Culex Quinquefasciatus Research Articles

Assessment of biorational larvicides and botanical oils against Culex quinquefasciatus Say (Diptera: Culicidae) larvae in laboratory conditions

Mosquitoes are known vectors that transmit deadly diseases to millions of people across the globe. The reliance on synthetic insecticides has been the sole way to combat mosquito vectors for decades. In recent years, the extensive use of conventional insecticides in mosquito suppression has led to significant pesticide resistance and serious human health hazards. In this light, investigating the potential application of biorational compounds for vector management has drawn significant attention. We, hereby, evaluated the efficacy of three microbial derivative biorational insecticides, abamectin, spinosad, and buprofezin, and two botanical oils, neem (Azadirachta indica A. Juss) and karanja oil (Pongamia pinnata Linn.) against the Culex quinquefasciatus under laboratory conditions. The fourth-instar C. quinquefasciatus larvae were exposed to different concentrations of the selected larvicides and lethality was estimated based on LC50 and LT50 with Probit analysis. All larvicides showed concentration-dependent significant effects on survival and demonstrated larvicidal activity against C. quinquefasciatus larvae. However, abamectin exerted the highest toxicity (LC50 = 10.36 ppm), exhibited statistically significant effects on C. quinquefasciatus larval mortality, followed by spinosad (LC50 = 21.32 ppm) and buprofezin (LC50 = 56.34 ppm). Abamectin caused larval mortality ranged from 30.00 to 53.33 % and 53.00–70.00 % at 06 and 07 h after treatment (HAT), respectively. In the case of botanicals, karanja oil (LC50 = 216.61 ppm) was more lethal (more than 1.5 times) and had a shorter lethal time than neem oil (LC50 = 330.93 ppm) and showed a classic pattern of relationship between concentrations and mortality over time. Overall, the present study highlighted the potential of deploying new generation biorational pesticides and botanicals in mosquito vector control programs.

Exposure to Zika and chikungunya viruses impacts aspects of the vectorial capacity of Aedes aegypti and Culex quinquefasciatus.

Zika (ZIKV) and chikungunya (CHIKV) are arboviruses that cause infections in humans and can cause clinical complications, representing a worldwide public health problem. Aedes aegypti is the primary vector of these pathogens and Culex quinquefasciatus may be a potential ZIKV vector. This study aimed to evaluate fecundity, fertility, survival, longevity, and blood feeding activity in Ae. aegypti after exposure to ZIKV and CHIKV and, in Cx. quinquefasciatus exposed to ZIKV. Three colonies were evaluated: AeCamp (Ae. aegypti-field), RecL (Ae. aegypti-laboratory) and CqSLab (Cx. quinquefasciatus-laboratory). Seven to 10 days-old females from these colonies were exposed to artificial blood feeding with CHIKV or ZIKV. CHIKV caused reduction in fecundity and fertility in AeCamp and reduction in survival and fertility in RecL. ZIKV impacted survival in RecL, fertility in AeCamp and, fecundity and fertility in CqSLab. Both viruses had no effect on blood feeding activity. These results show that CHIKV produces a higher biological cost in Ae. aegypti, compared to ZIKV, and ZIKV differently alters the biological performance in colonies of Ae. aegypti and Cx. quinquefasciatus. These results provide a better understanding over the processes of virus-vector interaction and can shed light on the complexity of arbovirus transmission.

Mosquito larvicidal bioassay with the fruit extracts of Diospyros kaki on filarial vector Culex quinquefasciatus

