Search Results (436)

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

The Asian tiger mosquito (Aedes albopictus) is an important vector of arboviruses, including dengue, chikungunya, and Zika. Its rapid global expansion has been facilitated by climate change and human activities. Phylogenetic studies of Ae. albopictus have largely relied on mitochondrial cytochrome c oxidase subunit 1 (COX1) and NADH dehydrogenase subunit 5 (ND5) markers, while the utility of cytochrome b (CYTB) remains underexplored. We collected Ae. albopictus from 13 sites in seven provinces of South Korea and analyzed COX1, ND5, and CYTB sequences. Genetic diversity indices were calculated, and phylogenetic relationships were reconstructed using maximum-likelihood trees and haplotype networks with a dataset obtained from GenBank. COX1 revealed 46 haplotypes, including six novel variants, with the highest diversity in southern coastal regions such as Busan and Suncheon. ND5 showed limited variation, with only two haplotypes. CYTB revealed three haplotypes, including region-specific variants in Busan and Wonju, supporting its role as a complementary marker. The Busan haplotype H41 bridged domestic and international lineages, suggesting Busan as a likely entry point. This study demonstrates that integrating COX1, ND5, and CYTB improves the resolution of Ae. albopictus phylogeography in Korea and highlights the need for continued molecular surveillance to guide vector control strategies. Full article

Arthropod-borne viruses (arboviruses) such as dengue, chikungunya, Zika, and yellow fever pose significant global health risks, with mosquitoes from the Aedes genus as the primary vectors responsible for human transmission. The Republic of the Marshall Islands (RMI), particularly the urbanized areas of Kwajalein and Majuro atolls, has experienced multiple outbreaks of dengue, Zika, and chikungunya with substantial health and economic impacts. Vector control remains the most effective method for reducing disease risk, but comprehensive data on local mosquito vector composition, distribution, and abundance are needed to guide new, effective control efforts. From 2022 to 2024, we conducted a longitudinal baseline assessment of mosquito abundance and species composition on Ebeye and nearby islets in Kwajalein Atoll, RMI, using BG-Sentinel traps and ovitraps. Aedes aegypti was the most prevalent species, accounting for 58% of all adult females collected across study locations, with higher relative abundances on Ebeye than on northern islets (4.7 vs. 2.3 per trap/night). Aedes albopictus was more abundant on northern islets (0.7 vs. 3.2 per trap/night), and Culex quinquefasciatus showed similar abundances (1.2 vs. 1.7 per trap/night). Rainfall and anthropogenic factors, including water storage practices and housing density, influenced mosquito abundance. These findings provide multi-seasonal baseline data to support targeted vector control strategies in RMI. Full article

The mosquito fauna was examined at the Mérida Zoological Park, a public site that is highly frequented and is a significant tourist attraction in the Yucatán Peninsula, in southeastern México. Between January 2023 and February 2024, 24 visits were made to the zoo to capture adult and immature stages of mosquitoes. Overall, 12 species belonging to five genera (Aedes, Anopheles, Culex, Ochlerotatus, and Uranotaenia) were documented. A total of 6601 adult mosquitoes of 10 species were captured by aspiration. The adult population of Culex quinquefasciatus Say was the most abundant, accounting for 80.84% (n = 5336) of the collection, while Aedes aegypti Linnaeus represented 11.53% (n = 761). The aviary was the site with the highest capture abundance (n = 2414) and species richness (n = 10). Aedes aegypti was abundant in the zoo restroom (n = 331) and had a higher proportion of blood-feeding females. A total of 1090 larvae and 160 pupae of nine species were collected from 26 mosquito breeding sites, accounting for 25% of positive containers (26/104). Aedes albopictus was frequently found in the larval stage (n = 43) compared to the adult stage (n = 3). The presence of mosquitoes with the potential to transmit pathogens poses a public health risk to zoo visitors and staff. Full article

