Dengue Vector Research Articles

Diversity of mosquito natural enemies and their feeding efficacy on Aedes vectors.

Mosquito-bome diseases are a major health issue among communities in Asia, and dengue has become a serious public health concern in Sri Lanka with varying magnitude since 1960. With the realization of the failures and limitations of current vector control strategies, the authorities are moving towards simple, low- cost, and eco-friendly vector management methods. Thus, the present study was devised to evaluate the potential densities of mosquito natural enemies in natural water habitats in Galle district, Sri Lanka, and to investigate the feeding efficacy of prominent mosquito natural enemies on main dengue vectors (Aedes sp.) in a laboratory setting. The survey was carried out using eight sentinel sites in Galle district, and samples of mosquito natural enemies and mosquito larvae were collected, and identified using taxonomic keys. Study records, the aquatic insects of family Hydrometridae, Belostomatidae, Notonectidae, Nepidae, Ranat- ridae, and Corixidae as dominant mosquito natural enemies, and Libellulidae and Dytiscidae insects as sub-dominant families. The highest density of the family Hydrometridae was recorded in rural, natural inland, and rocky study sites. The order Hemiptera was recorded as the key order of the mosquitos' natural enemies in Galle district. The family Hydrometridae had the highest density of recorded mosquito natural enemies. Aedes aegypti and Ae. albopictus were recorded as abundant vector mosquitoes. Family Nepidae is the most effective natural mosquito predator on Ae. aegypti and Ae. albopictus, and this knowledge will be vital for implementing future biological control strategies for Aedes vectors in Sri Lanka.

Bacillus thuringiensis israelensis VCRC B650 culture filtrate useful for mosquito oviposition attractant and larvicidal action

Oviposition attractants hold the potential attention for monitoring and controlling mosquitoes by enticing them to deposit eggs at specific locations. In this study, the bacterial culture filtrate of Bacillus thuringiensis var. israelensis VCRC B650, previously isolated from clay soil at an agricultural site in U.T of Puducherry, was investigated for the first time. This larvicidal bacterium was assessed for oviposition attractancy against dengue and filarial vectors, namely, gravid females of Aedes aegypti and Culex quinquefasciatus, respectively. The investigation revealed that, at 1:1 dilution of bacterial culture filtrate and water, Cx. quinquefasciatus exhibited significant attraction, with an oviposition activity index (OAI) value of +0.92, surpassing the standard threshold value of +0.30. The OAI of Bti culture filtrate at a 1:1 dilution was also compared with a standard oviposition attractant, p-cresol, at a concentration of 10ppm. It was observed that the Bti culture filtrate demonstrated a significant oviposition attractant effect, with 80 per cent more egg rafts laid, compared to p-cresol at 20 per cent. GC-MS analysis showed that there were 25 compounds present in the Bti culture supernatant, and out of those, only one compound, namely, benzaldehyde, was effective in showing oviposition attraction.

Wolbachia Natural Infection of Mosquitoes in French Guiana: Prevalence, Distribution, and Genotyping

Wolbachia are the most spread bacterial endosymbionts in the world. These bacteria can manipulate host reproduction or block virus transmission in mosquitoes. For this reason, Wolbachia-based strategies for vector control are seriously considered or have already been applied in several countries around the world. In South America, Wolbachia have been studied in human pathogen vectors such as sand flies and mosquitoes. In French Guiana, the diversity and distribution of Wolbachia are not well known in mosquitoes. In this study, we screened for Wolbachia natural infection in mosquitoes in French Guiana by using 16S rRNA, Wolbachia surface protein (WSP), and multi-locus sequence typing (MLST) molecular assays. A total of 29 out of 44 (65.9%) mosquito species were positive for natural Wolbachia infection according to the PCR results, and two Wolbachia strains co-infected three specimens of Mansonia titillans. Then, we analyzed the phylogenetic relationships among the Wolbachia detected. All of the tested specimens of Aedes aegypti, the major dengue vector of French Guiana, were negative. These results regarding Wolbachia strain, distribution, and prevalence in mosquitoes from French Guiana highlight Wolbachia–mosquito associations and pave the way for a future Wolbachia-based strategy for vector control in this Amazonian territory.

Context-specific variation in life history traits and behavior of Aedes aegypti mosquitoes.

