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The recent decades’ resurgence of bed bugs as a public health concern in industrialized countries has driven an increased interest on new sustainable insecticide-free methods to monitor and control these ectoparasites. Current methods of detection rely mainly on visual inspection or canine scent detection, which are methods that are time-consuming, require experience, are non-specific or require costly mission repetitions. Volatile organic compounds (VOCs) are considered an environmentally friendly alternative and a promising approach for bed bug detection. An overview of the released literature on VOCs, their chemical characteristics and their role in bed bugs’ intra- and inter-species communications allowed us to highlight the identification of 49 VOCs in Cimex lectularius (23 molecules) and C. hemipterus (26), which are emitted by both sexes during diverse compartments including aggregation (46), mating (11), defense (4), etc., and all life stages including exuviae or dead bed bugs as a principal indicator of infestation. The latter has a great importance for application of these semiochemicals in successful detection and control management of bed bugs and to prevent their further dispersion. This approach has the advantage of more reliability compared to conventional detection methods with no need for repeated inspections, household furniture moving or resident rehousing for bed bugs’ VOC detection, which are commonly performed by active or passive sampling with absorbing tubes and analyzed by gas chromatography-based analytical platforms.

Simple Summary The bed bugs, Cimex lectularius and C. hemipterus, have undergone a significant resurgence worldwide since the 1990s. Despite reports of bed bug infestations being on the rise in recent years in France, little is known about the geographical dispersion, species composition, and inter-and intraspecific genetic variation among bed bug populations in the Paris area. The collection of 1211 samples of bed bugs from different infested locations in Paris (15 arrondissements) and its suburb cities (18 cities) allowed us to highlight C. lectularius as the predominant species and to document for the first time the presence of C. hemipterus in four infested locations (15th and 19th arrondissements, Bobigny, and Villejuif) in the Paris area. Successful bidirectional sequencing of the cytochrome oxidase 1 (COI) gene for 132 specimens representing processed locations revealed two subpopulations of C. lectularius in Paris by neighbor-joining and network phylogenetic analyses. These results provide essential information for further epidemiological and public health studies and may help control management strategies in this metropolis. Abstract Cimex lectularius and C. hemipterus are blood-sucking insects with a long history of presence in human communities. We investigated the molecular diversity of the bed bug population of Paris and its suburb cities using cytochrome oxidase 1 (CO1) sequencing. A total of 1211 specimens belonging to different life stages were collected from 62 infested human dwellings in Paris (13 out of 20 arrondissements) and the surrounding cities (18 cities). Morphological determination and COI sequencing of 132 specimens demonstrated C. lectularius as the predominant species and, surprisingly, the presence of C. hemipterus in four infested areas of Paris and its suburb cities. Neighbor-joining tree and network analyses depicted the presence of two C. lectularius populations. Most samples from Paris and its suburb cities clustered in a major clade. The second population encompasses specimens from Paris (arrondissements 11 and 19) and its suburb cities (e.g., Bobigny, Pantin, and Montreuil) that clustered with Hungary, Czechia, and Finland. This is the second evidence for C. hemipterus infestation in France and the third in Europe, which challenges the classic pattern of C. hemipterus dispersion and implies sympatric occurrence of C. lectularius and C. hemipterus. Since Paris is one of the most popular tourist destinations in the world, our observations shed light on bed bugs’ dispersal dynamic and may help future vector control strategies.

Vector population control using insecticides is a key element of current strategies to prevent malaria transmission in Africa. The introduction of effective insecticides, such as the organophosphate pirimiphos-methyl, is essential to overcome the recurrent emergence of resistance driven by the highly diverse Anopheles genomes. Here, we use a population genomic approach to investigate the basis of pirimiphos-methyl resistance in the major malaria vectors Anopheles gambiae and A. coluzzii. A combination of copy number variation and a single non-synonymous substitution in the acetylcholinesterase gene, Ace1, provides the key resistance diagnostic in an A. coluzzii population from Côte d’Ivoire that we used for sequence-based association mapping, with replication in other West African populations. The Ace1 substitution and duplications occur on a unique resistance haplotype that evolved in A. gambiae and introgressed into A. coluzzii, and is now common in West Africa primarily due to selection imposed by other organophosphate or carbamate insecticides. Our findings highlight the predictive value of this complex resistance haplotype for phenotypic resistance and clarify its evolutionary history, providing tools to for molecular surveillance of the current and future effectiveness of pirimiphos-methyl based interventions., Author summary Control of mosquito populations via insecticidal tools or interventions is a mainstay of campaigns to reduce malaria transmission. However, especially in sub-Saharan Africa, continued insecticidal selection pressure on the most important species of Anopheles malaria mosquitoes has favoured the evolutionary selection of increasingly effective resistance mechanisms. We investigate the genetic basis of resistance to the organophosphate pirimiphos-methyl, the dominant insecticide now used for indoor residual spraying campaigns in Africa. Genome-wide association analysis of a population from Cote d’Ivoire showed that resistant specimens share a unique combination of mutations in one gene, the acetylcholinesterase enzyme, which constitute the prime cause of pirimiphos-methyl resistance. Further testing of these mutations in diagnostic assays involving two major malaria vectors, A. coluzzii and A. gambiae, validate their use as informative predictors of pirimiphos-methyl resistance. Using data from a large collection of whole genome sequenced specimens from a broader range of locations (Burkina-Faso, Côte d’Ivoire, Ghana, and Guinea), our evolutionary analyses demonstrate that these mutations emerged in A. gambiae and transferred into A. coluzzii by inter-specific hybridisation. Our results show how resistance mechanisms in key malaria vectors have developed and spread, and provide validated tools for molecular surveillance to inform public health campaigns.

