Residual Efficacy Research Articles

Temporary clogging effects induced by a sustainable anti-icing hydrogel on the hydraulic conductivity and inertia coefficient of open-graded asphalt pavements

Open-graded asphalt pavements require special winter maintenance procedures to ensure the effectiveness of anti-icing and deicing measures. A recently developed solution for this type of pavement is represented by an environmental friendly thickened bio-based salt hydrogel, which consists of a thermo-sensitive sodium chloride (NaCl) brine admixed with a gellant agent (seaweed fibers) having the ability to form a gel-like structure when hot-sprayed on a cold surface. This thin salt layer results in a long-lasting residual efficacy of the winter maintenance product and in a reduction of salt consumption, but affects the drainage capacity of the pavement. These transient clogging effects were evaluated on laboratory-made specimens through the measurement of their vertical hydraulic conductivity variations before and after the hydrogel application, using a 1-D air permeameter and a constant head water permeameter. The analyses, based on Darcy–Forchheimer model and Darcy model for lower Reynold numbers, revealed a significant short-term reduction of the hydraulic conductivity, that, anyway, tends to be almost totally restored once the critical weather event is over (after about 6 h).

Deltamethrin residual mission against Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae) on concrete for six weeks

Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae) is an important pest of stored-products and poultry houses. Despite the fact that there is knowledge about chemical management of this species, there are no data about the residual efficacy of deltamethrin. Therefore, this study compares the immediate and delayed efficacy of half label and label dose of deltamethrin treated on concrete surfaces, with or without food, over a six-week period against A. diaperinus adults and larvae. In first week, both doses of deltamethrin exhibited the highest immediate and delayed mortality at all food/no food scenarios, for both developmental stages, whereas its efficacy gradually decreased over the experimental period. Concerning adult mortality, it ranged between 6.7% and 31.1% the first week, while 1.1–13.3% the sixth week, after 7 days of exposure. Both doses exhibited elevated efficacy against A. diaperinus larvae. Label dose without food caused 100.0% mortality the 3rd day whereas label dose with food the 7th day of the first week. Total mortality (100.0%) was recorded at the end of the second week by both food/no food scenarios of label dose. The third week only label dose without food killed all larval individuals, the 7th day. During the sixth week, mortality ranged between 71.1% and 92.2%, at the termination of the experiments. Concerning delayed adult mortality, it ranged from 63.6% the first week to 7.9% the sixth week. As far as delayed larval mortality is concerned, all individuals died even the fifth week at label dose without food, the fourth week at label dose with food, the second and the first week for half label dose without food and with food respectively. Deltamethrin has elevated efficacy against A. diaperinus larvae despite the dose and food presence/absence.

Evaluation on the Activity and Efficacy of Omniprene™ WSP and XWSP Against the Southern House Mosquito Culex quinquefasciatus in Simulated Catch Basins.

Mosquitoes and mosquito-borne diseases remain one of the major public health burdens. In most cases, vector control is the main or the only intervention to mitigate these problems. We are facing the challenges of traditional, emerging, or resurging vectors and diseases, yet the availability and affordability of safe and effective mosquito control products are at a historical low. Development of new active ingredients (AI) and novel formulations based on currently available AI are demanded by mosquito control operations. This paper validated the bioactivity in the laboratory and evaluated the semi-field efficacy for 2 newly registered controlled-release products based on juvenile hormone analog S-methoprene: OmniPrene™ water-soluble pouch (WSP) and extended water-soluble pouch (XWSP). Along with technical S-methoprene, these 2 formulations showed high inhibition of adult emergence in laboratory bioassays against Aedes aegypti, Ae. albopictus, and Culex quinquefasciatus that are commonly found in catch basins. High initial and long-term residual efficacy were demonstrated in simulated catch basins against Cx. quinquefasciatus, where the OmniPrene WSP consistently provided over 90% control for 15 wk (105 days) and OmniPrene XWSP did the same for 38 wk (266 days). Considering the need for reliable mosquito control products, combined with commonly encountered product performance issues in catch basins, OmniPrene WSP and XWSP can be viable tools to combat mosquito species of public health concern that are associated with urban drainage systems.

