Larvae Of Aedes Research Articles

Functional Roles of Five Cytochrome P450 Transcripts in the Susceptibility of the Yellow Fever Mosquito to Pyrethroids Revealed by RNAi Coupled With Insecticide Bioassay.

We evaluated the possible roles of five cytochrome P450 transcripts in the susceptibility of both adults and larvae of Aedes aegypti to three pyrethroids using RNA interference (RNAi) coupled with insecticide bioassays. RNAi by feeding larvae with chitosan/dsRNA nanoparticles led to reductions of CYP6AA5, CYP6AL1, CYP9J32, CYP4J16A, and CYP4J16B transcripts by 38.7%, 46.0%, 46.52%, 44.0%, and 41.0%, respectively, and increased larval mortality by 46.0% to permethrin when CYP9J32 was silenced and by 41.2% to cypermethrin when CYP6AA5 was silenced. RNAi by injecting dsRNA in adults led to reductions of CYP6AA5, CYP6AL1, and CY4J16A transcripts by 77.9%, 80.0%, and 87.1% (p < 0.05), respectively, at 96 h and reduction of CYP9J32 transcript by 46.5% at 24 h after injection. In contrast, CYP4J16B was repressed by 78.2% at 72 h after injection. Exposure of the adults injected with CYP6AA5 dsRNA resulted in 1.5- to 2.0-fold increased susceptibility to cypermethrin as compared with the control. Homology modeling of CYP6AA5 followed by ligand docking showed that distances between the heme iron and the putative aromatic hydroxylation site were 9.2, 7.2, and 9.1 Å for permethrin, cypermethrin, and deltamethrin, respectively. For the aliphatic hydroxylation site, these distances were 5.3, 4.9, and 3.1 Å. These results supported that CYP6AA5 may be able to metabolize cypermethrin preferentially by aliphatic hydroxylation as indicated by the close interaction with the heme iron. Our study also suggests that the detoxification roles of cytochrome P450 genes in A. aegypti may vary according to the mosquito developmental stages, cytochrome P450 genes, and insecticides.

Modeling of the Habitat Characteristics and Ecological Niche of the Asian Tiger Mosquito in a Fine-Scale Area of a Primate Research Center Using the Maximum Entropy Model.

Aedes-borne diseases, such as Zika and Chikungunya, originate from an enzootic cycle in which non-human primates (NHPs) function as reservoirs. This study aimed to analyze the characteristic habitat and ecological niche models of Aedes albopictus within the confines of a Primate Research Center (PRC), to assess its potential as a site for zoonotic arbovirus transmission. Additionally, this study aimed to construct a comprehensive map to delineate the risks of arbovirus transmission. A 1-year direct field survey was conducted from January to December 2022 in the PRC to obtain comprehensive data on the presence of larvae, including their conditions, habitat types, and physicochemical characteristics. Larval collection was meticulously performed at potential breeding sites using a 350 ml dipper and pipette. Information on the ecological niche was compiled based on a combination of general environmental variables and mosquito presence data obtained from direct field surveys using the Maximum Entropy (MaxEnt) model. In total, 120 presence points for Ae. albopictus larvae were obtained from the PRC area, with 23.02% of the larvae found in buckets as artificial habitats, and 18.25% found in bromeliad plants as natural habitat types. Larvae of Ae. albopictus occupy artificial habitats that are not turbid, exposed to direct sunlight, and devoid of predators. The abundances and occurrences of Ae. albopictus larvae was found to be significantly influenced by pH and total dissolved solids. This study showed that the PRC was a suitable habitat for breeding Ae. albopictus larvae, with the distance to buildings emerging as a significant environmental variable in the species distribution model CONCLUSIONS: The fine-scale empirical model developed for Ae. albopictus and its habitat characteristics not only provide insights into the suitability of vector habitats, but can also be used assess the risk of arbovirus transmission, potentially informing strategies for controlling mosquito breeding sites within the PRC.

