A wAlbB Wolbachia transinfection displays stable phenotypic effects across divergent Aedes aegypti mosquito backgrounds

Aedes mosquitoes harboring intracellular Wolbachia bacteria are being released in arbovirus and mosquito control programs. With releases taking place around the world, understanding the contribution of host variation to Wolbachia phenotype is crucial. We generated a Wolbachia transinfection ( w AlbB Q ) in Aedes aegypti and performed backcrossing to introduce the infection into Australian or Malaysian nuclear backgrounds. Whole Wolbachia genome sequencing shows that the w AlbB Q transinfection is near-identical to the reference w AlbB genome, suggesting few changes since the infection was first introduced to Ae. aegypti over 15 years ago. However, these sequences were distinct from other available w AlbB genome sequences, highlighting the potential diversity of w AlbB in natural Ae. albopictus populations. Phenotypic comparisons demonstrate effects of w AlbB infection on egg hatch and nuclear background on fecundity and body size, but no interactions between w AlbB infection and nuclear background for any trait. The w AlbB infection was stable at high temperatures and showed perfect maternal transmission and cytoplasmic incompatibility regardless of host background. Our results demonstrate the stability of w AlbB across host backgrounds and point to its long-term effectiveness for controlling arbovirus transmission and mosquito populations. Importance Wolbachia bacteria are being used to control the transmission of dengue and other arboviruses by mosquitoes. For Wolbachia release programs to be effective globally, Wolbachia infections must be stable across mosquito populations from different locations. In this study, we transferred Wolbachia (strain w AlbB) to Aedes aegypti mosquitoes with an Australian genotype and introduced the infection to Malaysian mosquitoes through backcrossing. We found that the phenotypic effects of Wolbachia are stable across both mosquito backgrounds. We sequenced the genome of w AlbB and found very few genetic changes despite spending over 15 years in a novel mosquito host. Our results suggest that the effects of Wolbachia infections are likely to remain stable across time and host genotype.

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Permethrin Resistance in Aedes aegypti Affects Aspects of Vectorial Capacity

Insects ◽

10.3390/insects12010071 ◽

2021 ◽

Vol 12 (1) ◽

pp. 71

Author(s):

Tse-Yu Chen ◽

Chelsea T. Smartt ◽

Dongyoung Shin

Keyword(s):

Aedes Aegypti ◽

Sodium Channel ◽

Mosquito Control ◽

Vector Competence ◽

Vectorial Capacity ◽

Parental Population ◽

Control Programs ◽

Channel Gene ◽

Sodium Channel Gene ◽

Specific Pcr

Aedes aegypti, as one of the vectors transmitting several arboviruses, is the main target in mosquito control programs. Permethrin is used to control mosquitoes and Aedes aegypti get exposed due to its overuse and are now resistant. The increasing percentage of permethrin resistant Aedes aegypti has become an important issue around the world and the potential influence on vectorial capacity needs to be studied. Here we selected a permethrin resistant (p-s) Aedes aegypti population from a wild Florida population and confirmed the resistance ratio to its parental population. We used allele-specific PCR genotyping of the V1016I and F1534C sites in the sodium channel gene to map mutations responsible for the resistance. Two important factors, survival rate and vector competence, that impact vectorial capacity were checked. Results indicated the p-s population had 20 times more resistance to permethrin based on LD50 compared to the parental population. In the genotyping study, the p-s population had more homozygous mutations in both mutant sites of the sodium channel gene. The p-s adults survived longer and had a higher dissemination rate for dengue virus than the parental population. These results suggest that highly permethrin resistant Aedes aegypti populations might affect the vectorial capacity, moreover, resistance increased the survival time and vector competence, which should be of concern in areas where permethrin is applied.

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Investigating Male Aedes aegypti (Diptera: Culicidae) Attraction to Different Oviposition Containers Using Various Configurations of the Sound Gravid Aedes Trap

Journal of Medical Entomology ◽

10.1093/jme/tjz229 ◽

2019 ◽

Vol 57 (3) ◽

pp. 957-961

Author(s):

Kyran M Staunton ◽

Barukh B Rohde ◽

Michael Townsend ◽

Jianyi Liu ◽

Mark Desnoyer ◽

...

