Moon phase effect on mosquito vectors of West Nile virus in Madagascar: biodiversity, abundance, host attractiveness and feeding rates

Tantely Luciano Michaël, Guis Hélène, Raharinirina Manou Rominah, Randrianandrianina L., Cardinale Eric, Garros Claire, Girod Romain. 2018. Moon phase effect on mosquito vectors of West Nile virus in Madagascar: biodiversity, abundance, host attractiveness and feeding rates. In : ASTMH 67th Annual Meeting Abstract Book. ASTMH. New Orleans : ASTMH, 48. ASTMH (American Society of Tropical Medicine and Hygiene) 67th Annual Meeting, New Orleans, États-Unis, 28 Octobre 2018/1 Novembre 2018.

Résumé : West Nile Virus (WNV) infection occurs throughout Madagascar. Its epidemiological cycle involves horses, human, birds and mosquitoes. Our entomological data shows unexpected information on mosquitoes vectors diversity and biology that relates to the collection methods. This study highlights the effect of lunar cycle that has not been previously considered in previous studies in Madagascar. During 2017, the influence of the two lunar phases (full versus new moon) on mosquito populations was analyzed in a farm located in the surroundings of Antananarivo city, Madagascar. Each month, mosquito collections were performed twice: one night during the full moon and one during the new moon. Six light traps were used: three indoors (in horse's box stall, in a house, in a cowshed), while three outdoors (near a pigsty, near a chicken coop, near a water point). During 24 night catches, 36,448 specimens belonging to 23 species were collected with Culex antennatus (64%) and Cx. quinquefasciatus (30%) the most abundant species. Cx. antennatus was mostly collected in traps associated with domestic animals while Cx. quinquefasciatus in trap placed in house. Each month, the total number of females caught during new moon was 1 to 3,5 times higher than those caught during full moon (ANOVA; F=34.4, DF=3, P<0,05). Larger numbers of mosquitoes, driven mainly by Cx. antennatus, were collected during the new moon in the three outdoor traps; and inversely during the full moon in the cowshed. This new moon effect was observed in the house but driven mainly by Cx. quinquefasciatus. Lunar phase did not influence the abundance of mosquitoes in horse's box stall and the variation of mosquitos' diversity. The total number of fed and unfed females followed (F=0.709, DF=39, P>0,05) the same pattern than the abundance of mosquitoes collected in the farm. The lunar cycle has an effect on mosquito abundance and host attractiveness and might vary according to the mosquito species. This lunar effect and the location of traps should be taken into consideration for one target species during entomological investigations aiming at unraveling West-Nile virus transmission when using light traps.

Mots-clés libres : Madagascar, Mosquito, West Nile virus, Population dynamics, Dynamics

Auteurs et affiliations

• Tantely Luciano Michaël, Institut Pasteur de Madagascar (MDG)
• Guis Hélène, CIRAD-BIOS-UMR ASTRE (MDG) ORCID: 0000-0002-0355-0898
• Raharinirina Manou Rominah, Institut Pasteur de Madagascar (MDG)
• Randrianandrianina L.
• Cardinale Eric, CIRAD-BIOS-UMR ASTRE (REU) ORCID: 0000-0002-3434-3541
• Garros Claire, CIRAD-BIOS-UMR ASTRE (REU) ORCID: 0000-0003-4378-5031
• Girod Romain, Institut Pasteur de Guyane française (GUF)

Source : Cirad-Agritrop (https://agritrop.cirad.fr/589835/)

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