Aedes aegypti, the vector for dengue, chikungunya, yellow fever, and Zika, poses a growing global epidemiological risk. Despite extensive research on Ae. aegypti's life history traits and behavior, critical knowledge gaps persist, particularly in integrating these findings across varied experimental contexts. The plasticity of Ae. aegypti's traits throughout its life cycle allows dynamic responses to environmental changes, yet understanding these variations within heterogeneous study designs remains challenging. A critical aspect often overlooked is the impact of using lab-adapted lines of Ae. aegypti, which may have evolved under laboratory conditions, potentially altering their life history traits and behavioral responses compared to wild populations. Therefore, incorporating field-derived populations in experimental designs is essential to capture the natural variability and adaptability of Ae. aegypti. The relationship between larval growing conditions and adult traits and behavior is significantly influenced by the specific context in which mosquitoes are studied. Laboratory conditions may not replicate the ecological complexities faced by wild populations, leading to discrepancies in observed traits and behavior. These discrepancies highlight the need for ecologically relevant experimental conditions, allowing mosquito traits and behavior to reflect field distributions. One effective approach is semi-field studies involving field-collected mosquitoes housed for fewer generations in the lab under ecologically relevant conditions. This growing trend provides researchers with the desired control over experimental conditions while maintaining the genetic diversity of field populations. By focusing on variations in life history traits and behavioral plasticity within these varied contexts, this review highlights the intricate relationship between larval growing conditions and adult traits and behavior. It underscores the significance of transstadial effects and the necessity of adopting study designs and reporting practices that acknowledge plasticity in adult traits and behavior, considering variations due to larval rearing conditions. Embracing such approaches paves the way for a comprehensive understanding of contextual variations in mosquito life history traits and behavior. This integrated perspective enables the synthesis of research findings across laboratory, semi-field, and field-based investigations, which is crucial for devising targeted intervention strategies tailored to specific ecological contexts to combat the health threat posed by this formidable disease vector effectively.

Synergistic Larvicidal and Pupicidal Toxicity and the Morphological Impact of the Dengue Vector (Aedes aegypti) Induced by Geranial and trans-Cinnamaldehyde.

Monoterpenes are effective and eco-friendly alternatives to conventional chemical larvicides. We tested single and binary mixtures of monoterpenes-geranial and trans-cinnamaldehyde-for their larvicidal and pupicidal activities against Aedes aegypti L. and for non-target toxicity on guppies (Poecilia reticulata Peters), using 1% (w/w) temephos as a reference. Geranial and trans-cinnamaldehyde at 250 ppm showed stronger larvicidal and pupicidal activities with a 100% mortality rate and an LT50 ranging from 0.3 to 0.6 h. All combinations were strongly synergistic against larvae and pupae compared to single formulations, with an increased mortality value (IMV) of 6% to 93%. The combination of geranial + trans-cinnamaldehyde (1:1) at 200 ppm showed the highest impact, with an IMV of 93%. The strongest larvicidal and pupicidal activities, a 100% mortality rate, and an LT50 of 0.2 h were achieved by geranial + trans-cinnamaldehyde (1:1) 500 ppm. They were thirty times more effective than a 1% temephos solution (LT50 ranging from 6.7 to 96 h) and caused obviously shriveled cuticles and a swollen respiratory system. All single and binary mixtures were not toxic to the guppies. Thus, the combination of geranial + trans-cinnamaldehyde has great potential as a safe insecticide for controlling mosquito larvae and pupae.

Use of Ovitrap for The Spatial Mapping of Aedes spp. in The Endemic Area of Dengue Fever of Baitussalam District Aceh Besar

The strategy for controlling dengue vector through periodic monitoring is an effective mitigation effort. Periodic monitoring of dengue vectors is generally more often conducted in the larval stage rather than the egg stage. Monitoring Aedes eggs periodically using ovitraps is more effective because it is not restricted by season. The objective of this study is to conduct spatial mapping of Aedes spp. distribution using ovitraps in Baitussalam Subdistrict, Aceh Besar. This study used observational methods and purposive sampling to determine the sample houses for ovitrap placement. A total of 50 houses in 5 gampong/village were observed. Analysis was conducted using the GPS Essentials application and Google Earth Pro software. The results showed that there were 4 gampong with Aedes spp. egg distribution in Baitussalam Subdistrict, Aceh Besar, namely Gampong Blang Krueng, Gampong Baet, Gampong Kajhu, and Gampong Cadek, while in Gampong Lam Ujong, no ovitraps positive for Aedes eggs. Ovitraps are an effective method for mapping Aedes spp. in efforts to control dengue. Keyword: Aedes spp; Dengue fever; ovitrap; spatial mapping.