La Crosse virus (LACV) is a mosquito-borne virus (family Peribunyaviridae) that can result in severe human infection in children under sixteen. Historically, LACV comprised two lineages, predominantly in the Midwest and Appalachian regions of the US. In 2005, a virus of a third lineage was detected in the Northeast; however, this and subsequently isolated strains of lineage III have not, to date, been implicated in human disease. One hypothesis for this discrepancy is that vector mosquitoes have a reduced vector competency for LACV lineage III, thus preventing horizontal transmission and clinical cases. Here, we utilized two mosquito species, Aedes triseriatus, the native vector, and Aedes albopictus, an invasive potential vector, each from both a historic LACV range (Virginia) and from the region of lineage III (Connecticut). Utilizing oral feeding and intrathoracic inoculation methods of viral exposure, rates of LACV infection, dissemination, and transmission (proxied via salivary secretion) and capability for vertical transmission (proxied via virus-positive ovaries) were determined by harvesting mosquito bodies, legs, saliva, and ovaries, respectively. Overall, we did not detect consistent differences in transmission between any lineage, species, or state of origin, at day 14 post-infection. However, we highlight the transmission potential of LACV lineage III in all mosquito populations tested here, representing the first evidence of lineage III competency in Aedes triseriatus and Aedes albopictus, indicating the potential for human disease. We thus suggest that the absence of human cases of LACV lineage III is not modulated by a lack of vector competency in mosquitoes. Full article

Insecticide resistance is increasing globally, and tools must be developed to combat this issue facing mosquito control programs that protect public health and inform operational decisions. Field trials to assess insecticide formulated products (FPs) are logistically demanding and weather-dependent and the Centers for Disease Control and Prevention bottle bioassays are optimized to test technical active ingredient (AI) residue, not aerosolized FP. Here, the methodological gap between AI and FP efficacy testing is addressed. The current study assessed the knockdown/mortality of laboratory and wild populations of Aedes albopictus and Culex pipiens/quinquefasciatus to four FPs (Biomist^®, Duet^®, AquaDuet^®, ReMoa Tri^®) in wind tunnel experiments. The number of FP droplets on mosquitoes was analyzed. Regression analyses showed that droplet counts on mosquitoes were significantly (p < 0.05) related to mosquito mortality for some FPs. The wild Culex population was resistant to all FPs in the wind tunnel. Here, when wind tunnel experiments resulted in a relatively low mortality rate (<90%), this indicates mosquito resistance to the FP. In these situations, a field trial would likely not achieve good results and may not be necessary. Alternatively, when wind tunnel experiments resulted in a nearly perfect mortality rate, a confirmatory field trial could be conducted, if needed. Full article

Background and Objectives: Climate change is modifying the ecological and climatic conditions that influence the distribution and activity of arthropod vectors. Rising temperatures and prolonged warm seasons have favored the establishment of Aedes albopictus in Mediterranean regions, increasing the risk of autochthonous Dengue transmission. Therefore, this study describes the evolution of Dengue surveillance in Sardinia between 2018 and 2024, integrating human and entomological data to assess trends, system performance, and implications for prevention and control. Materials and Methods: Data on human cases were retrieved from national notification systems (namely PREMAL, arbo.iss.it) and the New Health Information System. Entomological surveillance data were obtained from the Experimental Zooprophylactic Institute of Sardinia. Mosquitoes were collected using BG-Sentinel^® traps and ovitraps, covering major cities and points of entry. Descriptive analyses were conducted for both datasets. Results: Sixteen Dengue cases were reported during the study period, all imported and laboratory-confirmed in 81% of cases. Most patients were adults (mean age 38 years), and 77% required hospitalization. The most frequent travel origins were Southeast Asia, Africa, and Latin America. No autochthonous cases were identified. Entomological surveillance showed a progressive increase in Aedes albopictus captures from 2020 onwards, with seasonal peaks between September and October. Despite intensified sampling and expanded geographic coverage, no mosquito pools tested positive for the Dengue virus. Conclusions: Although no locally acquired Dengue infections have been detected, the widespread and increasing presence of Aedes albopictus indicates that Sardinia meets the ecological prerequisites for possible autochthonous transmission. Strengthening the timeliness and completeness of human surveillance, improving clinicians’ awareness of reporting requirements, promoting vaccination for travelers, and maintaining continuous entomological monitoring are essential to prevent and promptly manage future outbreaks. Full article

A compartmental, deterministic model was used to explore the effects of temperature dependency in mosquito mortality on the likelihood of epidemics and the size of outbreaks of Chikungunya virus under Florida temperature conditions. Two known vectors, Aedes albopictus and Ae. aegypti, were included, with similar structure but allowing mortality and abundance parameters to vary between them. The mortality relationship with temperature had a central optimal survival region, with increasing mortality outside these regions. The central temperature and the annual mean temperature were most influential in the likelihood of an epidemic, although the variance explained was low. The central temperature, annual mean temperature and day of virus infection influenced the size of the outbreaks. Regression models including two-way interactions explained more of the variance in outcomes than the main effects models, but there was still substantial variance left unexplained. Given the model structure, higher order interactions would be required to explain most of the variance. Full article

