A blend of F prostaglandins functions as an attractive sex pheromone in silver carp

A series of laboratory experiments tested the hypothesis that the Silver Carp (Hypophthalmichthys molitrix), an invasive river carp from China, employs a prostaglandin F_2α-derived sex pheromone that is attractive and species-specific. Using electro-olfactogram recording (EOG), we found that the olfactory system of this species is acutely sensitive to three F-series prostaglandins (PGFs) at picomolar concentrations and that this sensitivity is enhanced when juveniles are masculinized using androgens, consistent with expectations of a sex pheromone. Individual PGFs had behavioral activity but it was low, suggesting a mixture might be important. To pursue this possibility, we implanted carps with osmotic pumps containing prostaglandin F_2α (PGF_2α), a treatment previously shown to elicit release of a PGF-based spawning pheromone in the Common Carp. We found that PGF_2α-implanted Silver Carp released a species-specific odor that contained a blend of PGF_2α and two of its metabolites, which masculinized individuals detected and were attracted to with high sensitivity. Finally, we found that a mixture of these PGFs was attractive to masculinized Silver Carp, while a different mixture released by Bighead Carp was not. We conclude that Silver Carp likely use a species-specific PGF_2α-derived sex pheromone that is probably released at spawning and might be useful in its control. Confirmatory studies that explore pheromone function in naturally mature Silver Carp using natural odors in the field should now be conducted to further confirm our proof-of-concept study.