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1.
J Am Mosq Control Assoc ; 40(1): 32-49, 2024 Mar 01.
Article in English | MEDLINE | ID: mdl-38427588

ABSTRACT

The sterile insect technique (SIT) and the incompatible insect technique (IIT) are emerging and potentially revolutionary tools for controlling Aedes aegypti (L.), a prominent worldwide mosquito vector threat to humans that is notoriously difficult to reduce or eliminate in intervention areas using traditional integrated vector management (IVM) approaches. Here we provide an overview of the discovery, development, and application of SIT and IIT to Ae. aegypti control, and innovations and advances in technology, including transgenics, that could elevate these techniques to a worldwide sustainable solution to Ae. aegypti when combined with other IVM practices.


Subject(s)
Aedes , Wolbachia , Animals , Humans , Mosquito Control/methods , Mosquito Vectors , Insecta
2.
PLoS One ; 19(3): e0297964, 2024.
Article in English | MEDLINE | ID: mdl-38437189

ABSTRACT

Wolbachia is an endosymbiont bacterium present in many insect species. When Wolbachia-carrying male Aedes aegypti mosquitoes mate with non-carrier females, their embryos are not viable due to cytoplasmic incompatibility. This phenomenon has been exploited successfully for the purpose of controlling mosquito populations and the spread of mosquito-borne illnesses: Wolbachia carriers are bred and released into the environment. Because Wolbachia is not harmful to humans, this method of mosquito control is regarded as a safer alternative to pesticide spraying. In this article, we introduce a mathematical framework for exploring (i) whether a one-time release of Wolbachia carriers can elicit a sustained presence of carriers near the release site, and (ii) the extent to which spatial propagation of carriers may allow them to establish fixation in other territories. While some prior studies have formulated mosquito dispersal models using advection-reaction-diffusion PDEs, the predictive power of such models requires careful ecological mapping: advection and diffusion coefficients exhibit significant spatial dependence due to heterogeneity of resources and topography. Here, we adopt a courser-grained view, regarding the environment as a network of discrete, diffusively-coupled "habitats"-distinct zones of high mosquito density such as stagnant ponds. We extend two previously published single-habitat mosquito models to multiple habitats, and calculate rates of migration between pairs of habitats using dispersal kernels. Our primary results are quantitative estimates regarding how the success of carrier fixation in one or more habitats is determined by: the number of carriers released, sizes of habitats, distances between habitats, and the rate of migration between habitats. Besides yielding sensible and potentially useful predictions regarding the success of Wolbachia-based control, our framework applies to other approaches (e.g., gene drives) and contexts beyond the realm of insect pest control.


Subject(s)
Aedes , Charadriiformes , Wolbachia , Female , Humans , Animals , Male , Cytoplasm , Cytosol
3.
Nat Commun ; 15(1): 1980, 2024 Mar 04.
Article in English | MEDLINE | ID: mdl-38438367

ABSTRACT

The sterile insect technique is based on the overflooding of a target population with released sterile males inducing sterility in the wild female population. It has proven to be effective against several insect pest species of agricultural and veterinary importance and is under development for Aedes mosquitoes. Here, we show that the release of sterile males at high sterile male to wild female ratios may also impact the target female population through mating harassment. Under laboratory conditions, male to female ratios above 50 to 1 reduce the longevity of female Aedes mosquitoes by reducing their feeding success. Under controlled conditions, blood uptake of females from an artificial host or from a mouse and biting rates on humans are also reduced. Finally, in a field trial conducted in a 1.17 ha area in China, the female biting rate is reduced by 80%, concurrent to a reduction of female mosquito density of 40% due to the swarming of males around humans attempting to mate with the female mosquitoes. This suggests that the sterile insect technique does not only suppress mosquito vector populations through the induction of sterility, but may also reduce disease transmission due to increased female mortality and lower host contact.