Residual efficacy of the neonicotinoid insecticide clothianidin against pyrethroid-resistant Aedes aegypti.

Here we report the residual efficacy of the neonicotinoid insecticide clothianidin against pyrethroid-resistant Aedes aegypti. We first conducted a range-finding evaluation of clothianidin on three different substrates (wall, wood, cloth) using three doses (100, 300 and 600 mg a.i.m-2 ) and conducting World Health Organization (WHO) cone bioassays to assess acute (24 h) and delayed (up to 7 days) mortality. In experimental houses located in Merida (Mexico) and using free-flying pyrethroid-resistant Ae. aegypti females, we quantified the acute and delayed mortality after a 24-h exposure to the targeted indoor residual spraying (TIRS) of two clothianidin doses (100 and 300 mg a.i.m-2 ). Range-finding studies with WHO cones showed low (<50%) acute mortality for all surfaces, doses and times post spraying. Delayed mortality was higher, with average values above or close to the 60% mark (and 95% confidence interval estimates crossing 80% for the 600 mg a.i.m-2 dose). In experimental houses, a similar low acute mortality was quantified (range of mortality across 12 months was 2-44% for 100 mg a.i.m-2 and 8-61% for 300 mg a.i/m2 ). However, delayed mortality showed a strong effect of clothianidin on free-flying Ae. aegypti, with values above 80% up to 7months post-TIRS. Novel residual insecticide molecules have a promising outlook for Ae. aegypti control and can contribute to the expansion and adoption of TIRS in urban areas. clothianidin can contribute to the control of resistant Ae. aegypti and provide residual control for up to 7 months after application. © 2022 Society of Chemical Industry.

Evaluation of the Efficacy of Fludora® Fusion WP-SB 56.25 (Mixture of Clothianidin and Deltamethrin) against Anopheles coluzzii Laboratory and An. arabiensis Wild Colonies.

For malaria control, the application of long-lasting insecticidal nets and indoor residual spraying has led to a significant reduction in morbidity and mortality. However, the sustainability of these gains is hampered by the increase in insecticide resistance. It is therefore judicious to evaluate new insecticide formulations. In comparison to clothianidin and deltamethrin, the efficacy and residual effect of Fludora® Fusion was evaluated using an Anopheles coluzzii laboratory and An. arabiensis wild colonies in huts from August 2016 to June 2017 on cement and mud walls. Mortality was recorded at 24, 48, 72, and 96 h post exposure. Like deltamethrin and clothianidin, Fludora® Fusion showed delayed mortality rates above the WHO’s 80% threshold over a period of 11 months with the laboratory strain. With the wild strain, while residual efficacy was observed at 2 months for the three insecticides, no residual efficacy was observed at 8 months at 24 h in both substrates. However, the increased efficacy was observed with increased holding periods (72 h and 96 h). These findings suggest that Fludora® Fusion could be an alternative candidate since this duration covers the transmission period in most areas in Senegal.

The realized efficacy of indoor residual spraying campaigns falls quickly below the recommended WHO threshold when coverage, pace of spraying and residual efficacy on different wall types are considered.