Due to the emergence of resistance of the commonly used synthetic pesticide, vector control is in grave danger. Application of biocontrol agents may be a suitable alternative approach in vector control. The purpose of this study was to evaluate the larvicidal effectiveness of crude and methanolic fruit extracts of Diospyros kaki against Culex quinquefasciatus, the carrier of human filarial worm. The methanol extract showed promising result in biocontrol assay than crude extract. The methanolic extract had the LC50 and LC90 values of 46 ppm and 186 ppm, respectively against 1st instar larvae after 72 hours of exposure, The rate of mortality was positively associated with the solvent extracts in increasing concentrations, having a regression coefficient value near to 1 in each case, showing a definite positive dose-dependent mortality. During chemical characterization of the solvent extract by GC-MS and FT-IR studies, some bioactive compounds like 5,8,11,14,17-Eicosapentaenoic Acid, Methyl 4,7,10,13,16,19-Docosahexaenoate, cyclotrisiloxane hexamethyl and Arsenous acid, tris(trimethylsilyl) ester were identified that showed the larvicidal activity against mosquito larvae either singly or jointly. Thus, D. kaki fruit extract showed excellent potential as a bio control agent for Cx. quinquefasciatus and the isolated bioactive phytochemical may be utilized as a source of a powerful insecticide.

A New Aqueous Formulation from Indigenously Isolated Bacillus <i>Thuringiensis Israelensis</i> VCRC B646 for Mosquito Control

In the present study, in order to control mosquito vectors in the field, a new aqueous formulation was developed using an indigenously isolated bacterial strain of Bacillus thuringiensis israelensis VCRC B646. The composition of formulation was, Bti lyophilized powder (5%), sodium benzoate (0.15%), sodium alginate (2.5%), Congo red (0.03%), citric acid (0.15%), glycerol (6%), molasses (8%) and polyethylene glycol (3%) in 100ml of water. Laboratory bioassay was carried out using this formulation against the late third instar of mosquito larvae. The result showed that the LC50 and LC90 values against Aedes aegypti, Culex quinquefasciatus, and Anopheles stephensi were 0.0082 and 0.016 mg/ l, 0.0084 and 0.0172 mg/ l, 0.0139 and 0.0294 mg/ l, respectively. Results from simulated field trial showed that the efficacy of Bti formulation at LC90 level was highly significant up to six weeks (42 days). Thereafter, the formulation efficacy was started declining. No side effect was observed against non-target aquatic organisms. It was concluded from this study that the formulation developed from newly isolated strain if B. thuringiensis israelensis VCRC B646 was very useful on the control of mosquito vectors.

Potential efficacy of bimetallic nanoparticles synthesized from extracellular cell-free extract of Penicillium citrinum against Culex quinquefasciatus mosquito larvae, and their photocatalytic activity

The biological synthesis of nanoparticles finds application in the development of novel insecticides and bioremediation agents. In this study, bimetallic nanoparticles were synthesized using copper and zinc salts along with Penicillium citrinum secondary metabolite. The synthesized nanoparticles were analyzed for their insecticidal and photocatalytic efficacy on Culex quinquefasciatus larvae and organic dyes, respectively. The synthesized nanoparticles were characterized by UV spectroscopy, FTIR, XRD, SEM, EDX, and HR-TEM. The results showed fungal metabolite synthesized bimetallic nanoparticles were too toxic for Culex quinquefasciatus larvae, with LC50 and LC90 values of 1016.51 ppm, 4948.12 ppm for 24 h exposure; 184.80 ppm, 718.16 ppm for 48 h exposure, and 59.07 and 338.76 ppm for 72 h exposure, respectively. The Cu–Zn bimetallic nanoparticles showed mild photocatalytic activity on Xylenol orange (36%). This study shows that bimetallic NPs synthesized from Penicillium citrinum are advantageous for mosquito control as well as having photocatalytic dye degradation properties.

Biodiversity of mosquitoes (Diptera: Culicidae) in phytotelmata from Car Nicobar Island, India.

