Search Results (800)

Background/Objectives: Mosquitoes, including Culex quinquefasciatus and Aedes aegypti, are important vectors of dengue fever, Zika virus, West Nile virus, Japanese encephalitis virus, Eastern equine encephalitis virus, etc. Biological control has always been urgent in mosquito prevention due to resistance developing to synthetic insecticides and environmental toxicity by insecticides. Methods: The leaf essential oil of Mosla. chinensis was isolated, and major components were identified via GC-MS, followed by olfactory behavior assays to evaluate its repellent activity against C. quinquefasciatus. Additionally, the odorant-binding protein 1 and odorant-binding protein 2 (CquiOBP1-2) genes were prokaryotically expressed, and their fluorescence competitive binding activities with the active components of essential oils were examined. Results: The bioassays indicated this essential oil greatly repels C. quinquefasciatus, which will significantly protect people against vector-borne diseases. In the fluorescence competitive binding experiments, the CquiOBP1-2 proteins exhibit great binding capacities to volatile components, including Citronellal, Citronellol, Geraniol, Limonene and Isopulegol. Furthermore, the behavioral experimental results also indicate that the mixture of these five ligand compounds has an obvious repellent effect on mosquitoes, highlighting that they may be applied as potential mosquito repellent agents. Moreover, molecular docking and site-directed mutation analysis further confirm Phe123 and Gln77 are both key amino acid residues of CquiOBP1-2 proteins involved in the olfactory recognition of repellent ligand compounds from M. chinensis essential oil. Conclusions: The behavioral experimental verification and the exploration of olfactory molecular mechanisms are helpful to promote the biological control of plant essential oils in mosquito pests. Full article

Background/Objectives: Dengue prevention in rural Amazonian communities is shaped by knowledge, household feasibility, sociocultural dynamics, institutional continuity, and trusted communication. This study explored behavioral, sociocultural, and institutional barriers to dengue prevention and control in rural communities of the Peruvian Amazon. Methods: An exploratory qualitative study with an ethnographic orientation, informed by the Communication for Behavioural Impact (COMBI) framework, was conducted in three anonymized rural settlements in San Martín, Peru. The qualitative corpus included 120 adults, 84 in-depth interviews, six focus group discussions with 36 participants, 22 household and community observation records, 13 institutional communication materials, and seven local operational documents. Data were analyzed using an inductive thematic approach and triangulated across participant profiles, settlements, and sources. Results: Dengue was widely recognized as a mosquito-borne disease, but the central finding was a gap between general awareness and practical, routine application. Participants’ understanding of breeding sites, warning signs, and feasible source reduction was uneven. Prevention was mainly reactive, increasing after nearby cases, alerts, or fumigation, but weakening when risk was not visible. Irregular water supply, water storage, waste accumulation, gendered domestic labor, competing household priorities, reluctance to confront neighbors, and intermittent institutional action limited sustained prevention. Fumigation was perceived as the most visible institutional response, while communication was more credible when mediated by trusted local actors. Conclusions: Dengue prevention requires locally feasible household practices, safe water-storage guidance, trusted communicators, neighborhood coordination, continuous pre-outbreak engagement, and intersectoral support. Full article

