Many species of teleost fish detect and release F prostaglandins (PGFs), but the specific identities of these compounds and how they function as species-specific pheromones have yet to be resolved. This study addressed these questions in the common carp. An initial set of experiments established that mature male common carp were attracted to chemicals released by ovulated conspecifics, whereas the odor of female goldfish, a close relative, was less attractive. Tests of fractionated holding water from ovulated carp revealed that only the non-polar fraction was attractive on its own. Mass spectrometry and immunoassay next demonstrated that the non-polar fraction contained large quantities of prostaglandin F 2α (PGF 2α), 15keto-prostaglandinF 2α, and 13,14-dihydro-15keto-prostaglandin F 2α (100 g fish released over 1 μg of all 3 PGFs per h at a ratio of 1.0:1.7:0.7). Ovulated goldfish released the same three PGFs but at a slightly greater rate and in a different ratio. Tests of synthetic mixtures of these PGFs revealed that the carp-specific mixture attracted male carp but was no better than the goldfish-specific mixture or PGF 2α alone and that PGF 2α was just as attractive as mixture of all three PGFs. A final set of attraction tests revealed that although PGF 2α could explain all of the activity of the non-polar portion of female carp holding water, it could not explain the entire activity of female water but that a mixture of PGFs and the polar fraction could. We conclude that ovulated female carp release a multi-component sex pheromone complex that is comprised of PGF 2α and unknown species-specific polar compound(s) that synergize the activity of the former. The pheromone also might be useful in controlling this invasive species. The observation that a fish hormonal sex pheromone incorporates bodily metabolites in addition to relatively common hormonal products demonstrates a mechanism by which species specificity may be conferred to this common type of sex pheromone.
Bibliographical noteFunding Information:
Acknowledgments This study was funded by the Invasive Animals Cooperative Research Centre (Canberra, Australia) and the Minnesota Agricultural Experiment Station. The authors thank Haude Levesque, Mario J. Travaline, and Jay Maher for technical support. Two anonymous reviewers provided helpful suggestions.
- Common carp
- Cyprinus carpio
- Electrospray ion mass spectrometry (ESI-MS/MS)
- Enzyme-linked immunosorbent assay (ELISA)
- Hormonal pheromone
- Invasive species
- Mass spectrometry (MS)
- Pheromone complex
- Species-identifying pheromone