Bed bugs, Cimex lectularius and C. hemipterus, are common blood-sucking ectoparasites of humans with a large geographical distribution, worldwide. In France, little is known about the status of bed bugs&rsquo, infestation and their resistance to insecticides, particularly, pyrethroids. Here, we aimed to find mutations in the kdr gene, known to be involved in resistance to insecticides. We gathered bed bugs from various infested locations, including 17 private houses, 12 HLM building complex, 29 apartments, 2 EHPAD, and 2 immigrants&rsquo, residences. A total of 1211 bed bugs were collected and morphologically identified as C. lectularius. Two fragments of the kdr gene, encompassing codons V419L and L925I, were successfully amplified for 156 specimens. We recorded sense mutation in the first amplified fragment (kdr1) in 89 out of 156 (57%) samples, in which in 61 out of 89 (68.5%) sequences, a change of valine (V) into leucine (L) V419L was observed. Within the second fragment (kdr2), a homozygous mutation was recorded in 73 out of 156 (46.7%) specimens at the codon 925. At this position, 43 out of 73 (58.9%) specimens had a sense mutation leading to the replacement of leucine (L) by isoleucine (I). Among 162 mutant sequences analyzed (89 for the kdr1 fragment and 73 for the kdr2 one), we detected single point mutation in 26.6%, while 73.4% presented the mutation in both kdr1 and kdr2 fragments. All modifications recorded in bed bug populations of Paris are described to be involved in the knockdown resistance (kdr) against pyrethroids.

Bed bugs, Cimex lectularius and C. hemipterus, are common blood-sucking ectoparasites of humans with a large geographical distribution, worldwide. In France, little is known about the status of bed bugs’ infestation and their resistance to insecticides, particularly, pyrethroids. Here, we aimed to find mutations in the kdr gene, known to be involved in resistance to insecticides. We gathered bed bugs from various infested locations, including 17 private houses, 12 HLM building complex, 29 apartments, 2 EHPAD, and 2 immigrants’ residences. A total of 1211 bed bugs were collected and morphologically identified as C. lectularius. Two fragments of the kdr gene, encompassing codons V419L and L925I, were successfully amplified for 156 specimens. We recorded sense mutation in the first amplified fragment (kdr1) in 89 out of 156 (57%) samples, in which in 61 out of 89 (68.5%) sequences, a change of valine (V) into leucine (L) V419L was observed. Within the second fragment (kdr2), a homozygous mutation was recorded in 73 out of 156 (46.7%) specimens at the codon 925. At this position, 43 out of 73 (58.9%) specimens had a sense mutation leading to the replacement of leucine (L) by isoleucine (I). Among 162 mutant sequences analyzed (89 for the kdr1 fragment and 73 for the kdr2 one), we detected single point mutation in 26.6%, while 73.4% presented the mutation in both kdr1 and kdr2 fragments. All modifications recorded in bed bug populations of Paris are described to be involved in the knockdown resistance (kdr) against pyrethroids.

The sustainability of malaria control in Africa is threatened by the rise of insecticide resistance in Anopheles mosquitoes, which transmit the disease(1). To gain a deeper understanding of how mosquito populations are evolving, here we sequenced the genomes of 765 specimens of Anopheles gambiae and Anopheles coluzzii sampled from 15 locations across Africa, and identified over 50 million single nucleotide polymorphisms within the accessible genome. These data revealed complex population structure and patterns of gene flow, with evidence of ancient expansions, recent bottlenecks, and local variation in effective population size. Strong signals of recent selection were observed in insecticide-resistance genes, with several sweeps spreading over large geographical distances and between species. The design of new tools for mosquito control using gene-drive systems will need to take account of high levels of genetic diversity in natural mosquito populations.

The sustainability of malaria control in Africa is threatened by rising levels of insecticide resistance, and new tools to prevent malaria transmission are urgently needed. To gain a better understanding of the mosquito populations that transmit malaria, we sequenced the genomes of 765 wild specimens ofAnopheles gambiaeandAnopheles coluzziisampled from 15 locations across Africa. The data reveal high levels of genetic diversity, with over 50 million single nucleotide polymorphisms across the 230 Mbp genome. We observe complex patterns of population structure and marked variations in local population size, some of which may be due at least in part to malaria control interventions. Insecticide resistance genes show strong signatures of recent selection associated with multiple independent mutations spreading over large geographical distances and between species. The genetic variability of natural populations substantially reduces the target space for novel gene-drive strategies for mosquito control. This large dataset provides a foundation for tracking the emergence and spread of insecticide resistance and developing new vector control tools.

