Application Of Larvicides Research Articles

Assessment of the Knowledge, Prevalence, and Control Strategies of Malaria Among Households in Sunyani Municipality, Bono Region, Ghana.

Malaria remains a global public health concern for centuries. The study assessed the knowledge, prevalence and control strategies of malaria among households in the Sunyani Municipality, Bono Region, Ghana. A simple random sampling method was used to administer semi-structured questionnaires to the respondents (n = 422). STATA version 14.0 was used to analyse the data and the results were presented in charts, graphs, and tables. The study shows that the knowledge level of malaria, its vector of transmission and mosquitoes breeding sites among the respondents was quite high. Among the respondents, 43% reported to have been infected by malaria once in a year and 94% indicated that, their relatives have been infected with malaria parasites previously. Also, majority, 65% of the respondents selected environmental management and sanitation (EMS), followed by settlement (building houses) away from wetlands, 20.0% as alternative vector control methods to be employed to supplement the core vector control methods in the Municipality. Further, majority, 69% of the respondents indicated that enforcement of environmental sanitation bye-laws will compel residents to clean their environment, and this is likely to eliminate most mosquito breeding sites, whiles 46% called on Government to support, and employ more Environmental Health Officers and Sanitary Labourers, and adequately resource them to work effectively. Health authorities in the Sunyani Municipality must intensified education on malaria at all levels with the aim to influence the attitudes of households towards its prevention and control. Central and Local Government must employ more Environmental Health Officers, and empower and adequately resourced them to strictly enforce the environmental sanitation bye-laws. Malaria control authorities in the study area must consider employing environmental management and sanitation (EMS) and application of larvicides for mosquito larval control as alternative/supplementary malaria prevention and control methods to compliments the current core vector control methods.

Assessment of Truck-Mounted Area-Wide S-methoprene Applications to Manage West Nile Virus Vector Species in the Suburbs of Chicago, IL, USA.

West Nile virus remains the leading cause of arboviral neuroinvasive disease in the United States, despite extensive efforts to control the mosquito vectors involved in transmission. In this study, we evaluated the effectiveness of Altosid SR-20 (active ingredient, S-methoprene 20%) larvicide applications using truck-mounted ultra-low volume (ULV) dispersal equipment to target Culex pipiens Linnaeus (Diptera: Culicidae) and Cx. restuans (Theobald)larvae. A combination of emergence bioassays, open-field measurements of deposited S-methoprene and spray distribution using gas chromatography-mass spectrometry, and assessments of adult Culex spp. populations in response to applications were conducted over the summer of 2020 within the North Shore Mosquito Abatement District (IL, USA). Open-field applications revealed that dispersed Altosid SR-20 using ULV equipment was effective (75% emergence inhibition in susceptible lab strain Cx. pipiens larvae) up to 53 m. In suburban neighborhood applications, we found that S-methoprene deposition and larval emergence inhibition (EI) in front yards did not differ significantly from backyards. An overall EI of 46% and 28% were observed for laboratory strain Cx. pipiens and wild Cx. restuans larvae respectively, and both had an EI significantly higher than the untreated control group. The EI of exposed wild Cx. pipiens larvae did not differ from the untreated controls, suggesting an increased tolerance to S-methoprene. No difference in abundance of gravid or host-seeking adult Culex spp. post-application was detected between treated and untreated sites. These results document the ability of area-wide application to distribute S-methoprene, but this strategy will need further modifications and evaluation for Culex spp. management.

A novel approach of phyllanthus niruri supported Ag-Cu-Co for anti-oxidant, anti-bacterial, larvicidal and photodegradation applications

Novel Ag-Cu-Co trimetallic nanoparticles were synthesized by green method using phyllanthus niruri extract as a reducing and stabilizing agent. It was analyzed using Ultraviolet-Visible, Fourier Transform Infrared, Scanning Electron Microscope, X-ray Diffraction, Particle size and Thermal analyses etc. The UV–Vis studies confirmed the absorption value of Ag-Cu-Co at 241 nm respectively. The crystalline size of the P. niruri supported Ag-Cu-Co was found in the range of 17–19 nm with quasi spherical in shape. From the antibacterial study the synthesized Ag-Cu-Co showed maximum zone of inhibition for E. coli and it was found to be 25 mm. The photocatalytic degradation study confirmed the effective activity against methylene blue and the percentage degradation was confirmed to be 83.28 percentage. The LC50 value was found to be 14.768 percentage which confirmed the potent larvicidal activity of synthesized material. Hence, it has proved that the synthesized green nanoparticles as proficient catalyst for antioxidant, antibacterial, larvicidal and effective degradation of dye molecules.

