First report of Anopheles (Cellia) multicolor during a study of tolerance to salinity of Anopheles arabiensis larvae in Nouakchott, Mauritania

Abstract

Background Anopheles multicolor is known to be present in the arid areas of Africa north of the Sahara Desert, especially in oases. To date, its presence in Mauritania has not been reported. Here, we present the first record of its presence in Nouakchott, the capital of Mauritania. The larvae of An. multicolor, together with those of An. arabiensis, the major malaria vector in the city, were found thriving in highly saline surface water collections. Methods Entomological surveys were carried out during 2016–2017 in Nouakchott. Mosquito larval habitats were investigated through larval surveys while indoor resting culicid fauna were collected using hand-held aspirator. Physicochemical parameters of the larval habitats were measured on-site, at the time mosquitoes were collected. Larvae and pupae were reared to adults in the insectaries. Morphological and polymerase chain reaction (PCR)-based methods were used to identify newly emerged adults. Batches of fourth-instar larvae were used to assess salinity tolerance by exposing them to increasing concentrations of NaCl, and mortality was monitored throughout development. Results Morphological and molecular results confirmed that the specimens were An. multicolor and An. arabiensis. Sequences of 24 An. multicolor adult mosquitoes showed 100% nucleotide identity with the published sequences of An. multicolor from Iran. The physicochemical analysis of the water from the two larval habitats revealed highly saline conditions, with NaCl content ranging between 16.8 and 28.9 g/l (i.e. between c.50–80% seawater). Anopheles multicolor and An. arabiensis fourth-instar larvae survival rates at 17.5 g/l NaCl were 86.5% and 75%, respectively. Anopheles arabiensis larvae showed variable levels of salt tolerance according to the larval habitat. Adult An. multicolor specimens were collected resting indoor at low frequency (0.7%) compared to the other culicid mosquitoes. Conclusions To the best of our knowledge, this paper is the first report of An. multicolor in Mauritania, extending the known distributional range of the species to the south, as well as to the west. Highly salt-tolerant populations of An. arabiensis and An. multicolor were observed. Because salt-water collections are widespread in Nouakchott, the relevance of these findings for the dynamics and epidemiology of malaria transmission needs to be assessed.

Changing epidemiology of Plasmodium vivax malaria in Nouakchott, Mauritania: a six-year (2015–2020) prospective study

“…By contrast, the unusually high amount of precipitation recorded in Nouakchott in 2009, 2010, and 2013 (130–195 mm, compared to the average annual precipitation of 79 mm in 2015–2020) probably contributed to increase malaria transmission in the early 2010s. In addition, floods occurred in the city in 2010 and 2013 [ 37 ]. Because of the absence of a water evacuation system, the city remained flooded for several weeks, or even months in some districts, during those years.…”

Moustiques, distribution et richesse spécifique dans huit pays d’Afrique : Cap-Vert, Mauritanie, Sénégal, Gambie, Mali, Burkina Faso, Niger et Tchad

“…Pour les autres pays, de telles synthèses n'existent pas et les informations disponibles sont dispersées. Pour chacun des pays de la zone d'étude, les sources bibliographiques additionnelles (par ordre chronologique) ont été les suivantes: Cap-Vert: Ribeiro et al [ 117 ], Cambournac et al [ 13 , 14 ], Alves et al [ 1 ], Correia et al [ 23 ], Salgueiro et al [ 125 ]; Burkina: Hamon & Rickenbach [ 72 ], Hamon [ 62 ], Hamon et al [ 67 , 71 ], Balay & Hamon [ 3 ], Germain et al [ 53 ], Gayral et al [ 51 , 52 ], Hervy & Couret [ 75 ], Huang [ 80 , 82 ], Robert et al [ 121 , 122 , 123 ]; Gambie: Findlay & Davey [ 48 ], Bertram et al [ 5 ], Snow & Boreham [ 135 , 136 ], Snow [ 133 , 134 ], Gillies & Wilkes [ 57 ], Port & Wilkes [ 114 ], Germain et al [ 54 ], Bryan et al [ 11 ]; Mali: Bouffard [ 8 ], Holstein [ 78 ], Hamon [ 61 ], Hamon et al [ 68 ], Hamon & Brengues [ 64 ], Tandina et al [ 141 , 142 ]; Mauritanie: Hamon et al [ 69 , 70 ], Pichon & Ouedraogo [ 113 ], Diallo et al [ 41 ], Dia et al [ 36 ], Sow et al [ 139 ], Mint Lekweiry et al [ 105 ], Ouldabdallahi Moukah et al [ 110 ], Mint Mohamed Lemine et al [ 106 ], Ould Lemrabott et al [ 111 ]; Niger: Hamon et al [ 62 , ...…”

“…Mauritanie: Hamon et al [ 69 , 70 ], Pichon & Ouedraogo [ 113 ], Diallo et al [ 41 ], Dia et al [ 36 ], Sow et al [ 139 ], Mint Lekweiry et al [ 105 ], Ouldabdallahi Moukah et al [ 110 ], Mint Mohamed Lemine et al [ 106 ], Ould Lemrabott et al [ 111 ];…”

“… Anopheles ( Cellia ) marshallii (Theobald, 1903): espèce signalée au Burkina [ 149 ] et sur une unique femelle dans la collection ARIM [ 2 ] (boite ADU 1055, décembre 1963, Koumbia, Burkina, J. Hamon réc.). Anopheles ( Cellia ) multicolor Cambouliu, 1902: espèce signalée au Niger [ 85 ] et en Mauritanie [ 111 ]. C'est une espèce paléarctique du Nord Sahara, en limite de distribution dans ces deux pays.…”

“…Anopheles ( Cellia ) multicolor Cambouliu, 1902: espèce signalée au Niger [ 85 ] et en Mauritanie [ 111 ]. C'est une espèce paléarctique du Nord Sahara, en limite de distribution dans ces deux pays.…”