Subject(s)
Aedes , Infertility, Male , Humans , Female , Male , Animals , Mice , Reproduction , Cell Communication , Insecta
4.
Sci Rep ; 14(1): 5628, 2024 03 07.
Article in English | MEDLINE | ID: mdl-38454095

ABSTRACT

Vector control is a key intervention against mosquito borne diseases. However, conventional methods have several limitations and alternate strategies are in urgent need. Vector control with endectocides such as ivermectin is emerging as a novel strategy. The short half-life of ivermectin is a limiting factor for its application as a mass therapy tool for vector control. Isoxazoline compounds like fluralaner, a class of veterinary acaricides with long half-life hold promise as an alternative. However, information about their mosquitocidal effect is limited. We explored the efficacy of fluralaner against laboratory reared vector mosquitoes-Aedes aegypti, Anopheles stephensi, and, Culex quinquefasciatus. 24 h post-blood feeding, fluralaner showed a significant mosquitocidal effect with LC50 values in the range of 24.04-49.82 ng/mL for the three different mosquito species tested. Effects on life history characteristics (fecundity, egg hatch success, etc.) were also observed and significant effects were noted at drug concentrations of 20, 25 and 45 ng/mL for Ae. aegypti, An. stephensi, and, Cx. quinquefasciatus respectively. At higher drug concentration of 250 ng/mL, significant mortality was observed within 1-2 h of post blood feeding. Potent mosquitocidal effect coupled with its long half-life makes fluralaner an excellent candidate for drug based vector control strategies.


Subject(s)
Aedes , Anopheles , Culex , Insecticides , Isoxazoles , Animals , Ivermectin/pharmacology , Insecticides/pharmacology , Mosquito Vectors , Larva , Plant Extracts/pharmacology
5.
Parasit Vectors ; 17(1): 117, 2024 Mar 07.
Article in English | MEDLINE | ID: mdl-38454517

ABSTRACT

BACKGROUND: Indoor residual spraying (IRS) capitalizes on the natural behavior of mosquitoes because Aedes aegypti commonly seeks indoor resting sites after a blood meal. This behavior allows mosquitoes to be exposed to insecticide-treated surfaces and subsequently killed. Combinations of deltamethrin and clothianidin with different modes of action have shown promise in IRS, effectively targeting both susceptible and pyrethroid-resistant malaria vectors. However, the effects of this approach on Aedes mosquitoes remain unclear. The present study tested the effects of deltamethrin-clothianidin mixture treatment on behavioral responses and life history traits of Taiwanese and Indonesian populations of Ae. aegypti. METHODS: We adopted an excito-repellent approach to explore the behavioral responses of pyrethroid-resistant Ae. aegypti populations from Indonesia and Taiwan to a deltamethrin-clothianidin mixture used in contact irritancy and non-contact repellency treatments. We further evaluated the life history traits of surviving mosquitoes (i.e., delayed mortality after 7-day post-treatment, longevity, fecundity, and egg hatching) and investigated the potential transgenerational hormetic effects of insecticide exposure (i.e., development rate and survival of immatures and adult mosquitos). RESULTS: All tested field populations of Ae. aegypti displayed strong contact irritancy responses; the percentage of escape upon insecticide exposure ranged from 38.8% to 84.7%. However, repellent effects were limited, with the escape percentage ranging from 4.3% to 48.9%. We did not observe immediate knockdown or mortality after 24 h, and less than 15% of the mosquitoes exhibited delayed mortality after a 7-day exposure period. However, the carryover effects of insecticide exposure on the survival of immature mosquitoes resulted in approximately 25% higher immature mortality than that in the control. By contrast, we further documented stimulated survivor reproduction and accelerated transgenerational immature development resulting from the sublethal effects of the insecticide mixture. In particular, the number of eggs laid by treated (both treatments) female mosquitoes increased by at least 60% compared with that of eggs laid by control female mosquitoes. CONCLUSIONS: IRS with deltamethrin-clothianidin effectively deters Aedes mosquitoes from entering residential areas and thereby reduces mosquito bites. However, the application rate (deltamethrin: 25 mg/m2; clothianidin: 200 mg/m2) may be insufficient to effectively kill Aedes mosquitoes. Insecticide response appears to vary across mosquito species; their behavioral and physiological responses to sublethal doses have crucial implications for mosquito control programs.


Subject(s)
Aedes , Guanidines , Insecticides , Life History Traits , Neonicotinoids , Nitriles , Pyrethrins , Thiazoles , Female , Animals , Insecticides/pharmacology , Aedes/physiology , Indonesia , Insecticide Resistance , Ovum , Pyrethrins/pharmacology , Mosquito Control/methods , Mosquito Vectors
6.
Parasit Vectors ; 17(1): 106, 2024 Mar 04.
Article in English | MEDLINE | ID: mdl-38439081

