Aegypti Research Articles

ANÁLISE QUANTITATIVA DOS CASOS DE DENGUE NOS MUNICÍPIOS DO LITORAL NORTE DE SÃO PAULO NO PERÍODO DE JANEIRO DE 2014 A DEZEMBRO 2023

Dengue is characterized as a disease caused by a virus of the Flavivirus genus, transmitted by mosquitoes of the Aedes genus, with Aedes aegypti being the main vector. Due to its wide distribution and adaptation to urban and peri-domestic environments, dengue is predominantly found in urban areas. The ideal habitat for the mosquito is a tropical climate, which makes Brazil ideal for its proliferation. In addition to climatic factors, disorderly urbanization also contributes to the multiplication of the mosquito, increasing the places where it can reproduce. The vector's life cycle comprises the egg, four larval stages, a pupal stage and the adult, with an average lifespan of 10 to 42 days. Dengue symptoms generally include malaise, fever and weakness, and the disease tends to be self-limiting in most cases, being diagnosed through laboratory tests and clinical case. The aim of this study is to analyze the number of dengue cases in the municipalities of the north coast of São Paulo, Brazil, from January 2014 to December 2023, with the highest rate being observed in the municipality of São Sebastião with 14.95% of dengue cases in relation to the total population and the lowest rate of cases in Ilhabela with a percentage of around 7.37%. The year with the highest number of cases in the region was 2015 in the municipalities of Caraguatatuba, Ubatuba and São Sebastião and Ilhabela in 2014.

Establishing a dominant early larval sex-selection strain in the Asian malaria vector Anopheles stephensi

BackgroundGenetic biocontrol interventions targeting mosquito-borne diseases require the release of male mosquitoes exclusively, as only females consume blood and transmit pathogens. Releasing only males eliminates the risk of increasing mosquito bites and spreading pathogens while enabling effective population control. The aim of this study is to develop robust sex-sorting methods for early larval stages in mosquitoes, enabling scalable male-only releases for genetic biocontrol interventions.MethodsTo address the challenge of sex-sorting in the Asian malaria vector Anopheles stephensi, we engineer Sexing Element Produced by Alternative RNA-splicing of a Transgenic Observable Reporter (SEPARATOR). This dominant fluorescent-based method, previously proven effective in Aedes aegypti, exploits sex-specific alternative splicing of a reporter to ensure exclusive male-specific expression early in development. The sex-specific alternative RNA splicing of the doublesex gene was selected as a target for engineering SEPARATOR due to its evolutionary conservation in insects. To expand SEPARATOR’s applicability for genetic sexing, we assessed the cross-species sex-specific RNA splicing activity of the An. gambiae doublesex (AngDsx) splicing module in An. stephensi. Male-specific enhanced green fluorescent protein (EGFP) expression was verified throughout the mosquito life cycle using a fluorescent stereomicroscope.ResultsOur results confirm that SEPARATOR regulates male-specific EGFP expression in An. stephensi and enables reliable positive male selection from the first instar larval stages. Molecular analysis demonstrates that male-specific EGFP expression is dependent on doublesex sex-specific splicing events. Additionally, the splicing module from An. gambiae operates effectively in An. stephensi, demonstrating evolutionary conservation in sex-specific splicing events between these species.ConclusionsSEPARATOR’s independence from sex-chromosome linkage provides resistance to breakage that could be mediated by meiotic recombination and chromosomal rearrangements, making it highly suitable for mass male releases. By enabling precise male selection from the first instar larval stages, SEPARATOR represents a significant advancement that will aid in the genetic biocontrol for Anopheles mosquitoes.Graphical

Monitoring of pyrethroid resistance in Aedes aegypti: first report of double and triple kdr mutations in Buenos Aires Province