Recovery of silver nanoparticles and management of food wastes: Obstacles and opportunities

• The natural fruits and vegetable wastes (FVW) are ample sources of bioactive compound. • Green synthesis of AgNPs from FVW reduces environmental pollution and confers on its added value. • AgNPs from FVW can be useful in recovery of bioactive compounds. • FVW derived nanoparticles can be used as anticancer, antibacterial anti-fungal and anti-viral agents. • Suitable worker friendly method of nanomaterial recovery from FVW needs to be explored. The growing scale of human enterprise and lack of family-owned livestock is leading to lesser recycling and higher production of food wastes. The safe technology, for removal of pollutants and recovery of profitable goods and chemicals, is required to mitigate the agri and food waste mediated global crisis. The reuse of waste resources reduces the cost of fabrication and the vulnerability to hazardous chemicals, and promotes circularity and green synthesis. The green synthesis of metal nanoparticles and their oxide from food waste can be a new eco-friendly, cost-effective, and appropriate alternative to traditional methods. The green synthesis of silver nanoparticles is quick and executed at ambient temperature. The application of nanotechnology for the effective recycling of food waste have enormous potential in India, where only ∼30% of domestic wastes is recycled. The present paper reviews the available literature on characteristics and impacts of kitchen wastes, viable options for recovering nanoparticles through green synthesis, and explores the potential applications of nanoparticles synthesized from kitchen wastes. There is significant scope and prospect for further research in this emerging field. With suitable examples of metal nanoparticles recovered from the kitchen wastes, this review critically explores various applications of nanoparticles recovered from the vegetable and fruit wastes in wastewater treatment, antimicrobial, antifungal, insecticidal, larvicidal, and other biomedical applications. Pointing to the contemporary constraints of an ecosystem and human health the paper concludes suitable strategies for utilizing vegetable and fruit wastes for the generation of nanoparticles, including recommendations for future developments.

Biologically Synthesized Silver Nanoparticles and Their Diverse Applications.

Nanotechnology has become the most effective and rapidly developing field in the area of material science, and silver nanoparticles (AgNPs) are of leading interest because of their smaller size, larger surface area, and multiple applications. The use of plant sources as reducing agents in the fabrication of silver nanoparticles is most attractive due to the cheaper and less time-consuming process for synthesis. Furthermore, the tremendous attention of AgNPs in scientific fields is due to their multiple biomedical applications such as antibacterial, anticancer, and anti-inflammatory activities, and they could be used for clean environment applications. In this review, we briefly describe the types of nanoparticle syntheses and various applications of AgNPs, including antibacterial, anticancer, and larvicidal applications and photocatalytic dye degradation. It will be helpful to the extent of a better understanding of the studies of biological synthesis of AgNPs and their multiple uses.

Sublethal exposure to pyriproxyfen does not impair the abilities of the backswimmer Buenoa amnigenus to prey upon Aedes aegypti larvae.

Pyriproxyfen is a juvenile hormone analogue that is commonly used to control the immature stages of mosquitoes in both artificial and natural water reservoirs. Recently, concerns have been raised regarding the community effectiveness of pyriproxyfen in preventing vector-transmitted diseases. Such concerns have been based on the unintended effects on non-target organisms and the selection of resistant mosquito populations. This investigation was, therefore, conducted to evaluate the toxicity of pyriproxyfen to Aedes aegypti (Diptera: Culicidae) larvae and the backswimmer Buenoa amnigenus (Hemiptera: Notonectidae), a naturally occurring mosquito larvae predator. We also assessed the abilities of backswimmers exposed to sublethal levels of pyriproxyfen to prey upon mosquito larvae (L2) under three larval densities (3, 6, or 9 larvae/100 mL of water) using artificial containers. Our results revealed that pyriproxyfen killed backswimmers only at concentrations higher than 100 μg active ingredient [a.i.]/L, which is 10 times higher than that recommended for larvicidal field application (i.e, 10 μg a.i./L). The abilities of backswimmers exposed to sublethal levels of pyriproxyfen (100 μg a.i./L) to prey upon mosquito larvae were not affected. Harmful effects on the backswimmer predatory abilities were detected only at concentrations of 150 μg a.i./L and when there was a higher prey availability (i.e., 9 larvae/100 mL of water). Together, our findings indicate that the reduced community effectiveness of this insecticide derives from factors other than its detrimental effects on non-target organisms such as backswimmers.