Background Culicoides imicola Kieffer, 1913 is the main vector of bluetongue virus (BTV) and African horse sickness virus (AHSV) in Sub-Saharan Africa. Understanding the population genetic structure of this midge and the nature of barriers to gene flow will lead to a deeper understanding of bluetongue epidemiology and more effective vector control in this region. Methods A panel of 12 DNA microsatellite markers isolated de novo and mitochondrial DNA were utilized in a study of C. imicola populations from Africa and an outlier population from the Balearic Islands. The DNA microsatellite markers and mitochondrial DNA were also used to examine a population of closely related C. bolitinos Meiswinkel midges. Results The microsatellite data suggest gene flow between Kenya and south-west Indian Ocean Islands exist while a restricted gene flow between Kenya and South Africa C. imicola populations occurs. Genetic distance correlated with geographic distance by Mantel test. The mitochondrial DNA analysis results imply that the C. imicola populations from Kenya and south-west Indian Ocean Islands (Madagascar and Mauritius) shared haplotypes while C. imicola population from South Africa possessed private haplotypes and the highest nucleotide diversity among the African populations. The Bayesian skyline plot suggested a population growth. Conclusions The gene flow demonstrated by this study indicates a potential risk of introduction of new BTV serotypes by wind-borne infected Culicoides into the Islands. Genetic similarity between Mauritius and South Africa may be due to translocation as a result of human-induced activities; this could impact negatively on the livestock industry. The microsatellite markers isolated in this study may be utilised to study C. bolitinos, an important vector of BTV and AHSV in Africa and identify sources of future incursions. Electronic supplementary material The online version of this article (doi:10.1186/s13071-015-1277-4) contains supplementary material, which is available to authorized users.

Following veterinary alerts of Rift Valley fever (RVF) in the districts of Fianarantsoa I and II in November 2008 and in the district of Ambalavao in April 2009, entomological and virological investigations were carried out to identify the mosquito species that could act as RVF virus (RVFV) vectors in the region. A total of 12,785 adult mosquitoes belonging to 5 genera and 21 species were collected. After identification, mosquitoes were pooled by species, sex, and female status (fed or unfed) and then stored at −80°C. Of 319 pools of unfed monospecific female mosquito tested by real-time RT–polymerase chain reaction, RVFV was detected in 1 pool of Anopheles coustani, 5 pools of An. squamosus, and 2 pools of Culex antennatus mosquitoes. The virus was isolated in mosquito cell lines from two of the five Real Time-RT–polymerase chain reaction (real time-RT-PCR) positive pools of An. squamosus mosquitoes. From the eight RVFV strains detected, partial S, M, and L genome segments sequences were obtaine...

International audience; Mosquito diversity and abundance were examined in six Madagascan villages in either arid (Toliary II district) or humid (Mampikony district) ecotypes, each with a history of Rift Valley fever virus transmission. Centers for Disease Control and Prevention light traps without CO2 (LT) placed near ruminant parks and animal-baited net trap (NT) baited with either zebu or sheep/goat were used to sample mosquitoes, on two occasions between March 2011 and October 2011. Culex tritaeniorhynchus(Giles) was the most abundant species, followed by Culex antennatus (Becker) and Anopheles squamosus/cydippis (Theobald/de Meillon). These three species comprised more than half of all mosquitoes collected. The NTcaptured more mosquitoes in diversity and in abundance than the LT, and also caught more individuals of each species, except for An. squamosus/cydippis. Highest diversity and abundance were observed in the humid and warm district of Mampikony. No host preference washighlighted, except for Cx. tritaeniorhynchus presenting a blood preference for zebu baits. The description of species diversity, abundance, and host preference described herein can inform the development of control measures to reduce the risk of mosquito-borne diseases in Madagascar.

International audience; So far, no published data was available concerning the circulation of Bluetongue virus (BTV) in Madagascar. During a survey on Rift Valley Fever, we were able to detect a virus belonging to BTV. Therefore, we conducted a study aiming at characterizing molecularly the BTV isolated and assess the importance of circulation of BTV in Madagascar. A total of 4393 sera from ruminants selected randomly by stratification and sampled in 30 districts of Madagascar were tested for BTV. Moreover, 175 cattle were followed during 11 months.Phylogenetic analyses were performed from virus isolated from unfed pools of mosquitoes.Overall, the estimated mean seroprevalence of infection at the national level was 95.9% (95% CI: [95.2–96.5]) in cattle and 83.7% (95% CI: [81.4–85.9]) in small ruminants. Estimation of incidence rate was 54 per 100 cattle-years assuming that the incidence rate is constant allyear along. Phylogenetic analyses revealed that BTV detected belong to serotype 2.In conclusion, our results showed that BTV is endemic in Madagascar and highly prevalent among cattle. In our study we did not work on the vector involved in transmission of BTV in cattle. Thus, research should be conducted to better describe epidemiology of BTV in Madagascar including vectors and assess economic impact of the disease associated to BTV infections.