Larvicidal potential of Trachyspermum ammi essential oil and Delphinium speciosum extract against malaria, dengue, and filariasis mosquito vectors

Mosquito-borne diseases, such as malaria, dengue, and Zika, pose major public health challenges globally, affecting millions of people. The growing resistance of mosquito populations to synthetic insecticides underscores the critical need for effective and environmentally friendly larvicides. Although chemical pesticides can initially be effective, they often lead to negative environmental consequences and health hazards for non-target species, including humans. This study aimed to evaluate the larvicidal effects of Trachyspermum ammi essential oil and Delphinium speciosum extract on the larvae of three major mosquito species: Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus. Mosquito larvae of Ae. aegypti, An. stephensi, and Cx. quinquefasciatus were reared under controlled laboratory conditions. The larvicidal activity of T. ammi essential oil and D. speciosum extract was evaluated through standard bioassays, using various concentrations of essential oils (10, 20, 40, 80, and 160 ppm) and extracts (160, 320, 640, 1280, and 2560 ppm) to determine the lethal concentration (LC50) values after 24 h of exposure. Fresh plant materials were collected, with the essential oil extracted via hydro-distillation, and the extract prepared using methanol solvent extraction. The chemical composition of T. ammi essential oil was examined using gas chromatography-mass spectrometry (GC-MS). Additionally, the preliminary analysis of the chemical compounds in D. speciosum extract was carried out using thin layer chromatography (TLC) and nuclear magnetic resonance spectroscopy (NMR) techniques. The results indicated that the essential oil of T. ammi exhibited more effective larvicidal activity compared to the D. speciosum extract. Specifically, the essential oil demonstrated LC50 values of 18 ppm for Cx. quinquefasciatus and 19 ppm for Ae. aegypti. In contrast, the D. speciosum extract showed the strongest larvicidal effect against An. stephensi, with an LC50 of 517 ppm. Concentrations of 40 ppm of the essential oil and 1280 ppm of the extract resulted in 100% mortality across all three species. Both the essential oil of T. ammi and the D. speciosum extract exhibited concentration-dependent larvicidal activity, and these results were statistically significant (p < 0.001) compared to the no-treatment group. GC-MS analysis revealed thymol (88.95%), o-cymen-5-ol (4.11%), and γ-terpinene (2.10%) as the major constituents of the T. ammi essential oil. Additionally, TLC verified the presence of alkaloids in both chloroform and methanolic extracts. Proton NMR identified a diterpene structure for these alkaloids. These findings suggest that T. ammi essential oil is a promising candidate for natural mosquito control strategies. Given its efficacy, further research is warranted to explore its potential in integrated vector management programs.

A pilot field study on Dengue vectors with locally manufactured inexpensive gravid female traps

High prevalence of Aedes aegypti and Ae. albopictus vectors and dengue incidence as well as the presence of the four dengue virus serotypes underscore the need for effective and simple tools to monitor dengue vectors in Sri Lanka. Field studies were therefore undertaken with inexpensive gravid female trap (GFT) fabricated from local materials in Jaffna city in northern Sri Lanka. The study was initiated in April 2022, and GFT-based mosquito collection was conducted from June 2022 to April 2023. Five blocks of 30 to 40 houses, were selected in areas of high dengue prevalence in Jaffna city. Thirty houses were selected within each block and provided with five traps to be placed indoor and outdoor in each house. Conventional larval indices were determined at the beginning, middle and end of the study. Nine rounds of GFT collections were performed to identify and quantify trapped mosquitoes, their parity, and infection with virus serotypes. A total of 2177 and 3069 Aedes were collected respectively in indoor and outdoor GFTs, during nine rounds of collections and identified at the species level where possible. A total of 679 and 433 Ae. aegypti and Ae. albopictus were collected in indoor traps and 377 and 1288 in outdoor traps respectively. Adult and larval indices decreased respectively by 50% and 100% by the end of the study. Parous mosquitoes comprised 93% (of 120) and 94% (of 288) of the collected Ae. aegypti and Ae. albopictus respectively. In 110 pools of female Ae. aegypti and Ae. albopictus screened for virus serotype by PCR, five pools of Ae. aegypti and six pools of Ae. albopictus from both indoor and outdoor collections were positive for DENV-2. GFTs fabricated with locally available and inexpensive materials described here can be effective for monitoring the prevalence of Aedes vector species, parity and dengue virus infection status. The larval indices suggest that the use of GFTs can contribute to reducing dengue transmission.