ABSTRACT

BACKGROUND: Although whole-genome sequencing (WGS) is the preferred genotyping method for most genomic analyses, limitations are often experienced when studying genomes characterized by a high percentage of repetitive elements, high linkage, and recombination deserts. The Asian tiger mosquito (Aedes albopictus), for example, has a genome comprising up to 72% repetitive elements, and therefore we set out to develop a single-nucleotide polymorphism (SNP) chip to be more cost-effective. Aedes albopictus is an invasive species originating from Southeast Asia that has recently spread around the world and is a vector for many human diseases. Developing an accessible genotyping platform is essential in advancing biological control methods and understanding the population dynamics of this pest species, with significant implications for public health. METHODS: We designed a SNP chip for Ae. albopictus (Aealbo chip) based on approximately 2.7 million SNPs identified using WGS data from 819 worldwide samples. We validated the chip using laboratory single-pair crosses, comparing technical replicates, and comparing genotypes of samples genotyped by WGS and the SNP chip. We then used the chip for a population genomic analysis of 237 samples from 28 sites in the native range to evaluate its usefulness in describing patterns of genomic variation and tracing the origins of invasions. RESULTS: Probes on the Aealbo chip targeted 175,396 SNPs in coding and non-coding regions across all three chromosomes, with a density of 102 SNPs per 1 Mb window, and at least one SNP in each of the 17,461 protein-coding genes. Overall, 70% of the probes captured the genetic variation. Segregation analysis found that 98% of the SNPs followed expectations of single-copy Mendelian genes. Comparisons with WGS indicated that sites with genotype disagreements were mostly heterozygotes at loci with WGS read depth < 20, while there was near complete agreement with WGS read depths > 20, indicating that the chip more accurately detects heterozygotes than low-coverage WGS. Sample sizes did not affect the accuracy of the SNP chip genotype calls. Ancestry analyses identified four to five genetic clusters in the native range with various levels of admixture. CONCLUSIONS: The Aealbo chip is highly accurate, is concordant with genotypes from WGS with high sequence coverage, and may be more accurate than low-coverage WGS.


Subject(s)
Aedes , Mosquito Vectors , Humans , Animals , Genotype , Mosquito Vectors/genetics , Heterozygote , Aedes/genetics
7.
Int J Med Mushrooms ; 26(3): 41-53, 2024.
Article in English | MEDLINE | ID: mdl-38505902

ABSTRACT

The worldwide scientific community is well aware that mosquitoes are the sole agents responsible for transmitting various dreadful diseases and critical illnesses caused by vector-borne pathogens. The primary objective of this current research was to evaluate the effectiveness of methanol extract from Tricholoma equestre mushroom in controlling the early life stages of Culex quinquefasciatus Say, Anopheles stephensi Liston, and Aedes aegypti (Linnaeus in Hasselquist) mosquitoes. The larvae, pupae and eggs of these mosquitoes were exposed to four different concentrations (62.5 to 500 ppm). After 120 h of treatment, the methanol extract of T. equestre exhibited ovicidal activity ranging from 66% to 80% against the eggs of the treated mosquitoes. It also demonstrated promising larvicidal and pupicidal activity with LC50 values of 216-300 and 230-309 ppm against the early life stages of all three mosquito species. Extensive toxicity studies revealed that the methanol extract from T. equestre had no harmful effects on non-target organisms. The suitability index (SI) or predator safety factor (PSF) indicated that the methanol extract did not harm Poecilia reticulata Peters 1859, (predatory fish), Gambusia affinis S. F. Baird & Girard 1853, dragonfly nymph and Diplonychus indicus Venkatesan & Rao 1871 (water-bug). Gas chromatography-mass spectrometry (GCMS) analysis identified key compounds, including 3-butenenitrile, 2-methyl-(25.319%); 1-butanol, 2-nitro-(18.87%) and oxalic acid, heptyl propyl ester (21.82%) which may be responsible for the observed activity. Furthermore, the formulation based on the methanol extract demonstrated similar effectiveness against all treated mosquitoes at the laboratory level and was found to be non-toxic to mosquito predators. This groundbreaking research represents the first confirmation that methanol extract from T. equestre could be effectively employed in preventing mosquito-borne diseases through mosquito population control programs.