Anopheles funestus is a primary vector of malaria in Africa south of the Sahara. We assessed its rangewide population genetic structure based on samples from 11 countries, using 10 physically mapped microsatellite loci, two per autosome arm and the X (N = 548), and 834 bp of the mitochondrial ND5 gene (N = 470). On the basis of microsatellite allele frequencies, we found three subdivisions: eastern (coastal Tanzania, Malawi, Mozambique and Madagascar), western (Burkina Faso, Mali, Nigeria and western Kenya), and central (Gabon, coastal Angola). A. funestus from the southwest of Uganda had affinities to all three subdivisions. Mitochondrial DNA (mtDNA) corroborated this structure, although mtDNA gene trees showed less resolution. The eastern subdivision had significantly lower diversity, similar to the pattern found in the codistributed malaria vector Anopheles gambiae. This suggests that both species have responded to common geographic and/or climatic constraints. The western division showed signatures of population expansion encompassing Kenya west of the Rift Valley through Burkina Faso and Mali. This pattern also bears similarity to A. gambiae, and may reflect a common response to expanding human populations following the development of agriculture. Due to the presumed recent population expansion, the correlation between genetic and geographic distance was weak. Mitochondrial DNA revealed further cryptic subdivision in A. funestus, not detected in the nuclear genome. Mozambique and Madagascar samples contained two mtDNA lineages, designated clade I and clade II, that were separated by two fixed differences and an average of 2% divergence, which implies that they have evolved independently for approximately 1 million years. Clade I was found in all 11 locations, whereas clade II was sampled only on Madagascar and Mozambique. We suggest that the latter clade may represent mtDNA capture by A. funestus, resulting from historical gene flow either among previously isolated and divergent populations or with a related species.

The population structure of Anopheles gambiae in Africa was studied using 11 microsatellite loci in 16 samples from 10 countries. All loci are located outside polymorphic inversions. Heterogeneity among loci was detected and two putative outlier loci were removed from analyses aimed at capturing genome-wide patterns. Two main divisions of the gene pool were separated by high differentiation (FST > 0.1). The northwestern (NW) division included populations from Senegal, Ghana, Nigeria, Cameroon, Gabon, Democratic Republic of Congo (DRC), and western Kenya. The southeastern (SE) division included populations from eastern Kenya, Tanzania, Malawi, and Zambia. Inhospitable environments for A. gambiae along the Rift Valley partly separate these divisions. Reduced genetic diversity in the SE division and results of an analysis based on private alleles support the hypothesis that a recent bottleneck, followed by colonization from the NW populations shaped this structure. In the NW division, populations possessing the M rDNA genotype appeared to form a monophyletic clade. Although genetic distance increased with geographic distance, discontinuities were suggested between certain sets of populations. The absence of heterozygotes between sympatric M and S populations in the DRC and the high differentiation in locus 678 (⁠FST > 0.28) contrasted with low differentiation in all other loci (⁠ -0.02 < FST < 0.09⁠) and with the persistence of departures from Hardy-Weinberg expectations within each form in the DRC. Neither recent reproductive isolation alone nor selection alone can explain these results, a situation that is compatible with incipient speciation. Because it is possible that the molecular forms play different roles in malaria transmission, future studies should treat them separately.

International audience; The incidence of bubonic plague in Madagascar is high. This study reports the susceptibility of 32 different populations of a vector, the flea Xenopsylla cheopis (Siphonaptera: Pulicidae), to the insecticide Deltamethrin. Despite the use of Deltamethrin against fleas, plague epidemics have re-emerged in Madagascar. The majority of the study sites were located in the Malagasy highlands where most plague cases have occurred over the last 10 years. X. cheopis fleas were tested for susceptibility to Deltamethrin (0.05%): only two populations were susceptible to Deltamethrin, four populations were tolerant and 26 populations were resistant. KD50 (50% Knock-Down) and KD90 (90% Knock-Down) times were determined, and differed substantially from 9.4 to 592.4 minutes for KD50 and 10.4 min to 854.3 minutes for KD90. Susceptibility was correlated with latitude, but not with longitude, history of insecticide use nor date of sampling. Combined with the number of bubonic plague cases, our results suggest that an immediate switch to an insecticide other than Deltamethrin is required for plague vector control in Madagascar.