In vitro evaluation of the pathogenicity of fungi isolated from the Urabá region (Antioquia, Colombia) against Aedes aegypti larvae

Introduction. Aedes aegypti is an important vector of arboviral diseases like dengue among others. Traditional control strategies, such as the use of insecticides, have lost effectiveness due to the emergence of resistance in mosquito populations. Biological control and fungi applied for biocontrol are presented as viable and ecological alternatives. Objective. To evaluate in vitro pathogenicity of Trichoderma sp. isolates obtained from Urabá (Antioquia) on larvae of Ae. aegypti, and to determine the mean lethal concentration and mean lethal time of the most pathogenic isolate. Materials and methods. Using the sentinel larvae method of Ae. aegypti, fungi were isolated from water bodies in the Urabá region (Antioquia). The isolates were characterized morphologically and molecularly to determine their taxonomic identity. Pathogenicity tests were performed in vitro on Ae. aegypti larvae in the L2/L3 stages. Subsequently, a strain was selected to establish its mean lethal concentration and mean lethal time. Results. Trichoderma sp. strain AP-91 caused high mortality in larval populations of Ae. aegypti. We estimated a mean lethal concentration of 1.8 × 107 conidia/ml and a mean lethal time of 20.67 hours. Conclusion. The strain AP-91 showed potential for its use as biological control of Ae. aegypti, making it a suitable candidate for scale-up cultures applied to integrated vector management. This research suggests exploring compounds and enzymes produced by the AP-91 strain to understand better its pathogenicity.

THE RELATIONSHIP BETWEEN COMMUNITY BEHAVIOR AND SOWING OF ABATE POWDER IN PREVENTING AEDES LARVAE AT PASI PEUKAN BARO VILLAGE AND PASI RAWA VILLAGE SIGLI SUB DISTRICT, PIDIE REGENCY

Background: Dengue Hemorrhagic Fever (DHF) in Aceh Province in 2022 were recorded at 2,079 cases,, with 16 deaths. with the morbidity rate for Dengue Hemorrhagic Fever (DHF) in 2022 amounting to 38 per 100,000 population. Cases of dengue fever in Pidie Regency in 2022 were 318 cases. Research Objective: To determine community behavior towards sowing abate powder to prevent aedes larvae in Kota Sigli Subdistrict, Regency Pidie, Aceh Province, data collected in the form of larva surveys, distribution of research questionnaires and observation were conducted from 24 January to 28 February 2024 with the number of respondent involved 71 respondents in Pasi Peukan Baro village and 84 respondents in Pasi Rawa village, and total were 155 respondents. Research Method: Quantitative research with a cross-sectional study research design. Results: The results of Chi Square analysis in Pasi Peukan Baro village was showed a relationship between knowledge (p-value 0.000) and attitude (p-value 0.016) with community sowing behavior of abate powder in preventing aedes larvae.Meanwhile in Pasi Rawa village there is a relationship between education (p-value 0.028) and knowledge (p-value 0.000) with community sowing behavior of abate powder in preventing aedes larvae. Based on the results of the logistic regression test, the most dominant factors that were significantly related in Pasi Peukan Baro village are the age variable (p-value=0.074, CI 95%=0.032-1.170 OR=0.194) and the variable knowledge (p-value=0.001, CI 95%=3.305-95.053, OR=17.724) while in Pasi Rawa village the most dominant factor is knowledge variable (p-value=0.000, CI 95%=19.089-1831.905, OR=187.000). Conclusion:In Pasi Peukan Baro village there is a relationship between the knowledge variable and attitude variable with community sowing behavior of abate powder in preventing aedes larvae.There is a relationship between education variable and knowledge variable with community sowing behavior of abate powder in Pasi Rawa village.

Assessing the potential of native copepods in Guatemala for Aedes vector control.

In this study we examine the feeding efficiency of copepods locally found in Guatemala on first instar Aedes aegypti larvae. Copepods are a potential tool for Aedes vector control that has shown promising results in the laboratory and in community-based field trials. Four different copepod species from different habitat types were included in the laboratory assays of this study. All four tested copepod species decreased the number of the first instar Aedes larvae that were inserted into the glass vessels compared with controls. However, average predation rates between the tested species were highly different, with Thermocyclops crassus and Mesocyclops longisetus achieving the highest, with 31.0% (standard deviation [SD] 18.9) and 28. 9% (SD 11.2), respectively. The copepod species with identified high predation rates are potential candidates for planned and other future field trials for community-based Aedes vector control with copepods in the region.