Potential Establishment, Prevalence of Dengue Vector, Aedes sp. and its Risk Map in Hurghada Region, Red Sea, Egypt

Potential Establishment, Prevalence of Dengue Vector, Aedes sp. and its Risk Map in Hurghada Region, Red Sea, Egypt

Knowledge, attitudes, and practices of healthcare professionals regarding dengue fever in high-risk regions of southeastern Iran

BackgroundDengue fever (DF) is one of the most prevalent arboviral infections worldwide. In Iran, the dengue-positive serological cases as well as the presence of the dengue vector Aedes aegypti have raised health concerns, highlighting the need to enhance the dengue surveillance system. This study aims to assess the knowledge, attitudes, and practices (KAP) of healthcare professionals (HCPs) regarding dengue fever in a large and high-risk region of southeastern Iran.MethodsA total of 492 HCPs were recruited using a multi-stage sampling method from May 2022 to July 2023. Data were collected using a self-administered questionnaire. Data analysis was done using independent t-tests, one-way analysis of variance (ANOVA), one-factor and multi-factor general linear models, and simple and multiple regression models.ResultsAbout two-thirds (71%) of the participants did not receive any training on DF. A small percentage of participants were familiar with ovitrap (32.6%) and only 21.7% knew that destroying larval breeding sites could not eliminate the dengue vector. The knowledge of disease symptoms among HCPs was found to be lower in border areas compared to non-border areas (P = 0.018). However, the practice situation in HCPs working in border areas was better than in non-borders (P = 0.003). According to the multiple regression model, the most influential factors associated with knowledge, attitude, and practice were the type of healthcare facility and passing the DF training course. Additionally, education level, work experience, and gender were identified as other factors associated with it, respectively. Significant correlations were found between knowledge and practice (P < 0.001), indicating that higher knowledge led to better practice. Similarly, a positive attitude was significantly linked to better practice (P < 0.001).ConclusionRegular, targeted, and continuous training courses are necessary to improve the knowledge level of HCPs, particularly those with lower education levels working in low-level health centers. Utilizing comprehensive dengue KAP studies to evaluate the status and impact of health education programs and identify gaps between knowledge and practice should be a research priority.

Effective Mosquito Repellents: Myrcene- and Cymene-Loaded Nanohydrogels against Aedes aegypti.

Aedes mosquito-borne diseases remain a significant global health threat, necessitating effective control strategies. This study introduces monoterpenes-based nanohydrogels for potential use as repellents against Aedes aegypti, the primary dengue vector worldwide. We formulated hydrogels using cymene- and myrcene-based nanoemulsions with different polymers: chitosan, carboxymethylcellulose (CMC), and carbopol®. Our evaluations of rheological, texture, and bioadhesive properties identified CMC hydrogel as the most promising gelling agent for topical application, exhibiting sustained monoterpene release over 12 h with low skin permeation and high retention in the stratum corneum. Myrcene-loaded CMC hydrogel achieved a 57% feeding deterrence compared to 47% with cymene hydrogel in the mosquito membrane-feeding model. Molecular docking studies revealed interactions between myrcene and an essential amino acid (Ile116) in the Ae. aegypti odorant-binding protein 22 (AeOBP22), corroborating its higher repellent efficacy. These findings suggest that myrcene-loaded CMC hydrogels offer a promising, minimally invasive strategy for personal protection against Ae. aegypti and warrant further investigation to optimize monoterpene concentrations for vector control.

Functional dissection of mosquito humidity sensing reveals distinct Dry and Moist Cell contributions to blood feeding and oviposition