The Culicidae mosquito family breeds in various natural and artificial water bodies. Phytotelmata are plant structures that hold water and are used by many mosquito species during their life cycle. Mosquitoes are disease vectors, and phytotelmata play an important role in harbouring them. Investigating these phytotelmata will facilitate to develop appropriate site specific vector control strategy. Approximately 750 phytotelmata in 16 locations on Car Nicobar Island was examined. Mosquito larvae were collected from different habitats such as tree holes, root holes, leaf axils, and bamboo stumps. On average, the number of larvae per 10 ml of water ranged from 0.003 to 3.833. Among the 16 mosquito species identified, there were vectors of malaria (Anopheles sundaicus), dengue (Aedes aegypti and Aedes albopictus) and filariasis (Culex quinquefasciatus), belonging to seven genera. The most common phytotelmata were coconut trees (17.5%) followed by Java apple trees (10.3%) and bamboo stumps (7.1%). The most widespread mosquito species was Aedes edwardsi, followed by Aedes malayensis and Ae. albopictus, and the per cent of phytotelmata that contained these species were 42.6, 22.0, and 16.8% respectively. Anopheles mosquitoes had the highest container index (6.1%) in root holes, while Aedes and Culex mosquitoes were more frequently found in bamboo stumps. The alpha biodiversity indices indicated that the mosquito population in Car Nicobar Island was highly diverse (S = 16; DMg = 36.9). Tree holes showed the highest diversity, as all 16 species were collected from them. Assessment of phytotelmata, there is a significant relationship observed between mosquito genus, village, habitat, and tree families, on the remote island of Car Nicobar. Considering the presence of disease-transmitting mosquito vectors in the phytotelmata, these habitats should be considered when implementing control measures to eliminate mosquito-borne infections.

Histological validation of in-vivo larvicidal efficacy of marine Streptomyces sp. RD06 secondary metabolites against filariasis causing Culex quinquefasciatus and statistical media optimization for larvicidal derivatives production

Mosquito-borne disease pandemics, such as the Zika virus and chikungunya, have escalated cognizance of how critical it is to implement proficient mosquito vector control measures. The prevention of Culicidae is becoming more difficult these days because of the expeditious imminence of synthetic pesticide resistance and the universal expansion of tremendously invasive mosquito vectors. The present study highlights the insecticidal and larvicidal efficacy of the prospective novel actinobacterium derived from the marine Streptomyces sp. RD06 secondary metabolites against Culex quinquefasciatus mosquito. The pupicidal activity of Streptomyces sp. RD06 showed LC50=199.22 ± 11.54 and LC90= 591.84 ± 55.41 against the pupa. The purified bioactive metabolites 1, 2-Benzenedicarboxylic acid, diheptyl ester from Streptomyces sp. RD06 exhibited an LC50 value of 154.13 ± 10.50 and an LC90 value of 642.84 ± 74.61 tested against Cx. quinquefasciatus larvae. The Streptomyces sp. RD06 secondary metabolites exhibited 100 % non-hatchability at 62.5 ppm, and 82 % of hatchability was observed at 250 ppm. In addition, media optimization showed that the highest biomass production was attained at a temperature of 41.44 °C, pH 9.23, nitrogen source 11.43 mg/ml, and carbon source 150 mg/ml. Compared to control larvae, the histology and confocal microscopy results showed destruction to the anal gill, lumen content, and epithelial layer residues in the treated larvae. Utilizing an eco-friendly method, these alternative inventive insecticidal derivatives from Streptomyces sp. RD06 eradicates Culex quinquefasciatus. This study highlights the promising potential of these Streptomyces sp. RD06 secondary metabolites to develop affordable and efficacious mosquito larvicides to replace synthetic insecticides in the future.

Antibodies to Aedes aegypti D7L salivary proteins as a new serological tool to estimate human exposure to Aedes mosquitoes.

Aedes spp. are the most prolific mosquito vectors in the world. Found on every continent, they can effectively transmit various arboviruses, including the dengue virus which continues to cause outbreaks worldwide and is spreading into previously non-endemic areas. The lack of widely available dengue vaccines accentuates the importance of targeted vector control strategies to reduce the dengue burden. High-throughput tools to estimate human-mosquito contact and evaluate vector control interventions are lacking. We propose a novel serological tool that allows rapid screening of human cohorts for exposure to potentially infectious mosquitoes. We tested 563 serum samples from a longitudinal pediatric cohort study previously conducted in Cambodia. Children enrolled in the study were dengue-naive at baseline and were followed biannually for dengue incidence for two years. We used Western blotting and enzyme-linked immunosorbent assays to identify immunogenic Aedes aegypti salivary proteins and measure total anti-Ae. aegypti IgG. We found a correlation (rs=0.86) between IgG responses against AeD7L1 and AeD7L2 recombinant proteins and those to whole salivary gland homogenate. We observed seasonal fluctuations of AeD7L1+2 IgG responses and no cross-reactivity with Culex quinquefasciatus and Anopheles dirus mosquitoes. The baseline median AeD7L1+2 IgG responses for young children were higher in those who developed asymptomatic versus symptomatic dengue. The IgG response against AeD7L1+2 recombinant proteins is a highly sensitive and Aedes specific marker of human exposure to Aedes bites that can facilitate standardization of future serosurveys and epidemiological studies by its ability to provide a robust estimation of human-mosquito contact in a high-throughput fashion.