Pseudomonas mosselii: a potential alternative for managing pyrethroid-resistant Aedes aegypti.

Aedes aegypti is a widespread mosquito in tropical and subtropical regions that causes significant mortality and morbidity in humans by transmitting diseases, such as dengue fever and Zika virus disease. Synthetic insecticides, such as pyrethroids, have been used to control Ae. aegypti, but these insecticides can also affect nontarget organisms and contaminate soil and water. This study aimed to investigate the mosquitocidal activity of Pseudomonas mosselii isolated from pond sludge against larvae of Ae. aegypti. Based on the initial results, similar time-course profiles were obtained for the mosquitocidal activity of the bacterial culture and its supernatant, and the pellet resuspended in Luria-Bertani (LB) medium also showed delayed toxicity. These results imply that the toxic component can be released into the medium from live bacteria. Further research indicated that the toxic component appeared in the supernatant approximately 4 h after a 3-mL stock was cultured in 200 mL of LB medium. The stabilities of the P. mosselii culture and supernatant stored at different temperatures were also evaluated, and the best culture stability was obtained at 28 °C and supernatant stability at 4 °C. The bacterial culture and supernatant were toxic to larvae and pupae of not only susceptible Ae. aegypti but also pyrethroid-resistant strains. This study highlights the value of the mosquitocidal activity of P. mosselii, which has potential as an alternative insecticide to control pyrethroid-resistant Ae. aegypti in the field. © 2024 Society of Chemical Industry.

Spatiotemporal Modeling of Aedes aegypti Risk: Enhancing Dengue Virus Control through Meteorological and Remote Sensing Data in French Guiana.

French Guiana lacks a dedicated model for developing an early warning system tailored to its entomological contexts. We employed a spatiotemporal modeling approach to predict the risk of Aedes aegypti larvae presence in local households in French Guiana. The model integrated field data on larvae, environmental data obtained from very high-spatial-resolution Pleiades imagery, and meteorological data collected from September 2011 to February 2013 in an urban area of French Guiana. The identified environmental and meteorological factors were used to generate dynamic maps with high spatial and temporal resolution. The study collected larval data from 261 different surveyed houses, with each house being surveyed between one and three times. Of the observations, 41% were positive for the presence of Aedes aegypti larvae. We modeled the Aedes larvae risk within a radius of 50 to 200 m around houses using six explanatory variables and extrapolated the findings to other urban municipalities during the 2020 dengue epidemic in French Guiana. This study highlights the potential of spatiotemporal modeling approaches to predict and monitor the evolution of vector-borne disease transmission risk, representing a major opportunity to monitor the evolution of vector risk and provide valuable information for public health authorities.

The Use of Eco-Enzyme as a Larvacide for Aedes aegypti Mosquito Larvae

Nearly half of the world's population is at risk of dengue infection, an arboviral infection that is typically spread by the mosquito Aedes aegypti. Insecticide use and community awareness campaigns are the main vector control strategies currently in use in some countries, and they didn’t done many ways to reduce dengue. Eco-enzyme is the product of fermentation from organic waste such as vegetable, fruit, and sugar. Eco-enzyme can be used in agriculture, medicine, and others. This study aims to analyze the toxicity level of ecoenzyme as the larvicide for Aedes aegypti larvae. An analytical experimental study were conducted in Bionas Parasitology Laboratory from February to March 2024. As many as 20 Aedes aegypti larvae were used in each of exposure. Each exposure were replicated four times. The mortality of Aedes aegypti larvae was analyzed by a two-way ANOVA test, followed by a Fisher's least significant defference (LSD) post hoc test with a significance level of (p&lt;0.01). This data was analysed by Statistical Product and Service Solutions(SPSS)Inc. 25.0. The concentrations of ecoenzyme induce mortality of the third instar of Aedes aegypti larvae were started from 2% concentration, and the highest was found in 10% concentrations which resulted in average of 50% mortality. In this context, the analysis results show that time, concentration, and the interaction between time and concentration have a significant influence on the observed quantities. These findings can have important implications in the context of studies or experiments related to the variables being tested. Below are the profile plots of each variable (concentration and time of exposure) which give significant influence on the mortality of Aedes larvae