BackgroundDengue is an emerging disease in Argentina due to the colonization of Aedes aegypti, the mosquito vector. Buenos Aires Province is the biggest and most populated district in Argentina, suffering dengue outbreaks of growing magnitude. During epidemic periods, pyrethroid insecticides are used in this country to control adult mosquitoes. Pyrethroid resistance in dengue vectors has been reported worldwide, making it necessary to implement resistance management strategies. The voltage-gated sodium channel is the target site of pyrethroids. Mutations in the gene encoding this protein, called kdr mutations, are usually the molecular cause of pyrethroid resistance in insects. In Ae. aegypti from the Americas, three kdr substitutions were described: V410L, V1016I, and F1534C. The diagnostic of kdr mutations is recommended for the early detection of pyrethroid resistance as well as the consequent planning of evidence-based control policies.MethodsWe distributed ovitraps across 16 localities in Buenos Aires Province, collecting 22,123 eggs. A total of 522 mosquitoes were genotyped in positions 1016 and 1534 of voltage-gated channel using multiplex high-resolution melting and/or TaqMan probe methods. A subset of 449 samples was also genotyped by a singleplex high-resolution melting method developed ad hoc and/or Sanger sequencing.ResultsWe have documented, for the first time to our knowledge in the central region of Argentina, the presence of the 1016Ikdr + 1534Ckdr allele. Additionally, our study reports the first identification of the V410L mutation in central Argentina. These results underscore a growing trend of pyrethroid resistance in Ae. aegypti, fueled by the widespread use of these insecticides.ConclusionsWe detected 1016Ikdr + 1534Ckdr and 410Lkdr mutations in central Argentina for the first time and improved the processivity and accuracy of kdr genotyping methods. The results are both a tool for resistance monitoring and a sign of alarm to direct efforts towards finding sustainable methods for vector control to complement or replace pyrethroids. Joint efforts between academia and authorities to develop and implement public policies for vector control are a productive way to transfer scientific results for their application in public health.Graphical

Eco-friendly synthesis of silver nanoparticles via Cassava starch: structural analysis and biocidal applications against aedes aegypti and pathogenic bacteria

Eco-friendly synthesis of silver nanoparticles via Cassava starch: structural analysis and biocidal applications against aedes aegypti and pathogenic bacteria

Spatial and temporal predictions of mosquito potential breeding sites and densities: integration of satellite imagery, in-situ data, and process-based modeling

Abstract. Dengue fever, primarily transmitted worldwide by the mosquito Aedes aegypti, poses significant public health challenges in tropical and subtropical regions. While effective vector control is crucial in the absence of reliable dengue vaccines, traditional control methods face obstacles like mosquito resistance to insecticides and a very high cost. By combining geospatial data, including satellite imagery, as descriptors, and entomological surveys as target variables in a Random Forest model, we predicted the number of potential mosquito breeding sites, derived the associated environmental carrying capacity for larvae, and used the Arbocarto process-based model to predict Ae.aegypti population densities in an urban region of French Guiana, South America. Our findings highlight that remote sensing data may help predict the number of potential breeding sites over urban areas. Our simulations indicate higher mosquito densities in urban residential areas and a strong spatial and temporal heterogeneity. These densities fluctuate according to intra-annual variations in temperature and precipitation, with higher densities associated with intermediate housing. A comparison with the conventional estimation of environmental carrying capacity for larvae in the current Arbocarto procedure highlights the advantages of our approach. Our study demonstrates the utility of integrating remote sensing with predictive modeling to enhance vector surveillance and control strategies, and provides a replicable approach for monitoring a dengue vector mosquito population in dynamic urban landscapes.