Assessing the potential of nano-formulated chlorfenapyr and clothianidin insecticides-treated sugar baits against Anopheles funestus, Anopeles coluzzii and Culex quinquefasciatus mosquitoes

Mosquitoes serve as vectors for various diseases like malaria, dengue fever, yellow fever, and lymphatic filarial diseases causing significant global health problems, highlighting the importance of vector control. The study was conducted to assess the effectiveness of nanoformulated clothianidin and chlorfenapyr insecticides treated with ATSB in controlling three mosquito strains. The development of a natural thiolated polymer-coated ATSB nano formulation involved incorporating nano-carriers to deliver insecticides. Field- collected mosquito strains were subjected to laboratory-based bioassays using 1 % and 1.5 % concentrations of each conventionally used and nanoformulated insecticide with ATSB solution. Adult mosquitoes were left overnight to contact with N-ATSB and efficacy was recorded after 36 and 72 h. The results showed that nanoformulated chlorfenapyr was significantly more effective as compared to clothianidin against An. funestus and Cx. quinquefasciatus but the results were not significantly different against An. coluzzii (100 %). An. coluzzii was found to be the most susceptible strain followed by An. funestus and showed 100 % and ∼ 98 % mortality against nanoformulated chlorfenapyr (1.5 %). Nanoformulated clothianidin induced more than 92 % and ∼ 100 % mortality against An. funestus and An. coluzzii respectively. However, Cx. quinquefasciatus significantly showed less mortality against nanoformulated clothianidin (88 %) and chlorfenapyr (>95 %) as compared to Anopheline strains. Furthermore, results indicate that nanoformulated insecticides significantly caused greater and prolonged fatality as compared to conventional form, suggesting effective and suitable strategies for vector management.

Update on the composition and distribution of the mosquito fauna (Diptera: Culicidae) in Cabo Verde, a country at risk for mosquito-borne diseases.

Mosquitoes play a critical role as vectors of pathogens affecting both humans and animals. Therefore, understanding their biodiversity and distribution is crucial to developing evidence-based vector control strategies. The current study updated the composition and distribution of mosquito species through a comprehensive survey of all municipalities of Cabo Verde. From October 2017 to September 2018, mosquito larvae and pupae were collected from 814 aquatic habitats. Anopheles gambiae (Giles, 1902) and Culex pipiens (Linnaeus, 1758) complexes were subjected to PCR-based techniques for sibling species identification. Ten mosquito species from 5 genera were identified: Aedes aegypti (Linnaeus, 1762), Aedes caspius (Pallas, 1771), Anopheles arabiensis (Patton, 1905), Anopheles pretoriensis (Theobald, 1903), Culex bitaeniorhynchus (Giles, 1901), Cx. pipiens, Culex quinquefasciatus (Say, 1823), Culex tritaeniorhynchus (Giles, 1901), Culiseta longiareolata (Macquart, 1838), and Lutzia tigripes (de Grandpre & de Charmoy, 1901). Santiago Island reported the highest number of species (n = 8). Ae. aegypti and Cx. quinquefasciatus were the most widely distributed species across the country. An. arabiensis was the sole species identified within the An. gambiae complex. The findings from our study will help guide health policy decisions to effectively control mosquito-borne diseases.