Effectiveness of a Buffalo Turbine and A1 Mist Sprayer for the Areawide Deployment of Larvicide for Mosquito Control in an Urban Residential Setting.

The control of medically important container-inhabiting mosquitoes is an ongoing challenge for mosquito control operations. Truck-mounted application equipment is a common option for rapid areawide larvicide deployment utilized by mosquito control operations. We tested the effectiveness of two truck-mounted sprayers (A1 Super Duty + Buffalo Turbine CSM3), for the deployment of water-dispersible biopesticides (VectoBac WDG:VectoLex WDG 50:50). Sixty residences within four residential neighborhoods in New Jersey were treated in 2019 and 2020. Three empty bioassay cups were placed in specific locations on each property (front yard/ back yard/ side of house), with an additional cup placed in an adjacent catch basin. This approach was replicated in two untreated control neighborhoods. Following larvicide application, cups were subjected to bioassays wherein larval mortality was tracked through adult eclosion. Overall, average larval mortality rates were 56% higher in treated cups compared against untreated controls. Mortality rates were affected by cup location, with 39% mortality in bioassay cups from back yards, 54% in those from the sides of houses, 73% in front yards, and 76% from cups in catch basins. Mortality did not differ significantly between the four treated neighborhoods, nor by the type of sprayer used. Our research shows that truck-mounted sprayers can be an effective method for larvicide deployment in residential neighborhoods, but effectiveness may depend upon the location of the target treatment area in relation to residences and other geographic obstacles.

Laboratory and semi-field evaluation of the efficacy of Bacillus thuringiensis var. israelensis (Bactivec®) and Bacillus sphaericus (Griselesf®) for control of mosquito vectors in northeastern Tanzania

Bacterial larvicides Bacillus thuringiensis var. israelensis (Bti) and Bacillus sphaericus (Bs) have been used extensively for mosquito control. However, their efficacy varies greatly mainly due to factors related to target mosquitoes, larval habitat conditions, and inherent larvicide properties. We evaluated the efficacy of Bti (Bactivec®) and Bs (Griselesf®) for control of Anopheles gambiae complex, Culex quinquefasciatus and Aedes aegypti larvae under laboratory and semi-field conditions in northeastern Tanzania. Laboratory bioassays were conducted with five to six different concentrations of Bti and Bs, replicated four times and the experiment repeated on three different days. Larvae mortality was recorded at 24 or 48 h after the application of larvicide and subjected to Probit analysis. Laboratory bioassays were followed by semi-field trials to establish initial and residual activity of Bti and Bs. Semi-field trials were conducted in artificial larval habitats in the open sunlit ground and in “mosquito spheres”. These artificial larval habitats were colonized with mosquito larvae, treated with Bti and Bs, and the impact of treatments on mosquito larvae was monitored daily. Lethal concentration values that caused 50% and 95% mortalities of test larvae (LC50 and LC95) showed that An. gambiae complex and Cx. quinquefasciatus tested were highly susceptible to Bti and Bs under laboratory conditions. Likewise, larvae of Ae. aegypti were highly susceptible to Bti, with LC95 value as low as 0.052 mg/l. However, Ae. aegypti larvae were not susceptible to Bs under practical doses of laboratory settings. In semi-field trials, all treatment dosages for Bti provided 91.0–100% larval mortality within 24 h whereas Bs resulted in 96.8–100% larval mortality within the same time-frame. Bs had a more prolonged residual activity, with pupal reductions range of 55.7–100% for 9 days at all application rates while the corresponding pupal reduction with Bti was 15.4–100% for 5 days. Due to the low residual activity of Bti and Bs tested, weekly application at a maximum label rate would be appropriate to reduce mosquito larvae in natural larval habitats. Based on laboratory findings, Bs product tested would not be recommended for use in the control of Ae. aegypti.