Impact of Nanoparticles Synthesized From Azadirachta indica (A. Juss) for Targeted Control of Malarial, Dengue, and Filariasis Vectors With Minimized Aquatic Toxicity

ABSTRACTIn the present study, biogenic silver nanoparticles (AgNPs) synthesized using Azadirachta indica leaf extract were evaluated for their toxic effects on both target and non‐target species. The botanical synthesized nanoparticles were tested against Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus and non‐targeted species Artemia salina and Eudrilus eugeniae at 24 h posttreatment. AgNPs were characterized using the following analytical techniques: UV‐Vis spectroscopy, FT‐IR, x‐ray diffraction (XRD), energy‐dispersive x‐ray spectroscopy (EDX), and scanning electron microscope (SEM) analysis. Results showed that AgNPs caused larvicidal activity with 90.66% mortality in An. stephensi, 97.33% in Ae. aegypti, and 93.33% in Cx. quinquefasciatus at 24 h posttreatment. A. indica‐derived AgNPs had lower LC50 (lethal concentration 50) and LC90 (lethal concentration 90) values of 44.803 and 252.886 ppm/mL in An. stephensi, 18.358 and 189.553 ppm/mL in Ae. Aegypti, and 36.492 and 219.800 ppm/mL in Cx. quinquefasciatus, respectively. Furthermore, AgNPs demonstrated lower toxicity effects with 50.66% mortality in A. salina and 38.66% mortality in E. eugeniae at 24 h posttreatment. Additionally, they exhibited lower LC50 and LC90 values of 240.996 and 533.618 ppm/mL in A. salina and 301.122 and 548.944 ppm/kg in E. eugeniae at 24 h posttreatment, respectively. The findings conclude that green‐synthesized AgNPs from plants offer a promising, cost‐effective, and target‐specific alternative for eco‐friendly mosquito larvicides. Future work should focus on developing these plant‐based agents with minimal non‐target toxicity to support sustainable pest control. Further research may explore large‐scale applications and assess the long‐term environmental impacts of AgNPs in integrated vector management programs.

Variable effects of transient Wolbachia infections on alphaviruses in Aedes aegypti.

Wolbachia pipientis (= Wolbachia) has promise as a tool to suppress virus transmission by Aedes aegypti mosquitoes. However, Wolbachia can have variable effects on mosquito-borne viruses. This variation remains poorly characterized, yet the multimodal effects of Wolbachia on diverse pathogens could have important implications for public health. Here, we examine the effects of transient somatic infection with two strains of Wolbachia (wAlbB and wMel) on the alphaviruses Sindbis virus (SINV), O'nyong-nyong virus (ONNV), and Mayaro virus (MAYV) in Ae. aegypti. We found variable effects of Wolbachia including enhancement and suppression of viral infections, with some effects depending on Wolbachia strain. Both wAlbB- and wMel-infected mosquitoes showed enhancement of SINV infection rates one week post-infection, with wAlbB-infected mosquitoes also having higher viral titers than controls. Infection rates with ONNV were low across all treatments and no significant effects of Wolbachia were observed. The effects of Wolbachia on MAYV infections were strikingly strain-specific; wMel strongly blocked MAYV infections and suppressed viral titers, while wAlbB had more modest effects. The variable effects of Wolbachia on vector competence underscore the importance of further research into how this bacterium impacts the virome of wild mosquitoes including the emergent human pathogens they transmit.

Differential sensitivity and specificity of Aedes aegypti and Anopheles gambiae to adenine nucleotide phagostimulants—an all-or-none response?

BackgroundThe decision to imbibe a blood meal is predominantly dependent on the sensitivity and specificity of haematophagous arthropods to blood-derived adenine nucleotides, in particular adenosine triphosphate (ATP). Despite previous efforts to identify and characterise the specificity and sensitivity to ATP and other adenine nucleotides, as well as the role of other blood-derived phagostimulants across the Culicidae, comparisons across species remain difficult.MethodsThe feeding response of the yellow fever mosquito Aedes aegypti and the African malaria vector Anopheles gambiae to adenine nucleotides in the presence of a carbonate buffer was assessed using a membrane feeding assay. The proportion of mosquitoes engorged and the volume imbibed by all mosquitoes was scored visually and spectrophotometrically. In addition, the proportion of prediuresing An. gambiae, as well as the volume engorged and prediuresed, was examined.ResultsAedes aegypti was more sensitive to adenine nucleotides than An. gambiae, but both species maintained specificity to these phagostimulants, demonstrating a dose-dependent bimodal feeding pattern, thereby expanding our understanding of the all-or-none blood-feeding hypothesis. Feeding on the bicarbonate buffer by An. gambiae—but not that of Ae. aegypti—demonstrated a species-specific variation in how blood phagostimulants are encoded. Adenine nucleotides, with and without bovine serum albumin, were observed to dose-dependently regulate the proportion of An. gambiae prediuresing and the volumes prediuresed but not volumes engorged.ConclusionsTaken together, the results of this study expand our understanding of how mosquitoes differentially assess and respond to blood meal constituents, and provide a basis for further physiological and molecular studies.Graphical