Toxicity, biochemical and molecular docking studies of Acacia nilotica L., essential oils against insect pests

Botanical essential oils are natural insecticides derived from plants, offering eco-friendly alternatives to synthetic chemicals for pest control. In this study, the essential oils were extracted from Acacia nilotica seed cotyledons, and their toxicity was tested against insect pests. Furthermore, the chemical components of the essential oils were identified through gas chromatography-mass spectrometry (GC-MS) analysis. The essential oil extracted from A. nilotica seeds exhibited the highest mortality rates of 60% and 98% in Culex quinquefasciatus, and 60% and 96.66% mortality in Plutella xylostella at 24 and 48 h after treatment, respectively. The essential oils resulted in a lower LC50 of 159.263 ppm/mL, and LC90 of 320.930 ppm/mL within 24 h. In 48 h, the LC50 was 52.070 ppm/mL and the LC90 was 195.123 ppm/mL for C. quinquefasciatus. In the essential oil treatment of P. xylostella, the lower LC50 was 165.900 ppm/mL, and the LC90 was 343.840 ppm/mL 24 h after the treatment. At 48 h post-treatment, the LC50 decreased to 62.965 ppm/mL, and the LC90 decreased to 236.795 ppm/mL in P. xylostella. The study investigated the impact of essential oils on insect enzymes 24 h after treatment. The study revealed significant changes in the levels of insect enzymes, including a decrease in acetylcholinesterase enzymes and an increase in glutathione S-transferase compared to the control group. Essential oils had minimal effects, resulting in mortality rates of 30.66% and 46% at 24 and 48 h after treatment on Artemia salina. After 48 h, minimal toxic effects of essential oils were observed on E. eugeniae, with a mortality rate of 11.33%. The GC-MS analysis of A. nilotica seed-derived essential oils revealed ten major chemical constituents, including 6-hydroxymellein, phthalic acid, trichloroacetic acid, hexadecane, acetamide, heptacosane, eicosane, pentadecane, 1,3,4-eugenol, and chrodrimanin B. Among these constituents, Heptacosane is the major chemical component, and this molecule has a high potential for involvement in insecticidal activity.

Essential oil and fenchone extracted from Tetradenia riparia (Hochstetter.) Codd (Lamiaceae) induce oxidative stress in Culex quinquefasciatus larvae (Diptera: Culicidae) without causing lethal effects on non-target animals.

We investigated the larvicidal activity of the essential oil (EO) from Tetradenia riparia and its majority compound fenchone for controlling Culex quinquefasciatus larvae, focusing on reactive oxygen and nitrogen species (RONS), catalase (CAT), glutathione S-transferase (GST), acetylcholinesterase (AChE) activities, and total thiol content as oxidative stress indicators. Moreover, the lethal effect of EO and fenchone was evaluated against Anisops bouvieri, Diplonychus indicus, Danio rerio, and Paracheirodon axelrodi. The EO and fenchone (5 to 25µg/mL) showed larvicidal activity (LC50 from 16.05 to 18.94µg/mL), followed by an overproduction of RONS, and changes in the activity of CAT, GST, AChE, and total thiol content. The Kaplan-Meier followed by Log-rank (Mantel-Cox) analyses showed a 100% survival rate for A. bouvieri, D. indicus, D. rerio, and P. axelrodi when exposed to EO and fenchone (262.6 and 302.60µg/mL), while α-cypermethrin (0.25µg/mL) was extremely toxic to these non-target animals, causing 100% of death. These findings emphasize that the EO from T. riparia and fenchone serve as suitable larvicides for controlling C. quinquefasciatus larvae, without imposing lethal effects on the non-target animals investigated.