Spatio-temporal occurrence and habitat characteristics of Aedes aegypti (Diptera: Culicidae) larvae in Southern Afar region, Ethiopia

BackgroundDescribing spatio-temporal occurrence and habitat characteristics of Aedes mosquito larvae is crucial for the control of Aedes borne viral diseases. This study assessed spatio-temporal abundance and habitat characteristics of Aedes larvae in the Southern Afar Region, Ethiopia.MethodsImmature mosquitoes were surveyed in Awash Sebat, Awash Arba, and Werer towns of the Southern Afar Region once per month from May 2022 to April 2023. Larvae and pupae surveys were carried out along the available water-holding containers. The collected larvae/pupae were reared to adults and identified by species/genus morphologically. The physical and chemical properties of the habitats were also characterized.ResultsA total of 9099 Aedes larvae/pupae were collected, of which 53.6% (4875) were from Awash Sebat, 29.5% (2687) from Awash Arba and 16.9% (1537) from Werer. Water-holding tyres harboured the highest number of Aedes larvae/pupae followed by water-storage drums. All the Aedes larvae/pupae reared to adults were morphologically identified as Aedes aegypti. The overall Container Index was 47.28%, House Index 18.19%, Breteau Index 59.94% and Pupal Index 171.94. Significant positive relations were observed in the occurrences of Ae. aegypti larvae/pupae with water-holding tyre (AOR = 15.89, CI = 3.55–71.09, p < 0.001), water storage drums (AOR = 19.84, CI = 4.64–84.89, p < 0.001), domestic habitat (AOR = 3.76, CI = 1.27–11.12, p = 0.017), and significant negative relations were observed with Ae. aegypti larvae/pupae occurrence and tap water source (AOR = 0.08, CI = 0.02–0.31, p = 0.001). Ae. aegypti larvae/pupae densities showed positive relations with dissolved oxygen (β = 0.523, p < 0.001) and total hardness (β = 0.475, p = 0.034) of water.ConclusionsDiverse types of artificial water-holding containers were positive for Ae. aegypti larvae/pupae. Ae. aegypti larvae/pupae were abundant in used water-holding tyres, water storage drums, and cement tanks in Awash Sebat, Awash Arba, and Werer towns. This could put the residents of the towns at high risk of infections with Ae. aegypti transmitted viral diseases such as chikungunya and dengue outbreaks. Thus, we recommend artificial water-holding container management as a strategy to control Ae. aegypti and hence the arboviral diseases transmission.

Breeding Place Preference of Aedes sp. at the Tsunami Area Banda Aceh City

The rebuilding of the post-tsunami community residential in Banda Aceh has had an impact on the emergence of Aedes habitat. The Aedes choose a container to breed based on biotic and abiotic factors that support their survival. This study aimed to the identification of Aedes species, location and type positive containers Aedes larvae at the area tsunami Banda Aceh. Methods an observational study of a cross-sectional approach involved 100 houses. Data larvae were collected using the single larvae method. Observations of containers were carried out in natural and artificial containers, indoors and outdoors. Positive containers Aedes larvae were recorded for the type of container and location found. The result of the study found two species of Aedes, there were Aedes aegypti and Aedes albopictus. Larvae of Ae. aegypti was generally found in containers indoors (71%) and containers outdoors (29%). Larvae of Ae. albopictus were found in containers indoors (10%) and containers outdoors (90%). The types of positive breeding containers of Ae. aegypti found were bathtubs (71%), discarded tires (9%), plastic drums (5%), water tanks (5%), watering pots (5%) and flower pots (5%). The containers were observed found larvae of Ae. albopictus were the bucket (30%), plastic drum (20%), bathtub (10%), discarded tires (10%), pet drinking place (10%), mineral water jar (10%) and coconut shells (10%). Monitoring of containers indoors and outdoors that can hold water is important supports the eradication program breeding places of Ae. aegypti and Ae. albopictus.