Subject(s)
Aedes , Agaricales , Anopheles , Culex , Insecticides , Odonata , Animals , Methanol/pharmacology , Mosquito Vectors , Insecticides/pharmacology , Insecticides/chemistry , Plant Extracts/chemistry , Larva , Plant Leaves/chemistry
8.
Aust J Rural Health ; 2024 Mar 20.
Article in English | MEDLINE | ID: mdl-38506501

ABSTRACT

INTRODUCTION: Yellow fever is caused by an RNA flavivirus. Immunisation in conjunction with vector control is at the forefront of yellow fever control and elimination. OBJECTIVE: This narrative review describes the impact and importance of yellow fever vaccinations for northern Australian health practitioners. DESIGN: Selected key policies, studies and medical guidelines are reviewed and presented. FINDING: Large yellow fever outbreaks, associated with vector spread, have occurred in the last decade in Africa and South America, increasing the risk of international spread of the virus. Mobile populations, like travellers or migrant workers, continue to be at risk of yellow fever. Quality assurance, including yellow fever centre accreditation and initiatives to decrease fraudulent yellow fever vaccination documentation, has evolved in the past few years. Fractional dosing of yellow fever vaccines has been shown to provide protection for 1 year in outbreak scenarios, but further studies are needed. DISCUSSION: Although Australia is yellow fever-free, the disease could be introduced by viraemic persons as a competent Aedes mosquito vector is present in northern Australia. In addition to surveillance and vector control, health education and yellow fever vaccination remain the best lines of defence. In the event of an outbreak, a response via fractional dosing could prove to be effective in controlling the virus. CONCLUSION: Health care providers in northern Australia should be aware of the risks of yellow fever and its introduction to northern Australia and be able to discuss vaccination status with their clients when needed.

9.
J Gen Virol ; 105(3)2024 Mar.
Article in English | MEDLINE | ID: mdl-38488850

ABSTRACT

Arboviruses such as chikungunya, dengue and zika viruses cause debilitating diseases in humans. The principal vector species that transmits these viruses is the Aedes mosquito. Lack of substantial knowledge of the vector species hinders the advancement of strategies for controlling the spread of arboviruses. To supplement our information on mosquitoes' responses to virus infection, we utilized Aedes aegypti-derived Aag2 cells to study changes at the transcriptional level during infection with chikungunya virus (CHIKV). We observed that genes belonging to the redox pathway were significantly differentially regulated. Upon quantifying reactive oxygen species (ROS) in the cells during viral infection, we further discovered that ROS levels are considerably higher during the early hours of infection; however, as the infection progresses, an increase in antioxidant gene expression suppresses the oxidative stress in cells. Our study also suggests that ROS is a critical regulator of viral replication in cells and inhibits intracellular and extracellular viral replication by promoting the Rel2-mediated Imd immune signalling pathway. In conclusion, our study provides evidence for a regulatory role of oxidative stress in infected Aedes-derived cells.


Subject(s)
Aedes , Arboviruses , Chikungunya Fever , Zika Virus Infection , Zika Virus , Humans , Animals , Reactive Oxygen Species , Mosquito Vectors , Oxidative Stress , Immunity, Innate
10.
Philos Trans R Soc Lond B Biol Sci ; 379(1901): 20230063, 2024 May 06.
Article in English | MEDLINE | ID: mdl-38497256

ABSTRACT

Discussions of host-microbe interactions in mosquito vectors are frequently dominated by a focus on the human pathogens they transmit (e.g. Plasmodium parasites and arboviruses). Underlying the interactions between a vector and its transmissible pathogens, however, is the physiology of an insect living and interacting with a world of bacteria and fungi including commensals, mutualists and primary and opportunistic pathogens. Here we review what is known about the bacteria and fungi associated with mosquitoes, with an emphasis on the members of the Aedes genus. We explore the reciprocal effects of microbe on mosquito, and mosquito on microbe. We analyse the roles of bacterial and fungal symbionts in mosquito development, their effects on vector competence, and their potential uses as biocontrol agents and vectors for paratransgenesis. We explore the compartments of the mosquito gut, uncovering the regionalization of immune effectors and modulators, which create the zones of resistance and immune tolerance with which the mosquito host controls and corrals its microbial symbionts. We examine the anatomical patterning of basally expressed antimicrobial peptides. Finally, we review the relationships between inducible antimicrobial peptides and canonical immune signalling pathways, comparing and contrasting current knowledge on each pathway in mosquitoes to the model insect Drosophila melanogaster. This article is part of the theme issue 'Sculpting the microbiome: how host factors determine and respond to microbial colonization'.


