title: Identification and Optimization of Microbial Attractants for Philornis downsi, an Invasive Fly Parasitic on Galapagos Birds.
abstract: We investigated the role of olfactory cues from actively fermenting yeast (Saccharomyces cerevisiae) in attraction of adult Philornis downsi and identified two synergistically attractive yeast volatiles. Larvae of this invasive fly parasitize the hatchlings of passerines and threaten the Galapagos avifauna. Gas chromatography coupled with electroantennographic detection (GC-EAD), coupled gas chromatography-mass spectrometry (GC-MS), and field trapping experiments were used to identify volatile compounds from a yeast-sugar solution. EAD responses were consistently elicited by 14 yeast volatiles. In a series of field trapping experiments, a mixture of the 14 EAD-active compounds was similarly attractive to P. downsi when compared to the yeast-sugar solution, and we found that acetic acid and ethanol were essential for attraction. A mixture of 0.03 % acetic acid and 3 % ethanol was as attractive as the 14-component blend, but was not as attractive as the yeast-sugar solution. Philornis downsi showed positive and negative dose-responses to acetic acid in the ranges of 0.01 ~ 0.3 % and 0.3 ~ 9 %, respectively. Further optimization showed that the mixture of 1 % acetic acid and 3 % ethanol was as attractive as the yeast-sugar solution. Both mixtures of acetic acid and ethanol were more selective than the yeast-sugar solution in terms of non-target moths and Polistes versicolor wasps captured. These results indicate that acetic acid and ethanol produced by yeasts are crucial for P. downsi attraction to fermented materials on which they feed as adults and can be used to manage this invasive fly in Galapagos.
authors.affiliation: College of Environmental Science and Forestry, State University of New York, Syracuse, NY, USA.|USDA-ARS, US Pacific Basin Agricultural Research Laboratory, 64 Nowelo St., Hilo, HI, USA.
authors.forename: Dong H
authors.initials: DH
authors.lastname: Cha
authors.affiliation: College of Environmental Science and Forestry, State University of New York, Syracuse, NY, USA.
authors.forename: Alejandro E
authors.initials: AE
authors.lastname: Mieles
authors.affiliation: Charles Darwin Foundation for the Galapagos Islands, Puerto Ayora, Santa Cruz Island, Galapagos Islands, Ecuador.
authors.forename: Paola F
authors.initials: PF
authors.lastname: Lahuatte
authors.affiliation: Charles Darwin Foundation for the Galapagos Islands, Puerto Ayora, Santa Cruz Island, Galapagos Islands, Ecuador.
authors.forename: Andrea
authors.initials: A
authors.lastname: Cahuana
authors.affiliation: Charles Darwin Foundation for the Galapagos Islands, Puerto Ayora, Santa Cruz Island, Galapagos Islands, Ecuador.|Facultad de Ciencias Agrícolas, Universidad Central del Ecuador, Quito, Ecuador.
authors.forename: Marie Piedad
authors.initials: MP
authors.lastname: Lincango
authors.affiliation: Charles Darwin Foundation for the Galapagos Islands, Puerto Ayora, Santa Cruz Island, Galapagos Islands, Ecuador.
authors.forename: Charlotte E
authors.initials: CE
authors.lastname: Causton
authors.affiliation: Department of Behavioural Biology, University of Vienna, 1090, Vienna, Austria.
authors.forename: Sabine
authors.initials: S
authors.lastname: Tebbich
authors.affiliation: Department of Behavioural Biology, University of Vienna, 1090, Vienna, Austria.
authors.forename: Arno
authors.initials: A
authors.lastname: Cimadom
authors.affiliation: College of Environmental Science and Forestry, State University of New York, Syracuse, NY, USA. sateale@esf.edu.
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Teale
mesh_terms: D000818:Animals; D001717:Birds / Q000469:parasitology*; D004305:Dose-Response Relationship, Drug; D005285:Fermentation; D058865:Introduced Species; D009117:Muscidae / Q000187:drug effects / Q000382:microbiology* / Q000502:physiology*; D055696:Olfactory Perception / Q000187:drug effects; D010675:Pheromones / Q000737:chemistry / Q000494:pharmacology; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D014835:Volatilization
chemical_list: D010675:Pheromones
keywords: Attractant; Avian parasite; Galapagos; Invasive; Philornis downsi; Yeast