Indoor residual spraying (IRS) has been and remains an important malaria control intervention in southern Mozambique, South Africa and Eswatini. A better understanding of the effectiveness of IRS campaigns is critical to guide future elimination efforts. We analyze the three IRS campaigns conducted during a malaria elimination demonstration project in southern Mozambique, the “Magude project”, and propose a new method to calculate the efficacy of IRS campaigns adjusting for IRS coverage, pace of house spraying and IRS residual efficacy on different wall types. Anopheles funestus sensu lato (s.l.) and An. gambiae s.l. were susceptible to pirimiphos-methyl and DDT. Anopheles funestus s.l. was resistant to pyrethroids, with 24h post-exposure mortality being lower for An. funestus sensu stricto (s.s.) than for An. parensis (collected indoors). The percentage of structures sprayed was above 90% and percentage of people covered above 86% in all three IRS campaigns. The percentage of households sprayed was above 83% in 2015 and 2016, but not assessed in 2017. Mosquito mortality 24h post-exposure stayed above 80% for 196 days after the 2016 IRS campaign and 222 days after the 2017 campaign and was 1.5 months longer on mud walls than on cement walls. This was extended by up to two months when 120h post-exposure mortality was considered. The district-level realized IRS efficacy was 113 days after the 2016 campaign. While the coverage of IRS campaigns in Magude were high, IRS protection did not remain optimal for the entire high malaria transmissions season. The use of a longer-lasting IRS product could have further supported the interruption of malaria transmission in the district. To better estimate the protection afforded by IRS campaigns, National Malaria Control Programs and partners are encouraged to adjust the calculation of IRS efficacy for IRS coverage, pace of house spraying during the campaign and IRS efficacy on different wall types combined with wall type distribution in the sprayed area.

Nanoemulsion of Myrtus communis essential oil and evaluation of its larvicidal activity against Anopheles stephensi

Excessive use of chemical insecticides has caused environmental pollution and vector resistance. Herbal essential oils with larvicidal properties are good alternatives to synthetic insecticides.mIn this study, larvicide properties of Myrtus communis essential oil and its nanoemulsion against Anopheles stephensi were investigated. Components of Myrtus communis essential oil were identified by GC–MS. Nanoemulsion of essential oil was made with Tween 80, Span 20, and water. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) determined particle size and morphology of nanoemulsions. The larvicide activity compared with bulk essential oil. A total of 107 M. communis essential oil compounds were discovered. The morphology of a selected nanoemulsion was spherical. LC 50 and LC 90 of M. communis essential oil were calculated as 26.1 and 46.2 µg/ml, respectively. The larvicide activity of nanoemulsion increased by 40% compared to the bulk essential oil. The nanoemulsion's larvicide activity (100%) lasted up to 3 days, while the essential oil had larvicide properties only for up to 24 h. Myrtus communis essential oil was found to be an effective larvicide and classified as an active larvicide. The residual efficacy of the nanoformulation of M. communis significantly increased compared with the bulk essential oil.

One kind of challenging tetrapeptide biomimetic chromatographic resin for antibody separation

Short peptide biomimetic chromatography technology as a developing protein separation technology has huge potential for antibody purification. In this study, four tetrapeptide ligands (Ac-FYKH, Ac-YEHF, Ac-YFLH and Ac-FYHI) with high potential binding ability to antibody were selected for the optimal ligand to antibody purification. The results showed that Ac-YEHF-4FF resin had higher binding capacity and selectivity for hIgG among the four resins. And at pH 7.0 and 0.3 ml/min, the highest Q10%-hIgG of Ac-YEHF-4FF resin was 26.2 mg/ml resin while its Q10%-BSA was just 2.2 mg/ml resin. Further, Ac-YEHF-4FF resin was used to purify protein mixtures. By binding at pH 7.0 and being eluted at pH 5.0 and pH 4.0, Ac-YEHF-4FF resin was well used to separate hIgG from BSA containing feedstock, HSA containing feedstock and human serum with the purity and yield both more than 95 %. And the screened resin could also separate mAb from CHO cell culture supernatant with purity 94.3 % and yield 97.5 %. The adsorption and separation results of Ac-YEHF-4FF resin indicated that the goal of getting the efficacy of critical residues from protein A to biomimetic its structure and function could be achieved, which had great significance to the establishment and improvement of tetrapeptide biomimetic chromatography, and also provided a new method for the field of antibody separation and purification.

