When ovulated, female fish of many species are known to release a F-prostaglandin-derived sex pheromone that attracts conspecific males. Recently, this pheromone was identified in the common carp as a mixture of prostaglandin F 2α (PGF 2α) and unidentified body metabolites, which we termed a 'pheromone complex'. The present study sought to test the activity of this pheromone complex in the field by developing a system using carps implanted with PGF 2α as pheromone donors. An initial experiment determined that osmotic pumps that delivered up to 0. 4 mg of PGF 2α per hour could be implanted into carp without any apparent effects on their health. A second experiment found that PGF 2α-implanted male and female carp released biologically relevant (and equivalent) quantities of PGF 2α, along with two of its seemingly inactive metabolites, for up to 2 weeks. Laboratory experiments demonstrated that the odor of PGF 2α-implanted carp was highly attractive to male conspecifics, and included necessary body metabolites; it attracted males as strongly as ovulated carp odor, and much better than PGF 2α alone. Finally, a field test demonstrated that PGF 2α-implanted female carp attracted mature male, but not female carp, from a distance of 20 m. This is the first demonstration of the activity of a PGF 2α-based pheromone in a natural environment and confirms the use of a PGF-pheromone complex in the carp. We suggest that the implant technique may be useful in future studies of how PGF pheromones function and could be further developed to attract invasive fish for use in control.
Bibliographical noteFunding Information:
Acknowledgements This study was funded by the Invasive Animals Cooperative Research Centre (Canberra, Australia). Arrangements for field tests were made by the Ramsey-Washington Metro Watershed District (Minnesota, USA). P. Bajer, C. Chizinski, E. Coil, E. Fox, C. Johnson, J. Maher, J. Osborne, J. Silbernagel, J. Sloan, M. J. Travaline, and J. Wein provided invaluable assistance in the laboratory and field.
- Cyprinus carpio
- Hormonal pheromone
- Integrated pest management
- Invasive species
- Liquid chromatography-mass spectrometry (LC-MS/MS)
- Pheromone complex
- Prostaglandin metabolism