title: Colonization of malaria vectors under semi-field conditions as a strategy for maintaining genetic and phenotypic similarity with wild populations.
abstract: BACKGROUND
  Malaria still accounts for an estimated 207 million cases and 627,000 deaths worldwide each year. One proposed approach to complement existing malaria control methods is the release of genetically-modified (GM) and/or sterile male mosquitoes. As opposed to laboratory colonization, this requires realistic semi field systems to produce males that can compete for females in nature. This study investigated whether the establishment of a colony of the vector Anopheles arabiensis under more natural semi-field conditions can maintain higher levels of genetic diversity than achieved by laboratory colonization using traditional methods.
  
  
  METHODS
  Wild females of the African malaria vector An. arabiensis were collected from a village in southern Tanzania and used to establish new colonies under different conditions at the Ifakara Health Institute. Levels of genetic diversity and inbreeding were monitored in colonies of An. arabiensis that were simultaneously established in small cage colonies in the SFS and in a large semi-field (SFS) cage and compared with that observed in the original founder population. Phenotypic traits that determine their fitness (body size and energetic reserves) were measured at 10(th) generation and compared to founder wild population.
  
  
  RESULTS
  In contrast to small cage colonies, the SFS population of An. arabiensis exhibited a higher degree of similarity to the founding field population through time in several ways: (i) the SFS colony maintained a significantly higher level of genetic variation than small cage colonies, (ii) the SFS colony had a lower degree of inbreeding than small cage colonies, and (iii) the mean and range of mosquito body size in the SFS colony was closer to that of the founding wild population than that of small cage colonies. Small cage colonies had significantly lower lipids and higher glycogen abundances than SFS and wild population.
  
  
  CONCLUSIONS
  Colonization of An. arabiensis under semi-field conditions was associated with the retention of a higher degree of genetic diversity, reduced inbreeding and greater phenotypic similarity to the founding wild population than observed in small cage colonies. Thus, mosquitoes from such semi-field populations are expected to provide more realistic representation of mosquito ecology and physiology than those from small cage colonies.
authors.affiliation: Ifakara Health Institute, Environmental Health and Ecological Sciences Thematic Group, Ifakara, Kilombero, Morogoro, United Republic of Tanzania. kija@ihi.or.tz.
authors.forename: Kija R
authors.initials: KR
authors.lastname: Ng'habi
authors.affiliation: Vector Genetics Laboratory, Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of Calfornia, Davis, USA. yoslee@ucdavis.edu.
authors.forename: Yoosook
authors.initials: Y
authors.lastname: Lee
authors.affiliation: In2Care BV, Costerweg 5, 6702 AA, Wageningen, The Netherlands. bart@in2care.org.
authors.forename: Bart G J
authors.initials: BG
authors.lastname: Knols
authors.affiliation: Ifakara Health Institute, Environmental Health and Ecological Sciences Thematic Group, Ifakara, Kilombero, Morogoro, United Republic of Tanzania. dmwasheshi@ihi.or.tz.
authors.forename: Dickson
authors.initials: D
authors.lastname: Mwasheshi
authors.affiliation: Vector Genetics Laboratory, Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of Calfornia, Davis, USA. gclanzaro@ucdavis.edu.
authors.forename: Gregory C
authors.initials: GC
authors.lastname: Lanzaro
authors.affiliation: Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK. Heather.Ferguson@glasgow.ac.uk.
authors.forename: Heather M
authors.initials: HM
authors.lastname: Ferguson
mesh_terms: D000818:Animals; D000852:Anopheles / Q000145:classification* / Q000235:genetics / Q000254:growth & development*; D017753:Ecosystem; D005260:Female; D014644:Genetic Variation; D005838:Genotype; D007178:Inbreeding; D008297:Male; D009032:Mosquito Control / Q000379:methods; D010641:Phenotype; D013636:Tanzania