Ocimum gratissimum essential oil and eugenol against Ctenocephalides felis felis and Rhipicephalus sanguineus: In vitro activity and residual efficacy of a eugenol-based spray formulation

Fleas and ticks are among the main ectoparasites that affect pets. The indiscriminate and incorrect use of chemical antiparasitics may be related to increased insect resistance and environmental contamination, requiring prospection for active ingredients that are less harmful to animals, humans and the environment. The use of essential oils and their isolated compounds has been reported as a potential alternative to synthetic antiparasitics, but there is a lack of studies involving the design and development of stable and safe natural products-based formulations. Therefore, the aim of this study was to establish LC50 and LC90 of Ocimum gratissimum essential oil and eugenol on immature stages and adults of Ctenocephalides felis felis and Rhipicephalus sanguineus; and to design and to determine the in vitro efficacy and residual effect of a natural product-based spray formulation for flea and tick control in pets. Bioassays were carried out according to the filter paper impregnation technique for fleas and through the larval packet test for ticks. O. gratissimum essential oil and eugenol presented pulicidal and acaricidal activity in vitro against immature stages and adults of C. felis felis and immature stages of R. sanguineus. The greater potency of eugenol against fleas and ticks led to the choice of eugenol as the active ingredient in the pharmaceutical form developed. The developed eugenol-based sprays presented adequate physical and chemical characteristics and stability, had pulicidal and acaricidal efficacy after 24 h and residual effect against fleas for up to 48 days.

Laboratory and experimental hut trial evaluation of VECTRON ™ T500 for indoor residual spraying (IRS) against insecticide resistant malaria vectors in Burkina Faso.

Background: Malaria cases in some areas could be attributed to vector resistant to the insecticide. World Health Organization recommended insecticides for vector control are limited in number. It is essential to find rotational partners for existing Indoor Residual Spraying (IRS) products. VECTRON ™ T500 is a novel insecticide with broflanilide as active ingredient. It has a mode of action on mosquitoes completely different to usually used. The aim of this study was to determine the optimum effective dose and efficacy of VECTRON TMT500 against susceptible and resistant strains of Anopheles in Burkina Faso. Methods: VECTRON™T500 was sprayed at 50, 100 and 200 mg/m² doses onto mud and concrete blocks using Potter Spray Tower. The residual activity of broflanilide was assessed through cone bioassays 1 week and then monthly up to 14 months post spraying. Its efficacy was evaluated at 100 and 150 mg/m² against wild free-flying mosquitoes in experimental huts on both substrates. Actellic 300CS was applied at 1000 mg/m² as reference product. Cone assays were conducted monthly, using susceptible and resistant mosquito strains. Results: In the laboratory, VECTRON ™T500 showed residual efficacy (≥80% mortality) on An. gambiae Kisumu up to 12 and 14 months, respectively, on concrete and mud blocks. Similar results were found with 100 and 200 mg/m² using An. coluzzii pyrethroid resistant strain. In experimental huts, a total of 19,552 An. gambiae s.l. were collected. Deterrence, blood-feeding inhibition and exophily with VECTRON™ treated huts were very low. At 100 and 150 mg/m², mortality of wild An. gambiae s.l. ranged between 55% and 73%. Monthly cone bioassay mortality remained >80% up to 9 months. Conclusions: VECTRON™ T500 shows great potential as IRS formulation for malaria vector control. It can be added to the arsenal of IRS products for use in rotations to control malaria and manage mosquito insecticide resistance.

Evaluation of the residual efficacy and physical durability of five long-lasting insecticidal nets (LLINs) in Senegal

