title: Seasonal variation in metabolic rate, flight activity and body size of Anopheles gambiae in the Sahel.
abstract: Malaria in Africa is vectored primarily by the Anopheles gambiae complex. Although the mechanisms of population persistence during the dry season are not yet known, targeting dry season mosquitoes could provide opportunities for vector control. In the Sahel, it appears likely that M-form A. gambiae survive by aestivation (entering a dormant state). To assess the role of eco-physiological changes associated with dry season survival, we measured body size, flight activity and metabolic rate of wild-caught mosquitoes throughout 1 year in a Sahelian locality, far from permanent water sources, and at a riparian location adjacent to the Niger River. We found significant seasonal variation in body size at both the Sahelian and riparian sites, although the magnitude of the variation was greater in the Sahel. For flight activity, significant seasonality was only observed in the Sahel, with increased flight activity in the wet season when compared with that just prior to and throughout the dry season. Whole-organism metabolic rate was affected by numerous biotic and abiotic factors, and a significant seasonal component was found at both locations. However, assay temperature accounted completely for seasonality at the riparian location, while significant seasonal variation remained after accounting for all measured variables in the Sahel. Interestingly, we did not find that mean metabolic rate was lowest during the dry season at either location, contrary to our expectation that mosquitoes would conserve energy and increase longevity by reducing metabolism during this time. These results indicate that mosquitoes may use mechanisms besides reduced metabolic rate to enable survival during the Sahelian dry season.
authors.affiliation: Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 12735 Twinbrook Parkway, Rockville, MD 20852, USA. diana.huestis@nih.gov
authors.forename: Diana L
authors.initials: DL
authors.lastname: Huestis
authors.forename: Alpha S
authors.initials: AS
authors.lastname: Yaro
authors.forename: Adama I
authors.initials: AI
authors.lastname: Traoré
authors.forename: Kathryne L
authors.initials: KL
authors.lastname: Dieter
authors.forename: Juliette I
authors.initials: JI
authors.lastname: Nwagbara
authors.forename: Aleah C
authors.initials: AC
authors.lastname: Bowie
authors.forename: Abdoulaye
authors.initials: A
authors.lastname: Adamou
authors.forename: Yaya
authors.initials: Y
authors.lastname: Kassogué
authors.forename: Moussa
authors.initials: M
authors.lastname: Diallo
authors.forename: Seydou
authors.initials: S
authors.lastname: Timbiné
authors.forename: Adama
authors.initials: A
authors.lastname: Dao
authors.forename: Tovi
authors.initials: T
authors.lastname: Lehmann
mesh_terms: D000349:Africa; D000818:Animals; D000852:Anopheles / Q000033:anatomy & histology* / Q000502:physiology*; D001481:Basal Metabolism; D049628:Body Size; D005426:Flight, Animal; D008288:Malaria / Q000469:parasitology*; D012621:Seasons; D013696:Temperature