Scorpion venom is a rich source of diverse bioactive molecules with medicinal importance. While the venoms of many Buthidae scorpions have been extensively studied for their toxicity and therapeutic potential, Hottentotta judaicus scorpion venom (HjSV) remains poorly explored. In this study, using LC-ESI-MS, we show that HjSV has a complex composition. We find that HjSV has no significant cytotoxic effects on three human cancer cell lines, even at concentrations of up to 1000 µg/mL. However, it exerts a dose-dependent insecticidal effect against Drosophila melanogaster, a well-established genetic model organism, and two medically relevant mosquito species, Aedes albopictus and Culex pipiens. These findings highlight the venom’s selective activity and reveal a species-dependent susceptibility in insects, with mosquitoes being more sensitive than Drosophila. Furthermore, we show that at sub-lethal doses, HjSV alters D. melanogaster behavioral patterns, significantly reducing locomotor activity and increasing sleep duration. Altogether, our results provide new insights into the dual role of HjSV as both an insecticidal agent and behavioral modulator, shedding light on its ecological function in prey subduing and its potential application in pest control strategies. Full article

Alphavirus chikungunya (CHIKV) is an arthropod-borne alphavirus of the Togaviridae family, transmitted primarily by Aedes aegypti and Ae. albopictus mosquitoes. CHIKV infection often results in debilitating manifestations that compromise quality of life and generate significant socioeconomic impacts. Recurrent epidemics in tropical and subtropical regions underscore the urgent need to better understand the host immune responses and their contribution to disease outcome. CHIKV establishes infection by overcoming the host’s initial immunological barriers. Innate immune cells, including fibroblasts, dendritic cells, macrophages, monocytes, neutrophils and natural killer (NK) cells, are among the first to respond to infection, ensuring a rapid antiviral defense and supporting the development of adaptive immune responses. However, excessive release of inflammatory mediators and prolonged infiltration of innate cells into joint tissues contribute to disease chronicity and the persistence of arthralgia. In this review, we provide a comprehensive synthesis of current evidence on innate cells that serve as targets for CHIKV infection, highlighting mechanisms that promote effective antiviral defense as well as those responsible for pathological inflammation and chronic disease and identifying key gaps that remain to be addressed. Full article

While a great deal of research has been conducted to identify the biotic mechanisms influencing the co-occurrence of aquatic Ae. aegypti and Ae. albopictus mosquitoes, including inter-specific larval competition and mating interference, few studies have been completed to investigate their oviposition behaviors under co-occurrence scenarios. Herein, we performed three experiments to understand the influence of conspecific and heterospecific L4-larvae presence in oviposition by antagonist Aedes spp. mosquitoes. We compared egg counts of Ae. aegypti and Ae. albopictus in cups with water and conspecific or heterospecific larvae (either present or removed), or no larvae as control. In the first experiment, we used small cages; in the second experiment, we used larger cages increasing the number of treatment replicates per cage; and in the third experiment, we removed larvae before allowing gravid females to oviposit. In experiments 1 and 2, Ae. aegypti laid more eggs in conspecific cups, while Ae. albopictus distributed eggs evenly between conspecific and heterospecific cups, and both species laid fewer eggs in controls. In these experiments, more eggs were laid during the first 24 h. In experiment 3, both species laid more eggs in conspecific larvae-conditioned water as compared to controls in the first 24 h; however, in Ae. Aegypti, this inclination was lost with time. Our results suggest that co-occurrence of Ae. aegypti and Ae. albopictus may be explained by Ae. aegypti’s ability to avoid oviposition in habitats colonized by heterospecific L4-larvae. Yet chemical cues in conspecific L4-larvae-conditioned water were insufficient to replicate this behavior, and therefore, additional cues may be involved. Full article