Subject(s)
Aedes , Microbiota , Animals , Humans , Drosophila melanogaster , Bacteria , Immunity, Innate , Antimicrobial Peptides
11.
PLoS Genet ; 20(3): e1011196, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38466721

ABSTRACT

Hematophagous mosquitoes require vertebrate blood for their reproductive cycles, making them effective vectors for transmitting dangerous human diseases. Thus, high-intensity metabolism is needed to support reproductive events of female mosquitoes. However, the regulatory mechanism linking metabolism and reproduction in mosquitoes remains largely unclear. In this study, we found that the expression of estrogen-related receptor (ERR), a nuclear receptor, is activated by the direct binding of 20-hydroxyecdysone (20E) and ecdysone receptor (EcR) to the ecdysone response element (EcRE) in the ERR promoter region during the gonadotropic cycle of Aedes aegypti (named AaERR). RNA interference (RNAi) of AaERR in female mosquitoes led to delayed development of ovaries. mRNA abundance of genes encoding key enzymes involved in carbohydrate metabolism (CM)-glucose-6-phosphate isomerase (GPI) and pyruvate kinase (PYK)-was significantly decreased in AaERR knockdown mosquitoes, while the levels of metabolites, such as glycogen, glucose, and trehalose, were elevated. The expression of fatty acid synthase (FAS) was notably downregulated, and lipid accumulation was reduced in response to AaERR depletion. Dual luciferase reporter assays and electrophoretic mobility shift assays (EMSA) determined that AaERR directly activated the expression of metabolic genes, such as GPI, PYK, and FAS, by binding to the corresponding AaERR-responsive motif in the promoter region of these genes. Our results have revealed an important role of AaERR in the regulation of metabolism during mosquito reproduction and offer a novel target for mosquito control.


Subject(s)
Aedes , Receptors, Steroid , Animals , Female , Humans , Aedes/genetics , Aedes/metabolism , Ecdysone/metabolism , Mosquito Vectors/genetics , Receptors, Cytoplasmic and Nuclear/genetics , Receptors, Cytoplasmic and Nuclear/metabolism , Homeostasis/genetics , Insect Proteins/genetics , Insect Proteins/metabolism
12.
J Am Chem Soc ; 2024 Mar 14.
Article in English | MEDLINE | ID: mdl-38484471

ABSTRACT

Mosquito control methods are vital to curtail the spread of life-threatening illnesses, such as dengue fever, malaria, and yellow fever. Vector control technologies must be selective to minimize deleterious effects on our ecosystem. Successful methods that control mosquito larva populations utilize the uniquely high alkaline nature of the midgut. Here, we present novel protected triazabutadienes (pTBD) that are deprotected under basic conditions of the larval midgut, releasing an aryl diazonium ion (ADI) that results in protein modification. The probes contain a bioorthogonal terminal alkyne handle, enabling a selective Cu-click reaction with an azidofluorophore for quantification by SDS PAGE and visualization using fluorescence microscopy. A control TBD, unable to release an ADI, did not label the midgut. We envision our chemical probes will aid in the development of new selective mosquito control methods, thus preventing the spread of mosquito-borne illnesses with minimal impact on other organisms in the ecosystem.