Essential Oils of The Leaves of Syzygium hemilamprum (F. Muell.) Craven & Biffin.: Chemical Analysis, Antimicrobial, Mosquito Larvicidal, Molecular Docking, and ADMET Studies.

The chemical composition of the essential oil and n-hexane extract from Syzygium hemilamprum leaves was first performed. Gas chromatography-mass spectrometry (GC-MS) analysis revealed that the essential oil was predominantly composed of monoterpene hydrocarbons (71.5 %) and oxygenated derivatives (20.2 %), with β-pinene (31.5 %), limonene (19.4 %), α-pinene (12.3 %), and α-terpineol (7.4 %) being the principal constituents. The n-hexane extract contained monoterpene hydrocarbons (42.2 %) and non-terpenic compounds (34.0 %), with β-pinene (32.8 %) and n-hexadecane (10.2 %) as the major components. Antimicrobial and mosquito larvicidal assays demonstrated that both samples exhibited antimicrobial activity against Staphylococcus aureus (Gram-positive), Pseudomonas aeruginosa (Gram-negative), and Saccharomyces cerevisiae (yeast), with a minimum inhibitory concentration (MIC) of 128 μg/mL for all tested organisms. Both samples also showed significant mosquito larvicidal activity against Aedes aegypti and Culex quinquefasciatus, with LC50 and LC90 values below 20 μg/mL at 24 and 48 hours post-treatment. Molecular docking studies suggested that limonene and α-terpineol could serve as potent inhibitors of mosquito odorant binding proteins. Additionally, an in silico analysis was performed to evaluate the physicochemical and ADMET (absorption, distribution, metabolism, and toxicity) properties of the major constituents of the essential oil.

Pathogenicity and sub-lethal activity of orally administered entomopathogenic fungi against two adult mosquito species, Aedes aegypti (Diptera: Culicidae) and Anopheles stephensi (Diptera: Culicidae)

Entomopathogenic fungi (EPF) are known for their efficacy in controlling adult mosquito populations by penetrating through their cuticle. However, the effect of oral administration of EPF on the biological parameters of Aedes aegypti and Anopheles stephensi remains largely unexplored. This study aimed to assess the effect of orally administrated EPF isolates on the survival, feeding behavior, fecundity, fertility, follicle development and host-searching behavior in response to yeast-generated CO2 of Ae. aegypti and An. stephensi. An initial screening of 50 isolates involved exposure of adult Ae. aegypti and An. stephensi by integument inoculation. Subsequently, the entomopathogenic effect of the five highly virulent isolates was confirmed through oral administration revealing Beauveria pseudobassiana 42–51 as a potent mosquito killer. B. pseudobassiana 42–51 was administered orally to evaluate sub-lethal effects. The results showed a 63 % and 43 % reduction in blood feeding of Ae. aegypti and An. stephensi, respectively. Furthermore, a decrease in egg hatching rate was observed, with a reduction of 83% for Ae. aegypti and 74% for An. stephensi on the seventh day following fungal administration, showing decreased hatchability in both species. Poor and abnormal follicle development was observed in both mosquito species. Also, the host-searching behavior was evaluated by attraction to CO2 utilizing a Y-tube olfactometer. A tendency of reduction in the attraction rate towards the odor was observed three days post-fungal administration. These findings underscore the significant impact of oral administration of B. pseudobassiana 42–51 on mosquitoes, highlighting not only its lethal effects but also sub lethal impacts on their biology. Moreover, this fungus may exhibit the potential to simultaneously control both mosquito species and serve as a biocontrol agent for the management of vector-borne diseases.