There were epidemic-epizootics of Rift Valley Fever (RVF) affecting humans and cattle in Madagascar in the district of Anjozorobe in 2008. Little is known about the role of Malagasy mosquitoes in the circulation of RVF virus. Therefore, we investigated the species diversity, dynamics and biology of potential RVF virus vectors in the rainforest, rainforest edge (village of Anorana), and savanna biotope (village of Antanifotsy) of this district between November 2008 and July 2010. We captured 56,605 adults of 35 different species. Anopheles squamosus (Theobald), Anopheles coustani (Laveran), Culex antennatus (Becker), Culex pipiens (L.), and Culex univittatus (Theobald) were the most abundant during the rainy season with Cx. pipiens the most abundant species in the rainforest (47%), and An. squamosus the most abundant species in the rainforest edge and in the savanna biotope (56%, 60%, respectively). Only Cx. univittatus was abundant in the dry season. The parous rate was > 60% throughout the rainy season for An. squamosus and it was > 50% from the middle to the end of the rainy season for Cx. pipiens . Two additional species have been found only at larval stage. Cattle were the most attractive bait for all species, followed by sheep and poultry. Human was the least attractive for all species. Most of the 163 bloodmeals tested were taken from cattle. Three were from poultry, one was from dog and one was a mixed bloodmeal taken from sheep and cattle. These results on vectorial capacity parameters may allow considering the involvement of mosquito transmission of the virus in the district of Anjozorobe during the recent epidemic-epizootic.

The primary Afrotropical malaria mosquito vector Anopheles gambiae sensu stricto has a complex population structure. In west Africa, this species is split into two molecular forms and displays local and regional variation in chromosomal arrangements and behaviors. To investigate patterns of macrogeographic population substructure, 25 An. gambiae samples from 12 African countries were genotyped at 13 microsatellite loci. This analysis detected the presence of additional population structuring, with the M-form being subdivided into distinct west, central, and southern African genetic clusters. These clusters are coincident with the central African rainforest belt and northern and southern savannah biomes, which suggests restrictions to gene flow associated with the transition between these biomes. By contrast, geographically patterned population substructure appears much weaker within the S-form. publishersversion published

International audience; In Madagascar, Anopheles gambiae has been found below altitudes of 1,000 m. We sampled An. gambiae sensu lato (sl) between 2008 and 2010 in the Central Highlands of Madagascar at altitudes over 1,200 m. The study site consists of rainforest, rainforest edge, and an open savanna biotope. Anopheles gambiae and An. arabiensis, as well as molecular forms of An. gambiae, were identified molecularly. An. gambiae accounted for 26.7% at the edge of the rainforest and 2.3% in the open savanna biotope. One specimen of this species was caught in the forest. An. arabiensis accounted for 66.3% at the edge of the rainforest and 97.7 % in the open savanna biotope. All An. gambiae adults tested belonged to the S molecular form. An. gambiae is present at high altitudes in Madagascar, with a high prevalence at the rainforest edge. Several factors, including the appearance of new favorable biotopes, recolonization after a reduction of indoor vector control, and climate change, may contribute to its distribution. The changing distribution of An. gambiae may have consequences for the distribution and incidence of malaria in the Malagasy Highlands.

Five formulations of deltamethrin and one of permethrin were impregnated into cotton and nylon netting and tested for their efficacy and persistence in killing Anopheles gambiae Giles which were attempting to penetrate the netting in search of blood meals. Emulsifiable concentrates persisted better than wettable powders of deltamethrin, and all the deltamethrin formulations performed better than permethrin, even though the latter was applied at an eight times higher dose. The insecticidal effect of both compounds persisted better on nylon than on cotton ; it was adversely affected by repeated washing.

The Animal Risk regional network: surveillance and research in the Indian Ocean. To meet the challenges of emerging diseases in the Indian Ocean region, in 2009 animal health stakeholders set up the Animal Risk-OI network, designed to provide technicaland scientific support to surveillance systems and to suggest ways of improving health risk control in the area. The network is supported by OIE referring bodies for the Indian Ocean—veterinary services and animal health research organizations. Animal Risk-OI is not intended to replace current monitoring systems but to help consider arising issues through bimonthly webconferences, annual meetings and quarterly newsletters, and to provide information for research aiming to clarify theepidemiology of certain diseases and recommend suitable control measures. This paper presents the preliminary findings following the monitoring and investigation of diseases considered by network partners to be of top priority. Apart from pursuing synergy between surveillance and research activities, the network aims to bridge the gap between animal and human health to instigate ajoint, standardized approach to the assessment and control of health risks in the Indian Ocean region., Pour répondre aux défis lancés par les maladies émergentes dans l’Océan Indien, les acteurs de la santé animale ont mis en place depuis début 2009 le réseau AnimalRisk-OI. Ce réseau a pour objectif d’apporter un soutien technique et scientifique aux systèmes de surveillance et de proposer des réponses pour une meilleure gestion des risques sanitaires dans la zone. Les partenaires sont les référents de l’OIE dans l’Océan Indien, à savoir les services vétérinaires ainsi que les structures de recherché impliquées en santé animale. Le réseau AnimalRisk-OI n’a pas pour vocation de se substituer aux systèmes de surveillance existants, mais il est chargé d’animer une réflexion autour des problématiques observées par des téléweb conférences bimensuelles, des réunions annuelles et des bulletins d’information trimestriels et de nourrir des actions de recherche qui visent à mieux comprendre l’épidémiologie de certaines maladies et donc de proposer des mesures de gestion adéquates pour mieux les maîtriser. Les premiers résultats de la surveillance et des investigations sur certaines maladies considérées prioritaires par les partenaires sont présentés ici. Les orientations envisagées, outre la poursuite de la synergie entre les actions de surveillance et de recherche, sont un rapprochement avec la santé humaine pour permettre une approche commune et harmonisée de l’appréciation et de la gestion des risques sanitaires dans l’Océan Indien.