Tyrosinase-mediated synthesis of larvicidal active 1,5-diphenyl pent-4-en-1-one derivatives against Culex quinquefasciatus and investigation of their ichthyotoxicity

1,5-diphenylpent-4-en-1-one derivatives were synthesised using the grindstone method with Cu(II)-tyrosinase used as a catalyst. This method showed a high yield under mild reaction conditions. The synthesised compounds were identified by FTIR, 1H NMR, 13C NMR, mass spectrometry, and elemental analysis. In this study, a total of 17 compounds (1a–1q) were synthesised, and their larvicidal and antifeedant activities were evaluated. Compound 1i (1-(5-oxo-1,5-diphenylpent-1-en-3-yl)-3-(3-phenylallylidene)thiourea) was notably more active (LD50: 28.5 µM) against Culex quinquefasciatus than permethrin(54.6 µM) and temephos(37.9 µM), whereas compound 1i at 100 µM caused 0% mortality in Oreochromis mossambicus within 24 h in an antifeedant screening, with ichthyotoxicity determined as the death ratio (%) at 24 h. Compounds 1a, 1e, 1f, 1j, and 1k were found to be highly toxic, whereas 1i was not toxic in antifeedant screening. Compound 1i was found to possess a high larvicidal activity against C. quinquefasciatus and was non-toxic to non-target aquatic species. Molecular docking studies also supported the finding that 1i is a potent larvicide with higher binding energy than the control (− 10.0 vs. − 7.6 kcal/mol) in the 3OGN protein. Lead molecules are important for their larvicidal properties and application as insecticides.

Fabrication and characterization of noble crystalline silver nanoparticles from Pimenta dioica leave extract and analysis of chemical constituents for larvicidal applications

The current works report the bio-efficacy of Pimenta dioica leaf derived silver nanoparticles (Pd@AgNPs) and leaf extract obtained trough different solvents against the larvae of malaria, filarial and dengue vectors. Synthesis of silver nanoparticles (AgNPs) was done by adding 10 ml of P. dioica leaf extract into 90 ml of 1 mM silver nitrate solution, a slow colour change was observed depicting the formation of AgNPs. Further, Pd@AgNPs was confirmed through Ultraviolet–visible spectroscopy which exhibited characteristic absorption peak at 422 nm wavelength. X-ray diffraction and selected area electron diffraction analysis confirmed monodispersed and crystalline nature of Pd@AgNPs with 32 nm an average size. Scanning electron microscopy and transmission electron microscopy showed the most of Pd@AgNPs were spherical and triangular in shape and energy-dispersive X-ray spectroscopy revealed silver elemental nature of nanoparticles. Zeta potential of Pd@AgNPs is highly negative which confirmed its stable nature. Pd@AgNPs showed prominent absorption peaks at 1015, 1047, 1243, 1634, 2347, 2373, 2697 and 3840 cm−1 which are corresponding to following compounds polysaccharides, carboxylic acids, water, alcohols, esters, ethers, amines, amides and phenol, respectively as reported by Fourier-transform infrared spectroscopy analysis. Gas chromatography–mass spectrometry and Liquid chromatography–mass spectrometry analysis revealed 39 and 70 compounds, respectively, which might be contributed for bio-reduction, capping, stabilization and larvicidal behavior of AgNPs. A comparable lethality (LC50 and LC90) was observed in case of Pd@AgNPs over leaf extract alone. The potential larvicidal activity of Pd@AgNPs was observed against the larvae of Aedes aegypti,(LC50, 2.605; LC90, 5.084 ppm) Anopheles stephensi (LC50, 3.269; LC90, 7.790 ppm) and Culex quinquefasciatus (LC50, 5.373; LC90, 14.738 ppm without affecting non-targeted organism, Mesocyclops thermocyclopoides after 72 hr of exposure. This study entails green chemistry behind synthesis of AgNPs which offers effective technique for mosquito control and other therapeutic applications.

Operational Basin Larvicide Evaluations in Northern Cook County, Illinois During 2019 and 2020.

