Colonization of Anopheles coustani, a neglected malaria vector in Madagascar

Anopheles coustani has long been recognized as a secondary malaria vector in Africa. It has recently been involved in the transmission of both Plasmodium falciparum and P. vivax in Madagascar. As most secondary malaria vectors, An. coustani mainly bites outdoors, which renders the control of this mosquito species difficult using classical malaria control measures, such as the use of bed nets or indoor residual spraying of insecticides. For a better understanding of the biology and vector competence of a vector species, it is useful to rear the species in the laboratory. The absence of a colony hinders the assessment of the bionomics of a species and the development of adapted control strategies. Here, we report the first successful establishment of an An. coustani colony from mosquitoes collected in Madagascar. We used a forced copulation procedure as this mosquito species will not mate in cages. We describe our mosquito colonization procedure with detailed biological features concerning larval to adult development and survival, recorded over the first six critical generations. The procedure should be easily applicable to An. coustani from different African countries, facilitating local investigation of An. coustani vector competence and insecticide resistance using the colony as a reference

Adhérer ou ne pas adhérer : Stratégie adaptative de Plasmodium falciparum pour persister en saison sèche

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Evolution of sexually-transferred steroids and mating-induced phenotypes in Anopheles mosquitoes

Human malaria, which remains a major public health problem, is transmitted by a subset of Anopheles mosquitoes belonging to only three out of eight subgenera: Anopheles, Cellia and Nyssorhynchus. Unlike almost every other insect species, males of some Anopheles species produce steroid hormones which are transferred to females during copulation to influence their reproduction. Steroids are consequently a potential target for malaria vector control. Here, we analysed the evolution of sexually-transferred steroids and their effects on female reproductive traits across Anopheles by using a set of 16 mosquito species (five Anopheles, eight Cellia, and three Nyssorhynchus), including malaria vector and non-vector species. We show that male steroid production and transfer are specific to the Cellia and therefore represent a synapomorphy of this subgenus. Furthermore, we show that mating-induced effects in females are variable across species and differences are not correlated with sexually-transferred steroids or with Anopheles ability to transmit human malaria. Overall, our findings highlight that Anopheles mosquitoes have evolved different reproductive strategies, independently of being a malaria vector or not

Investigation on the role of the alkyl side chain of cardanol on benzoxazine polymerization kinetics and polymer properties

International audienc

Progressive substitution of phenol by a bio-based analogue for the preparation of polybenzoxazines thermosets

International audienc

Establishment of a colony of Anopheles darlingi from French Guiana for vector competence studies on malaria transmission

Sec. Vector BiologyInternational audienceAnopheles darlingi is a major vector of both Plasmodium falciparum and Plasmodium vivax in South and Central America including French Guiana. However, the vector competence and physiology of this mosquito species have been scarcely studied due to difficulties in rearing it in the laboratory. Here, we report the successful establishment of a robust colony, from a mosquito collection in French Guiana. We describe our mosquito colonization procedure with relevant information on environmental conditions, mating ability, larval development, and survival, recorded over the first six critical generations. Experimental infection showed that our An. darlingi colony has a moderate permissiveness to in vitro produced gametocytes of the P. falciparum NF54 strain originating from Africa. This colony, which has reached its 21st generation, will allow further characterization of An. darlingi life-history traits and of Plasmodium –mosquito interactions with South American malaria parasites

Evolution of sexually-transferred steroids and mating-induced phenotypes in Anopheles mosquitoes

Abstract Human malaria, which remains a major public health problem, is transmitted by a subset of Anopheles mosquitoes belonging to only three out of eight subgenera: Anopheles, Cellia and Nyssorhynchus. Unlike almost every other insect species, males of some Anopheles species produce steroid hormones which are transferred to females during copulation to influence their reproduction. Steroids are consequently a potential target for malaria vector control. Here, we analysed the evolution of sexually-transferred steroids and their effects on female reproductive traits across Anopheles by using a set of 16 mosquito species (five Anopheles, eight Cellia, and three Nyssorhynchus), including malaria vector and non-vector species. We show that male steroid production and transfer are specific to the Cellia and therefore represent a synapomorphy of this subgenus. Furthermore, we show that mating-induced effects in females are variable across species and differences are not correlated with sexually-transferred steroids or with Anopheles ability to transmit human malaria. Overall, our findings highlight that Anopheles mosquitoes have evolved different reproductive strategies, independently of being a malaria vector or not