Effects of Daily Weather on Aedes Genus (Culicidae: Diptera) Arthropod Mosquito Vectors Profusion and Dengue Epidemics Transmission: A Systematic Review

Dengue is a vector borne flavivirus usually caused by DENV1 virus, and a quantity of cases reported with DENV2, DENV3, and DENV4 viruses transmitted by Aedes aegypti and Aedes albopictus (Diptera) day biting female vector mosquitoes, belongs to Culicidae family. The symptoms of dengue were first clinically confirmed in Japan during 1943, and later, it was recorded simultaneously in the Asia, Africa, and North America during the 1980. Dengue epidemics situation was reported in the 142 countries across the world Dengue and severe dengue, (Global Strategy for dengue prevention and control, (2012–2020), 2020) and the epidemics had been changed to endemic situation in many of the countries for the past 2 decades, and the people who have been living in the epidemic countries estimated at risk about 450 million. The occurrence of dengue outbreaks and it’s extend have been reported in the tropical and sub-tropical countries across the globe largely in metropolitan, small towns, and semi-urban settlements. The climate variables viz. temperature, relative humidity, saturation deficiency, and rainfall, are fuelled for conducing environment for the vector longevity, survival and also for dengue virus incubations in mosquitoes. Temperature ranges between > 21 and < 34, and relative humidity >70% and <90% has influence on the impact of variations on the vector survival, fecundity, fertility and longevity of female Aedes aegypti and flying capacity is reduced with temperature < 10 0C, and laying egg is reduced with increase of mean temperature >35 0C. Dengue epidemics clusters are directly correlated with abundance of Aedes species mosquitoes which are controlled by the annual average precipitation 300 mm to 1200 mm. The longitudinal dengue epidemics transmissions are mainly associated with monsoon and tend to have seasonal patterns, particularly, during and after the monsoon. Climatic factors are playing important role in the increase or decrease of vector mosquitoes as well as dengue epidemics. Therefore, the present study is addressed on the echelon of daily weather and seasonal change in climate condition and its control on the incidence of dengue outbreaks.

Pengaruh faktor sosial ekonomi dan lingkungan terhadap prevalensi demam berdarah dengue di wilayah kerja Puskesmas Sangurara, Bulili dan Birobuli Kota Palu

Dengue fever is one of the diseases that is still a problem in Indonesia. The incidence of DHF cases in Central Sulawesi, especially Palu City, has increased every year. Environmental and socio-economic factors affect the breeding of Aedes Aegypti mosquitoes. This study aims to determine the effect of socio[1]economic and environmental conditions on the incidence of DHF in the working areas of Sangurara, Bulili and Birobuli health centers in Palu City, Central Sulawesi. The method used quantitative with cross sectional research design. Sampling using Simple Random Sampling technique. The number of samples was 51 cases and 51 controls. Analysis technique used Chi- Square. From the results of the study, the variables that significantly influenced the incidence of DHF were education (p-value = 0.012), occupation (p-value = 1.000), income (p-value = 0.029), frequency of draining containers (p-value = 0.008), habit of hanging clothes (p-value = 0.031), home environment conditions (p-value = 0.005). While the variables that did not affect the incidence of DHF were the availability of lids on containers (p-value = 1.000), and the presence of larvae in containers (p-value = 0.127). This study concluded that education, income, frequency of container draining, habit of hanging clothes and home environmental conditions had a significant influence on the incidence of DHF and there was no influence between occupation, availability of container lids and the presence of larvae in containers.