Bioactive components in Psidium guajava extracts elicit biotoxic attributes and distinct antioxidant enzyme modulation in the larvae of vectors of lymphatic filariasis and dengue

Control of mosquito vectors, which have caused a global disease burden, has employed various methods. However, the challenges posed by current physical and chemical methods have raised concerns about vector control programs, leading to the search for alternative methods that are less toxic, eco-friendly, and cost-effective. This study investigated the larvicidal potential of aqueous, methanol, and ethylacetate extracts of Guava (Psidium guajava) against Aedes aegypti and Culex quinquefasciatus larvae. Functional group and phytochemical characterization were performed using Fourier-Transform Infrared Spectroscopy (FTIR) and GC-MS analysis to identify the bioactive compounds in the extracts. Larval bioassays were conducted using WHO standard procedures at concentrations of 12.5, 25, 50, 125, and 250 mg/L, and mortality was recorded after 24, 48, and 72 h. Additionally, antioxidant enzyme profiles in the larvae were studied. All of the solvent extracts showed larvicidal activity, with the methanol extract exhibiting the highest mortality against Ae. aegypti and Cx. quinquefasciatus larvae, followed by aqueous and ethylacetate extracts. FTIR spectroscopic analysis revealed the presence of OH, C–H of methyl and methylene, CO and CC. The GC-MS analysis indicated that the methanol, aqueous, and ethylacetate extracts all had 27, 34, and 43 phytoactive compounds that were effective at causing larvicidal effects, respectively. Different concentrations of each extract significantly modulated the levels of superoxide dismutase, catalase, glutathione peroxidase, and reduced glutathione in larvae. This study's findings indicate the potential for developing environmentally friendly vector control products using the bioactive components of extracts from P. guajava leaves.

Self-consistent numerical model of mosquito dynamics with specified kinematic parameters of wing movement

Mosquito flight dynamics was considered using an advanced mathematical model with experimentally determined and biologically relevant parameters. The model was developed using a self-consistent algorithm. It described mosquito’s body and wing oscillations using mechanics equations and aerodynamic flows, simultaneously. Six equations were used for the mechanics of the mosquito (relative to the center of mass), and Navier–Stokes equations simulated aerodynamics. Numerical methods employed deformable computational mesh with specific mesh construction near the wing boundaries. Using size, shape and weight characteristics of the Culex quinquefasciatus (male) mosquito the flight dynamics was computed and analyzed. It was determined that the mosquito lift force was proportional to the square of the wing frequency. Specifically, we found a critical frequency of approximately 820 Hz that corresponded to mosquito freezing when the lift force compensated gravity. This number was consistent to experimentally determined mosquito flight characteristics. Mechanism of mosquito’s lift force generation was discussed.

Terrestrial subsidies and light affect an aquatic micro‐ecosystem in unexpected ways

Abstract The effects of resource subsidies on a recipient ecosystem depends on a variety of factors. Firstly, increasing the supply of limiting nutrients tends to increase the accumulation of biomass across different compartments of the recipient food web. Secondly, in the case of aquatic microorganisms, this accumulation may also be contingent on inputs of energy through light, mediating interactions between heterotrophic bacteria and autotrophic algae. Thirdly, macroscopic consumers feed upon microorganisms and recycle nutrients through excretion and egestion, profoundly affecting nutrient cycling. In order to examine the context‐dependency of nutrient cycling in aquatic systems, we performed an experiment in mesocosms where we followed the responses of dissolved nutrients, microorganisms, and larvae of the cosmopolitan mosquito Culex quinquefasciatus (Diptera: Culicidae) to two terrestrial subsidies differing in carbon (C):nutrient, in combination with two light intensities. We found that the interactions amongst bacteria and algae themselves remained generally unimportant after accounting for treatment effects, and that light did mediate some of the effects of nutrient subsidies on microorganisms. We also found that the presence of mosquito larvae was associated with altered concentrations of nitrogen (N) in some treatments, ultimately benefitting algae. Finally, we found that low C:nutrient subsidies generally increased the development rate of mosquito larvae, and that increased light exposure led to higher mosquito survival. Overall, these patterns may be explained by strong nitrogen limitation in our system, causing both group of microorganisms to respond similarly to variations in nutrient supply without direct covariation, and to the key role of N recycling by mosquito larvae in sustaining algal densities in exposed treatments. The context‐dependency in our study may reflect elemental or molecular constraints other than phosphorus. Our experiment thus calls for greater synthesis amongst ecological theories.