Following veterinary alerts of Rift Valley fever (RVF) in the districts of Fianarantsoa I and II in November 2008 and in the district of Ambalavao in April 2009, entomological and virological investigations were carried out to identify the mosquito species that could act as RVF virus (RVFV) vectors in the region. A total of 12,785 adult mosquitoes belonging to 5 genera and 21 species were collected. After identification, mosquitoes were pooled by species, sex, and female status (fed or unfed) and then stored at -80°C. Of 319 pools of unfed monospecific female mosquito tested by real-time RT-polymerase chain reaction, RVFV was detected in 1 pool of Anopheles coustani, 5 pools of An. squamosus, and 2 pools of Culex antennatus mosquitoes. The virus was isolated in mosquito cell lines from two of the five Real Time-RT-polymerase chain reaction (real time-RT-PCR) positive pools of An. squamosus mosquitoes. From the eight RVFV strains detected, partial S, M, and L genome segments sequences were obtained. The phylogenetic analysis of these sequences showed that the strains circulating in mosquitoes were genetically close to those that circulated in livestock and humans during RVF outbreaks in 2008 and 2009. This study, therefore, provides strong evidence that An. squamosus, An. coustani, and Cx. antennatus could play a role as vectors of the RVFV during the disease outbreaks in 2008-2009. Bioecological, genetic, and RVF transmission studies on these three mosquito species are needed to address this question and thus improve prevention and control of future RVF outbreaks in Madagascar, where these species are present.

Biological invasions generally induce profound effects on the structure of resident communities. In Mayotte, where Aedes aegypti and Ae. lilii were already present, the recent introduction of Ae. albopictus raises public health concerns because it may affect the risk of arbovirus transmission. Entomological surveys were carried out in six locations on the island following a transect defined by a gradient from urban to rural habitats during a dry and a wet season. A total of 438 larval habitats containing Aedes spp. immature stages were surveyed. We evaluated the characteristics of larval habitats and analyzed the field distribution of Aedes spp. throughout Mayotte using generalized linear models. Artificial containers used for water storage were significantly more productive for Ae. albopictus immature stages than for Ae. aegypti ones. Most of natural larval habitats collected were colonized by Ae. aegypti, and it was also the most common Aedes species encountered in rural habitats. Conversely, Ae. albopictus greatly predominated in urban and suburban habitats and during the dry season. Ae. lilii was uncommon and occurred preferentially in leaf axillae and dead leaves on the ground. Ae. albopictus has rapidly colonized the inhabited areas of Mayotte. A displacement of Ae. aegypti populations by Ae. albopictus populations in urban areas might be happening. The increasing urbanization seems to greatly favor the presence of the invasive species. Thus, arbovirus surveillance programs should focus, as a priority, on areas where this vector is present because of a higher risk of emergence of an epidemic source of arboviruses.

Point mutations in the voltage-gated sodium channel gene involved in knockdown resistance to DDT and pyrethroid insecticides have been described in several insect species. In the malaria vector Anopheles gambiae Giles sensu stricto (Diptera: Culicidae) two mutations have been identified. The first, consisting of a leucine-phenylalanine substitution at amino acid position 1014, is widespread in West Africa. The second, a leucine-serine substitution at the same position, has to date only been detected in western Kenya. Analysis of the kdr polymorphism in a sample of 106 An. gambiae s.s. of the rDNA S-form/Type I collected in Libreville (Gabon) surprisingly revealed the presence of both East and West African kdr mutations with frequencies of 63% and 37%, respectively. No wild-type alleles were detected and there was an excess of heterozygous genotypes (P = 0.04). In addition, an inconsistency was found during the kdr genotyping procedures by polymerase chain reaction, which could have lead to an underestimation of resistance alleles. The implications of these findings are discussed.

The impact of a vector eradication programme, conducted in the 1980s, on Anopheles gambiae populations from the islands of São Tomé and Príncipe, was evaluated by microsatellite DNA analysis. Significant genetic differentiation was observed within and between the two islands and between the islands and a population from Gabon, suggesting a degree of isolation between them. Large estimates of long-term N(e) suggested that the control programme did not affect the effective population size of the vector. Heterozygosity tests were also not consistent with a recent bottleneck.