Keyword(s):

Aedes Aegypti ◽

Zika Virus ◽

Disease Transmission ◽

Urban Landscape ◽

Mosquito Control ◽

Transmission Risk ◽

Northern Australia ◽

Control Programs ◽

Male Dispersal ◽

Olfactory Attractant

Abstract Aedes aegypti (Linnaeus), the primary vectors of the arboviruses dengue virus and Zika virus, continue to expand their global distributions. In efforts to better control such species, several mosquito control programs are investigating the efficacy of rearing and releasing millions of altered male Aedes throughout landscapes to reduce populations and disease transmission risk. Unfortunately, little is known about Ae. aegypti, especially male, dispersal behaviors within urban habitats. We deployed Sound-producing Gravid Aedes Traps (SGATs) in Cairns, northern Australia, to investigate male Ae. aegypti attraction to various oviposition container configurations. The traps were arranged to include: 1) water only, 2) organically infused water, 3) infused water and L3 larvae, 4) infused water and a human-scented lure, and lastly 5) no water or olfactory attractant (dry). Our data suggest that males were more attracted to SGATs representing active larval sites than potential larval sites, but were equally attracted to dry SGATs relative to those containing water and/or infusion. Additionally, we found that female Ae. aegypti were equally attracted to wet SGATs, with or without infusion, but not dry ones. These results suggest that male Ae. aegypti within northern Australia are more attracted to active larval sites and equally attracted to dry containers as wet or infused ones. Additionally, female Ae. aegypti are unlikely to enter dry containers. Such findings contribute to our understanding of potentially attractive features for local and released Ae. aegypti throughout the northern Australian urban landscape.

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Susceptibility Status of Aedes aegypti L. Against Different Classes of Insecticides in New Delhi, India to Formulate Mosquito Control Strategy in Fields

The Open Parasitology Journal ◽

10.2174/1874421401806010052 ◽

2018 ◽

Vol 6 (1) ◽

pp. 52-62 ◽

Cited By ~ 1

Author(s):

Roopa Rani Samal ◽

Sarita Kumar

Keyword(s):

Secondary Metabolites ◽

Aedes Aegypti ◽

Control Strategy ◽

Mosquito Control ◽

Current Status ◽

New Delhi ◽

Probit Regression ◽

Statistical Parameters ◽

Insecticide Susceptibility ◽

Control Programs

Background: Mosquito control is a major concern throughout the world because of rising cases of mosquito-borne diseases. The outbreak of Zika, Dengue and Chikungunya has caused grave situations raising urgent need to control Aedes aegypti. Moreover, extensive use of synthetic insecticides in mosquito control programs has resulted in high levels of insecticide resistance leading to the use of magnified concentrations, impacting human health and environment adversely. The knowledge about current status of the insecticide susceptibility against Ae. aegypti could help to devise mosquito control strategy. Objective: Present study evaluates the larvicidal potential of thirteen insecticides belonging to seven different classes; organochlorines, organophosphates, carbamates, pyrethroids, neonicotinoids, avermectins and secondary metabolites; against early fourth instars of Ae. aegypti. Materials and Methods: The insecticide susceptibility was evaluated as per WHO protocol. Fatality counts were made after 24h of exposure; and the LC50, LC90 and other statistical parameters were computed by probit-regression analysis. Results: The data reveals the maximum efficacy of pyrethroids and fenitrothion, with lethal values less than 0.001 ppm. Avermectins, organochlorines and carbamates were moderately toxic, while neonicotinoid posed appreciable toxicity. In contrast, berberine, a secondary plant metabolite was found inefficient. The larvicidal efficacy of tested insecticides against Ae. aegypti was found in the decreasing order of pyrethroids > organophosphates > avermectins > organochlorines > carbamates > neonicotinoids > secondary metabolites. Conclusion: Present investigations explore various toxicants as Dengue vector control agents in order to devise a suitable control strategy for mosquito control in fields.

