title: Development and assessment of plant-based synthetic odor baits for surveillance and control of malaria vectors.
abstract: BACKGROUND
  Recent malaria vector control measures have considerably reduced indoor biting mosquito populations. However, reducing the outdoor biting populations remains a challenge because of the unavailability of appropriate lures to achieve this. This study sought to test the efficacy of plant-based synthetic odor baits in trapping outdoor populations of malaria vectors.
  
  
  RESULTS
  Three plant-based lures ((E)-linalool oxide [LO], (E)-linalool oxide and (E)-β-ocimene [LO + OC], and a six-component blend comprising (E)-linalool oxide, (E)-β-ocimene, hexanal, β-pinene, limonene, and (E)-β-farnesene [Blend C]), were tested alongside an animal/human-based synthetic lure (comprising heptanal, octanal, nonanal, and decanal [Blend F]) and worn socks in a malaria endemic zone in the western part of Kenya. Mosquito Magnet-X (MM-X) and lightless Centre for Disease Control (CDC) light traps were used. Odor-baited traps were compared with traps baited with either solvent alone or solvent + carbon dioxide (controls) for 18 days in a series of randomized incomplete-block designs of days × sites × treatments. The interactive effect of plant and animal/human odor was also tested by combining LO with either Blend F or worn socks. Our results show that irrespective of trap type, traps baited with synthetic plant odors compared favorably to the same traps baited with synthetic animal odors and worn socks in trapping malaria vectors, relative to the controls. Combining LO and worn socks enhanced trap captures of Anopheles species while LO + Blend F recorded reduced trap capture. Carbon dioxide enhanced total trap capture of both plant- and animal/human-derived odors. However, significantly higher proportions of male and engorged female Anopheles gambiae s.l. were caught when the odor treatments did not include carbon dioxide.
  
  
  CONCLUSIONS
  The results highlight the potential of plant-based odors and specifically linalool oxide, with or without carbon dioxide, for surveillance and mass trapping of malaria vectors.
authors.affiliation: Behavioral and Chemical Ecology Department, International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya.
authors.forename: Vincent O
authors.initials: VO
authors.lastname: Nyasembe
authors.affiliation: Behavioral and Chemical Ecology Department, International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya.
authors.forename: David P
authors.initials: DP
authors.lastname: Tchouassi
authors.affiliation: Behavioral and Chemical Ecology Department, International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya.
authors.forename: Hillary K
authors.initials: HK
authors.lastname: Kirwa
authors.affiliation: Department of Ecology and Organismal Biology, The Ohio State University, Columbus, Ohio, United States of America.
authors.forename: Woodbridge A
authors.initials: WA
authors.lastname: Foster
authors.affiliation: Center for Medical, Agricultural, and Veterinary Entomology, U.S. Department of Agriculture, Agricultural Research Service, Gainesville, Florida, United States of America.
authors.forename: Peter E A
authors.initials: PE
authors.lastname: Teal
authors.affiliation: Behavioral and Chemical Ecology Department, International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya ; Center for Development Research, University of Bonn, Bonn, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Borgemeister
authors.affiliation: Behavioral and Chemical Ecology Department, International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya.
authors.forename: Baldwyn
authors.initials: B
authors.lastname: Torto
mesh_terms: D000080462:Acyclic Monoterpenes; D000447:Aldehydes; D000475:Alkenes; D000818:Animals; D000081008:Bicyclic Monoterpenes; D001643:Bridged Bicyclo Compounds; D002630:Chemotactic Factors / Q000378:metabolism* / Q000494:pharmacology; D003511:Cyclohexanols; D053138:Cyclohexenes; D005260:Female; D007300:Insect Control / Q000379:methods*; D007303:Insect Vectors / Q000187:drug effects / Q000502:physiology*; D007630:Kenya; D016013:Likelihood Functions; D000077222:Limonene; D008288:Malaria / Q000517:prevention & control*; D008297:Male; D039821:Monoterpenes; D009812:Odorants / Q000032:analysis*; D062486:Public Health Surveillance / Q000379:methods*; D012717:Sesquiterpenes; D013729:Terpenes; D014320:Triphenylmethyl Compounds
chemical_list: D000080462:Acyclic Monoterpenes; D000447:Aldehydes; D000475:Alkenes; D000081008:Bicyclic Monoterpenes; D001643:Bridged Bicyclo Compounds; D002630:Chemotactic Factors; D003511:Cyclohexanols; D053138:Cyclohexenes; D039821:Monoterpenes; D012717:Sesquiterpenes; D013729:Terpenes; D014320:Triphenylmethyl Compounds; C443996:beta-ocimene; C062671:beta-farnesene; C010789:beta-pinene; C000593345:linalool oxide; C010463:n-hexanal; D000077222:Limonene