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.

Modeling intra-mosquito dynamics of Zika virus and its dose-dependence confirms the low epidemic potential of Aedes albopictus.

Originating from African forests, Zika virus (ZIKV) has now emerged worldwide in urbanized areas, mainly transmitted by Aedes aegypti mosquitoes. Although Aedes albopictus can transmit ZIKV experimentally and was suspected to be a ZIKV vector in Central Africa, the potential of this species to sustain virus transmission was yet to be uncovered until the end of 2019, when several autochthonous transmissions of the virus vectored by Ae. albopictus occurred in France.

Strategic Approach, Advances, and Challenges in the Development and Application of the SIT for Area-Wide Control of Mosquitoes in Reunion Island.

The global expansion of together with the absence of specific treatment and vaccines for most of the arboviruses it transmits, has stimulated the development of more sustainable and ecologically acceptable methods for control of disease transmission through the suppression of natural vector populations. The sterile insect technique (SIT) is rapidly evolving as an additional tool for mosquito control, offering an efficient and more environment-friendly alternative to the use of insecticides. Following the devastating chikungunya outbreak, which affected 38% of the population on Reunion Island (a French overseas territory in the southwest of the Indian Ocean), there has been strong interest and political will to develop effective alternatives to the existing vector control strategies.

Field evaluation of seasonal trends in relative population sizes and dispersal pattern of Aedes albopictus males in support of the design of a sterile male release strategy.

Background: To develop an efficient sterile insect technique (SIT) programme, the number of sterile males to release, along with the spatial and temporal pattern of their release, has to be determined. Such parameters could be estimated from a reliable estimation of the wild population density (and its temporal variation) in the area to treat. Here, a series of mark-release-recapture experiments using laboratory-reared and field-derived Aedes albopictus males were carried out in Duparc, a selected pilot site for the future application of SIT in the north of La Reunion Island.

Comparison of Efficiency of BG-Sentinel Traps Baited with Mice, Mouse-Litter, and CO₂ Lures for Field Sampling of Male and Female Aedes albopictus Mosquitoes.

Determining the abundance and distribution of male mosquitoes in the wild and establishing species seasonality in candidate pilot sites is of particular interest with respect to the use of the sterile-male technique. With the knowledge that using mice as bait in BG-Sentinel traps effectively enhances male and female trapping success, the present study was designed to determine whether attractants derived from mouse odour blend could be a viable substitute for live mice to lure mosquitoes into traps. The effects of baiting BG-Sentinel traps with mice, carbon dioxide (CO₂), and attractants derived from litter mouse odours (mouse litter (ML)) and a mouse odour blend (MOB) on the efficiency of trapping males and females were tested using a Latin square design.

Human IgG Antibody Response to Aedes Nterm-34kDa Salivary Peptide, an Epidemiological Tool to Assess Vector Control in Chikungunya and Dengue Transmission Area.

Background: Arboviral diseases are an important public health concerns. Vector control remains the sole strategy to fight against these diseases. Because of the important limits of methods currently used to assess human exposure to Aedes mosquito bites, much effort is being devoted to develop new indicators.

Enhancement of the BG-sentinel trap with varying number of mice for field sampling of male and female Aedes albopictus mosquitoes.

Background: Trapping male mosquitoes in the field is essential for the development of area-wide vector control programs with a sterile insect technique (SIT) component. To determine the optimal temporal and spatial release strategy, an estimation of the wild population density and its temporal dynamics is essential. Among the traps available for such data collection, the BG-Sentinel trap developed by the Biogents company uses a combination of visual cues, convection currents and olfactory signals.

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.

Seasonal variation in size estimates of Aedes albopictus population based on standard mark-release-recapture experiments in an urban area on Reunion Island.

The implementation of the sterile insect technique for area-wide vector control requires that natural population density be accurately estimated to determine both the appropriate time to treat and the adequate number of sterile males for release. Herein, we used mark-release-recapture (MRR) to derive seasonal abundance estimates of Aedes albopictus population sizes within a delimited geographical area in Reunion Island. Population size of Ae.

Human antibody response to Aedes albopictus salivary proteins: a potential biomarker to evaluate the efficacy of vector control in an area of Chikungunya and Dengue Virus transmission.

Aedes borne viruses represent public health problems in southern countries and threat to emerge in the developed world. Their control is currently based on vector population control. Much effort is being devoted to develop new tools to control such arbovirus.

Spatial and temporal heterogeneities of Aedes albopictus density in La Reunion Island: rise and weakness of entomological indices.