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Trap Location and Premises Condition Influences on Aedes aegypti (Diptera: Culicidae) Catches Using Biogents Sentinel Traps During a ‘Rear and Release’ Program: Implications for Designing Surveillance Programs

Journal of Medical Entomology ◽

10.1093/jme/tjz018 ◽

2019 ◽

Vol 56 (4) ◽

pp. 1102-1111 ◽

Cited By ~ 7

Author(s):

Kyran M Staunton ◽

Peter Yeeles ◽

Michael Townsend ◽

Somayeh Nowrouzi ◽

Christopher J Paton ◽

...

Keyword(s):

Aedes Aegypti ◽

Building Materials ◽

Mosquito Control ◽

Male And Female ◽

Spatial Stability ◽

Control Programs ◽

Surveillance Programs ◽

Trap Location ◽

Release Program ◽

Trap Catches

AbstractAs the incidence of arboviral diseases such as dengue, Zika, chikungunya, and yellow fever increases globally, controlling their primary vector, Aedes aegypti (L.) (Diptera: Culicidae), is of greater importance than ever before. Mosquito control programs rely heavily on effective adult surveillance to ensure methodological efficacy. The Biogents Sentinel (BGS) trap is the gold standard for surveilling adult Aedes mosquitoes and is commonly deployed worldwide, including during modern ‘rear and release’ programs. Despite its extensive use, few studies have directly assessed environmental characteristics that affect BGS trap catches, let alone how these influences change during ‘rear and release’ programs. We assessed male and female Ae. aegypti spatial stability, as well as premises condition and trap location influences on BGS trap catches, as part of Debug Innisfail ‘rear and release’ program in northern Australia. We found similar trends in spatial stability of male and female mosquitoes at both weekly and monthly resolutions. From surveillance in locations where no males were released, reduced catches were found at premises that contained somewhat damaged houses and unscreened properties. In addition, when traps were located in areas that were unsheltered, more than 10 m from commonly used sitting areas or more visually complex catches were also negatively affected. In locations where males were released, we found that traps in treatment sites, relative to control sites, displayed increased catches in heavily shaded premises and were inconsistently influenced by differences in house sets and building materials. Such findings have valuable implications for a range of Ae. aegypti surveillance programs.

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A wMel Wolbachia variant in Aedes aegypti from field-collected Drosophila melanogaster with increased phenotypic stability under heat stress

10.1101/2022.01.02.474744 ◽

2022 ◽

Author(s):

Xinyue Gu ◽

Perran A Ross ◽

Julio Rodriguez-Andres ◽

Katie L. Robinson ◽

Qiong Yang ◽

...

Keyword(s):

Drosophila Melanogaster ◽

Heat Stress ◽

Aedes Aegypti ◽

Cytoplasmic Incompatibility ◽

Vector Competence ◽

Temperature Tolerance ◽

Seasonal Temperature ◽

Maternal Transmission ◽

Tropical Regions ◽

Host Fitness

Mosquito-borne diseases such as dengue, Zika and chikungunya remain a major cause of morbidity and mortality across tropical regions. Population replacement strategies involving the wMel strain of Wolbachia are being used widely to control mosquito-borne diseases transmitted by Aedes aegypti. However, these strategies may be influenced by environmental temperature because wMel is vulnerable to heat stress. wMel infections in their native host Drosophila melanogaster are genetically diverse, but few transinfections of wMel variants have been generated in Ae. aegypti mosquitoes. Here we successfully transferred a wMel variant (termed wMelM) originating from a field-collected D. melanogaster population from Victoria, Australia into Ae. aegypti. The new wMelM variant (clade I) is genetically distinct from the original wMel transinfection (clade III) generated over ten years ago, and there are no genomic differences between wMelM in its original and transinfected host. We compared wMelM with wMel in its effects on host fitness, temperature tolerance, Wolbachia density, vector competence, cytoplasmic incompatibility and maternal transmission under heat stress in a controlled background. wMelM showed a higher heat tolerance than wMel, with stronger cytoplasmic incompatibility and maternal transmission when eggs were exposed to heat stress, likely due to higher overall densities within the mosquito. Both wMel variants had minimal host fitness costs, complete cytoplasmic incompatibility and maternal transmission, and dengue virus blocking under standard laboratory conditions. Our results highlight phenotypic differences between closely related Wolbachia variants. wMelM shows potential as an alternative strain to wMel in dengue control programs in areas with strong seasonal temperature fluctuations.