13.
Lancet Glob Health ; 12(4): e563-e571, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38485425

ABSTRACT

BACKGROUND: There have been declines in global immunisation coverage due to the COVID-19 pandemic. Recovery has begun but is geographically variable. This disruption has led to under-immunised cohorts and interrupted progress in reducing vaccine-preventable disease burden. There have, so far, been few studies of the effects of coverage disruption on vaccine effects. We aimed to quantify the effects of vaccine-coverage disruption on routine and campaign immunisation services, identify cohorts and regions that could particularly benefit from catch-up activities, and establish if losses in effect could be recovered. METHODS: For this modelling study, we used modelling groups from the Vaccine Impact Modelling Consortium from 112 low-income and middle-income countries to estimate vaccine effect for 14 pathogens. One set of modelling estimates used vaccine-coverage data from 1937 to 2021 for a subset of vaccine-preventable, outbreak-prone or priority diseases (ie, measles, rubella, hepatitis B, human papillomavirus [HPV], meningitis A, and yellow fever) to examine mitigation measures, hereafter referred to as recovery runs. The second set of estimates were conducted with vaccine-coverage data from 1937 to 2020, used to calculate effect ratios (ie, the burden averted per dose) for all 14 included vaccines and diseases, hereafter referred to as full runs. Both runs were modelled from Jan 1, 2000, to Dec 31, 2100. Countries were included if they were in the Gavi, the Vaccine Alliance portfolio; had notable burden; or had notable strategic vaccination activities. These countries represented the majority of global vaccine-preventable disease burden. Vaccine coverage was informed by historical estimates from WHO-UNICEF Estimates of National Immunization Coverage and the immunisation repository of WHO for data up to and including 2021. From 2022 onwards, we estimated coverage on the basis of guidance about campaign frequency, non-linear assumptions about the recovery of routine immunisation to pre-disruption magnitude, and 2030 endpoints informed by the WHO Immunization Agenda 2030 aims and expert consultation. We examined three main scenarios: no disruption, baseline recovery, and baseline recovery and catch-up. FINDINGS: We estimated that disruption to measles, rubella, HPV, hepatitis B, meningitis A, and yellow fever vaccination could lead to 49 119 additional deaths (95% credible interval [CrI] 17 248-134 941) during calendar years 2020-30, largely due to measles. For years of vaccination 2020-30 for all 14 pathogens, disruption could lead to a 2·66% (95% CrI 2·52-2·81) reduction in long-term effect from 37 378 194 deaths averted (34 450 249-40 241 202) to 36 410 559 deaths averted (33 515 397-39 241 799). We estimated that catch-up activities could avert 78·9% (40·4-151·4) of excess deaths between calendar years 2023 and 2030 (ie, 18 900 [7037-60 223] of 25 356 [9859-75 073]). INTERPRETATION: Our results highlight the importance of the timing of catch-up activities, considering estimated burden to improve vaccine coverage in affected cohorts. We estimated that mitigation measures for measles and yellow fever were particularly effective at reducing excess burden in the short term. Additionally, the high long-term effect of HPV vaccine as an important cervical-cancer prevention tool warrants continued immunisation efforts after disruption. FUNDING: The Vaccine Impact Modelling Consortium, funded by Gavi, the Vaccine Alliance and the Bill & Melinda Gates Foundation. TRANSLATIONS: For the Arabic, Chinese, French, Portguese and Spanish translations of the abstract see Supplementary Materials section.


Subject(s)
COVID-19 , Hepatitis B , Measles , Meningitis , Papillomavirus Infections , Papillomavirus Vaccines , Rubella , Vaccine-Preventable Diseases , Yellow Fever , Humans , Papillomavirus Infections/prevention & control , Pandemics , COVID-19/epidemiology , COVID-19/prevention & control , Vaccination , Immunization , Hepatitis B/drug therapy
14.
Exp Biol Med (Maywood) ; 249: 10114, 2024.
Article in English | MEDLINE | ID: mdl-38510492

ABSTRACT

Bunyamwera virus (BUNV) (Bunyamwera orthobunyavirus) has been found in Sub-Saharan Africa and demonstrated recently as cocirculating with Rift Valley Fever Virus (RVFV). Little is known regarding the breadth of transmission modalities of Bunyamwera. Given its co-occurence with RVFV, we hypothesized the transmission system of BUNV shared similarities to the RVFV system including transmission by Ae. aegypti mosquitoes and environmentally mediated transmission through fomites and environmental contamination. We exposed Ae. aegypti mosquitoes to BUNV and evaluated their ability to transmit both vertically and horizontally. Further, we investigated the potential for a novel transmission modality via environmental contamination. We found that the LSU colony of Ae. aegypti was not competent for the virus for either horizontal or vertical transmission; but, 20% of larva exposed to virus via contaminated aquatic habitat were positive. However, transstadial clearance of the virus was absolute. Finally, under simulated temperature conditions that matched peak transmission in Rwanda, we found that BUNV was stable in both whole blood and serum for up to 28 days at higher total volume in tubes at moderate quantities (103-5 genome copies/mL). In addition, infectiousness of these samples was demonstrated in 80% of the replicates. At lower volume samples (in plates), infectiousness was retained out to 6-8 days with a maximum infectious titer of 104 PFU/mL. Thus, the potential for contamination of the environment and/or transmission via contaminated fomites exists. Our findings have implications for biosafety and infection control, especially in the context of food animal production.


Subject(s)
Aedes , Bunyamwera virus , Rift Valley fever virus , Animals , Rift Valley fever virus/genetics
15.
Pest Manag Sci ; 2024 Mar 22.
Article in English | MEDLINE | ID: mdl-38517127