Over the course of 2019 and 2020, 7 larvicide formulations for use in catch basins were evaluated using a standardized pass/fail protocol. A comparison between 1- and 2-pouch doses of VectoLex® water-soluble pouches (WSP; 10 g per pouch) and 20 g of VectoLex FG (loose granules) suggests that the WSP formulation may have a shorter duration than the FG formulation. Results also suggest that 20 g doses of each of 2 larvicides, Duplex™-G and Sumilarv® 0.5G, may have a minimum effective duration in basins for approximately 40 days. A 20 g dose of Altosid® XR-G and a single briquet Altosid XR each had an observed minimum effective duration of 20 days. Sustain MBG had an observed duration of only 7 wk posttreatment. These observations provide evidence that, in some locations, 20 g granular applications may have a longer effective duration than a single briquet. This work highlights the utility of applying a standardized protocol for routine quality control assessments of the thousands of catch basin larvicide applications performed seasonally by mosquito abatement districts.

The community-wide effectiveness of municipal larval control programs for West Nile virus risk reduction in Connecticut, USA.

BACKGROUNDMosquito larval control through the use of insecticides is the most common strategy for suppressing West Nile virus (WNV) vector populations in Connecticut (CT), USA. To evaluate the ability of larval control to reduce entomological risk metrics associated with WNV, we performed WNV surveillance and assessments of municipal larvicide application programs in Milford and Stratford, CT in 2019 and 2020. Each town treated catch basins and nonbasin habitats (Milford only) with biopesticide products during both WNV transmission seasons. Adult mosquitoes were collected weekly with gravid and CO2‐baited light traps and tested for WNV; larvae and pupae were sampled weekly from basins within 500 m of trapping sites, and Culex pipiens larval mortality was determined with laboratory bioassays of catch basin water samples.RESULTSDeclines in 4th instar larvae and pupae were observed in catch basins up to 2‐week post‐treatment, and we detected a positive relationship between adult female C. pipiens collections in gravid traps and pupal abundance in basins. We also detected a significant difference in total light trap collections between the two towns. Despite these findings, C. pipiens adult collections and WNV mosquito infection prevalence in gravid traps were similar between towns.CONCLUSIONLarvicide applications reduced pupal abundance and the prevalence of host‐seeking adults with no detectable impact on entomological risk metrics for WNV. Further research is needed to better determine the level of mosquito larval control required to reduce WNV transmission risk.

Emerging properties of malaria transmission and persistence in urban Accra, Ghana: evidence from a participatory system approach

BackgroundSeveral studies that aim to enhance the understanding of malaria transmission and persistence in urban settings failed to address its underlining complexity. This study aims at doing that by applying qualitative and participatory-based system analysis and mapping to elicit the system’s emergent properties.MethodsIn two experts’ workshops, the system was sketched and refined. This system was represented through a causal loop diagram, where the identification of leverage points was done using network analysis.Results45 determinants interplaying through 56 linkages, and three subsystems: urbanization-related transmission, infection-prone behaviour and healthcare efficiency, and Plasmodium resistance were identified. Apart from the number of breeding sites and malaria-positive cases, other determinants such as drug prescription and the awareness of householders were identified by the network analysis as leverage points and emergent properties of the system of transmission and persistence of malaria.ConclusionBased on the findings, the ongoing efforts to control malaria, such as the use of insecticide-treated bed nets and larvicide applications should continue, and new ones focusing on the public awareness and malaria literacy of city dwellers should be included. The participatory approach strengthened the legitimacy of the recommendations and the co-learning of participants.

Bioinspired synthesize of CuO nanoparticles using Cylindrospermum stagnale for antibacterial, anticancer and larvicidal applications

Bioinspired synthesize of CuO nanoparticles using Cylindrospermum stagnale for antibacterial, anticancer and larvicidal applications

Mixed phytochemicals mediated synthesis of copper nanoparticles for anticancer and larvicidal applications