Hemocyte-targeted gene expression in the female malaria mosquito using the hemolectin promoter from Drosophila

Hemocytes, the immune cells in mosquitoes, participate in immune defenses against pathogens including malaria parasites. Mosquito hemocytes can also be infected by arthropod-borne viruses but the pro- or anti-viral nature of this interaction is unknown. Although there has been progress on hemocyte characterization during pathogen infection in mosquitoes, the specific contribution of hemocytes to immune responses and the hemocyte-specific functions of immune genes and pathways remain unresolved due to the lack of genetic tools to manipulate gene expression in these cells specifically. Here, we used the Gal4-UAS system to characterize the activity of the Drosophila hemocyte-specific hemolectin promoter in the adults of Anopheles gambiae, the malaria mosquito. We established an hml-Gal4 driver line that we further crossed to a fluorescent UAS responder line, and examined the expression pattern in the adult progeny driven by the hml promoter. We show that the hml regulatory region drives hemocyte-specific transgene expression in a subset of hemocytes, and that transgene expression is triggered after a blood meal. The hml promoter drives transgene expression in differentiating prohemocytes as well as in differentiated granulocytes. Analysis of different immune markers in hemocytes in which the hml promoter drives transgene expression revealed that this regulatory region could be used to study phagocytosis as well as melanization. Finally, the hml promoter drives transgene expression in hemocytes in which o’nyong-nyong virus replicates. Altogether, the Drosophila hml promoter constitutes a good tool to drive transgene expression in hemocyte only and to analyze the function of these cells and the genes they express during pathogen infection in Anopheles gambiae

Efficient ΦC31 integrase–mediated site-specific germline transformation of Anopheles gambiae

Current transgenic methodology developed for mosquitoes has not been applied widely to the major malaria vector Anopheles gambiae, which has proved more difficult to genetically manipulate than other mosquito species and dipteran insects. In this protocol, we describe ΦC31-mediated site-specific integration of transgenes into the genome of A. gambiae. The ΦC31 system has many advantages over 'classical' transposon-mediated germline transformation systems, because it allows integration of large transgenes at specific, characterized genomic locations. Starting from a general protocol, we have optimized steps from embryo collection to co-injection of transgene-containing plasmid and in vitro–produced ΦC31 integrase mRNA. We also provide tips for screening transgenic larvae. The outlined procedure provides robust transformation in A. gambiae, resulting in homozygous transgenic lines in ∼2–3 months

Differential contribution of Anopheles coustani and Anopheles arabiensis to the transmission of Plasmodium falciparum and Plasmodium vivax in two neighbouring villages of Madagascar

International audienceBackground: Malaria is still a heavy public health concern in Madagascar. Few studies combining parasitology and entomology have been conducted despite the need for accurate information to design effective vector control measures. In a Malagasy region of moderate to intense transmission of both Plasmodium falciparum and P. vivax, parasitol-ogy and entomology have been combined to survey malaria transmission in two nearby villages. Methods: Community-based surveys were conducted in the villages of Ambohitromby and Miarinarivo at three time points (T1, T2 and T3) during a single malaria transmission season. Human malaria prevalence was determined by rapid diagnostic tests (RDTs), microscopy and real-time PCR. Mosquitoes were collected by human landing catches and pyrethrum spray catches and the presence of Plasmodium sporozoites was assessed by TaqMan assay. Results: Malaria prevalence was not significantly different between villages, with an average of 8.0% by RDT, 4.8% by microscopy and 11.9% by PCR. This was mainly due to P. falciparum and to a lesser extent to P. vivax. However, there was a significantly higher prevalence rate as determined by PCR at T2 (χ 2 2 = 7.46, P = 0.025). Likewise, mosquitoes were significantly more abundant at T2 (χ 2 2 = 64.8, P < 0.001), especially in Ambohitromby. At T1 and T3 mosquito abundance was higher in Miarinarivo than in Ambohitromby (χ 2 2 = 14.92, P < 0.001). Of 1550 Anopheles mosquitoes tested, 28 (1.8%) were found carrying Plasmodium sporozoites. The entomological inoculation rate revealed that Anopheles coustani played a major contribution in malaria transmission in Miarinarivo, being responsible of 61.