Essential oils obtained from Siparuna plants, e.g., S. guianensis and S. gesnerioides, have potential for use as biorational insecticides. However, the activities of S. gesnerioides oils remain largely unexplored compared to S. guianensis oils. Using an integrative approach combining toxicological bioassays, geometric morphometrics, and in silico modeling, we assessed the adulticidal potential, selectivity, and the effects of early-life exposure to these oils on the larval susceptibility and adult wing morphometry of Aedes aegypti. Adulticidal assays revealed high toxicity, with S. guianensis (LC₅₀ = 15.0 nL/mL) being 15-fold more potent than S. gesnerioides (LC₅₀ = 233.0 nL/mL). Beyond acute lethality, early-life (i.e., eggs to L2 larvae) exposure to sublethal concentrations (S. guianensis = 7.4 nL/mL and S. gesnerioides = 118.0 nL/mL) was associated with wing morphometric disruptions and increased fluctuating asymmetry in Ae. aegypti adults, especially in those exposed to S. gesnerioides essential oil. Furthermore, early-life exposure to S. gesnerioides modulated L4 larvae susceptibility, which was associated with lower mortality in subsequent exposures. Selectivity assays demonstrated low acute oral toxicity in initial laboratory screenings with Apis mellifera, while molecular docking approaches predicted higher affinity of bicyclogermacrene and α-copaene for Ae. aegypti TRPV channels. Collectively, while S. gesnerioides oil was less acutely toxic, early-life sublethal exposures reduced fourth instar larvae (L4) susceptibility, which may have contributed to developmental instability and morphological alterations in adults. Our findings highlight the potential of Siparuna essential oils in mosquito management by impacting mosquito fitness beyond acute mortality. Full article

Dengue virus infection is a febrile illness caused by the Orthoflavivirus Dengue, which is transmitted by the mosquitoes Aedes aegypti or Aedes albopictus. Despite the fact that Dengue virus (DENV) is present in tropical and subtropical areas, climate change with global warming has been associated with the spread of Aedes aegypti and Aedes albopictus mosquitoes in several other regions worldwide. Notably, as the presence of Aedes albopictus has been confirmed in Southern Europe, already locally transmitted cases of Dengue virus infection have been reported in Europe. Apart from Europe, Australia has reported DENV cases in the 21st century that have been associated with the transmission of Aedes aegypti in the neighboring islands. Climate change, namely increasing temperatures, higher humidity and rainfalls, together with the development of urban heat islands, uncontrollable deforestation and urbanization, travelling and trade, has contributed significantly to the spread of DENV infection. Modern diagnosis based upon the advent of “multi-omics” techniques and machinery learning programs will be of the utmost importance for the early and accurate diagnosis of DENV infection. Finally, preventive measures for controlling Dengue virus infection, such as the use of repellents, educational programs, and improvement in water storage and waste management at the community levels would be very useful. Regarding climate change, the One Health Approach by integrating collaboration of various sectors and raising public awareness seems to be of the utmost importance in this context. Further investigations regarding the development of antiviral agents and vaccines will be an important asset in our armamentarium against DENV infection. Full article

A rare example of long-term elimination of Aedes aegypti occurred in Brisbane, where legislatively enforced removal of rainwater tanks led to its disappearance by the mid-1950s. However, widespread tank installation during a later drought reintroduced critical breeding habitat, enabling persistence in this subtropical region. With Ae. aegypti re-invading towns ~150 km north of Brisbane, we assessed the potential for sustained elimination. Using a genomics-informed simulation modeling framework, we integrated population genomic inference of connectivity and migration with entomological and environmental data to parameterize elimination scenarios. Genomic analyses revealed strong overall isolation among neighbouring populations in the region, with limited recent migration detected between the two southernmost populations, in Murgon and Wondai. We therefore focused simulations on these populations. Our results indicate that elimination is feasible with moderate releases of incompatible Wolbachia-infected (IIT) males (sorting error ≤ 10⁻⁶), provided non-compliant rainwater tanks are removed first. This combined strategy achieved >99% suppression and elimination in 35% of simulations in one town, whereas IIT alone resulted in moderate suppression (61–93%) and increased the risk of Wolbachia establishment at higher release ratios. Full article