Rift Valley fever virus (Phlebovirus, Bunyaviridae) is an arbovirus causing intermittent epizootics and sporadic epidemics primarily in East Africa. Infection causes severe and often fatal illness in young sheep, goats and cattle. Domestic animals and humans can be contaminated by close contact with infectious tissues or through mosquito infectious bites. Rift Valley fever virus was historically restricted to sub-Saharan countries. The probability of Rift Valley fever emerging in virgin areas is likely to be increasing. Its geographical range has extended over the past years. As a recent example, autochthonous cases of Rift Valley fever were recorded in 2007–2008 in Mayotte in the Indian Ocean. It has been proposed that a single infected animal that enters a naive country is sufficient to initiate a major outbreak before Rift Valley fever virus would ever be detected. Unless vaccines are available and widely used to limit its expansion, Rift Valley fever will continue to be a critical issue for human and animal health in the region of the Indian Ocean.

Mosquito control remains a central pillar of efforts to reduce malaria burden in sub-Saharan Africa. However, insecticide resistance is entrenched in malaria vector populations, and countries with a high malaria burden face a daunting challenge to sustain malaria control with a limited set of surveillance and intervention tools. Here we report on the second phase of a project to build an open resource of high-quality data on genome variation among natural populations of the major African malaria vector species Anopheles gambiae and Anopheles coluzzii. We analyzed whole genomes of 1142 individual mosquitoes sampled from the wild in 13 African countries, as well as a further 234 individuals comprising parents and progeny of 11 laboratory crosses. The data resource includes high-confidence single-nucleotide polymorphism (SNP) calls at 57 million variable sites, genome-wide copy number variation (CNV) calls, and haplotypes phased at biallelic SNPs. We use these data to analyze genetic population structure and characterize genetic diversity within and between populations. We illustrate the utility of these data by investigating species differences in isolation by distance, genetic variation within proposed gene drive target sequences, and patterns of resistance to pyrethroid insecticides. This data resource provides a foundation for developing new operational systems for molecular surveillance and for accelerating research and development of new vector control tools. It also provides a unique resource for the study of population genomics and evolutionary biology in eukaryotic species with high levels of genetic diversity under strong anthropogenic evolutionary pressures.

Background The malaria burden in Madagascar dropped down last decade, largely due to scale-up of control measures. Nevertheless, a significant rise of malaria cases occurred in 2011–2012 in two regions of the rainy South-Eastern Madagascar, where malaria is considered as mesoendemic and the population is supposed to be protected by its acquired immunity against Plasmodium. A multidisciplinary investigation was conducted in order to identify the causes of the outbreak. Methods In March 2012, a cross-sectional study was conducted in 20 randomly selected clusters, involving the rapid diagnostic testing of all ≥6 month-old members of households and a questionnaire about socio-demographic data and exposure to malaria control interventions. Changes in environmental conditions were evaluated by qualitative interview of local authorities, climatic conditions were evaluated by remote-sensing, and stock outs of malaria supplies in health facilities were evaluated by quantitative means. Two long-lasting insecticidal nets (LLINs) were sampled in each cluster in order to evaluate their condition and the remanence of their insecticidal activity. The entomological investigation also encompassed the collection Anopheles vectors in two sites, and the measure of their sensitivity to deltamethrin. Results The cross-sectional survey included 1615 members of 440 households. The mean Plasmodium infection rate was 25.6 % and the mean bed net use on the day before survey was 71.1 %. The prevalence of Plasmodium infections was higher in 6–14 year-old children (odds ratio (OR) 7.73 [95 % CI 3.58–16.68]), in rural areas (OR 6.25 [4.46–8.76]), in poorest socio-economic tercile (OR 1.54 [1.13–2.08]), and it was lower in individuals sleeping regularly under the bed net (OR 0.51 [0.32–0.82]). Stock outs of anti-malarial drugs in the last 6 months have been reported in two third of health facilities. Rainfalls were increased as compared with the three previous rainy seasons. Vectors collected were sensitive to pyrethroids. Two years after distribution, nearly all LLINs collected showed a loss of physical integrity and insecticide activity, Conclusions Increased rainfall, decreasing use and reduced insecticide activity of long-lasting insecticide-treated nets, and drug shortages may have been responsible for, or contributed to, the outbreak observed in South-Eastern Madagascar in 2011–2012. Control interventions for malaria elimination must be sustained at the risk of triggering harmful epidemics, even in zones of high transmission.

