title: Identification of morphological and chemical markers of dry- and wet-season conditions in female Anopheles gambiae mosquitoes.
abstract: BACKGROUND
  Increased understanding of the dry-season survival mechanisms of Anopheles gambiae in semi-arid regions could benefit vector control efforts by identifying weak links in the transmission cycle of malaria. In this study, we examined the effect of photoperiod and relative humidity on morphologic and chemical traits known to control water loss in mosquitoes.
  
  
  METHODS
  Anopheles gambiae body size (indexed by wing length), mesothoracic spiracle size, and cuticular hydrocarbon composition (both standardized by body size) were examined in mosquitoes raised from eggs exposed to short photoperiod and low relative humidity, simulating the dry season, or long photoperiod and high relative humidity, simulating the wet-season.
  
  
  RESULTS
  Mosquitoes exposed to short photoperiod exhibited larger body size and larger mesothoracic spiracle length than mosquitoes exposed to long photoperiod. Mosquitoes exposed to short photoperiod and low relative humidity exhibited greater total cuticular hydrocarbon amount than mosquitoes exposed to long photoperiod and high relative humidity. In addition, total cuticular hydrocarbon amount increased with age and was higher in mated females. Mean n-alkane retention time (a measure of cuticular hydrocarbon chain length) was lower in mosquitoes exposed to short photoperiod and low relative humidity, and increased with age. Individual cuticular hydrocarbon peaks were examined, and several cuticular hydrocarbons were identified as potential biomarkers of dry- and wet-season conditions, age, and insemination status.
  
  
  CONCLUSIONS
  Results from this study indicate that morphological and chemical changes underlie aestivation of Anopheles gambiae and may serve as biomarkers of aestivation.
authors: Kaira M
authors: KM
authors: Wagoner
authors: Tovi
authors: T
authors: Lehmann
authors: Diana L
authors: DL
authors: Huestis
authors: Brandie M
authors: BM
authors: Ehrmann
authors: Nadja B
authors: NB
authors: Cech
authors: Department of Biology, University of North Carolina Greensboro, 235 Eberhart Bldg, Greensboro, NC 27402, USA. g_wasser@uncg.edu.
authors: Gideon
authors: G
authors: Wasserberg
mesh_terms: D000818:Animals; D000852:Anopheles / Q000033:anatomy & histology* / Q000378:metabolism*; D015415:Biomarkers; D005260:Female; D007814:Larva / Q000502:physiology; D011891:Rain; D012621:Seasons
chemical_list: D015415:Biomarkers