The synthesis of copper nanoparticles (CuNPs) using Wrightia tinctoria (Wt) R.Br extract is defined in this article as being convenient, environmentally friendly, and non-toxic. UV-visible spectrophotometry, FT-IR, XRD, particle size analyser, SEM-EDAX and TEM methods were used to describe the physicochemical properties of Wt extract mediated synthesized CuNPs (Wt-CuNPs). The Wt-CuNPs synthesized was found to be monodispersed and spherical, with an average size of 15 nm. Gas chromatography and mass spectrometry (GC-MS) research revealed that the Wt R.Br plant extract contains various phytochemical compounds. The properties of Wt-CuNPs were verified by the findings of characterization tests. Via in silico molecular docking experiments with established targets, the underlying mechanisms of cytotoxicity against breast cancer and larvicidal behaviour against Aedes aegypti of Wt-CuNPs were investigated. Interestingly, in vitro cytotoxicity studies showed 50% cell death (IC50) of Wt-CuNPs treated MCF-7 cells and Vero Cells (Kidney epithelial cells) were displayed at 119.23 μg.mL−1 and 898.75 μg.mL−1, respectively. Also, Wt-CuNPs showed least LC50 and LC90 values for larvicidal activity against A. aegypti were of 32.10 μg.mL−1 and 21.70 μg.mL−1, respectively. Furthermore, Wt-CuNPs is found to be less toxic and biocompatible in haemolytic assays. The findings clearly showed that biosynthesized Wt-CuNPs have been used as a possible anticancer and larvicidal agent, as well as being environmentally friendly.

Automatic detection of surface-water bodies from Sentinel-1 images for effective mosquito larvae control

Surface-water body maps are imperative for effective mosquito larvae control. This study aims to select a method for the automatic and regular mapping of surface-water bodies in rice fields and wetlands using Sentinel-1 synthetic aperture radar data. Four methods were adapted and developed for automated application: the Otsu valley-emphasis algorithm, a classification method based on the textural feature of entropy, a method using K-means unsupervised classification, and a method using the Haralick’s textural feature of dissimilarity and fuzzy-rules classification. The results were assessed using field data collected during the mosquito breeding periods of 2018 and 2019 in the region of Central Macedonia (Greece). The Otsu valley-emphasis technique provides the highest overall accuracy (0.835). The accuracy is higher at the beginning of the summer (0.948) than at the end of the rice-growing season due to higher density of vegetation. Results using this method were further assessed during the main larvicide application period. The presence of vegetation, built-up areas, floating algae in rice-paddies, salt-crust formations in wetlands, and water depth, were found to affect the performance of the algorithm. A WebGIS platform was designed for the visualization of the produced water maps along with other data related to mosquito-larvae presence.

Effectiveness of adulticide and larvicide in controlling high densities of Aedes aegypti in urban environments.

Current management and control of Aedes aegypti populations in urban areas are based on the spraying of insecticides. Here, we evaluated the effectiveness of spraying larvicide (Bacillus thuringiensis israelensis) using a truck-mounted Buffalo Turbine and adulticide (Deltamethrin) using a Grizzly ULV Sprayer in an urban area with high densities of Ae. aegypti and many cryptic and difficult to reach aquatic breeding habitats. Experiments were conducted in a tire shop located in Miami-Dade County, Florida with approximately 100,000 used airplane tires. Insecticide interventions were performed after a baseline survey consisting of 3 weeks of collections, followed by two insecticide interventions: (i) application of the adulticide followed by the application of larvicide on the subsequent week; and (ii) application of both adulticide and larvicide on two consecutive weeks. The first insecticide intervention resulted in a non-significant decrease in the relative abundance of Ae. aegypti. On the other hand, the second insecticide intervention significantly reduced the Ae. aegypti relative abundance (P < 0.002). Our results demonstrated that the combined insecticide interventions on two consecutive weeks significantly reduced the relative abundance of Ae. aegypti. This result indicated that the larvicide was successfully propelled reaching cryptical and difficult to reach aquatic habitats. However, even though the number of mosquitoes was greatly reduced, it was still greatly above the 10-mosquito threshold by trap night used by the Miami-Dade Mosquito Control Division to deploy an inspector to survey the area. Considering the lack of new and effective mosquito control tools, efficient and mobile insecticide propellers such as Buffalo Turbine can be of great help to manage mosquito populations in urban areas.