Dengue fever, a mosquito-borne viral disease, has become a significant global health concern in recent decades, particularly in Iran. This integrative review provides a comprehensive assessment of the epidemiological trends of dengue fever in Iran from its initial emergence to the present, identifying and evaluating factors contributing to both the emergence and re-emergence of the disease at national and international levels. The review highlights critical global determinants influencing dengue transmission, including climate change, environmental modifications, unplanned urbanization, increased international travel and trade, and the pivotal roles of public awareness and healthcare infrastructure. Climatic variables, such as rising temperatures and altered precipitation patterns, create favorable conditions for mosquito breeding, enabling vectors like Aedes aegypti and Aedes albopictus to expand into new regions. We also explore how environmental changes, unplanned urbanization and other factors further exacerbate the situation. Control strategies addressing these factors are presented. In Iran, the incidence of dengue fever is increasing, yet research remains limited. The highest number of local cases has been reported in Chabahar and Bandar Lengeh, Hormozgan and Sistan and Baluchestan Provinces, respectively. Eleven key factors—culminating in socio-cultural practices, climate change, unplanned urbanization, cross-border mobility, and gaps in vector control and healthcare infrastructure—have been identified as contributing to recent outbreaks in Iran. In conclusion, our review underscores that mitigating dengue vulnerability in Iran requires an urgent, multi-faceted strategy targeting improved urban water management, enhanced cross-border surveillance, and strengthened healthcare system capacity. Full article

Juniperus is one of the vital genera of the Cupressaceae family; many Juniperus species (juniper) have served as traditional folk medicines. The aims of this study are to analyze its chemical composition and to evaluate the mosquito larvicidal activity of leaf essential oil and its constituents. The constituents of leaf essential oil were analyzed by GC-MS. Leaf essential oil is mainly composed of hydrocarbon monoterpenes and, secondly, oxygenated monoterpenes. Leaf essential oil exhibited good brine shrimp lethality activity, which is highly correlated with larvicidal activity, with the LC₅₀ of 49.89 μg/mL. Leaf essential oil showed a strong mosquito larvicidal activity against two Dengue vector mosquitoes, Aedes aegypti and Ae. albopictus, the LC₅₀ values for both species were lower than 50 μg/mL. Among the major constituents of leaf essential oil, compounds limonene, sabinene, and β-myrcene also exhibited a significant larvicidal effect. Through these investigations, it is expected that leaf essential oil from J. chinensis var. kaizuka and its constituents are of potential use as environmental control chemicals against Dengue vector mosquitoes. Full article

Pollution with heavy metals, such as cadmium (Cd), can significantly affect insect growth, development, and behavior. The midgut is an essential organ for stress response. Chitin synthase-2 (CHS-2) is closely associated with forming the peritrophic membrane (PM). The fourth-instar larvae of Aedes albopictus were exposed to varying concentrations of Cd. The results showed that Cd inhibited chitin synthesis and metabolism-related genes, but thickened the midgut PM, indicating that the larvae could respond to Cd stress through the midgut PM. Silencing CHS-2 by RNA interference resulted more severe vacuolization and malformation of midgut epithelial cells without midgut PM protection. Additionally, there was an intensified redox reaction, upregulated expression of metallothionein (MT) and heat shock proteins 70 (HSP70), and increased activity of antioxidant enzymes at some scattered time points. This study confirms that CHS-2 is involved in oxidative stress induced by Cd exposure by regulating PM formation. This study also contributes to further understanding the resistance mechanism of Ae. albopictus under Cd stress, thereby establishing a theoretical foundation for the future studies of them, which is concerned with the possibility of Ae. albopictus as a water environment detection and the control of Ae. albopictus based on resistance mechanism. Full article

Oviposition attractants can enhance both the surveillance and control of container-breeding Aedes mosquitoes. Although green tea has been reported to attract Ae. aegypti, the specific bioactive botanical compounds responsible remain unidentified. We evaluated teas across fermentation stages (non-fermented, fully fermented, and post-fermented) at 5 g/L for gravid Ae. albopictus using dual-choice assays. The most attractive tea (Liu-pao) was further tested across concentrations (0.5–5 g/L) and infusion ages (1–28 days). Autoclaved vs. non-autoclaved infusions assessed microbial contributions, while headspace volatiles were analyzed via HS-SPME-GC-MS. Individual compounds (cedrol and linalool oxide) were bioassayed. Only Liu-pao tea consistently attracted Ae. albopictus (OAI ≥ 0.3), peaking at 5 g/L after 7–14 days (OAIs 0.73/0.67). A 0.5 g/L infusion aged 21–28 days also attracted Ae. aegypti (OAIs 0.89/0.63). Autoclaving did not reduce attraction, confirming volatile compounds, not live microbe-mediated effects. Cedrol (1 mg/L) elicited moderate attraction (OAI 0.29) in Ae. albopictus, while linalool oxide was inactive. Post-fermented Liu-pao tea acts as a potent botanical attractant for Aedes mosquitoes. Cedrol contributes partially, but whole tea infusions outperform single compounds. These findings support developing multi-volatile “attract-and-kill” strategies targeting gravid mosquitoes. Full article