BackgroundThe preventive and curative strategies of malaria are based on promoting the use of long-lasting insecticidal nets (LLINs) and treating confirmed cases with artemisinin-based combination therapy. These strategies have led to a sharp decline in the burden of malaria, which remains a significant public health problem in sub-Saharan countries. The objective of this study was to determine and compare the residual efficacy of LLINs recommended by the World Health Organization.MethodsThe study was conducted in six villages in two sites in Senegal located in the Sahelo-Sudanian area of the Thiès region, 70 km from Dakar and in Mbagame, a semi-urban zone in the Senegal River Valley. A census was conducted of all sleeping places in each household to be covered by LLINs. Five brands of LLIN were distributed, and every six months, retention rates, net use, maintenance, physical integrity, insecticide chemical content, and biological efficacy were examined for each type of LLIN.ResultsA total of 3012 LLINs were distributed in 1249 households in both sites, with an average coverage rate of 94% (95% CI 92.68–95.3). After 36 months, the average retention rate was 12.5% and this rate was respectively 20.5%, 15.1%, 10%, 7%, and 3% for Olyset Net®, Dawa Plus® 2.0, PermaNet® 2.0, NetProtect® and Life Net®, respectively. The proportion of LLINs with holes and the average number of holes per mosquito net increased significantly during each follow-up, with a large predominance of size 1 (small) holes for all types of LLINs distributed. During the three-year follow-up, bioassay mortality rates of a susceptible strain of insectary reared Anopheles coluzzii decreased in the following net types: in Dawa Plus® 2.0 (100% to 51.7%), PermaNet® 2.0 (96.6% to 83%), and Olyset Net® (96.6% to 33.3%). Mortality rates remained at 100% in Life Net® over the same time period. After 36 months, the average insecticide content per brand of LLIN decreased by 40.9% for Dawa Plus® 2.0, 31% for PermaNet® 2.0, 39.6% for NetProtect® and 51.9% for Olyset Net® and 40.1% for Life Net.ConclusionsAlthough some net types retained sufficient insecticidal activity, based on all durability parameters measured, none of the net types survived longer than 2 years.

Laboratory and experimental hut trial evaluation of VECTRON ™ T500 for indoor residual spraying (IRS) against insecticide resistant malaria vectors in Burkina Faso

Background: Malaria cases in some areas could be attributed to vector resistant to the insecticide. World Health Organization recommended insecticides for vector control are limited in number. It is essential to find rotational partners for existing Indoor Residual Spraying (IRS) products. VECTRON ™ T500 is a novel insecticide with broflanilide as active ingredient. It has a mode of action on mosquitoes completely different to usually used. The aim of this study was to determine the optimum effective dose and efficacy of VECTRON TM T500 against susceptible and resistant strains of Anopheles in Burkina Faso. Methods: VECTRON™T500 was sprayed at 50, 100 and 200 mg/m² doses onto mud and concrete blocks using Potter Spray Tower. The residual activity of broflanilide was assessed through cone bioassays 1 week and then monthly up to 14 months post spraying. Its efficacy was evaluated at 100 and 150 mg/m² against wild free-flying mosquitoes in experimental huts on both substrates. Actellic 300CS was applied at 1000 mg/m² as reference product. Cone assays were conducted monthly, using susceptible and resistant mosquito strains. Results: In the laboratory, VECTRON ™ T500 showed residual efficacy (≥80% mortality) on An. gambiae Kisumu up to 12 and 14 months, respectively, on concrete and mud blocks. Similar results were found with 100 and 200 mg/m² using An. coluzzii pyrethroid resistant strain. In experimental huts, a total of 19,552 An. gambiae s.l. were collected. Deterrence, blood-feeding inhibition and exophily with VECTRON™ treated huts were very low. At 100 and 150 mg/m², mortality of wild An. gambiae s.l. ranged between 55% and 73%. Monthly cone bioassay mortality remained >80% up to 9 months. Conclusions: VECTRON™ T500 shows great potential as IRS formulation for malaria vector control. It can be added to the arsenal of IRS products for use in rotations to control malaria and manage mosquito insecticide resistance.

Implementing OECD GLP principles for the evaluation of novel vector control tools: a case study with two novel LLINs, SafeNet® and SafeNet NF®