Lethal Concentration (LC50) of Myristicin (Myristica fragrans Houtt) on Larva Aedes aegypti Instar III

Myristicin is an active substance that can be found in nutmeg plants. The purpose of this study was to determine the LC50 myristicin against larval instar III of Aedes aegypti. The method used is the experimental method. The samples used were myristicin isolates with varying concentrations of 5 ppm, 10 ppm, 15 ppm, and 20 ppm against Aedes aegypti instar III larvae. The parameters observed were LC50 Aedes aegypti larvae for 24 hours. The results obtained are based on calculations using IBM SPSS Statistics 22.0 using the probit formula it is known that LC50 isolate myristicin which can kill larvae at 12 hours is 10 ppm and the positive control is 10 ppm. These results are better when compared with results in other studies with LC50 of 111,002 ppm and positive control at 24 hours. Based on the results of research that has been done, it can be concluded that the LC50 isolate of Myristicin (Myristica fragrants Houtt) against Aedes aegypti Instar III larvae at the 12th hour is 10 ppm.

Identifying ecological factors mediating the spread of three invasive mosquito species: citizen science informed prediction

AbstractDue to their potential role in pathogen transmission, invasive mosquitoes pose considerable threats to human and animal health. Several studies have identified the most important ecological drivers mediating the establishment and spread of key mosquito species (e.g., Aedes aegypti, and Ae. albopictus), and made predictions for future distribution. We evaluated the effect of an exhaustive list of environmental predictors on the distribution of three invasive species in Hungary (Ae. albopictus, Ae. japonicus, and Ae. koreicus) by using the same standards for data collection based on citizen science observations. Current distribution maps of these species were generated from a 5-year survey, then were compared with various predictor maps reflecting climate, habitat type, food supply, traffic, and interspecific competition by using a boosted regression trees approach that resulted in a subset of variables with the strongest impact. The best predictor sets were used to predict the probability of occurrence of the focal species for the whole country, and these predictions based on citizen science were evaluated against the results of an independent recent field surveillance. We uncovered species-specific patterns and found that different predictor sets were selected for the three different species, and only predictions for Ae. albopictus could be validated with direct trapping data. Therefore, citizen science informed distribution maps can be used to identify ecological predictors that determine the spread of invasive mosquitoes, and to estimate risk based on the predicted distribution in the case of Ae. albopictus.

Toxicity and Sublethal Effect of Chlorantraniliprole on Multiple Generations of Aedes aegypti L. (Diptera: Culicidae)

Due to the quick development of insecticide resistance, it is crucial to optimize management programs by understanding the sublethal effects of effective insecticides like chlorantraniliprole on Aedes aegypti L. populations. Using age-stage and two-sex life tables, we investigated the sublethal impacts of chlorantraniliprole on Ae. aegypti. Larval duration in the progeny of exposed parents was reduced by 0.33–0.42 days, whereas, the longevity of male and female adults was decreased by 1.43–3.05 days. Similarly, the egg-laying capacity of F1 and F2 progeny of the exposed parents was significantly reduced from 27.3% to 41.2%. The mean generation time (T) increased up to 11.8% in exposed populations, and the net reproduction rate (Ro) decreased by 51.50–55.60%. After 24 h of chlorantraniliprole treatment, there was a significant increase in cytochrome P450 activity. Contrarily, the activity of glutathione S-transferase (GST) initially declined but started increasing after 48 h of treatment. This research highlights the importance of chlorantraniliprole in mosquito management, as well as the importance of considering sublethal effects when developing strategies to handle them. Having a thorough understanding of the harmful effects of insecticides on mosquito populations can greatly enhance the effectiveness of insecticide-based interventions, while also minimizing the risk of pest resurgence.

The V410L kdr allele in the VGSC confers higher levels of field resistance to permethrin in urban mosquito populations of Aedes aegypti (L.).