Aedes aegypti mosquitoes are major vectors of dengue, chikungunya, and other arboviral diseases. Ae. aegypti's capacity to reproduce and to spread disease depends on the female mosquitoes' ability to obtain blood meals and find water-filled containers in which to lay eggs (oviposit). While humidity sensation (hygrosensation) has been implicated in these behaviors, the specific hygrosensory pathways involved have been unclear. Here, we establish the distinct molecular requirements and anatomical locations of Ae. aegypti Dry Cells and Moist Cells and examine their contributions to behavior. We show that Dry Cell and Moist Cell responses to humidity involve different ionotropic receptor (IR) family sensory receptors, with dry air-activated Dry Cells reliant upon the IR Ir40a, and humid air-activated Moist Cells upon Ir68a. Both classes of hygrosensors innervate multiple antennal sensilla, including sensilla ampullacea near the antennal base as well as two classes of coeloconic sensilla near the tip. Dry Cells and Moist Cells each support behaviors linked to mosquito reproduction but contribute differently: Ir40a-dependent Dry Cells act in parallel with Ir68a-dependent Moist Cells to promote blood feeding, while oviposition site seeking is driven specifically by Ir68a-dependent Moist Cells. Together these findings reveal the importance of distinct hygrosensory pathways in blood feeding and oviposition site seeking and suggest Ir40a-dependent Dry Cells and Ir68a-dependent Moist Cells as potential targets for vector control strategies.

First detection of V410L kdr mutation in Aedes aegypti populations of Argentina supported by toxicological evidence

BackgroundAedes aegypti (L.) is the main vector of dengue, yellow fever, Zika, and chikungunya viruses in many parts of the world, impacting millions of people worldwide each year. Insecticide-based interventions have been effective in controlling Aedes mosquito populations for several years, but in recent times, resistance to these compounds has developed, posing a global threat to the control of this mosquito.MethodsOvitraps were used to collect A. aegypti eggs in the cities of Tartagal and San Ramón de la Nueva Orán (Salta), Puerto Iguazú (Misiones), and Clorinda (Formosa). World Health Organization (WHO)-impregnated papers with the discriminating concentration (DC) of permethrin, 5X, 10X and pirimiphos methyl were used for the toxicological bioassays. We also genotyped each sample for the three kdr single nucleotide polymorphisms (SNP): V410L, V1016I, and F1534C in individual TaqMan quantitative PCR (qPCR) reactions.ResultsAll investigated A. aegypti populations were highly resistant to permethrin, as the mortality percentage with the permethrin 10×DC remained below 98%. However, all populations were 100% susceptible to pirimiphos-methyl. Kdr genotyping demonstrated the presence of the V410L mutation for the first time in Argentina in all the populations studied. A prevalence of the triple mutant genotype (LL + II + CC) was observed in the northeastern cities of Clorinda (83.3%) and Puerto Iguazú (55.6%).ConclusionsThis study demonstrates for the first time the presence and intensity of resistance to permethrin in different populations from Argentina, and correlates the observed phenotype with the presence of kdr mutations (genotype).Graphical

In vivo efficacy of date palm pit extract based chromone derivative against Aedes aegypti dengue vectors in Saudi Arabia

AbstractThis study investigated the in vivo efficacy of a chromium derivative extracted from date palms pit against Aedes aegypti the third instar larvae, the known vector of dengue fever in Saudi Arabia. Chromone 1, a flavonoid chromone component, was isolated from the alcoholic extract of date palm pits (DPP) using High‐performance liquid chromatography (HPLC). The results showed that exposure of A. aegypti larvae to whole DPP extract and chromone 1 for 24 h resulted in significant insecticidal efficacy with LC50 values of 132.82 and 54.64 ppm, respectively. The same concentrations also effectively inhibited AChE (acetylcholinesterase) activity up to −56.83 and −58.58%, respectively, compared to controls. The acetylcholine bromide test further confirmed the interaction between chromone 1 and AChE. The results also revealed that the chromone 1 treatment altered Deoxyribonucleic Acid (DNA) and protein content. It also exhibited that the extract of date palm pits DPP can effectively serve as sustainable ingredients for the control management of A. aegypti.

Influence of nutrition during previtellogenesis on the follicular development in the Asian Tiger mosquito, Aedes albopictus (Skuse) (Diptera: Culicidae).

