Vector competence of Aedes albopictus field populations from Reunion Island exposed to local epidemic dengue viruses.

Dengue virus (DENV) is the most prevalent mosquito-borne Flavivirus that affects humans worldwide. Aedes albopictus, which is naturally infected with the bacteria Wolbachia, is considered to be a secondary vector of DENV. However, it was responsible for a recent DENV outbreak of unprecedented magnitude in Reunion Island, a French island in the South West Indian Ocean.

Genetic diversity of endosymbiotic bacteria infecting two mosquito species of the genus occurring in sympatry in the Comoros archipelago.

Introduction: The influence of on mosquito reproduction and vector competence has led to renewed interest in studying the genetic diversity of these bacteria and the phenotypes they induced in mosquito vectors. In this study, we focused on two species of , namely and , from three islands in the Comoros archipelago (in the Southwestern Indian Ocean).

Methods: Using the gene, we examined the mitochondrial genetic diversity of 879 individuals from 54 sites.

Investigation of Cytoplasmic Incompatibility Patterns in Culex pipiens: From Field Samples to Laboratory Isofemale Lines.

This protocol describes approaches to qualify Wolbachia-induced cytoplasmic incompatibility (CI) patterns (compatible, uni or bidirectional) in crosses between two or more Culex pipiens isofemale lines, hosting different Wolbachia (wPip) strains. Here, we describe how to (1) collect the larvae in the field and grow them to the adult stage in the insectary, (2) set up isofemale lines in the insectary, (3) genetically characterize the wPip group of these lines, and (4) perform reciprocal crosses to qualify CI.

Evidence of Eretmapodites subsimplicipes and Aedes albopictus as competent vectors for Rift Valley fever virus transmission in Mayotte.

Rift Valley fever (RVF) recently re-emerged in Mayotte. We described, for the first time, that the mosquito species Eretmapodites subsimplicipes, a highly abundant species in Mayotte, is a competent vector for the transmission of RVF virus using three distinct populations native to Mayotte. We also showed that Aedes albopictus specimens are able to transmit RVF virus (RVFV) as previously observed in mosquito populations of other countries emphasizing the need of the increase vigilance for this highly invasive species of global distribution.

Fitness costs associated with a GABA receptor mutation conferring dieldrin resistance in Aedes albopictus.

Understanding the dynamics of insecticide resistance genes in mosquito populations is pivotal for a sustainable use of insecticides. Dieldrin resistance in Aedes albopictus is conferred by the alanine to serine substitution (A302S or Rdl allele) in the γ-aminobutyric acid (GABA) receptor encoded by the Rdl gene. On Reunion Island, dieldrin resistance was initially reported in natural Ae.

Zika vector competence data reveals risks of outbreaks: the contribution of the European ZIKAlliance project.

First identified in 1947, Zika virus took roughly 70 years to cause a pandemic unusually associated with virus-induced brain damage in newborns. Zika virus is transmitted by mosquitoes, mainly Aedes aegypti, and secondarily, Aedes albopictus, both colonizing a large strip encompassing tropical and temperate regions. As part of the international project ZIKAlliance initiated in 2016, 50 mosquito populations from six species collected in 12 countries were experimentally infected with different Zika viruses.

Overview of dengue outbreaks in the southwestern Indian Ocean and analysis of factors involved in the shift toward endemicity in Reunion Island: A systematic review.

Background: Dengue is the world's most prevalent mosquito-borne viral disease. It is endemic in many tropical and subtropical countries and represents a significant global health burden. The first reports of dengue virus (DENV) circulation in the South West Indian Ocean (SWIO) islands date back to the early 1940s; however, an increase in DENV circulation has been reported in the SWIO in recent years.

Spatio-Temporal Dynamics of a Dieldrin Resistance Gene in Aedes albopictus and Culex quinquefasciatus Populations From Reunion Island.

