title: Reverse and conventional chemical ecology approaches for the development of oviposition attractants for Culex mosquitoes.
abstract: Synthetic mosquito oviposition attractants are sorely needed for surveillance and control programs for Culex species, which are major vectors of pathogens causing various human diseases, including filariasis, encephalitis, and West Nile encephalomyelitis. We employed novel and conventional chemical ecology approaches to identify potential attractants, which were demonstrated in field tests to be effective for monitoring populations of Cx. p. quinquefasciatus in human dwellings. Immunohistochemistry studies showed that an odorant-binding protein from this species, CquiOBP1, is expressed in trichoid sensilla on the antennae, including short, sharp-tipped trichoid sensilla type, which house an olfactory receptor neuron sensitive to a previously identified mosquito oviposition pheromone (MOP), 6-acetoxy-5-hexadecanolide. CquiOBP1 exists in monomeric and dimeric forms. Monomeric CquiOBP1 bound MOP in a pH-dependent manner, with a change in secondary structure apparently related to the loss of binding at low pH. The pheromone antipode showed higher affinity than the natural stereoisomer. By using both CquiOBP1 as a molecular target in binding assays and gas chromatography-electroantennographic detection (GC-EAD), we identified nonanal, trimethylamine (TMA), and skatole as test compounds. Extensive field evaluations in Recife, Brazil, a region with high populations of Cx. p. quinquefasciatus, showed that a combination of TMA (0.9 microg/l) and nonanal (0.15 ng/microl) is equivalent in attraction to the currently used infusion-based lure, and superior in that the offensive smell of infusions was eliminated in the newly developed synthetic mixture.
authors: Honorary Maeda-Duffey Laboratory, Department of Entomology, University of California Davis, Davis, California, United States of America. wsleal@ucdavis.edu
authors: Walter S
authors: WS
authors: Leal
authors: Rosângela M R
authors: RM
authors: Barbosa
authors: Wei
authors: W
authors: Xu
authors: Yuko
authors: Y
authors: Ishida
authors: Zainulabeuddin
authors: Z
authors: Syed
authors: Nicolas
authors: N
authors: Latte
authors: Angela M
authors: AM
authors: Chen
authors: Tania I
authors: TI
authors: Morgan
authors: Anthony J
authors: AJ
authors: Cornel
authors: André
authors: A
authors: Furtado
mesh_terms: D000818:Animals; D002630:Chemotactic Factors / Q000138:chemical synthesis / Q000494:pharmacology; D003465:Culex / Q000187:drug effects / Q000472:pathogenicity / Q000502:physiology*; D004463:Ecology; D005260:Female; D006798:Housing / Q000592:standards; D006801:Humans; D007700:Kinetics; D010058:Oviposition / Q000187:drug effects / Q000502:physiology*; D011157:Population Dynamics; D018035:Receptors, Odorant / Q000138:chemical synthesis / Q000494:pharmacology / Q000502:physiology
chemical_list: D002630:Chemotactic Factors; D018035:Receptors, Odorant