BackgroundTo sustain high universal Long-Lasting Insecticidal Nets (LLINs) coverage, affordable nets that provide equivalent or better protection than standard LLINs, are required. Test facilities evaluating new LLINs require compliance to Good Laboratory Practice (GLP) standards to ensure the quality and integrity of test data. Following GLP principles allows for the reconstruction of activities during the conduct of a study and minimizes duplication of efficacy testing. This case study evaluated the efficacy of two LLINs: SafeNet NF® and SafeNet® LLIN.MethodsThe study was conducted according to GLP principles and followed World Health Organization guidelines for evaluating LLINs. The LLINs were assessed in experimental huts against wild, pyrethroid-resistant Anopheles arabiensis mosquitoes. Nets were either unwashed or washed 20 times and artificially holed to simulate a used torn net. Blood-feeding inhibition and mortality were compared with a positive control (Interceptor® LLIN) and an untreated net.ResultsMosquito entry in the huts was reduced compared to negative control for the unwashed SafeNet NF, washed Safenet LLIN and the positive control arms. Similar exiting rates were found for all the treatment arms. Significant blood-feeding inhibition was only found for the positive control, both when washed and unwashed. All insecticide treatments induced significantly higher mortality compared to an untreated net. Compared to the positive control, the washed and unwashed SafeNet NF® resulted in similar mortality. For the SafeNet® LLINs the unwashed net had an equivalent performance, but the mortality for the washed net was significantly lower than the positive control.Internal audits of the study confirmed that all critical phases complied with Standard Operating Procedures (SOPs) and the study plan. The external audit confirmed that the study complied with GLP standards.ConclusionsSafeNet NF® and SafeNet® LLIN offered equivalent protection to the positive control (Interceptor® LLIN). However, further research is needed to investigate the durability, acceptability, and residual efficacy of these nets in the community. This study demonstrated that GLP-compliant evaluation of LLINs can be successfully conducted by African research institutions.

The rainfastness and residual efficacy of the simultaneous application of benzimidazoles and iminoctadine triacetate, and a single application of a combination of tebuconazole and trifloxystrobin in the control of citrus green mold caused by &lt;i&gt;Penicillium digitatum&lt;/i&gt;

The rainfastness and residual efficacy of the simultaneous application of benzimidazoles and iminoctadine triacetate, and a single application of a combination of tebuconazole and trifloxystrobin in the control of citrus green mold caused by &lt;i&gt;Penicillium digitatum&lt;/i&gt;

Performance of Pyrethroid-Neonicotinoid Mixture Formulations Against Field-Collected Strains of the Tropical Bed Bug (Hemiptera: Cimicidae) on Different Substrates.

The residual performance of two pyrethroid-neonicotinoid mixture formulations: Temprid SC (10.5% beta-cyfluthrin and 21% imidacloprid) and Tandem (3.5% lambda-cyhalothrin and 11.6% thiamethoxam) on two substrates (glass and filter paper) against eight pyrethroid-resistant strains (BM-MY, BP-MY, CH-MY, GL-MY, KL-MY, SAJ-MY, TT-MY, and QLD-AU) of the tropical bed bug, Cimex hemipterus (F.) (Hemiptera: Cimicidae) collected from Malaysia, and Australia were evaluated. The aging effect of treatment residues on glass was also investigated. A susceptible C. lectularius L. strain (Monheim) was used for comparison. Temprid SC showed varying levels of performance against all C. hemipterus strains: TT-MY (PR50 = 6.5-fold, high performance), BM-MY, GL-MY, SAJ-MY, and QLD-AU (12.8-21.6-fold, moderate performance), BP-MY, and KL-MY (48.2-49-fold, poor performance), CH-MY (128.2-fold, very poor performance). On the other hand, Tandem displayed high performance against all C. hemipterus strains (1.8-8.3-fold). Tandem caused faster mortality than Temprid SC for all strains. Temprid SC and Tandem residues killed C. hemipterus significantly faster on glass than filter paper. Compared with fresh residues, the efficacy of Temprid SC residues significantly declined after one week of aging, while the effectiveness of Tandem residues declined after two weeks of aging. Further investigations using the topical assay method with a diagnostic dose of imidacloprid found two strains (CH-MY and GL-MY) resistant to imidacloprid. The six other strains (BM-MY, BP-MY, KL-MY, SAJ-MY, TT-MY, and QLD-AU) were susceptible.