The control of mosquito populations using insecticides is increasingly threatened by the spread of resistance mechanisms. Dieldrin resistance, conferred by point mutations in the Rdl gene encoding the γ-aminobutyric acid receptor, has been reported at high prevalence in mosquito populations in response to selective pressures. In this study, we monitored spatio-temporal dynamics of the resistance-conferring RdlR allele in Aedes (Stegomyia) albopictus (Skuse, 1895) and Culex (Culex) quinquefasciatus (Say, 1823) populations from Reunion Island.

Wolbachia modulates prevalence and viral load of Culex pipiens densoviruses in natural populations.

The inadequacy of standard mosquito control strategies calls for ecologically safe novel approaches, for example the use of biological agents such as the endosymbiotic α-proteobacteria Wolbachia or insect-specific viruses (ISVs). Understanding the ecological interactions between these "biocontrol endosymbionts" is thus a fundamental step. Wolbachia are transmitted vertically from mother to offspring and modify their hosts' phenotypes, including reproduction (e.

Contrasted transmission efficiency of Zika virus strains by mosquito species Aedes aegypti, Aedes albopictus and Culex quinquefasciatus from Reunion Island.

Background: Zika virus (ZIKV) is a mosquito-borne flavivirus that recently emerged in the South Pacific islands and Americas where unprecedented outbreaks were reported. Although Aedes aegypti is considered to be the main vector for ZIKV, other mosquito species have been shown to be potential vectors and differences in vector competence with respect to mosquito strain and ZIKV strain have been demonstrated. In this study we compared the vector competence of three mosquito species Aedes albopictus, Ae.

High genetic diversity but no geographical structure of Aedes albopictus populations in Réunion Island.

Background: In recent years, the Asian tiger mosquito Aedes albopictus has emerged as a species of major medical concern following its global expansion and involvement in many arbovirus outbreaks. On Réunion Island, Ae. albopictus was responsible for a large chikungunya outbreak in 2005-2006 and more recently an epidemic of dengue which began at the end of 2017 and is still ongoing at the time of writing.

Insecticide resistance genes affect Culex quinquefasciatus vector competence for West Nile virus.

Insecticide resistance has been reported to impact the interactions between mosquitoes and the pathogens they transmit. However, the effect on vector competence for arboviruses still remained to be investigated. We examined the influence of two insecticide resistance mechanisms on vector competence of the mosquito Culex quinquefasciatus for two arboviruses, Rift Valley Fever virus (RVFV) and West Nile virus (WNV).

Construction of a genetic sexing strain for Aedes albopictus: a promising tool for the development of sterilizing insect control strategies targeting the tiger mosquito.

Background: Aedes albopictus is an invasive mosquito species of global medical concern as its distribution has recently expanded to Africa, the Americas and Europe. In the absence of prophylaxis protecting human populations from emerging arboviruses transmitted by this mosquito species, the most straightforward control measures rely on the suppression or manipulation of vector natural populations. A number of environmental-friendly methods using mass releases of sterilizing males are currently under development.

Author Correction: Culex pipiens crossing type diversity is governed by an amplified and polymorphic operon of Wolbachia.

In the originally published HTML and PDF versions of this Article, gel images in Figures 7c and 8c were not prepared as per the Nature journal policy. These figure panels have now been corrected in both the PDF and HTML versions of the Article.In Fig.

Culex pipiens crossing type diversity is governed by an amplified and polymorphic operon of Wolbachia.

Culex pipiens mosquitoes are infected with Wolbachia (wPip) that cause an important diversity of cytoplasmic incompatibilities (CIs). Functional transgenic studies have implicated the cidA-cidB operon from wPip and its homolog in wMel in CI between infected Drosophila males and uninfected females. However, the genetic basis of the CI diversity induced by different Wolbachia strains was unknown.

Discovery of associated tunisia virus: a new ssRNA(+) virus representing a new insect associated virus family.