ABSTRACT

BACKGROUNDS: To provide a long-lasting formulation for spinosad (SP) targeting larval stages of Aedes aegypti (Linnaeus) and others alike, a SP tablet was developed based on microspheres, using polylactic acid as inside coating material. The microspheres were encapsulated using polyethylene glycol and 1-hexadecanol to form a sustained-release SP tablet. Micromorphology, active ingredient loading, structure identification, photolysis resistance, and biological activity were evaluated in this report. RESULTS: (1) SP microspheres have an average particle size of 6.16 ± 2.28 µm, low adhesion, and good dispersion as evaluated by scanning electron microscopy (SEM) and morphology; (2) The average active ingredient loading and encapsulation of SP microspheres were 32.80 ± 0.74% and 78.41 ± 2.22%, respectively; (3) The chemical structure of encapsulated SP was confirmed by FT-IR and 1H-NMR; (4) The photostability of the microspheres and the tablets were evaluated. The results showed that DT50 (time required to dissipate 50% of the mass originally present) of SP was 0.95 days in microspheres and 6.94 days in tablets. (5) The long-term insecticidal activity of SP tablets was investigated, and the tablet had a long-lasting activity against the mosquito larvae, showing 100% larval mortality for 63 days. CONCLUSIONS: The study provided a new long-lasting formulation of SP which displayed good efficacy in the control of Ae. aegypti larvae. This article is protected by copyright. All rights reserved.

16.
Turkiye Parazitol Derg ; 48(1): 39-44, 2024 03 05.
Article in English | MEDLINE | ID: mdl-38449366

ABSTRACT

Objective: A series of aromatic thiosemicarbazone-oxime [TP1 and TP2] derivatives and their Ni(II), Cu(II), and Co(II) complexes were synthesized, and their larvicidal activity was evaluated against Aedes aegypti and Aedes albopictus larvae. The efficacy of these substances to Aedes albopictus larvae has been demonstrated for the first time. Methods: Laboratory colonized Aedes aegypti and Aedes albopictus larvae were subjected to larvicidal activity tests. Larval mortality rates at 24 and 48 hours were recorded and LC50 values were calculated. The study was carried out at Aydin Adnan Menderes University in 2021. Results: For Aedes aegypti, LC50 of TP1 and its Co(II) complex were 15.41, 9.75, µg/mL whereas for TP2 and its Co(II) complex, LC50 were 21.62, 20.50 µg/mL after 24 and 48 h respectively. For Aedes albopictus, TP1 and its Co(II) complex showed an LC50 of 12.06, 8.75 µg/mL, whereas TP2 and its Co(II) complex showed an LC50 of 32.87, 25.48 µg/mL, for 24, and 48 h respectively. Conclusion: Both TP1 and TP2 compounds and their Co(II) complexes presented high efficacy against the larvae; it can be said that C=S groups in thiosemicarbazone derivatives are effective in showing activity and for this reason, studies should be continued to make these components effective.


Subject(s)
Aedes , Coordination Complexes , Thiosemicarbazones , Humans , Animals , Larva , Thiosemicarbazones/pharmacology
17.
Environ Microbiol ; 26(3): e16588, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38450576

ABSTRACT

Dengue represents an increasing public health burden worldwide. In Africa, underreporting and misdiagnosis often mask its true epidemiology, and dengue is likely to be both more widespread than reported data suggest and increasing in incidence and distribution. Wolbachia-based dengue control is underway in Asia and the Americas but has not to date been deployed in Africa. Due to the genetic heterogeneity of African Aedes aegypti populations and the complexity of the host-symbiont interactions, characterization of key parameters of Wolbachia-carrying mosquitoes is paramount for determining the potential of the system as a control tool for dengue in Africa. The wAlbB Wolbachia strain was stably introduced into an African Ae. aegypti population by introgression, and showed high intracellular density in whole bodies and different mosquito tissues; high intracellular density was also maintained following larval rearing at high temperatures. No effect on the adult lifespan induced by Wolbachia presence was detected. Moreover, the ability of this strain to strongly inhibit DENV-2 dissemination and transmission in the host was also demonstrated in the African background. Our findings suggest the potential of harnessing Wolbachia for dengue control for African populations of Ae. aegypti.


Subject(s)
Aedes , Dengue , Wolbachia , Animals , Burkina Faso/epidemiology , Wolbachia/genetics , Asia , Dengue/prevention & control
18.
Math Biosci Eng ; 21(2): 1884-1898, 2024 Jan 04.
Article in English | MEDLINE | ID: mdl-38454666

ABSTRACT

Here, we formulated a delayed mosquito population suppression model including two switching sub-equations, in which we assumed that the growth of the wild mosquito population obeys the Ricker-type density-dependent survival function and the release period of sterile males equals the maturation period of wild mosquitoes. For the time-switched delay model, to tackle with the difficulties brought by the non-monotonicity of its growth term to its dynamical analysis, we employed an essential transformation, derived an auxiliary function and obtained some expected analytical results. Finally, we proved that under certain conditions, the number of periodic solutions and their global attractivities for the delay model mirror that of the corresponding delay-free model. The findings can boost a better understanding of the impact of the time delay on the creation/suppression of oscillations harbored by the mosquito population dynamics and enhance the success of real-world mosquito control programs.