Following the 2006 Chikungunya disease in La Reunion, questions were raised concerning the monitoring survey of Aedes albopictus populations and the entomological indexes used to evaluate population abundance. The objectives of the present study were to determine reliable productivity indexes using a quantitative method to improve entomological surveys and mosquito control measures on Aedes albopictus. Between 2007 and 2011, 4 intervention districts, 24 cities, 990 areas and over 850,000 houses were used to fulfil those objectives.

Human leptospirosis on Reunion Island: past and current burden.

Since 1953, leptospirosis has been recognized as a public health problem on Reunion Island. In 2004, was implemented a specific surveillance system that included systematic reporting and the realization of environmental investigations around hospitalized cases. Here, we present the synthesis of historical data and the assessment of 9 years of leptospirosis surveillance.

Household-level expenditure on protective measures against mosquitoes on the island of La Réunion, France.

Background: For decades La Réunion has experienced a number of epidemics that have resulted in efforts to control the density of Aedes species on this Island. This study was conducted to assess household-level expenditure on protective measures against mosquito nuisance on the Island of La Réunion in 2012.

Methodology/principal Findings: Data was collected during a cross-sectional survey of 1024 households and used to determine the relationship between the use of chemically-based protective measures and subjective and objective indicators of the density of Aedes albopictus.

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.

Matrix-assisted laser desorption ionization--time of flight mass spectrometry: an emerging tool for the rapid identification of mosquito vectors.

Background: The identification of mosquito vectors is typically based on morphological characteristics using morphological keys of determination, which requires entomological expertise and training. The use of protein profiling by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), which is increasingly being used for the routine identification of bacteria, has recently emerged for arthropod identification.

Methods: To investigate the usefulness of MALDI-TOF-MS as a mosquito identification tool, we tested protein extracts made from mosquito legs to create a database of reference spectra.

Abiotic and biotic factors associated with the presence of Anopheles arabiensis immatures and their abundance in naturally occurring and man-made aquatic habitats.

Background: Anopheles arabiensis (Diptera: Culicidae) is a potential malaria vector commonly present at low altitudes in remote areas in Reunion Island. Little attention has been paid to the environmental conditions driving larval development and abundance patterns in potential habitats. Two field surveys were designed to determine whether factors that discriminate between aquatic habitats with and without An.

Evaluation of the human IgG antibody response to Aedes albopictus saliva as a new specific biomarker of exposure to vector bites.

Background: The spread of Aedes albopictus, a vector for re-emergent arbovirus diseases like chikungunya and dengue, points up the need for better control strategies and new tools to evaluate transmission risk. Human antibody (Ab) responses to mosquito salivary proteins could represent a reliable biomarker for evaluating human-vector contact and the efficacy of control programs.

Methodology/principal Findings: We used ELISA tests to evaluate specific immunoglobulin G (IgG) responses to salivary gland extracts (SGE) in adults exposed to Aedes albopictus in Reunion Island.

Spatial and temporal distribution patterns of Anopheles arabiensis breeding sites in La Reunion Island--multi-year trend analysis of historical records from 1996-2009.

Background: An often confounding facet of the dynamics of malaria vectors is the aquatic larval habitat availability and suitable conditions under which they can thrive. Here, we investigated the impact of environmental factors on the temporal and spatial distribution of larval habitats of Anopheles arabiensis in different locations on La Reunion Island.

Methods: A retrospective examination was made from archival data which provided the complete enumeration of An.

Wolbachia age-sex-specific density in Aedes albopictus: a host evolutionary response to cytoplasmic incompatibility?

Background: Wolbachia bacteria have invaded many arthropod species by inducing Cytoplasmic Incompatibility (CI). These symbionts represent fascinating objects of study for evolutionary biologists, but also powerful potential biocontrol agents. Here, we assess the density dynamics of Wolbachia infections in males and females of the mosquito Aedes albopitcus, an important vector of human pathogens, and interpret the results within an evolutionary framework.

Insecticide resistance in Culex pipiens quinquefasciatus and Aedes albopictus mosquitoes from La Réunion Island.

Resistance to insecticides was monitored on Culex pipiens quinquefasciatus mosquitoes collected in twelve localities of La Réunion, a geographically isolated island of the Indian Ocean. This mosquito is of medical concern in the region as a known vector for filariasis and a potential vector for West Nile and Rift Valley Fever viruses. Our bioassays indicated the presence of resistance to all tested insecticides, i.

Two Chikungunya isolates from the outbreak of La Reunion (Indian Ocean) exhibit different patterns of infection in the mosquito, Aedes albopictus.

Background: A Chikungunya (CHIK) outbreak hit La Réunion Island in 2005-2006. The implicated vector was Aedes albopictus. Here, we present the first study on the susceptibility of Ae.