through its analgesic, anti-inflammatory, and antioxidant abilities. Conclusions: This comprehensive exploration of P. amboinicus validates its diverse therapeutic potential across infectious diseases, oncology, and wound care. Further research and clinical trials are warranted to fully elucidate its mechanisms of action and optimize its therapeutic applications, paving the way for its integration into mainstream medical practices. Full article

To investigate the repellent efficacy of commercially available mosquito repellents in China against Haemaphysalis longicornis, four representative DEET-based repellents and biont-derived repellents were selected. This study utilized a modified circular filter paper method repellent testing device to establish an evaluation system for assessing the repellent effects of each product against three developmental stages of H. longicornis: larvae, nymphs, and adults. In our study, for DEET-based repellents, Johnson demonstrated the highest repellency against larvae within 1 h, with an average repellency rate exceeding 80.14%. Yamei and Johnson exhibited repellency rates more than 91.11% for nymphs within 1 h, surpassing the other two DEET products. Repellency rates of Longliqi and Xiaohuanxiong fluctuated between 80.95% and 100% at different time points. Yamei, Longliqi, and Johnson achieved 100% repellency to adults within 1 h, while Xiaohuanxiong showed slightly lower efficacy. The four biont-derived repellents showed significant variations in efficacy: larval-stage repellency ranged from 14.29% to 88.89%, nymphal-stage repellency from 57.89% to 100%, and adult-stage repellency from 50% to 79.49%. CaliforniaBaby exhibited the highest efficacy, comparable or superior to DEET-based products, whereas Longhu demonstrated the weakest repellency and poor persistence. We further conducted a persistence test for CaliforniaBaby and found that it maintained >75% repellency against H. longicornis for 6 h. This study provides scientific evidence for selecting tick repellents in practice, offers guidance for purchasing commercial biont-derived tick repellents, and serves as a reference for developing safer, more effective tick repellents. Full article

Human hosts exhibit remarkable variability in their attractiveness to mosquitoes, leading to differences in biting rates. It is essential to understand the factors behind this variability if we wish to develop more effective strategies for controlling the transmission of mosquito-borne diseases. While past studies have shed significant light on the forces shaping host attractiveness to mosquitoes, we continue to lack information about variation in attractiveness within individual hosts. For example, little attention has been paid to the potential impact of the menstrual cycle. Our study explored the relationship between the menstrual cycle, host attractiveness to mosquitoes, and the effectiveness of topical mosquito repellents. We found that mosquito landing rate was higher and repellent protection time was shorter during ovulation than during menstruation and the luteal phase. By beginning to clarify the intricate interplay between human physiology and mosquito behavior, our results contribute to the growing body of knowledge regarding the factors that affect within-individual variability in attractiveness to mosquitoes, which has implications for the efficacy of protection and disease prevention strategies. Full article

Background: West Nile virus (WNV) is a mosquito-borne RNA virus, with birds as reservoirs and humans as incidental hosts. WNV often causes asymptomatic infections, but severe neuroinvasive disease occurs in fewer than 1% of human cases. Recent climatic changes and occupational exposure have increased its spread, particularly in Southern Italy. This study aimed to assess WNV seroprevalence and occupational risks among outdoor workers to guide targeted public health interventions. Methods: This cross-sectional study was conducted in the Apulia region, southeastern Italy, from November 2023 to April 2024. Participants completed a detailed questionnaire on socio-demographics, occupational exposure, travel history, and health symptoms. Blood samples were analyzed using enzyme-linked immunosorbent assay (ELISA) and neutralization assays to detect WNV-specific antibodies. Results: 250 outdoor workers in southeastern Italy were recruited, including agricultural workers, veterinarians, forestry workers, and livestock breeders. The latter showed the highest WNV prevalence at 6.5%. Protective measures such as repellent use (β = −0.145, OR = 0.95, p = 0.019) and personal protective equipment (PPE) usage (β = −0.12, OR = 0.94, p = 0.04) significantly reduced the likelihood of WNV infection. Conclusions: The study highlights the significant occupational risk posed by WNV to outdoor workers involved in livestock breeding in Southern Italy, likely due to their frequent exposure to mosquito-prone environments. Tailored public health strategies and education programs are needed to protect high-risk outdoor workers from WNV, amidst the backdrop of changing climatic conditions that favor increased transmission. Full article