Arboviral diseases are emerging as important public health threats in Saudi Arabia, driven by rapid urbanization, climate variability, the expansion of Aedes aegypti populations, international travel, and large-scale religious mass gatherings. Dengue virus remains the most established arboviral infection in the Kingdom, particularly in the southwestern regions such as Jazan and the western urban centers of Makkah and Jeddah, where ecological and climatic conditions are conducive to sustained vector survival and transmission. This review synthesizes current evidence on the epidemiology, vector ecology, climatic determinants, diagnostics, and prevention strategies of arboviral diseases in Saudi Arabia. Particular attention is paid to the impacts of rising temperatures, changes in rainfall patterns, urban heat island effects, population mobility, and cross-border movement on vector expansion and disease emergence. The review also identifies gaps in surveillance, diagnostics, insecticide resistance monitoring, and integrated vector management programs. Emerging preparedness strategies include climate-informed early warning systems, Geographic Information System-based risk mapping, multiplex molecular diagnostics, genomic surveillance, and community-based vector control. The review emphasizes the importance of implementing a One Health approach that combines data on humans, the environment, entomology, and climate. Currently, sustained endemic transmission of chikungunya and Zika viruses has not been conclusively demonstrated in Saudi Arabia, but increased environmental suitability and connectivity with other areas highlight the need for proactive surveillance and preparedness. Full article

Leptolegnia chapmanii is an oomycete pathogen of mosquito larvae. We investigated whether nutritional factors promoting cyst germination in vitro are associated with early infection events and instar-specific susceptibility in Aedes aegypti. Cysts of the Brazilian isolate ARSEF 12829 germinated rapidly in soybean seed extract, sunflower seed extract and minimal medium supplemented with yeast extract, whereas basal minimal medium did not promote germination. In sunflower seed extract, germination increased significantly with incubation time; in minimal medium, germination at 24 h was much higher with ≥0.2% yeast extract than with 0.1%. In third-instar larvae, a few cysts attached to the cuticle during the first 30–60 min, with no external germ tubes observed. At 3 h, melanized hyphal structures were detected in the midgut, and histological sections showed germinated and ungerminated cysts in the endoperitrophic space, with hyphae crossing the peritrophic matrix and midgut epithelium toward the hemocoel. Mortality increased with cyst concentration and exposure time and decreased with larval instar. At 3.3 × 10³ cysts/mL, final mortality reached 100% in L1–L3 and 91.2% in L4 larvae. These results link rapid cyst germination with early midgut invasion and high larvicidal activity. Full article

Aedes aegypti and Anopheles darlingi represent health challenges due to synthetic insecticide resistance. Hence, the essential oil from Piper humillimum is an alternative for vector control. In this study, the essential oil (3.5 ± 0.4% yield) alongside germacrene D (61.51%) and δ-cadinene (17.46%) showed larvicidal activity (LC₅₀ of 34.75 to 46.04 µg/mL), accompanied by an increase of hydrogen peroxide (H₂O₂) production (36.67 ± 1.52 to 81.33 ± 1.52 µmol H₂O₂ min⁻¹ mg⁻¹ protein), causing lipid (43.3 ± 6.02 to 81.67 ± 3.05 nmol malondialdehyde mg⁻¹ protein) and protein damages (61.67 ± 6.80 to 83.00 ± 2.64 nmol carbonyls mg⁻¹ protein). Further triggering an increase in superoxide dismutase (83.31 ± 6.80 to 95.00 ± 3.60 U mg⁻¹ protein) and catalase (74.31 ± 7.02 to 82.09 ± 1.00 µmol H₂O₂ min⁻¹ mg⁻¹ protein) activities. In addition, mixed-function oxidases (61.17 ± 11.37 to 73.52 ± 6.42 nmol cyt c min⁻¹ mg⁻¹ protein), α- and β-esterase (38.41 ± 4.04 to 61.31 ± 9.29 µmol min⁻¹ mg⁻¹ protein) levels increased. Conversely, glutathione S-transferase (GST) (11.01 ± 2.00 to 9.67 ± 3.05 µmol min⁻¹ mg⁻¹ protein) and acetylcholinesterase (AChE) (14.33 ± 3.78 to 17.00 ± 1.00 μmol min⁻¹ mg⁻¹ protein) were inhibited, corroborated by molecular docking, with germacrene D and δ-cadinene showing binding energies of −7.9 and −7.9 kcal/mol, 1.63 and 1.94 Ki for AChE, while for GST were −6.4 and 6.6 kcal/mol, and 20.5 and 15.50 Ki, respectively. These results demonstrate that the essential oil from P. humillimum is a promising multi-target alternative for the control of the investigated vectors. Full article