Laboratory and experimental hut trial evaluation of VECTRON™ T500 for indoor residual spraying (IRS) against insecticide resistant malaria vectors in Burkina Faso

Background: Malaria cases in some areas could be attributed to vector resistant to the insecticide. World Health Organization recommended insecticides for vector control are limited in number. It is essential to find rotational partners for existing Indoor Residual Spraying (IRS) products. VECTRON™ T500 is a novel insecticide with broflanilide as active ingredient. It has a mode of action on mosquitoes completely different to usually used. The aim of this study was to determine the optimum effective dose and efficacy of VECTRONTM against susceptible and resistant strains of Anopheles in Burkina Faso. Methods: VECTRON™ was sprayed at 50, 100 and 200 mg/m² doses onto mud and concrete blocks using Potter Spray Tower. The residual activity of broflanilide was assessed through cone bioassays 1 week and then monthly up to 14 months post spraying. Its efficacy was evaluated at 100 and 150 mg/m² against wild free-flying mosquitoes in experimental huts on both substrates. Actellic 300CS was applied at 1000 mg/m² as reference product. Cone assays were conducted monthly, using susceptible and resistant mosquito strains. Results: In the laboratory, VECTRON™ showed residual efficacy (≥80% mortality) on An. gambiae Kisumu up to 12 and 14 months, respectively, on concrete and mud blocks. Similar results were found with 100 and 200 mg/m² using An. coluzzii pyrethroid resistant strain. In experimental huts, a total of 19,552 An. gambiae s.l. were collected. Deterrence, blood-feeding inhibition and exophily with VECTRON™ treated huts were very low. At 100 and 150 mg/m², mortality of wild An. gambiae s.l. ranged between 55% and 73%. Monthly cone bioassay mortality remained &gt;80% up to 9 months. Conclusions: VECTRON™ shows great potential as IRS formulation for malaria vector control. It can be added to the arsenal of IRS products for use in rotations to control malaria and manage mosquito insecticide resistance.

Household modifications after the indoor residual spraying (IRS) campaign in Mozambique reduce the actual spray coverage and efficacy.

Indoor residual spraying of insecticides (IRS) is a key malaria vector control strategy. Whilst human attitude towards IRS is monitored before or shortly after implementation, human activities leading to the modification of insecticide-treated walls post-IRS are not. This could inadvertently reduce the protective effects of IRS. We monitored the extent of modifications to the sprayed indoor wall surfaces by household owners for six months post-IRS campaigns in two districts targeted for malaria elimination in southern Mozambique. In parallel, we assessed building of any additional rooms onto compounds, and mosquito net use. We quantified the contribution of wall modifications, added rooms, prolonged spray campaigns, and product residual efficacies on actual IRS coverage and relative mosquito bite reduction, using a mechanistic approach. Household owners continually modified insecticide-treated walls and added rooms onto compounds. Household surveys in southern Mozambique showed frequent modification of indoor walls (0-17.2% of households modified rooms monthly) and/or added rooms (0-16.2% of households added rooms monthly). Actual IRS coverage reduced from an assumed 97% to just 39% in Matutuine, but only from 96% to 91% in Boane, translating to 43% and 5.8% estimated increases in relative daily mosquito bites per person. Integrating post-IRS knowledge, attitude, and practice (KAP) surveys into programmatic evaluations to capture these modification and construction trends can help improve IRS program efficiency and product assessment.

Residual antimicrobial coating efficacy against SARS-CoV-2.