Pengendalian Sarang Nyamuk dan Kepadatan Jentik Aedes sp. di Kelurahan Kalumbuk Kecamatan Kuranji Kota Padang

Dengue Hemorrhagic Fever (DHF) is a disease caused by the dengue virus transmitted through the bite of the Aedes sp mosquito. This disease is endemic in Padang City, where 11 sub-districts have been recorded as being infected with dengue fever, the 3 sub-districts with the highest number of dengue cases, one of which is Kuranji sub-district with the highest number of cases. The aim of this research was to determine the relationship between controlling mosquito nests and the density of Aedes sp larvae. in Kalumbuk Village, Kuranji District, Padang City. This research design is analytical observation with a cross sectional approach. The research was carried out in September - December 2023. The population of this study was 460 families. Using a proportional random sampling technique using the Slovin formula, a sample of 82 families was obtained, and the data analysis used was the chi-square test statistic. The results of the research show that the implementation of controlling mosquito nests in Kalumbuk Village, Kuranji District is classified as poor (46.3%), larval density does not meet the quality standards, namely 91.5% (&lt;95%), there is a relationship between controlling mosquito nests and Aedes larvae density. sp. with a p-value of 0.003. Conclusion: there is a significant relationship between controlling mosquito nests and the density of Aedes sp larvae. in Kalumbuk Village, Kuranji District, Padang City. It is recommended that the Community Health Center conduct outreach and activate 1 house 1 jumantik and the community can control mosquito nests with the 3M Plus program periodically once a week so that it can break the chain of transmission of dengue fever.

Green purification of Acmella oleracea extract by wiped-film short path molecular distillation boosts the insecticidal activity on mosquito larvae

The development of insecticide resistance by mosquito vectors highlighted an urgent need for effective and sustainable botanical insecticides. Acmella oleracea R.K. Jansen (Asteraceae)-derived extracts and the major constituents N-alkylamides have already demonstrated their potential as insecticidal and acaricidal agents. Nowadays, the development of scalable green extraction and purification processes in the manufacture of biopesticides is a topic of great interest. In this context, supercritical fluid extraction and wiped-film short path molecular (WSM) distillation techniques were combined for the first time to obtain an eco-friendly N-alkylamides-enriched fraction (AEF) from A. oleracea. This was characterized by a notably higher content of spilanthol and N-alkylamides than the supercritical fluid extract (SFE), as determined by HPLC-DAD-MS analysis. The AEF also contained free fatty acids (e.g., palmitic, linoleic, and linolenic acids) as revealed by GC-FID analysis. The mosquito larvicidal activity of SFE, AEF, and pure spilanthol was assessed against 3rd instar larvae of Aedes albopictus Skuse, Anopheles stephensi Liston, and An. gambiae Giles. Results showed that AEF exhibited an insecticidal efficacy comparable with that of spilanthol, and higher than that of SFE. These products were tested against human keratinocytes (HaCaT) confirming their dermal safety. The present study paves the way for the utilization of WSM distillation in the agrochemical industry for the manufacture of botanical insecticides. Indeed, this technique allows to avoid the use of organic solvents related to conventional extraction and spilanthol isolation procedures and gives a product devoid of undesired pigments appealing to other industrial application as well.