Dengue fever poses a global public health threat, with 2.5 billion people at risk of infection each year. Because the Aedes albopictus is the primary vector of dengue, it is closely monitored and handled. The efficiency of Dengue eradication is strongly dependent on understanding a female mosquito's physiological age. This study addresses key entomological issues about the impact of previtellogenic nutrition on egg production mechanisms. Ovarian development included two distinct periods: previtellogenesis and vitellogenesis. Sugar intake during previtellogenesis influences the size of the blood meal. The major parameter influencing the vitellogenesis process is the presence of a hematophagous feeding event following sugar concentration. Upon subjecting female mosquitoes to sucrose, the ovarian follicles entered the third phase of previtellogenesis. Once females feed on blood following sucrose, ovarian development enters the vitellogenesis, and the oocyte cytoplasm reveals that the yolk granules are organized in one or two rows like a crown, increasing oocyte size. Females fed 15% sucrose before a blood meal, have the largest vitellogenic growth, and follicular size, which is seven times greater than those fed water only. Fecundity increased by 78.7% by adding 7% sucrose to the diet. Mitochondria within oocytes increase, most likely due to their transportation from the nurse cells, where the yolk is synthesized. This study describes in detail the histological alterations detected in the ovaries during the previtellogenesis as well as those associated with yolk formation, suggesting that yolk protein deposition in the oocyte is associated with blood meal, independent of sucrose feeding. RESEARCH HIGHLIGHTS: Adult nutrition during previtellogenesis significantly impacts various biological parameters and the physiological age of adults of Aedes albopictus. Female mosquitoes experienced significant growth in vitellogenic development, vectorial capacity, and follicular size after consuming a diet with 15% sucrose before a blood meal.

Predatory Potential of Nymphal Odonates on Aedes aegypti Developing in Freshwater and Brackish Water Habitats.

Aedes aegypti, the primary vector of dengue, undergoes preimaginal development in brackish water (BW). However, dengue vector control exclusively targets freshwater (FW) habitats. The present study evaluated the predatory efficacy of nymphal odonates that can develop in both FW and BW. Nymphs of three damselfly and three dragonfly species from FW and BW habitats were identified and acclimatized to FW (<0.5 gL-1 salt) and BW (10 gL-1 salt) mesocosm conditions. The experiment was repeated nine times with nine different individual predators per species under both salinity conditions. One hundred L3 Ae. aegypti from FW and BW laboratory colonies were introduced to determine the predatory rate (PR) and clearance rate (CR) after 24, 48, and 72 h, and one hundred L3 larvae were introduced every 24 h. The dragonfly nymph Hydrobasileus croceus and the damselfly nymph Paracercion hieroglyphicum showed the highest PR and CR under both rearing conditions at all times. However, damselfly and dragonfly nymphs significantly (p < 0.05) differed in their CR under both FW and BW conditions. Thus, all six odonate species have predatory potential and this suggests that they could be used as biological control agents to eliminate preimaginal stages of Ae. aegypti developing in both FW and BW habitats.

Efficacy of sugar‐protein non‐membranous dietary system for diapause egg production in Aedes albopictus mosquitoes under short‐day conditions

AbstractThe Asian tiger mosquito, Aedes albopictus (Skuse) (Diptera: Culicidae), is a global vector of dengue, chikungunya and zika viruses. With extreme adaptability of survival as diapause eggs, this mosquito has invaded and established in temperate climatic zones. The diapause eggs are specially programmed to overcome the harsh winter conditions in temperate habitats. In the laboratory, diapausing females are reared from early larval instars under short‐day conditions (21°C and 16D:8 L photoperiods). Aedes albopictus is normally fed on Guinea pigs for the rearing of diapause mosquitoes which requires ethical approval from the animal use committee and costly arrangements. Therefore, the present study was conducted to find whether bovine serum albumin protein (10%) with sucrose (5%) solution (SAP‐10) offered through a membrane‐free feeding system would result in an alternative diet for the production of diapause eggs in comparison to blood‐feeding. This feeding system shows a considerable rate of engorgement of diapausing females under short‐day conditions and produced 30.8 diapause eggs/female in comparison to blood‐feeding on a guinea pig (40.9 eggs/female). The diapause rate of viable eggs for the SAP‐10 diet (95.28%) was similar to the blood‐feeding (96.32%). The findings suggest that the present diet feeding system is a promising tool for the rearing of diapause Ae. albopictus mosquitoes under short‐day conditions. Further studies are suggested to evaluate the physiological and developmental aspects of mosquitoes reared on the diet.