Aedes aegypti is a major invasive vector in China, where prolonged pyrethroid use has induced resistance, complicating dengue control. This study evaluated the resistance levels of Ae. aegypti to the pyrethroid beta-cypermethrin in Yunnan and explored the underlying mechanisms to inform control strategies. Mosquitoes were collected from five regions of Yunnan in 2015–2016. Larval bioassays, adult diagnostic dose determination, and adult bioassays were conducted to assess resistance to beta-cypermethrin. Mixed-function oxidase (MFO) amount was measured in larvae, and PCR amplification was used to detect mutations in the voltage-gated sodium channel (VGSC) gene. Correlations between enzyme activity, mutations, and phenotypic resistance were analyzed. Larval bioassays indicated that all five populations exhibited resistance to beta-cypermethrin, with resistance ratios ranging from 11.31 to 41.56. The adult diagnostic dose was determined as 0.74668 g/L, with mortality rates ranging from 8.89% to 58.89%, confirming resistance. A significant negative correlation was found between adult mortality and larval LC₅₀ values. MFO amount was closely correlated with resistance levels. The F1534C mutation was the only VGSC mutation detected, and its frequency showed a significant positive correlation with beta-cypermethrin resistance. Our data were collected in 2015–2016; resistance levels may have changed since then, and no confirmatory bioassays were performed by us after 2020. The findings demonstrate that the F1534C mutation and increased MFO amount contribute to enhanced beta-cypermethrin resistance of Ae. aegypti in Yunnan. By linking phenotype resistance to key molecular and biochemical mechanisms, these findings support the continued monitoring of resistance and provide a basis for the evidence-based optimization of dengue vector control strategies. Full article

Controlling the arbovirus vector Aedes aegypti represents a growing public health challange, intensifying the search for alternatives to combat the mosquito. In this context, the present study aims to evaluate the larvicidal activity of essential oils from three Piper species and their mixtures, as well as their preliminary toxicity and in silico acetylcholinesterase (AChE) inhibitory potential. The essential oils and mixtures were characterized by GC–MS. The larvicidal activity test was performed against third-stage larvae, and a preliminary toxicity test was preformed against Artemia salina. The results showed that the oils had a high content of phenylpropanoids such as safrole, dillapiole, and eugenol, as well as their derivatives. The mixtures showed lower toxicity when compared to the pure oils. P. aduncum oil showed the highest larvicidal action (LC₅₀ = 26.2 µg/mL), followed by P. callosum (LC₅₀ = 53.2 µg/mL), while P. divaricatum had the lowest activity (LC₅₀ = 123.8 µg/mL). Among the mixtures, the combination of P. divaricatum and P. aduncum stood out for its synergistic effect. Molecular docking analyses suggested that phytoconstituents interact favorably with AChE, supporting a neurotoxic mechanism associated with enzyme inhibition. Thus, Piper essential oils and mixtures are promising alternatives for the control of A. aegypti. Full article

The increasing resistance of mosquito vectors to synthetic insecticides poses a major challenge to vector control and global public health, underscoring the urgent need for sustainable, environmentally safe alternatives. This study evaluated the larvicidal activity of aqueous, ethanolic, methanolic, and hydroethanolic extracts of Calotropis procera (Aiton) W.T.Aiton leaves against Aedes aegypti larvae. Significant variations in activity were observed across extraction solvent, ecological zone, and harvest season, with hydroethanolic extracts—particularly those collected in Kombissiri during the dry season—exhibiting the lowest LC₅₀ values among the tested extracts (LC₅₀ < 1600 ppm), indicating moderate larvicidal activity. Phytochemical profiling by high-performance thin-layer chromatography (HPTLC) revealed the presence of several classes of secondary metabolites, including flavonoids, phenolic compounds, tannins, sterols/triterpenes, saponins, coumarins, alkaloids, and cardenolides. Correlation analysis revealed strong negative correlations between larvicidal activity and the concentrations of flavonoids and phenolic compounds, suggesting that higher levels of these metabolites are associated with increased larvicidal effectiveness and may contribute to the observed bioactivity, although these associations remain correlative and do not establish direct causality. These findings highlight the potential of C. procera as a source of plant-based larvicides and demonstrate the influence of environmental factors on their efficacy. From an environmental health perspective, such plant-derived solutions could provide preliminary data for the future optimization of sustainable vector control strategies, while reducing ecological impact and reliance on synthetic insecticides. Full article