Be quick or be dead: high temperatures reduce Aedes aegypti (Diptera: Culicidae) larval development time and pyriproxyfen larvicide efficiency in laboratory conditions

Several studies have assessed the efficiency of insect growth regulators to control Aedes aegypti under laboratory conditions. However, empirical evidence evaluating how insect growth regulators respond to different temperatures is scarce. In this paper, we evaluate whether temperature may influence the efficiency of pyriproxyfen. To do so, we analyzed the effect of three temperatures (20, 25 and 30 °C) combined with five pyriproxyfen concentrations (0.0001, 0.001, 0.01, 0.1 and 1 mg L−1) on Ae. aegypti larval control. Each experiment had five replicates containing 250 mL of the test solution and 20 larvae according to WHO protocol. Tests were conducted until all mosquitoes had either fully emerged from the control beakers or died. The outcomes showed that, as we increased the temperature, not only did the larval developmental time decrease (from 23.5 to 10.7 days) but also the concentration of larvicide required for 50% (EC50 of 0.0002 and 0.0050 mg L−1 for 20 and 30 °C, respectively) and 95% efficiency increased (EC50 of 0.009 and 0.013 mg L−1 for 20 and 30 °C, respectively). We highlight how temperature changes produce different results from larvicide applications (p < 0.05) and provide data that allow scientists and the government to evaluate field populations’ responses and integrate the use of larvicides more appropriately. We suggest that the effects of environmental factors on larvicide applications should be tested for field mosquito populations so that different temperature conditions can be integrated with the surveillance programs of Aedes aegypti.

Identification of molecular scaffolds from Caatinga Brazilian biome with potential against Aedes aegypti by molecular docking and molecular dynamics simulations

In this paper, we performed a virtual screening by docking and molecular dynamics approaches to identify molecular scaffolds as potential inhibitors of the Sterol Carrier Protein-2 (PDB ID: 1PZ4) from Aedes aegypti, using a homemade data bank of 248 secondary metabolites, found on Caatinga Brazilian biome. The insect is a known vector of important diseases around the world, as Zika, Chikungunya and Dengue fever. The compounds were selected after a search on SciFinderⓇ online platform, crossing the name of 40 Caatinga biome plants with words indicating the identification and/or isolation of molecules. Initial re-docking and docking procedures showed that the co-crystalized ligand (“palmitic acid”) presented a binding energy (-6.9 kcal/mol) higher than seventy-six of the total number of compounds evaluated (two hundred forty-eight). Five compounds were considered for sequential Molecular Dynamics (MD) calculations, by energetic and structural analysis. The MD plots and average binding energies obtained by MM/PBSA method confirm that the biflavonoid loniflavone, founded in the leaves of a Brazilian plant called “catingueira” (Cenostigma pyramidale (Tul.) E. Gagnon & G. P. Lewis, previously Caesalpinia priamidalis) was the most promissory in the interaction with 1PZ4. Two additional compounds from lignan and sesquiterpene molecular scaffolds were also identified as potential against A. aegypti. These results can be used as guidelines for testing compounds with larvicidal application.

Process Evaluation of a Community-Based Microbial Larviciding Intervention for Malaria Control in Rural Tanzania.

Microbial larviciding can be an effective component of integrated vector management malaria control schemes, although it is not commonly implemented. Moreover, quality control and evaluation of intervention activities are essential to evaluate the potential of community-based larviciding interventions. We conducted a process evaluation of a larval source management intervention in rural Tanzania where local staff were employed to apply microbial larvicide to mosquito breeding habitats with the aim of long-term reductions in malaria transmission. We developed a logic model to guide the process evaluation and then established quantitative indicators to measure intervention success. Quantitative analysis of intervention reach, exposure, and fidelity was performed to assess larvicide application, and interviews with larviciding staff were reviewed to provide context to quantitative results. Results indicate that the intervention was successful in terms of reach, as staff applied microbial larvicide at 80% of identified mosquito breeding habitats. However, the dosage of larvicide applied was sufficient to ensure larval elimination at only 26% of sites, which does not meet the standard set for intervention fidelity. We propose that insufficient training and protocol adaptation, environment and resource issues, and human error contributed to low larvicide application rates. This demonstrates how several small, context-specific details in sum can result in meaningful differences between intervention blueprint and execution. These findings may serve the design of other larval source management interventions by demonstrating the value of additional training, supervision, and measurement and evaluation of protocol adherence.