Search Results (244)

The escalating challenge of managing vector-borne pathologies necessitates the advancement of vector control strategies that are both highly potent and environmentally benign. This research evaluates the insecticidal efficacy and environmental plasticity of three Bacillus thuringiensis subsp. israelensis (Bti) H14 strains 33, 87/1, and 7-1/3 against laboratory and wild mosquito populations. In controlled laboratory assays, cultures with a spore density of 4.0–4.4 × 10⁹ spores/mL demonstrated significant larvicidal activity against larvae of all instars (L₁–L₄) of Aedes aegypti. The median lethal concentration (LC₅₀) was established between 1.15 and 1.48 µL/L, resulting in cumulative mortality rates of 95–96% within a 48 h exposure window. Proteomic profiling via SDS-PAGE and Western blotting validated the robust synthesis of the signature δ-endotoxin complex, specifically verifying the presence of Cry4Aa, Cry4Ba, Cry11Aa, and Cyt1Aa. Field applications in specific forest (Polissya) and steppe (Forest–Steppe) aquatic biotopes of Ukraine—characterized by distinct physicochemical profiles (differing significantly in light exposure, water hardness, salinity, and suspended solids)—substantiated the stability of the liquid formulations, achieving larval suppression rates of 95–100% within 48 h against wild Aedes-dominated assemblages at application rates of 0.25–1.0 mL/m² (equivalent to 2.5–10.0 L/ha). The demonstrated environmental adaptability suggests these novel strains are viable candidates for broad-spectrum ecological engineering applications. Their integration into sustainable vector control strategies offers a mechanism to enhance biosecurity without compromising the ecological balance of local biocenoses. Full article

Characterizing the mosquito virome is essential for understanding host–microbiota interactions and vector competence, but it can be influenced by sample scale, sequencing strategy, and host depletion. This study evaluated the effect of sampling scale on mosquito virome characterization using a third-generation sequencing (TGS) metagenomics approach based on PacBio HiFi long reads, applied to L4 larvae and adults of Aedes mariae, analyzing single individuals and pools of increasing size before and after host genome removal. The results showed that sequencing yield did not increase with pool size, indicating that the total number of reads is not proportional to the number of individuals. Host genome removal reduced the overall number of reads but altered their composition, increasing the relative proportion of assigned viral reads and reducing unclassified sequences. Despite a similar total read output, virome diversity increased with pool size, with larger pools showing greater taxonomic richness driven by the contribution of each individual. However, the high proportion of unassigned reads suggests the presence of uncharacterized viruses. This methodological workflow was technically feasible for both single-individual and pooled samples. Single-individual analyses may provide complementary information on individual-level virome composition and on low-abundance viral taxa that could be less apparent in pooled samples, whereas pooled samples may facilitate the detection of a broader range of viral taxa and may better capture the shared component of viral diversity within the analyzed population. Full article

Since its first detection in 2010, Aedes albopictus has spread across northern Algeria, where vector control relies on the use of chemical insecticides. This study aimed to evaluate the susceptibility of Ae. albopictus populations from Algiers to commonly used larvicides and adulticides, as well as to characterize the underlying resistance mechanisms. Eggs were collected from three sites in Algiers. The susceptibility of larvae to temephos and Bacillus thuringiensis israelensis (Bti), as well as that of adults to permethrin, deltamethrin, malathion, and bendiocarb was evaluated using WHO bioassays. Genotyping of knockdown resistance (kdr) mutations was performed via PCR and sequencing. Metabolic resistance mechanisms were investigated using CDC bottle bioassays. The larvae were found to be susceptible to temephos and Bti. Bioassays on adults demonstrated susceptibility to deltamethrin, suspected resistance to permethrin, and resistance to malathion and bendiocarb. Genotyping revealed low frequencies of heterozygous kdr mutations (V1016G, I1532T, F1534C/S). Synergist assays highlighted the key role of esterases in malathion resistance, a minimal involvement of glutathione S-transferases and an unexpected antagonistic effect of cytochrome P450 monooxygenases. Although larvicides remain effective, resistance to organophosphates, carbamates, as well as suspected resistance to permethrin, has been detected. Esterase-mediated metabolic resistance and kdr mutations may contribute to this profile. These findings highlight the need for resistance monitoring and integrated vector control to ensure sustainable control of Ae. albopictus. Full article