Aedes (Ae.) aegypti and Ae. albopictus are important vectors of arboviruses. Yet their blood-feeding pattern remains poorly characterised in Africa, including Cameroon. In this study, we characterised the blood-meal sources in both species collected from vegetation, household surroundings, and animal cages across four urban sites, one rural site, and a zoo-botanical garden where humans and animals in captivity are the main hosts. Overall, Aedes mosquitoes represented about half of 10,054 female mosquitoes collected, with Ae. albopictus strongly dominating Ae. aegypti among 5001 Aedes females, and only 5.95% of females visibly blood-fed. Sequencing a 748 base pairs (bp) fragment of the cytochrome oxidase I gene from 156 blood-fed abdomens yielded 126 high-confidence host assignments, of which 98.25% were humans, indicating a strong anthropophagic pattern in both species. Unpredictably, two Ae. albopictus individuals had fed on a baboon (Papio anubis) and a frugivorous bat (Pteropodidae), as confirmed by bio informatic analyses, highlighting the species’ opportunistic blood-feeding nature and providing preliminary molecular evidence consistent with a potential bridge-vector role in this setting. Despite the extreme anthropophagy of both species observed, results indicate that Ae. albopictus could also serve as a bridge vector enabling spillover of enzootic viruses to humans, including urbanised settings where wild animals are present. These findings emphasise the urgent need for enhanced arbovirus surveillance in Central Africa using a One Health approach. Full article

Dengue virus (DENV) poses a growing risk in Tanzania, yet its genetic diversity in mosquito populations remains poorly understood. Using Nanopore sequencing, we recovered full coding sequences from six DENV-2 positive mosquito pools collected in Dar es Salaam outside recognized outbreak periods. Phylogenetic analysis placed these sequences in a distinct monophyletic clade within genotype II, separate from strains linked to Tanzania’s 2014 outbreak. Instead, they clustered with Asian lineages and showed the closest relatedness to DENV-2 strains from Kenya (2013) and India (2014), with divergence estimated to have occurred around 2010. Variant profiling identified 212 low-frequency intra-pool variants, predominantly non-synonymous changes in the NS3, NS4B, and NS5 coding regions. These results suggest a previously unrecognized introduction of genotype II that is now circulating silently within local mosquito populations. Our findings highlight the value of genomic surveillance in mosquito vectors for early detection of arboviral threats, even in the absence of reported human cases. Full article

Control of resistant mosquito populations may be approached by the development of novel synergists to improve the performance of already commercialized compounds. Extracts of black pepper (Piper nigrum), Cha Plu (Piper sarmentosum), and Sichuan pepper (Zanthoxylum spp.) synergized natural pyrethrins applied topically to Aedes aegypti females. Both black pepper and Sichuan pepper extracts synergized natural pyrethrins over 13-fold. Synergism was also observed directly on the mosquito larval central nervous system (CNS), suggesting this effect is an important contributing factor distinct from that of reduced metabolism. Piperine, from black pepper, and α-hydroxysanshool (α-HS) from Sichuan pepper, synergized natural pyrethrins on susceptible CNS, but only piperine was capable of synergizing natural pyrethrins on the CNS of a pyrethroid-resistant strain of Ae. aegypti, indicating that these molecules may possess slightly different mechanisms of action or binding sensitivities. These results demonstrate that pepper alkamides are capable of enhancing select insecticidal chemistries via target-site synergism, a novel mechanism of synergism that might be important for enhancing future insecticidal formulations. Full article