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Assessment of fitness and vector competence of a New Caledonia wMel Aedes aegypti strain before field-release

PLoS Neglected Tropical Diseases ◽

10.1371/journal.pntd.0009752 ◽

2021 ◽

Vol 15 (9) ◽

pp. e0009752

Author(s):

Nicolas Pocquet ◽

Olivia O’Connor ◽

Heather A. Flores ◽

Jordan Tutagata ◽

Morgane Pol ◽

...

Keyword(s):

Aedes Aegypti ◽

Cytoplasmic Incompatibility ◽

New Caledonia ◽

Vector Competence ◽

Oral Feeding ◽

Maternal Transmission ◽

Strong Inhibitor ◽

Feeding Experiments ◽

Dengue Outbreaks ◽

Mosquito Saliva

Background Biological control programs involving Wolbachia-infected Aedes aegypti are currently deployed in different epidemiological settings. New Caledonia (NC) is an ideal location for the implementation and evaluation of such a strategy as the only proven vector for dengue virus (DENV) is Ae. aegypti and dengue outbreaks frequency and severity are increasing. We report the generation of a NC Wolbachia-infected Ae. aegypti strain and the results of experiments to assess the vector competence and fitness of this strain for future implementation as a disease control strategy in Noumea, NC. Methods/principal findings The NC Wolbachia strain (NC-wMel) was obtained by backcrossing Australian AUS-wMel females with New Caledonian Wild-Type (NC-WT) males. Blocking of DENV, chikungunya (CHIKV), and Zika (ZIKV) viruses were evaluated via mosquito oral feeding experiments and intrathoracic DENV challenge. Significant reduction in infection rates were observed for NC-wMel Ae. aegypti compared to WT Ae. aegypti. No transmission was observed for NC-wMel Ae. aegypti. Maternal transmission, cytoplasmic incompatibility, fertility, fecundity, wing length, and insecticide resistance were also assessed in laboratory experiments. Ae. aegypti NC-wMel showed complete cytoplasmic incompatibility and a strong maternal transmission. Ae. aegypti NC-wMel fitness seemed to be reduced compared to NC-WT Ae. aegypti and AUS-wMel Ae. aegypti regarding fertility and fecundity. However further experiments are required to assess it accurately. Conclusions/significance Our results demonstrated that the NC-wMel Ae. aegypti strain is a strong inhibitor of DENV, CHIKV, and ZIKV infection and prevents transmission of infectious viral particles in mosquito saliva. Furthermore, our NC-wMel Ae. aegypti strain induces reproductive cytoplasmic incompatibility with minimal apparent fitness costs and high maternal transmission, supporting field-releases in Noumea, NC.

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Dynamics of cytoplasmic incompatibility and mtDNA variation in natural Drosophila simulans populations.

Genetics ◽

10.1093/genetics/132.3.713 ◽

1992 ◽

Vol 132 (3) ◽

pp. 713-723 ◽

Cited By ~ 8

Author(s):

M Turelli ◽

A A Hoffmann ◽

S W McKechnie

Keyword(s):