In this study, electrically conductive polymer composites based on repellent N,N-diethyl-3-methylbenzamide with concentrations ranging from 6 to 30 wt% were developed. The electrical resistivity of repellent composites, as determined by electrochemical impedance spectra, ranges from 150 to 171 Ohm, which allows such materials to be used when a low voltage is applied. The study of the rheological properties of the obtained repellent composites and the analysis of the TGA curves demonstrated that the dynamic viscosity of the materials has a significant effect on the thermal diffusion of the repellent. The study of the thermal diffusion of N,N-diethyl-3-methylbenzamide demonstrated that a higher yield of repellent (up to 36.4 × 10⁻⁸ mol) is achieved when the material is applied in the form with the shortest conductor length of 14 mm. The graphs showing the relationship between the electrical flux and the concentration of N,N-diethyl-3-methylbenzamide, which was calculated via the Peltier and Thompson equations, show that, according to Onsager’s theory, the total flux of the substance is highest when a voltage is applied to the material with the shortest conductor length. Thus, the developed repellent composite is a promising material for protection against blood-sucking insects. Full article

The quality control of insect repellents contributes to the population’s health since these products prevent mosquito bites and vector-borne diseases. In this study, we developed and validated a novel analytical method using high-performance liquid chromatography with a diode array detector (HPLC-DAD) for the quantification of icaridin in insect repellent lotions. The analysis was performed on a phenyl chromatographic column 150 × 4.6 mm, 3.5 μm and stabilized at 30 °C. The detection of icaridin was achieved at 4.5 min with a 20 μL injection volume of the samples. The active ingredient was extracted from the lotion samples with isopropanol and water (50:50 v/v) and then diluted to the working concentration at 0.6 mg/mL with the mobile phase. The calibration curve was linear in the concentration range of 0.1 to 1.2 mg/mL. The method was robust, specific and precise (relative standard deviations—RSD < 2%). The accuracy of the method was demonstrated by icaridin recovery. The limit of detection and quantification were 0.03 mg/mL and 0.1 mg/mL, respectively. The present report puts forward a novel analytical method for the quantification of icaridin, contributing to improving the quality control and efficacy of marketed formulations and their different presentations such as lotions, gels and sprays, demonstrating its good applicability. Full article

The mosquito Aedes albopictus is a vector of several harmful viruses, necessitating the development of safer and more sustainable repellents than DEET. This study evaluated the potential of plant-based EOs extracted via steam distillation from Aloysia citrodora and Bursera graveolens plants harvested in Ecuador. A. citrodora EO exhibited a high sensory pleasantness with a citral-like aroma, while B. graveolens EO had lower sensory appeal due to off-flavors. At 200 µL L⁻¹, B. graveolens EO demonstrated strong ovideterrent activity, reducing egg laying by 64%, whereas A. citrodora EO displayed the highest larvicidal activity with an LC₅₀ value of 88.54 µL L⁻¹. Both EOs, applied at 0.20 µL cm⁻² on human skin, provided comparable repellency for over 45 min. The RD₅₀ values were 0.104 µL cm⁻² for A. citrodora EO and 0.136 µL cm⁻² for B. graveolens EO. When compared to DEET at 0.04 µL cm⁻², no significant differences in repellency were observed within the first 15 min post-application. These findings suggest that both EOs are effective alternatives to synthetic repellents, and A. citrodora EO emerges as a promising candidate due to its superior sensory attributes and larvicidal activity. Full article