Antibacterial, mosquito larvicidal, and cytotoxicity potential of AgNPs synthesized using Pittosporum undulatum under in vitro conditions

In this study, the phytochemical profile and silver nanoparticle (AgNPs)-synthesizing ability of Pittosporum undulatum methanol extract were investigated. Furthermore, biological applications of the AgNPs, such as antibacterial effect (against Klebsiella pneumoniae, Staphylococcus aureus, Bacillus subtilis, and Escherichia coli), mosquito larvicidal effect (against Anopheles stephensi, Culex quinquefasciatus, and Aedes aegypti), and cytotoxicity (against fibroblast cell line L929) were evaluated using in vitro experiments. The phytochemical analysis revealed that the methanol extract contained cardiac glycosides, terpenoids, saponins, alkaloids, flavonoids, glycosides, coumarins, phenolics, and tannins. Furthermore, standard characterization techniques such as UV–Vis spectrometry, SEM, TEM, FTIR, and XRD confirmed that the methanol extract of P. undulatum effectively synthesized the AgNPs. The synthesized AgNPs had a spherical shape and size of 20–200 nm. The bactericidal analysis revealed that the AgNPs have dose-dependent antibacterial activity. The MTT assay showed that the AgNPs were bio-compatible up to a dosage of 250 μg mL−1 in the normal fibroblast cell line L929. Furthermore, the LC50 values for AgNPs against larvae of An. stephensi, Cx. quinquefasciatus, and Ae. aegypti were 0.4, 4.7, and 1.2 ppm, respectively. Field trials demonstrated that the larvicidal effect was enhanced within 24–72 h, and the rate of reduction increased over time. Thus, our findings provide an ideal sustainable AgNP bio-pesticide to combat filarial, dengue, and malaria vectors.

Delineating dengue risk zones in Jaipur: An interdisciplinary approach to inform public health strategies.

Dengue fever (DF) is a pervasive public health concern in tropical climates, with densely populated regions, such as India, disproportionately affected. Addressing this issue requires a multifaceted understanding of the environmental and sociocultural factors that contribute to the risk of dengue infection. This study aimed to identify high-risk zones for DF in Jaipur, Rajasthan, India, by integrating physical, demographic, and epidemiological data in a comprehensive risk analysis framework. We investigated environmental variables, such as soil type and plant cover, to characterize the potential habitats of Aedes aegypti, the primary dengue vector. Concurrently, demographic metrics were evaluated to assess the population's susceptibility to dengue outbreaks. High-risk areas were systematically identified through a comparative analysis that integrated population density and incidence rates per ward. The results revealed a significant correlation between high population density and an increased risk of dengue, predominantly facilitated by vertical transmission. Spatially, these high-risk zones are concentrated in the northern and southern sectors of Jaipur, with the northern and southwestern wards exhibiting the most acute risk profiles. This study underscores the importance of targeted public health interventions and vaccination campaigns in vulnerable areas. It further lays the groundwork for future research to evaluate the effectiveness of such interventions, thereby contributing to the development of robust evidence-based strategies for dengue risk mitigation.

In silico Screening of Plectranthus amboinicus and Hyptis suaveolens Phyto-chemicals: Novel Repellents Targeting Odorant Binding Proteins of Aedes aegypti and Aedes albopictus

Background and Aim: Mosquitoes significantly threaten public health, transmitting dangerous diseases to humans and animals. Conventional insecticide spraying, while common, has limitations in effectively controlling vector-borne diseases. Many chemical pesticides harm humans and animals, and some persist in the environment and cause toxic effects. Recently, there has been renewed interest in plant-based products due to concerns about insecticide re-sistance, cross-resistance, potential toxicity associated with synthetic options, and rising costs. Therefore, this study aimed to screen the Plectranthus amboinicus and Hyptis suaveolens phy-tochemicals targeting the odorant binding proteins (OBPs) of Aedes aegypti and Aedes albopic-tus. Methods: In this study, we conducted molecular docking analyses using specific plant-derived compounds from H. suaveolens and P. amboinicus. Results: We focused on the interaction of these compounds with OBPs from dengue and chikungunya vectors (Aedes aegypti and Aedes albopictus). The selected phytochemical com-pounds exhibited strong binding with the OBP of both Ae. aegypti and Ae. albopictus. Tetrahy-drofuran-2-carboxylic acid, Carvacryl acetate, and Brallobarbital showed high binding affinity and significant interaction with Ae. aegypti. Tetrahydrofuran-2-carboxylic acid and 3-Methyl-4-isopropylphenol also demonstrated substantial binding affinity and effective interaction with Ae. albopictus OBP. Conclusion: These findings suggest that the identified compounds can potentially disrupt the attraction of mosquitoes to humans, thus reducing human-vector contact. They may offer a promising alternative for developing natural and efficient mosquito repellents, surpassing cur-rently used synthetic options like N, N-diethyl-meta-toluamide, and other conventional repel-lents.