Physico-chemical characteristics of breeding habitats in relation to larval density and relative abundance of Aedes mosquitoes from Siliguri sub-division, West Bengal, India

Aim: Characterization of physico-chemical parameters of Aedes mosquito breeding habitats from dengue-endemic Siliguri sub-divisional area and correlation of larval density with the habitat characteristics. Methodology: Natural and artificial water-holding containers found in four blocks, namely- Naxalbari, Matigara, Khoribari and Phansidewa of Siliguri sub-divisional area were surveyed for the collection of Aedes mosquito larvae. Water parameters such as pH, temperature, electric conductance (EC), total dissolved solid (TDS), chloride, salinity, total hardness (TH) and dissolved oxygen (DO) were measured and the larval density (LD) indices and relative abundance for Aedes spp., were calculated. Results: Out of 40 habitats, larvae of Aedes spp. were found in 20 habitats (50%). Ae. albopictus was found as the pre-dominant species (81.24%) in all the positive breeding habitats. Three habitat characteristics, like chloride (r= -0.959; p= 0.041), salinity (r= -0.958; p= 0.041)and TH (r= -0.961; p= 0.039) showed significant negative association with larval densityin the study. Whereas the remaining parameters, like-pH, temperature, EC, TDS, were positively correlated and DO showed a negative correlation with larval density. Although none of the later correlations were statistically significant. The larval density of Aedes spp. (mean ± SD) was lowest in Khoribari (27.66 ± 21.55) and highest in Phansidewa block (128.33 ± 187.26). Interpretation: Pre-dominance of Ae. albopictus reiterates its importance as a principal dengue vectorin rural, peri- or sub-urban area of the sub-division. Utilizing the obtained data, the efficacy of oviposition traps can be enhanced for locale-specific vector surveillance and development of novel techniques that may deter larval growth, development and survival in an area. Key words: Aedes mosquitoes, Dengue, Larval density, Mosquito-borne viral diseases, Siliguri

Assessment of environmental and spatial factors influencing the establishment of Anopheles gambiae larval habitats in the malaria endemic province of Woleu-Ntem, northern Gabon

BackgroundThis study aimed to assess the spatial distribution of Anopheles mosquito larval habitats and the environmental factors associated with them, as a prerequisite for the implementation of larviciding.MethodsThe study was conducted in December 2021, during the transition period between the end of the short rainy season (September–November) and the short dry season (December-February). Physical, biological, and land cover data were integrated with entomological observations to collect Anopheles larvae in three major towns: Mitzic, Oyem, and Bitam, using the "dipping" method during the transition from rainy to dry season. The collected larvae were then reared in a field laboratory established for the study period. After the Anopheles mosquitoes had emerged, their species were identified using appropriate morphological taxonomic keys. To determine the influence of environmental factors on the breeding of Anopheles mosquitoes, multiple-factor analysis (MFA) and a binomial generalized linear model were used.ResultsAccording to the study, only 33.1% out of the 284 larval habitats examined were found to be positive for Anopheles larvae, which were primarily identified as belonging to the Anopheles gambiae complex. The findings of the research suggested that the presence of An. gambiae complex larvae in larval habitats was associated with various significant factors such as higher urbanization, the size and type of the larval habitats (pools and puddles), co-occurrence with Culex and Aedes larvae, hot spots in ambient temperature, moderate rainfall, and land use patterns.ConclusionsThe results of this research mark the initiation of a focused vector control plan that aims to eradicate or lessen the larval habitats of An. gambiae mosquitoes in Gabon's Woleu Ntem province. This approach deals with the root causes of malaria transmission through larvae and is consistent with the World Health Organization's (WHO) worldwide objective to decrease malaria prevalence in regions where it is endemic.

Biocidal efficacy of olefinic N-alkylamides against Aedes aegypti and Culex quinquefasciatus larvae

Mosquito-borne diseases are a major public-health concern worldwide. The development of resistance in mosquitoes to the existing larvicides and the associated-risks necessitates the exploration of novel molecules to control vector-borne pathogens. This study demonstrates that N-alkylamides [2E,4E-N-isobutyl-undeca-2,4-diene-8,10-diynamide (1) and 2E,4E,8Z,10E-N-isobutyl-dodeca-2,4,8,10-tetraenamide (2)] of Acmella ciliata exhibit biocidal action against Aedes aegypti and Culex quinquefasciatus larvae. The LC50 for 1 and 2 were 44.19 and 18.28 ppm against Aedes larvae, and 30.89 and 11.75 ppm against Culex larvae, respectively. We further observed that the chain length, degree of unsaturation, and terminal methylation influence the larvicidal efficacy of N-alkylamides. HPLC-assisted quantification revealed that the content of both 1 (19.01 mg/g) and 2 (68.55 mg/g) was maximum in the flowers of A. ciliata. Thus, this study concludes that N-alkylamides are promising alternatives to control mosquito larvae and can be used as standard for quantitation in test samples.