In the global context of arboviral emergence, deep sequencing unlocks the discovery of new mosquito-borne viruses. Mosquitoes of the species , , and were sampled from 22 locations worldwide for transcriptomic analyses. A virus discovery pipeline was used to analyze the dataset of 0.

The evolutionary fate of heterogeneous gene duplications: A precarious overdominant equilibrium between environment, sublethality and complementation.

Gene duplications occur at a high rate. Although most appear detrimental, some homogeneous duplications (identical gene copies) can be selected for beneficial increase in produced proteins. Heterogeneous duplications, which combine divergent alleles of a single locus, are seldom studied due to the paucity of empirical data.

Comparison of Irradiation and Wolbachia Based Approaches for Sterile-Male Strategies Targeting Aedes albopictus.

The global expansion of Aedes albopictus together with the absence of vaccines for most of the arboviruses transmitted by this mosquito has stimulated the development of sterile-male strategies aiming at controlling disease transmission through the suppression of natural vector populations. In this context, two environmentally friendly control strategies, namely the Sterile Insect Technique (SIT) and the Wolbachia-based Incompatible Insect Technique (IIT) are currently being developed in several laboratories worldwide. So far however, there is a lack of comparative assessment of these strategies under the same controlled conditions.

Wolbachia-based population control strategy targeting Culex quinquefasciatus mosquitoes proves efficient under semi-field conditions.

In mosquitoes, the maternally inherited bacterial Wolbachia induce a form of embryonic lethality called cytoplasmic incompatibility (CI). This property can be used to reduce the density of mosquito field populations through inundative releases of incompatible males in order to sterilize females (Incompatible Insect Technique, or IIT, strategy). We have previously constructed the LR[wPip(Is)] line representing a good candidate for controlling field populations of the Culex quinquefasciatus mosquito in the islands of the south-western Indian Ocean.

Stable coexistence of incompatible Wolbachia along a narrow contact zone in mosquito field populations.

In arthropods, the intracellular bacteria Wolbachia often induce cytoplasmic incompatibility (CI) between sperm and egg, which causes conditional embryonic death and promotes the spatial spread of Wolbachia infections into host populations. The ability of Wolbachia to spread in natural populations through CI has attracted attention for using these bacteria in vector-borne disease control. The dynamics of incompatible Wolbachia infections have been deeply investigated theoretically, whereas in natural populations, there are only few examples described, especially among incompatible infected hosts.

Multiple insecticide resistances in the disease vector Culex p. quinquefasciatus from Western Indian Ocean.

Several mosquito-borne diseases affect the Western Indian Ocean islands. Culex pipiens quinquefasciatus is one of these vectors and transmits filariasis, Rift Valley and West Nile viruses and the Japanese encephalitis. To limit the impact of these diseases on public health, considerable vector control efforts have been implemented since the 50s, mainly through the use of neurotoxic insecticides belonging to Organochlorines (OC), Organophosphates (OP) and pyrethroids (PYR) families.

Population structure of Wolbachia and cytoplasmic introgression in a complex of mosquito species.

Background: The maternally inherited bacterium Wolbachia often acts as a subtle parasite that manipulates insect reproduction, resulting potentially in reproductive isolation between host populations. Whilst distinct Wolbachia strains are documented in a group of evolutionarily closely related mosquitoes known as the Culex pipiens complex, their impact on mosquito population genetics remains unclear. To this aim, we developed a PCR-RFLP test that discriminates the five known Wolbachia groups found in this host complex.

Rapid evolution of Wolbachia incompatibility types.

In most insects, the endosymbiont Wolbachia induces cytoplasmic incompatibility (CI), an embryonic mortality observed when infected males mate either with uninfected females or with females infected by an incompatible Wolbachia strain. Although the molecular mechanism of CI remains elusive, it is classically viewed as a modification-rescue model, in which a Wolbachia mod function disables the reproductive success of the sperm of infected males, unless eggs are infected and express a compatible resc function. The extent to which the modification-rescue model can predict highly complex CI pattern remains a challenging issue.