Entomological And Parasitological Indices Of Malaria Parasite Transmission In Imo State Polytechnic Omuma, Oru East, Nigeria

The study conducted between May and September of 2023 examined entomological and parasitological indicators of malaria parasite transmission in order to identify the predominant mosquito species and establish the malaria endemicity in the vicinity of Imo State Polytechnic Omuma. The Pyrethrum Spray Catch (PSC) was utilized to collect adult mosquitoes. Various mosquito species were gathered, categorized, and recognized. To detect the presence of a malaria parasite in the blood film stained with Giemsa stain, blood samples were taken from the same students whose rooms were utilized for the entomological survey during the parasitological study. Both the T-test and the Chi-square were used to assess the data. In all, 297 mosquitoes were detected in the research region (table 1), of which 230 Culex quinquefasciatus represented (77.4%) and 67 Anopheles gambiae (22.6%). The study was conducted at eight (8) sites. Comparing the results with the Anopheles gambiae recorded from the same site, Table 2b demonstrates that Culex quinquefasciatus had the highest prevalence and was substantially different at p<0.05. According to the results of the parasitological investigation, when 21 (42.0%) of the students residing in the hostel had their malaria parasite infection checked, 18 (85.7%) tested positive and 3 (14.3%) tested negative. When 29 students (58.0%) who were staying in the lodges had their malaria parasite infection checked, 23 (79.3%) of them tested positive, and 6 (20.7%) tested negative. Among the 50 learners randomly selected for parasitological analysis from the study’s school hostels and lodges, there was no significant difference (p>0.05) in the number of students who tested positive. The percentage of mosquito abundance and falciparum malaria presence found in this study are significant for public health. In order to develop strategies for the control of mosquito-borne diseases in Imo State Polytechnic Omuma and its surroundings, this study offers helpful baseline data.

Infection, dissemination, and transmission of lumpy skin disease virus in Aedes aegypti (Linnaeus), Culex tritaeniorhynchus (Giles), and Culex quinquefasciatus (Say) mosquitoes

Lumpy skin disease virus (LSDV) is a transboundary viral disease in cattle and water buffaloes. Although this Poxvirus is supposedly transmitted by mechanical vectors, only a few studies have investigated the role of local vectors in the transmission of LSDV. This study examined the infection, dissemination, and transmission rates of LSDV in Aedes aegypti, Culex tritaeniorhynchus, and Culex quinquefasciatus following artificial membrane feeding of 102.7, 103.7, 104.7 TCID50/mL LSDV in sheep blood. The results demonstrated that these mosquito species were susceptible to LSDV, with Cx tritaeniorhynchus exhibiting significantly different characteristics from Ae. aegypti and Cx. quinquefasciatus. These three mosquito species were susceptible to LSDV. Ae. aegypti showed it as early as 2 days post-infection (dpi), indicating swift dissemination in this particular species. The extrinsic incubation period (EIP) of LSDV in Cx. tritaeniorhynchus and Cx. quinquefasciatus was 8 and 14 dpi, respectively. Ingestion of different viral titers in blood did not affect the infection, dissemination, or transmission rates of Cx. tritaeniorhynchus and Cx. quinquefasciatus. All rates remained consistently high at 8–14 dpi for Cx. tritaeniorhynchus. In all three species, LSDV remained detectable until 14 dpi. The present findings indicate that, Ae. aegypti, Cx. tritaeniorhynchus, and Cx. quinquefasciatus may act as vectors during the LSDV outbreak; their involvement may extend beyond being solely mechanical vectors.

Application of computer vision and deep learning models to automatically classify medically important mosquitoes in North Borneo, Malaysia.