Biodiversity of aquatic insects flourished in the rain water collected from Kosti and Rabak cities, White Nile State, Sudan

Biodiversity including description of status of ecosystems and populations to the best to our knowledge and major threats for better biodiversity conservation. The aim of this study was to evaluate the biodiversity of aquatic insect population in the rain water collected from White Nile State. The samples of the rain water were collected during (March and October 2022) from Kosti and Rabak Cities, White Nile State, Sudan, in clean disposable plastic bottles from random sites. Anopheles, Culex and Aedes mosquito’s larvae were identified and counted, in addition to their aquatic predators (mayfly, dragon fly and water beetles), while algae and snails were just checked for their presence within this sites. The results at Kosti city during March 2022, showed the dominance of Anopheles (37 larvae) over Culex (14 larvae), while mayfly were the more abundant predators (16 naiads), followed by water beetle (6 beetles). In Rabak city, Culex (44 larvae) was the most dominant in addition to water beetles (12 beetles). During October 2022, Anopheles (78 larvae), Culex (34 larvae) and mayfly were the dominant organisms. In Rabak city, Culex (50 larvae) was the most dominant genus, while Aedes larvae were not noticed throughout this study. Mayfly and dragon fly naiads, and water beetles were not noticed in all Rabak site

Detection of DENV-1, DENV-3, and DENV-4 Serotypes in Aedes aegypti and Aedes albopictus, and Epidemic Risk in the Departments of Oueme and Plateau, South-Eastern Benin.

Background: This study conducted in the departments of Oueme and Plateau aims to assess the presence of the dengue virus and its different serotypes in Aedes aegypti and Aedes albopictus, as well as the epidemic risk incurred by the populations. Methods: Collections of adult mosquitoes using human landing catches (HLC) were carried out in six communes, three (Porto-Novo, Adjarra, and Avrankou) in the Oueme department and the rest (Ifangni, Kétou, and Pobè) in the Plateau department. Pools of ten Aedes mosquitoes were formed, and stored at -80°C in RNA later. RT-PCR was used to detect dengue virus, and conventional PCR for the different serotypes. Inspection of water containers and collection of Aedes larvae was performed inside and around each house to calculate the stegomyan indices. Results: In the six communes, the dengue virus was present both in Ae. aegypti and Ae. albopictus. Combined data of the two Aedes species at the communes level revealed infection rates ranging from 80.00% (95% CI: 61.43-92.29) to 96.67% (95% CI: 82.78-99.92). In all the communes, the values of stegomyan indices reached the WHO threshold, which indicates the existence of the risk of an arbovirus epidemic. In addition, the infection rates were similar for Ae. aegypti [88.19% (95% CI: 81.27-93.24)] and Ae. albopictus [86.79% (95% CI: 74.66-94.52)]. The three virus serotypes detected in the pools of Aedes were DENV-1, DENV-3, and DENV-4, with a high prevalence for the first two. Conclusion: This study revealed that three serotypes (DENV-1, DENV-3, and DENV-4) of dengue virus circulate in Ae. aegypti and Ae. albopictus in the departments of Oueme and Plateau. Moreover, the risk of transmission of arboviruses was globally high and variable from commune to commune. This information is essential for informed decision-making in the preventive control of the disease.

Variable gut pH as a potential mechanism of tolerance to Bacillus thuringiensis subsp. israelensis toxins in the biting midge Culicoides sonorensis.