Females of Aedes aegypti transmit emerging arboviruses including Zika, dengue, yellow fever, and chikungunya. Control of these adult mosquitoes heavily relies on synthetic insecticides, including pyrethroids. However, insecticide resistance development in populations poses a significant challenge to vector control, particularly from knockdown resistance (kdr) mutations in the voltage-gated sodium channel (VGSC), the target of pyrethroids. This study investigated the field efficacy of Permanone, a pyrethroid-based insecticide, against Ae. aegypti by assessing the impact of three common kdr mutations (V410L, V1016I, F1534C) on mosquito survival under a real operational mosquito control scenario, by quantifying the pesticide delivered in the field. Field cage tests (FCTs) were conducted while conducting a realistic mosquito control application. Female mosquitoes from six operational areas from Harris County, TX, USA were exposed to Permanone delivered with a handheld sprayer. Permanone deposited near the cages was estimated from aluminum boats placed in the field during FCTs using gas chromatography-mass spectrometry (GC-MS). Mortality rates were recorded, and individual mosquitoes were genotyped for kdr mutations. A probit regression model was used to analyze the factors influencing mosquito survivorship. As the distance from the application source route increased, the amount of Permanone deposited decreased, resulting in higher survivorship frequency of Ae. aegypti females with the triple-resistant kdr genotype (LL/II/CC). The L allele at the 410-site significantly contributed to an increased resistance level when co-occurring with other kdr mutations. This study linked the survival probabilities of mosquitoes with different kdr genotypes, and the amount of pesticide they received in the field. Pesticide quantification, control efficacy results and genotyping allowed us to empirically determine the impact of genotypic resistance on vector control in the field. © 2024 Society of Chemical Industry.

Larvicidal Efficacy of <i>Cassia singueana</i> methanol leaf extract against <i>Aedes aegypti</i> and <i>Culex quinquefasciatus</i>

Despite the persistent control measures, mosquitoes remain abundant and the disease they transmit persists globally posing significant health challenges. There is increasing enthusiasm for exploring botanical solutions as substitutes for conventional chemical insecticides, driven by their broad insecticidal attributes, eco-friendly nature and compatibility with various ecological settings. As such, the study was designed to assess the larvicidal properties of methanol leaf extract of Cassia singueana against Aedes aegypti and Culex quinquefasciatus. The plant was subjected to preliminary and GC-MS phytochemicals screening. Larvicidal bioassay was conducted using six different concentrations (0.10-3.20 mg/ml) and 31.25mg/l temphos and distilled water were used as positive and negative control respectively. The experimental set up was observed after 24 h and the lethal concentrations (LC50 and LC99) were determined using Probit analysis. Preliminary phytochemical screening of C. singueana methanol leaf extract revealed the presence of alkaloids, cardiac glycosides saponins, phenolic compounds, tannins, steroid carbohydrates, flavonoids, and terpenoids. Eighteen (18) bioactive compounds were identified in the methanol leaf extract of C. singueana which includes 1,5-Heptadien-3-yne, 2-Hydroxy-3-methylbenzaldehyde, 2-Butenoic acid, Acetonitrile, 2,2'-iminobis-, 7,11-Hexadecadienal,2-Hexyne, among others. The extract had larvicidal activity against A. aegypti and C. quinquefasciatus with LD99 of 5.44 mg/ml and 15.85 mg/ml respectively at 24 h post-treatment. This study offers valuable perspectives on the possible application and advancement of C. singueana leaf extract as a potential bioinsecticide against A. aegypti and C. quinquefasciatus and consequently control the diseases transmitted by them.

Eco-friendly synthesis of silver nanoparticles using Phyllanthus niruri leaf extract: Assessment of antimicrobial activity, effectiveness on tropical neglected mosquito vector control, and biocompatibility using a fibroblast cell line model

