Abstract
The parasitic fly Philornis downsi is a serious threat to the passerine birds of the Galapagos Islands. Development of control methods for this invasive ectoparasite has been largely unsuccessful. Pheromone-based control of P. downsi is appealing for ecosystems because pheromones are environmentally innocuous and species-specific. To elucidate an attractive pheromone for control purposes, cuticular and volatile compounds were sampled for chemical and behavioral analyses. Cuticular samples were also photo-oxidized to examine oxidation as a potential mechanism of pheromone production. There is marked sexual dimorphism in the cuticular composition, with adult males maturing over the course of a week. Male-specific cuticular compounds were volatile, while female cuticular compounds were non-volatile. There are many identical compounds between the aeration and photo-oxidation samples, indicating that the cuticular compounds undergo auto-oxidation and that oxidation is a viable means of pheromone production. This research provides a foundation for elucidation of a pheromone for P. downsi.