Background/Objectives: Artemisia annua essential oil (EO) possesses diverse biological activities; however, its practical application is limited by volatility, instability, and poor bioavailability. This study aimed to develop chitosan-coated nanostructured lipid carriers (CH-NLCs) for efficient encapsulation and delivery of A. annua EO and to evaluate their physicochemical characteristics and biological performance. Methods: The nanoformulation exhibited favorable physicochemical properties, including a high encapsulation efficiency (85.97 ± 1.30%) and a strongly positive surface charge (approximately +45 mV), indicating good colloidal stability. Structural analyses by SEM, FTIR, and XRD confirmed successful encapsulation of the EO within the nanocarrier matrix. Results: The CH-NLC formulation significantly enhanced larvicidal activity against Aedes aegypti larvae, reducing the LC₅₀ value from 213 ppm for the free EO to 142 ppm. Enhanced antifungal activity was also observed, with 47–56% greater inhibition against Malassezia furfur, Trichophyton mentagrophytes, and Candida albicans compared with the free EO. Furthermore, CH-NLC demonstrated improved cytotoxic activity against skin cancer cell lines, achieving IC₅₀ values of 21.4 ± 1.7 µg/mL and 30.1 ± 1.6 µg/mL against A431 and A375 cells, respectively, while maintaining lower toxicity toward normal HaCaT keratinocytes. Mechanistic investigations revealed enhanced apoptosis and an approximately 3-fold increase in intracellular reactive oxygen species (ROS) levels in treated cancer cells. Conclusions: Collectively, these findings indicate that chitosan-coated nanostructured lipid carriers effectively improve the stability and biological efficacy of A. annua essential oil and represent a promising platform for future biomedical and biocidal applications. 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

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 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

Efficient egg collection is important for large-scale mosquito rearing, but it presents logistical challenges and often yields suboptimal egg numbers in mass rearing cages. Furthermore, uneven distribution of eggs on oviposition substrates can lead to higher fatality of the first instar (L1) larvae among overlapping/stacked eggs. Previous studies showed that incorporating darker hues into oviposition pots (ovipots) improves egg collection, yet few discussed designs of containers for use in mass rearing cages. Using a no-choice experimental setup, the number of eggs collected per female was determined in cages of Wolbachia-infected Aedes aegypti mosquitoes provided with different ovipots. The percentage of dead larvae among the stacked eggs was also determined. Based on this information, different prototypes of a more efficient, larger ovipot were evaluated in mass rearing cages. A black-bottom container with white crepe paper collected the most eggs per blood-fed female by promoting higher oviposition rates. A significantly lower percentage (0.31%) of dead L1 larvae were found among relatively sparser eggs compared to 0.96% among stacked eggs. A larger, black-bottom ovipot with oviposition papers positioned at the center of the container, demonstrated suitability for use in mass rearing cages, promoting better egg distribution and yield. Full article

The evolution of resistance in mosquitoes to conventional insecticides such as pyrethroids presents a challenge to vector control. Thus, alternative active ingredients for insecticides to manage pyrethroid-resistant populations of mosquitoes are needed. The goal of this study was to evaluate the toxic and repellent efficacy of geraniol, a plant secondary metabolite, as a potential alternative for controlling pyrethroid-resistant Aedes aegypti. We found that addition of geraniol to rearing water of 1st instar larvae caused concentration-dependent mortality within 24 h in both strains. The resistance ratio of geraniol (2.8) was modest compared to that of cypermethrin (435.3). Topical application of geraniol to adult female mosquitoes caused dose-dependent mortality in both strains within 24 h. The resistance ratio of geraniol (1.1) was minimal compared to that for cypermethrin (457). In spatial repellency assays, geraniol repelled adult females from both strains in a dose-dependent manner. The repellency resistance ratio of geraniol (2.6) was modest compared to that for pyrethrum extract (>132). Our findings suggest that geraniol has potential use as a toxicant and repellent for controlling pyrethroid-resistant populations of Ae. aegypti. Full article