Restriction Site ◽

Cytoplasmic Incompatibility ◽

Drosophila Simulans ◽

Paternal Inheritance ◽

Maternal Transmission ◽

Egg Hatch ◽

Empirically Supported ◽

Mtdna Variation ◽

Mtdna Variants ◽

Parameter Values

Abstract In Drosophila simulans a cytoplasmically transmitted microorganism causes reduced egg hatch when infected males mate with uninfected females. The infection is rapidly spreading northward in California. Data on a specific mtDNA restriction site length polymorphism show that changes in the frequency of mtDNA variants are associated with this spread. All infected flies possess the same mtDNA allele, whereas the uninfected flies are polymorphic. Given that both paternal inheritance of the infection and imperfect maternal transmission have been demonstrated, one might expect instead that both infected and uninfected flies would possess both mtDNA variants. Our data suggest that imperfect female transmission of the infection (and/or the loss of the infection among progeny) is more common in nature than paternal transmission. A simple model of intrapopulation dynamics, with empirically supported parameter values, adequately describes the joint frequencies of the mtDNA variants and incompatibility types.

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A NEW LABORATORY COLONIZATION OF AEDES AEGYPTI AFTER REEMERGENCE AND UNSUCCESSFUL ERADICATION IN ST. AUGUSTINE, FLORIDA

Journal of the Florida Mosquito Control Association ◽

10.32473/jfmca.v67i1.127639 ◽

2021 ◽

Vol 67 (1) ◽

pp. 73-75

Author(s):

Rui-De Xue

Keyword(s):

Aedes Aegypti ◽

Filter Paper ◽

Mosquito Control ◽

Large Cage ◽

Egg Hatch ◽

Human Volunteers ◽

Veterinary Entomology ◽

And Control

After unsuccessful eradication attempts against Aedes aegypti (L.) following a sudden re-emergence in St. Augustine, Florida in early 2016; a new locally acquired colony strain of Ae. aegypti was established at the Anastasia Mosquito Control District (AMCD) in June 2017. Aedes aegypti adults were maintained in cages at the AMCD insectary. Larval and adult mosquitoes were collected from downtown St. Augustine, Florida. Female mosquitoes at 5-7 days old were fed upon the exposed forearm of human volunteers in the 1 st and 2 nd generations. Mating was observed in a large cage and confirmed with eggs deposited on wet filter paper in ovicups. Over 90% egg hatch was observed in the laboratory. The new colony strain of Ae. aegypti has been cataloged at the USDA, Center for Medical, Agricultural, and Veterinary Entomology facility in Gainesville, FL and is being used to further research and control this species across North Florida.

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Bioefficacy of Two Nonpyrethroid Insecticides for Targeted Indoor Residual Spraying Against Pyrethroid-Resistant Aedes aegypti

Journal of the American Mosquito Control Association ◽

10.2987/19-6866.1 ◽

2019 ◽

Vol 35 (4) ◽

pp. 291-294 ◽

Cited By ~ 1

Author(s):

Fabian Correa-Morales ◽

Martin Riestra-Morales ◽

Wilbert Bibiano-Marín ◽

Felipe Dzul-Manzanilla ◽

Luis Felipe Del Castillo-Centeno ◽

...

Keyword(s):

Aedes Aegypti ◽

Resistant Strain ◽

Mosquito Control ◽

Indoor Residual Spraying ◽

Control Programs ◽

Pirimiphos Methyl ◽

Residual Efficacy

ABSTRACT We evaluated the efficacy of bendiocarb (Ficam W® 80%) and pirimiphos-methyl (Actellic 300CS® 28.16%), applied to different surfaces potentially sprayable within houses during the application of a targeted indoor residual spraying (TIRS) against a field pyrethroid-resistant strain of Aedes aegypti. Bioassays with cones were performed on cement (walls), wood (doors), and textile (cloth) surfaces within typical houses in the Mexican city of Merida (n = 10). Optimal residual efficacy (>80% of mean mortality) of bendiocarb ranged from 3 months (cement) to 2 months (wood and textiles). Residual efficacy of pirimiphos-methyl ranged from 5 months (cement) to 2 months (wood and textiles). Both insecticides proved to be effective as adulticides against field Ae. aegypti and may be useful in mosquito control programs implementing TIRS with pyrethroid-resistant populations.

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