Toxins of Bacillus thuringiensis subsp. israelensis (Bti) are safer alternatives for controlling dipteran pests such as black flies and mosquitoes. The biting midge Culicoides sonorensis (Diptera: Ceratopogonidae) is an important pest of livestock in much of the United States and larval midges utilize semi-aquatic habitats which are permissive for Bti product application. Reports suggest that Bti products are ineffective at killing biting midges despite their taxonomic relation to black flies and mosquitoes. Here, we investigate the toxicity of a Bti-based commercial insecticide and its active ingredient in larval Culicoides sonorensis. A suspected mechanism of Bti tolerance is an acidic larval gut, and we used a pH indicator dye to examine larval Culicoides sonorensis gut pH after exposure to Bti. The lethal concentration to kill 90% (LC90) of larvae ofthe commercial product (386 mg/L) was determined to be almost 10 000 times more than that of some mosquito species, and no concentration of active ingredient tested achieved 50% larval mortality. The larval gut was found to be more acidic after exposure to Bti which inhibits Bti toxin activity. By comparison, 100% mortality was achieved in larval Aedes aegypti at the product's label rate for this species and mosquito larvae had alkaline guts regardless of treatment. Altering the larval rearing water to alkaline conditions enhanced Bti efficacy when using the active ingredient. We conclude that Bti is not practical for larval Culicoides sonorensis control at the same rates as mosquitos but show that alterations or additives to the environment could make the products more effective. © 2024 Society of Chemical Industry.

Nornicotine‐Typed Insecticides: The Potential Insecticides with Strong Activity Against Aedes Albopictus

AbstractAedes albopictus, the main vector of dengue, yellow fever, chikungunya, and Zika, has caused significant public health concerns, but there are still few effective insecticides. Nicotine and nornicotine‐typed compounds are well‐known for their potential as an insecticide, which has potential activity against Ae. albopictus. Here we report the effects of nornicotine‐typed insecticide against larvae of Ae. albopictus. We developed a novel synthetic strategy for nicotine and nornicotine‐typed compounds. Novel compounds A1‐A8 and B1‐B26 were synthesized by the synthesized nornicotine. And bioassays indicated that most of these compounds exhibited good effects against larvae of Ae. albopictus, and compounds A3, B4, B20, and B26 had excellent activity against Ae. albopictus, and they were not toxic to humans according to other reports. After considering the cost, compounds B4, B20, and B26 could be potential lead compounds against Ae. albopictus and other Aedes mosquitoes.

The Biocidal capacity of Datura (Datura stramonium L.) leaves and flowers and Cannabis (Cannabis sativa L.) seeds on some Mosquito’s larvae (Diptera: Culicidae)

Plant-based alternative pesticides are safe, effective, eco-friendly and can be used instead of synthetic pesticides. The aim of this study was to evaluate the biocidal capacity of Datura stramonium leaves (DL) and flowers (DF) and Cannabis sativa seeds (CS) on Anopheles arabiensis, Culex quiquefasciatus and Aedes aegypti larvae. The selected plant parts were collected from the experimental farm, the University garden. The LC50s of A. arabinoses larvae towards the ethanol extract of each plant part were taken to estimate the single diagnostic dose for the survival and deformities tests. GC-MS analysis for the selected plant parts was investigated. The results show that DL ethanol extract detected 14 compounds of which butanol,3-methyl is the main component (79.76%) followed by toluene (6.14%). Phytol was also detected (3.9%). 14 compounds were detected from DF of which formic acid,3-methylbut-2-yl ester was the main component (82.22%) followed by dodecanoic acid, ethyl ester (3.3%) and toluene (2.86%). Also, from CS, Dronabinol (41.4%) was the main component, followed by Cannabinol (10.38%), Phytol (10.38%) and Caryophylene (2.07%). The susceptibility test of An. arabiensis larvae revealed the LC50’s of 562.95 mg/L for DL, 424.41 mg/L for DF and 175.40 mg/L for CS. It was noticed that 3-6% of An. arabiensis and 1-28% of Culex quiquefasciatus and 12-22% of Aedes aegypti larvae developed to pupae and some of them developed to adult stage after one week. In the survival test, more than 70% of the larvae were killed by a concentration supposed to kill 50% or less of the larvae. Some deformations were monitored on Anopheles, Culex and Aedes larvae including swelled body, separated alimentary canal. Field assessment should be run and the concept of LC50 should be re-written.