Abstract Mosquitoes are rapidly advancing as vectors of several severe diseases. The increasing resistance of mosquitoes and the environmental harm caused by insecticides pose significant challenges for eradicating mosquito vectors. In this study, 18 plant extracts were tested for larvicidal properties against Aedes aegypti, Culex quinquefasciatus, and Anopheles stephensi larvae. Phyllanthus niruri (Pn) showed enhanced larvicidal activity in both laboratory and field trials. The biosynthesis of silver nanoparticles (AgNPs) using Pn leaf methanol extract (Pn-LME) was confirmed by UV-visible spectroscopy, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and Fourier-transform infrared spectroscopy. Among various concentrations, 3 mM AgNPs exhibited significant LC90 values of 0.83, 1.46, and 9.11 ppm compared to 9.25, 93.48, and 14.60 ppm of Pn-LME against A. stephensi, C. quinquefasciatus, and A. aegypti, respectively. This indicates the high mortality of mosquito vectors at low AgNP concentrations. Additionally, Pn-AgNPs showed enhanced antibacterial activity and no cytotoxicity in normal fibroblast cells (L929). Field trials demonstrated a 98.70% decrease in mosquito larval density at A. stephensi breeding sites, a 96.55% reduction at C. quinquefasciatus sites, and a 97.85% reduction at Ae. aegypti sites. This study presents an eco-friendly and cost-effective AgNP bio-pesticide synthesized from Pn leaves for controlling and preventing the transmission of filarial, dengue, and malaria vectors.

Unveiling the Larvicidal Potential of Golpar (Heracleum persicum Desf. ex Fisch.) Essential Oil and Its Main Constituents on Aedes and Anopheles Mosquito Vectors

Natural products are thoroughly studied as valuable alternatives to synthetic insecticides. Heracleum persicum Desf. ex Fisch. (Apiaceae), commonly known as Golpar, is an Iranian medicinal plant largely employed as a spice, which has previously revealed insecticidal potential. The chemical composition of H. persicum essential oil (EO) was investigated by GC-MS and was mainly dominated by hexyl butyrate (36.1%) and octyl acetate (23.7%). The EO and its main esters were tested on three mosquito species. Aedes aegypti (L.) larvae were the most sensitive to all tested products. Lethal concentrations (LC50) of 59.09, 53.59, and 47.05 ppm were recorded for the EO, hexyl butyrate, and octyl acetate, respectively. Aedes albopictus (Skuse) and Anopheles gambiae Giles demonstrated comparable sensitivity to the EO, with LC50 values of 102.97 and 97.91 ppm, respectively, whereas the isolated constituents appeared more active on An. gambiae (LC50 of hexyl butyrate and octyl acetate of 70.97 and 60.71 ppm, respectively) with respect to Ae. albopictus (LC50 of hexyl butyrate and octyl acetate of 85.40 and 91.38 ppm, respectively). Low toxicity was registered for both EO and single components against human embryonic kidney (HEK293) cells. Overall, the H. persicum EO, hexyl butyrate, and octyl acetate could be further considered for larvicide development.

Analysis of the interrelationship between precipitation and confirmed dengue cases in the city of Recife (Brazil) covering climate and public health information.

Large-scale epidemics of arboviruses, such as dengue, have heightened societal awareness regarding the necessity of combating the primary transmission vectors. Equally critical is the identification of environmental conditions and variables that influence vector population dynamics. Aedes aegypti, the primary vector of arboviruses such as dengue and Zika in Brazil, is closely associated with the climatic and geographical conditions of urban environments. This study examines the relationship between precipitation and confirmed dengue cases in Recife (Brazil), employing regression and quantile analyses to evaluate the influence of meteorological conditions on the disease's spread. The findings reveal a direct correlation between monthly averages of precipitation and confirmed cases, although this is apparent only when excluding years of epidemic peaks. The highest number of cases generally aligns with the rainy season, and the lowest with the dry season, with weak, moderate and strong precipitation events being closely linked to increased dengue incidence. However, notable discrepancies were identified: four out of six major outbreaks occurred in drier months, challenging the assumption of a straightforward relationship between rainfall and dengue incidence. These findings underscore the multifaceted nature of dengue dynamics, suggesting that while precipitation plays a significant role, other factors, including serotype circulation and broader climatic phenomena, are equally critical in driving outbreaks. This complexity highlights the need for a more comprehensive understanding of the mechanisms influencing dengue epidemics.