Mosquito-borne diseases have emerged in North Borneo in Malaysia due to rapid changes in the forest landscape, and mosquito surveillance is key to understanding disease transmission. However, surveillance programmes involving sampling and taxonomic identification require well-trained personnel, are time-consuming and labour-intensive. In this study, we aim to use a deep leaning model (DL) to develop an application capable of automatically detecting mosquito vectors collected from urban and suburban areas in North Borneo, Malaysia. Specifically, a DL model called MobileNetV2 was developed using a total of 4880 images of Aedes aegypti, Aedes albopictus and Culex quinquefasciatus mosquitoes, which are widely distributed in Malaysia. More importantly, the model was deployed as an application that can be used in the field. The model was fine-tuned with hyperparameters of learning rate 0.0001, 0.0005, 0.001, 0.01 and the performance of the model was tested for accuracy, precision, recall and F1 score. Inference time was also considered during development to assess the feasibility of the model as an app in the real world. The model showed an accuracy of at least 97%, a precision of 96% and a recall of 97% on the test set. When used as an app in the field to detect mosquitoes with the elements of different background environments, the model was able to achieve an accuracy of 76% with an inference time of 47.33 ms. Our result demonstrates the practicality of computer vision and DL in the real world of vector and pest surveillance programmes. In the future, more image data and robust DL architecture can be explored to improve the prediction result.

Species composition of larval mosquitoes (Diptera: Culicidae) in bamboo stumps in mid-western Nepal

ABSTRACT Bamboo stumps serve as important phytotelmata in which mosquitoes breed. The physiochemical parameters of water in the bamboo stumps influence the species composition and larval abundance of mosquito species. Bamboo stumps were scanned in monsoon season of 2022 by adopting a larval survey method in mid-western Nepal. Supplementary data such as water volume, temperature and pH were also recorded. The linear relationship between different physiochemical parameters with mosquito larval population and larval abundance of different mosquito species was analysed in RStudio-1.0.44 and Past software version 4.07. Altogether, 120 larval mosquitoes belonging to 7 species and 3 genera were recorded from 26 bamboo stumps. The larval abundance of immature mosquito shows positive correlation with water temperature, pH and volume of the water. The coexistence of larvae of dengue vectors (Aedes aegypti and Aedes albopictus) and vector of Lymphatic Filariasis (Culex quinquefasciatus) as well the coexistence of different larval mosquito species were recorded. This established bamboo stumps as important mosquito breeding habitats including vector species in mid-western Nepal.

Essential Oil of Ocimum basilicum against Aedes aegypti and Culex quinquefasciatus: Larvicidal Activity of a Nanoemulsion and In Silico Study

Diseases transmitted by vectors such as Aedes aegypti and Culex quinquefasciatus (Diptera: Culicidae) have been responsible for endemics and epidemics in several countries, causing irreparable damage to human health. For this reason, vector control is one of the main strategies to prevent the contamination and dissemination of these etiological agents. In this study, the essential oil (EO) of Ocimum basilicum was obtained by hydrodistillation, and the compounds were identified by GC/MS. A nanoemulsion was obtained through a low-energy input method and evaluated by photon correlation spectroscopy. Bioassays were performed against 4th instar larvae of A. aegypti and C. quinquefasciatus. Furthermore, additional in silico studies of biological activity prediction and molecular docking for the acetylcholinesterase enzyme and juvenile hormone protein targets were performed with the 53 identified compounds of the EO. The major compounds identified in greater quantity were linalool (32.66%) and anethole (32.48%). The obtained nanoemulsion had an average size diameter between 244.6 and 280.4 nm and a polydispersity index below 0.250 during the entire storage period. The nanoemulsion was tested at concentrations of 10, 20, 30, 40, and 50 mg/L and the following activity values were observed: LC50 = 42.15 mg/L and 40.94 mg/L and LC90 = 50.35 mg/L and 48.87 mg/L for A. aegypti (24 h and 48 h); LC50 = 39.64 mg/L and 38.08 mg/L and LC90 = 52.58 mg/L and 54.26 mg/L for C. quinquefasciatus (24 h and 48 h). The in silico results showed better activity values for linalool, anethole, carvone, α-selinene, eugenol, and limonene. The α-selinene compound showed the best binding affinity with the insect acetylcholinesterase enzyme (−9.1 Kcal) in molecular docking, showing the importance of antagonist compounds in elucidating the mechanism of action for the investigated targets. Thus, the studied nanoemulsion was considered active against the tested species, becoming a potential alternative as an ecological bioinsecticide due to bioactivity and simplicity of formulation.