title: The fitness of African malaria vectors in the presence and limitation of host behaviour.
abstract: BACKGROUND
  Host responses are important sources of selection upon the host species range of ectoparasites and phytophagous insects. However little is known about the role of host responses in defining the host species range of malaria vectors. This study aimed to estimate the relative importance of host behaviour to the feeding success and fitness of African malaria vectors, and assess its ability to predict their known host species preferences in nature.
  
  
  METHODS
  Paired evaluations of the feeding success and fitness of African vectors Anopheles arabiensis and Anopheles gambiae sensu stricto in the presence and limitation of host behaviour were conducted in a semi-field system (SFS) at Ifakara Health Institute, Tanzania. In one set of trials, mosquitoes were released within the SFS and allowed to forage overnight on a host that was free to exhibit a natural behaviour in response to insect biting. In the other, mosquitoes were allowed to feed directly on from the skin surface of immobile hosts. The feeding success and subsequent fitness of vectors under these conditions were investigated on six host types (humans, calves, chickens, cows, dogs and goats) to assess whether physical movements of preferred host species (cattle for An. arabiensis, humans for An. gambiae s.s.) were less effective at preventing mosquito bites than those of common alternatives.
  
  
  RESULTS
  Anopheles arabiensis generally had greater feeding success when applied directly to host skin than when foraging on unrestricted hosts (in five of six host species). However, An. gambiae s.s. obtained blood meals from free and restrained hosts with similar success from most host types (four out of six). Overall, the blood meal size, oviposition rate, fecundity and post-feeding survival of mosquito vectors were significantly higher after feeding on hosts free to exhibit behaviour, than those who were immobilized during feeding trials.
  
  
  CONCLUSIONS
  Allowing hosts to move freely during exposure to mosquitoes was associated with moderate reductions in mosquito feeding success, but no detrimental impact to the subsequent fitness of mosquitoes that were able to feed upon them. This suggests that physical defensive behaviours exhibited by common host species including humans do not impose substantial fitness costs on African malaria vectors.
authors.affiliation: Environmental Sciences Thematic Group, Ifakara Health Institute, Ifakara, Tanzania. ilyimo@ihi.or.tz
authors.forename: Issa N
authors.initials: IN
authors.lastname: Lyimo
authors.forename: Daniel T
authors.initials: DT
authors.lastname: Haydon
authors.forename: Kasian F
authors.initials: KF
authors.lastname: Mbina
authors.forename: Ally A
authors.initials: AA
authors.lastname: Daraja
authors.forename: Edgar M
authors.initials: EM
authors.lastname: Mbehela
authors.forename: Richard
authors.initials: R
authors.lastname: Reeve
authors.forename: Heather M
authors.initials: HM
authors.lastname: Ferguson
mesh_terms: D000349:Africa; D000818:Animals; D000852:Anopheles / Q000469:parasitology* / Q000502:physiology*; D001522:Behavior, Animal / Q000502:physiology; D002417:Cattle; D002645:Chickens; D004285:Dogs; D005247:Feeding Behavior / Q000502:physiology; D005260:Female; D005298:Fertility; D006041:Goats; D006790:Host-Parasite Interactions / Q000502:physiology*; D006801:Humans; D007303:Insect Vectors / Q000469:parasitology* / Q000502:physiology*; D008288:Malaria / Q000635:transmission*; D008297:Male