Phytotelmata are small, plant-held water pools that support unique assemblages of fauna and flora. Aquatic Diptera are a significant component of these microecosystems. Based on an exhaustive review of over 100 years of published literature, a global database of phytotelmata-associated aquatic Diptera with Bromeliaceae and Zingiberales (7 families) was compiled to explore diversity and ecology and identify gaps in the research. This database is designed to provide a valuable baseline and to serve as an objective, informed tool for future monitoring and research. A total of 4979 unique associations between aquatic Diptera larvae and 117 species in 26 genera of Bromeliaceae and 27 species in 10 genera across 6 families of Zingiberales were assembled in the database. These reported aquatic Diptera span 369 species, 80 genera, and 14 families, and include taxa with diverse ecological roles as detritivores, filter feeders, predators, and prey. Mosquitoes (Culicidae) had the greatest number of documented species (227), and non-biting midges (Chironomidae) had the greatest number of documented genera (26) in the dataset. Several mosquito vectors (e.g., Anopheles, Aedes, and Culex) also complete their life cycles in these habitats, although records of vector mosquitoes compose only 6% of the assembled data. Because phytotelmata provide year-round aquatic refugia, they sustain regional aquatic Diptera diversity yet are threatened by habitat loss and other anthropogenic pressures. Furthermore, despite the important role of phytotelmata in freshwater ecology, diversity in these ephemeral freshwater habitats remains under-documented. This comprehensive analysis of existing literature establishes the first global baseline for aquatic Diptera in phytotelmata and offers a foundation for biodiversity assessments, conservation strategies, and future ecological research. Full article

Malaria remains one of the main public health problems in Mauritania, and it is essential to identify the factors that determine the distribution and productivity of Anopheles breeding sites in order to develop more effective control strategies. A longitudinal survey with repeated measurements was conducted in Nouakchott between May 2023 and April 2024, in order to examine the factors influencing the distribution and productivity of Anopheles larval habitats. The larvae were collected by immersion in 60 water points, once a month during the dry season and twice a month during the rainy season, for a total of 294 observations. The physical and chemical characteristics of the sites were also measured. Logistic regression analyses with random effects showed that the presence of Culex and Aedes larvae, pH, and temperature were statistically significantly associated with positive water collection for Anopheles larvae (aOR = 3.03, 95%CI [1.14–8.07], p-value = 0.026; aOR = 0.18, 95%CI [0.05–0.60], p-value = 0.006; aOR = 3.17, 95%CI [1.32–7.61], p-value = 0.010 and aOR = 5.95, 95%CI [2.09–16.92], p-value < 0.001, respectively). Only Anopheles multicolor and An. arabiensis were present in Nouakchott. Our results could help health authorities by guiding the destruction of breeding sites with biological larvicides or physical elimination of peridomestic habitats. Full article

Heme released during blood digestion represents a major oxidative challenge for hematophagous insects, promoting the generation of reactive oxygen species (ROS) and redox imbalance. Although Aedes aegypti has evolved specialized mechanisms to mitigate heme toxicity, how these responses vary across developmental stages remains poorly understood. Here, we applied quantitative proteomics to compare the effects of heme exposure in larvae and adult females. In larvae, heme treatment predominantly led to downregulation of metabolic and antioxidant proteins, consistent with a shift toward energy conservation and growth regulation. Nonetheless, selective upregulation of proteins associated with mitochondrial MnSOD activity, lipid remodeling, and cytoskeletal organization indicates the engagement of complementary protective mechanisms. In contrast, adults exhibited a coordinated bioenergetic response, characterized by enrichment of mitochondrial pathways, redox-related proteins, and molecular chaperones, reflecting enhanced resilience to oxidative stress. Enrichment of cuticle-associated proteins in both stages further suggests heme-induced structural remodeling. Together, these findings demonstrate that A. aegypti employs divergent, stage-specific proteomic strategies to cope with heme toxicity: larvae suppress metabolic activity while maintaining structural and redox homeostasis, whereas adults reinforce mitochondrial function and proteostatic defenses. These insights advance our understanding of mosquito redox biology and highlight stage-specific vulnerabilities that may be exploited for innovative vector control strategies. 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