Subject(s)
Aedes , Models, Biological , Male , Animals , Mosquito Vectors , Mosquito Control/methods , Probability , Population Dynamics
19.
Vet Parasitol Reg Stud Reports ; 49: 100997, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38462302

ABSTRACT

Diseases transmitted by vectors have a significant collision on society and community health, particularly in tropical and subtropical regions, where they can cause large-scale outbreaks shortly after initial transmission. The intent of this investigation was to study the plant extract derived from Sigesbeckia orientalis L. in controlling the immature stages of Anopheles, Culex and Aedes mosquitoes, while also considering its potential toxicity to ecosystems. The immature stages were exposed to different extracts (62.5-500 ppm), and the mortality of larvae and pupae, as well as ovicidal activity, were noted after 24 and 120 h of the experiment. The hexane and ethyl aceate extract of S. orientalis presented 100% ovicidal activity against the eggs of Anopheles, Aedes and Culex at 500 ppm concentration after 5 days of treatment. The hexane and ethylacetate extracts presented strong larvicidal activity with LC50 values of 215.7, 332.0, 197.4 and 212.6, 694.9 and 201.7 ppm against treated mosquitoes at 24 h, respectively. The same extract also presented promising pupicidal activity. The LC50 values of hexane extract were 219.6, 353.6, 194.2 and LC50 values of ethyl acetate were 257.6, 387.8 and 259.07 ppm against early stage pupae of three vector mosquitoes, respectively. The extracts from S. orientalis had strong inhibitory activity against growth and development of mosquitoes. SI/PSF values showed that the extracts of S. orientalis did not harm Poecilia reticulata, Diplonychus indicus (Water bug), Gambusia affinis and dragon fly nymph at tested concentrations. Furthermore, examinations of histopathology and growth disruption revealed significant damage to the midgut cells in the treated larvae. The formulations utilizing hexane and ethyl acetate extracts exhibited potent activity without posing any toxicity towards non-target organisms. This study clearly indicated that hexane and ethylacetate extracts showed promising results against treated mosquitoes. The present study documents the first report of the extracts from S. orientalis and they can be further assessed to identify compounds for application purposes.


Subject(s)
Acetates , Aedes , Anopheles , Culex , Insecticides , Animals , Hexanes/pharmacology , Sigesbeckia , Ecosystem , Insecticides/pharmacology , Insecticides/chemistry , Mosquito Vectors , Larva
20.
PLoS One ; 19(2): e0293124, 2024.
Article in English | MEDLINE | ID: mdl-38324615

ABSTRACT

The development of insecticide resistance in mosquitoes of public health importance has encouraged extensive research into innovative vector control methods. Terpenes are the largest among Plants Secondary Metabolites and have been increasingly studied for their potential as insecticidal control agents. Although promising, terpenes are insoluble in water, and they show low residual life which limits their application for vector control. In this study, we developed and evaluated the performances of terpenoid-based nanoemulsions (TNEs) containing myrcene and p-cymene against the dengue vector Aedes aegypti and investigated their potential toxicity against non-target organisms. Our results showed that myrcene and p-cymene showed moderate larvicidal activity against mosquito larvae compared to temephos an organophosphate widely used for mosquito control. However, we showed similar efficacy of TNEs against both susceptible and highly insecticide-resistant mosquitoes from French Guyana, hence suggesting an absence of cross-resistance with conventional insecticides. We also showed that TNEs remained effective for up to 45 days in laboratory conditions. The exposure of zebrafish to TNEs triggered behavioral changes in the fish at high doses but they did not alter the normal functioning of zebrafish organs, suggesting a good tolerability of non-target organisms to these molecules. Overall, this study provides new insights into the insecticidal properties and toxicity of terpenes and terpenoid-based formulations and confirms that TNE may offer interesting prospects for mosquito control as part of integrated vector management.


Subject(s)
Acyclic Monoterpenes , Aedes , Alkenes , Cymenes , Dengue , Insecticides , Animals , Terpenes/pharmacology , Zebrafish , Mosquito Vectors , Insecticides/pharmacology , Dengue/prevention & control , Larva
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