International audience; An updated checklist of 235 mosquito species from Madagascar is presented. The number of species has increased considerably compared to previous checklists, particularly the last published in 2003 (178 species). This annotated checklist provides concise information on endemism, taxonomic position, developmental stages, larval habitats, distribution, behavior, and vector-borne diseases potentially transmitted. The 235 species belong to 14 genera: Aedeomyia (3 species), Aedes (35 species), Anopheles (26 species), Coquillettidia (3 species), Culex (at least 50 species), Eretmapodites (4 species), Ficalbia (2 species), Hodgesia (at least one species), Lutzia (one species), Mansonia (2 species), Mimomyia (22 species), Orthopodomyia (8 species), Toxorhynchites (6 species), and Uranotaenia (73 species). Due to non-deciphered species complexes, several species remain undescribed. The main remarkable characteristic of Malagasy mosquito fauna is the high biodiversity with 138 endemic species (59%). Presence and abundance of species, and their association, in a given location could be a bio-indicator of environmental particularities such as urban, rural, forested, deforested, and mountainous habitats. Finally, taking into account that Malagasy culicidian fauna includes 64 species (27%) with a known medical or veterinary interest in the world, knowledge of their biology and host preference summarized in this paper improves understanding of their involvement in pathogen transmission in Madagascar.; Une liste mise à jour des 235 espèces de moustiques de Madagascar est présentée. Le nombre d’espèces a considérablement augmenté par rapport à celui donné dans les listes précédentes, en particulier la dernière, publiée en 2003 (178 espèces). Cette liste fournit des informations concises sur l’endémisme, la position taxonomique, les stades de développement, les gîtes larvaires, la distribution, le comportement des moustiques, et aussi sur les maladies potentiellement transmises par les moustiques vecteurs. Ces 235 espèces sont réparties dans 14 genres : Aedeomyia (3 espèces), Aedes (35 espèces), Anopheles (26 espèces), Coquillettidia (3 espèces), Culex (au moins 50 espèces), Eretmapodites (4 espèces), Ficalbia (2 espèces), Hodgesia (au moins une espèce), Lutzia (une espèce), Mansonia (2 espèces), Mimomyia (22 espèces), Orthopodomyia (8 espèces), Toxorhynchites (6 espèces), Uranotaenia (73 espèces). En raison de complexes d’espèces non résolus, plusieurs espèces sont toujours non décrites. La principale caractéristique remarquable de la faune malgache de moustiques est la grande biodiversité avec 138 espèces endémiques (59 %). La présence et l’abondance des espèces, et leur association dans un endroit donné, pourrait être un bio-indicateur des particularités environnementales telles que les habitats urbains, ruraux, forestiers, déboisés et montagneux. Enfin, compte tenu que la faune malgache de moustiques comprend 64 espèces (27 %) ayant un intérêt médical ou vétérinaire connu dans le monde, la connaissance de leur biologie et de leur préférence d’hôtes résumée dans le présent document permet de comprendre leur implication dans la transmission d’agents pathogènes à Madagascar.

International audience; An updated checklist of 235 mosquito species from Madagascar is presented. The number of species has increased considerably compared to previous checklists, particularly the last published in 2003 (178 species). This annotated checklist provides concise information on endemism, taxonomic position, developmental stages, larval habitats, distribution, behavior, and vector-borne diseases potentially transmitted. The 235 species belong to 14 genera: Aedeomyia (3 species), Aedes (35 species), Anopheles (26 species), Coquillettidia (3 species), Culex (at least 50 species), Eretmapodites (4 species), Ficalbia (2 species), Hodgesia (at least one species), Lutzia (one species), Mansonia (2 species), Mimomyia (22 species), Orthopodomyia (8 species), Toxorhynchites (6 species), and Uranotaenia (73 species). Due to non-deciphered species complexes, several species remain undescribed. The main remarkable characteristic of Malagasy mosquito fauna is the high biodiversity with 138 endemic species (59%). Presence and abundance of species, and their association, in a given location could be a bio-indicator of environmental particularities such as urban, rural, forested, deforested, and mountainous habitats. Finally, taking into account that Malagasy culicidian fauna includes 64 species (27%) with a known medical or veterinary interest in the world, knowledge of their biology and host preference summarized in this paper improves understanding of their involvement in pathogen transmission in Madagascar.; Une liste mise à jour des 235 espèces de moustiques de Madagascar est présentée. Le nombre d’espèces a considérablement augmenté par rapport à celui donné dans les listes précédentes, en particulier la dernière, publiée en 2003 (178 espèces). Cette liste fournit des informations concises sur l’endémisme, la position taxonomique, les stades de développement, les gîtes larvaires, la distribution, le comportement des moustiques, et aussi sur les maladies potentiellement transmises par les moustiques vecteurs. Ces 235 espèces sont réparties dans 14 genres : Aedeomyia (3 espèces), Aedes (35 espèces), Anopheles (26 espèces), Coquillettidia (3 espèces), Culex (au moins 50 espèces), Eretmapodites (4 espèces), Ficalbia (2 espèces), Hodgesia (au moins une espèce), Lutzia (une espèce), Mansonia (2 espèces), Mimomyia (22 espèces), Orthopodomyia (8 espèces), Toxorhynchites (6 espèces), Uranotaenia (73 espèces). En raison de complexes d’espèces non résolus, plusieurs espèces sont toujours non décrites. La principale caractéristique remarquable de la faune malgache de moustiques est la grande biodiversité avec 138 espèces endémiques (59 %). La présence et l’abondance des espèces, et leur association dans un endroit donné, pourrait être un bio-indicateur des particularités environnementales telles que les habitats urbains, ruraux, forestiers, déboisés et montagneux. Enfin, compte tenu que la faune malgache de moustiques comprend 64 espèces (27 %) ayant un intérêt médical ou vétérinaire connu dans le monde, la connaissance de leur biologie et de leur préférence d’hôtes résumée dans le présent document permet de comprendre leur implication dans la transmission d’agents pathogènes à Madagascar.