This study evaluated the residual efficacy of commercially available antimicrobial coatings or films against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on non-porous surfaces. Products were applied to stainless steel or ABS plastic coupons and dried overnight. Coupons were inoculated with SARS-CoV-2 in the presence of 5% soil load. Recovered infectious SARS-CoV-2 was quantified by TCID50 assay. Tested product efficacies ranged from <1.0 to >3.0log10 reduction at a 2-h contact time. The log10 reduction in recovered infectious SARS-CoV-2 ranged from 0.44 to 3log10 reduction on stainless steel and 0.25 to >1.67log10 on ABS plastic. The most effective products tested contained varying concentrations (0.5%-1.3%) of the same active ingredient: 3-(trihydroxysilyl) propyldimethyloctadecyl ammonium chloride. Products formulated with other quaternary ammonium compounds were less effective against SARS-CoV-2 in this test. The residual antimicrobial products tested showed varied effectiveness against SARS-CoV-2 as a function of product tested. Several products were identified as efficacious against SARS-CoV-2 on both stainless steel and ABS plastic surfaces under the conditions evaluated. Differences in observed efficacy may be due to variation in active ingredient formulation; efficacy is, therefore, difficult to predict based upon listed active ingredient and its concentration. This study highlights the formulation-specific efficacy of several products against SARS-CoV-2 and may inform future development of residual antiviral products for use on non-porous surfaces. The identification of antimicrobial coatings or films showing promise to inactivate SARS-CoV-2 suggests that these products may be worth future testing and consideration.

RESIDUAL EFFECTS OF BIFENTHRIN SPRAYED ON PLANT FOLIAGES AGAINST AEDES ALBOPICTUS AND APIS MELLIFERA IN NORTH CENTRAL FLORIDA

A field study was conducted to test bifenthrin as a barrier treatment for its residual effects on adult mosquitoes Aedes albopictus and honey bees Apis mellifera in Gainesville, Florida. Plant foliage was treated with an American LongRay misting sprayer machine at the label rate of 0.318 mL/m². Treated plant leaves were then collected at 24 hr, one wk, and two wk post-treatment for laboratory bioassays against adult Ae. albopictus and A. mellifera. The mortalities of the mosquitoes and honeybees were significantly higher after exposures to the bifenthrin-treated plant leaves at 24 hr post-treatment, than the mortalities at one wk and two wk post-treatments. There were no significant differences in the mortalities of mosquitoes and honeybees exposed to treated plant leaves at one wk and two wk post-treatment. Also, the results showed that the treated plant leaves away from the spray path resulted in significantly high mortalities of both species at 24 hr post-treatment than the mortalities at 8 m and 11 m at one wk and two wk post-treatment. The commercial product of Talstar P (bifenthrin) sprayed on plant foliage resulted in significantly higher mortalities of mosquitoes and honeybees at 24 hr post-treatment at the 5 m distance. There was no significant residual efficacy of the product one week after post-treatment at any distance.

Efficacy of oral fluralaner (Bravecto) against Tunga penetrans in dogs: A negative control, randomized field study in an endemic community in Brazil.

The sand flea Tunga penetrans is one of the zoonotic agents of tungiasis, a parasitic skin disease of humans and animals. The dog is one of its main reservoirs. This negatively controlled, randomized, double-masked clinical trial evaluated the therapeutic and residual efficacy of fluralaner for treatment of dogs naturally infested with T. penetrans. Sixty-two dogs from an endemically affected community in Brazil were randomly assigned to either receive oral fluralaner (Bravecto chewable tablets) at a dose of 25 to 56 mg fluralaner/kg body weight, or no treatment (31 dogs per group). Dogs were clinically examined using a severity score for acute canine tungiasis (SCADT), parasitological examinations as defined by the Fortaleza classification, and pictures of lesions on days 0 (inclusion and treatment), 7 ± 2, 14 ± 2, 21 ± 2, 28 ± 2, 60 ± 7, 90 ± 7, 120 ± 7 and 150 ± 7. The percentage of parasite-free dogs after treatment was >90% between days 14 and 90 post-treatment with 100% efficacy on study days 21, 28 and 60. Sand flea counts on fluralaner treated dogs were significantly lower (p<0.025) than control dogs on all counts from day 7 to 120. The number of live sand fleas on treated dogs was reduced by > 90% on day 7, > 95% on days 14 and 90, and 100% from day 21 to 60, and with a significant difference between groups from day 7 to 120. From day 7 to day 120, mean SCADT scores were significantly reduced in treated dogs with a mean of 0.10 compared to 1.54 on day 120 in untreated dogs. Therefore, a single oral fluralaner administration is effective for treating and achieving long lasting (> 12 weeks) prevention for tungiasis in dogs.