title: Evaluation of two counterflow traps for testing behaviour-mediating compounds for the malaria vector Anopheles gambiae s.s. under semi-field conditions in Tanzania.
abstract: BACKGROUND
  Evaluation of mosquito responses towards different trap-bait combinations in field trials is a time-consuming process that can be shortened by experiments in contained semi-field systems. Possible use of the BG Sentinel (BGS) trap to sample Anopheles gambiae s.s. was evaluated. The efficiency of this trap was compared with that of the Mosquito Magnet-X (MM-X) trap, when baited with foot odour alone or combinations of foot odour with carbon dioxide (CO2) or lemongrass as behaviour-modifying cues.
  
  
  METHODS
  Female An. gambiae s.s. were released in an experimental flight arena that was placed in a semi-field system and left overnight. Catch rates for the MM-X and BGS traps were recorded. Data were analysed by fitting a generalized linear model to the (n+1) transformed catches.
  
  
  RESULTS
  Both types of traps successfully captured mosquitoes with all odour cues used. When the BGS trap was tested against the MM-X trap in a choice assay with foot odour as bait, the BGS trap caught about three times as many mosquitoes as the MM-X trap (P = 0.002). Adding CO2 (500 ml/min) to foot odour increased the number of mosquitoes caught by 268% for the MM-X (P < 0.001) and 34% (P = 0.051) for the BGS trap, compared to foot odour alone. When lemongrass leaves were added to foot odour, mosquito catches were reduced by 39% (BGS, P < 0.001) and 38% (MM-X, P = 0.353), respectively.
  
  
  CONCLUSIONS
  The BGS trap shows high potential for field trials due to its simple construction and high catch rate when baited with human foot odour only. However, for rapid screening of different baits in a contained semi-field system, the superior discriminatory power of the MM-X trap is advantageous.
authors.affiliation: Center of Ecology, Faculty of Life Sciences, University of Vienna, Vienna, Austria. schmied@gmail.com
authors.forename: Wolfgang H
authors.initials: WH
authors.lastname: Schmied
authors.forename: Willem
authors.initials: W
authors.lastname: Takken
authors.forename: Gerry F
authors.initials: GF
authors.lastname: Killeen
authors.forename: Bart G J
authors.initials: BG
authors.lastname: Knols
authors.forename: Renate C
authors.initials: RC
authors.lastname: Smallegange
mesh_terms: D000818:Animals; D000852:Anopheles / Q000187:drug effects*; D001522:Behavior, Animal / Q000187:drug effects; D002245:Carbon Dioxide / Q000494:pharmacology; D002630:Chemotactic Factors / Q000494:pharmacology; D005260:Female; D006801:Humans; D009032:Mosquito Control; D009812:Odorants; D013636:Tanzania
chemical_list: D002630:Chemotactic Factors; D002245:Carbon Dioxide