A Blend of F Prostaglandins Functions as an Attractive Sex Pheromone in Silver Carp

Abstract

A series of laboratory experiments tested the hypothesis that the Silver Carp (Hypophthalmichthys molitrix), an invasive river carp from China, employs a prostaglandin F2α-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 F2α (PGF2α), a treatment previously shown to elicit release of a PGF-based spawning pheromone in the Common Carp. We found that PGF2α-implanted Silver Carp released a species-specific odor that contained a blend of PGF2α 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 PGF2α-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.

Prostaglandin F 2α drives female pheromone signaling in cichlids, revealing a basis for evolutionary divergence in olfactory signaling

“…S3 A ). As carp have been shown to produce a blend of PGF 2α metabolites ( 52 ), we also tested for a male preference for a mixture of PGF 2α plus five known metabolites from mammals (15K-PGF 2α , PGFM, 13,14-DH PGF 2α , 19(R)-hydroxy PGF 2α , and 20-hydroxy PGF 2α ). However, our data showed that neither PGF 2α nor a mixture of the five known PGF 2α metabolites is sufficient to attract male cichlids ( Fig.…”

“…Thus, we do not believe that a failure of males to seek synthetic PGF 2α metabolites results from insufficient stimulation. In some species, the ratio of the metabolites produced has been suggested to be important for attraction ( 52 , 63 ). We delivered chemicals in approximately equimolar ratios, so we cannot exclude a model in which cichlids compare concentrations of individual compounds within a blend.…”

Proof-of-Concept Studies Demonstrate That Food and Pheromone Stimuli Can Be Used to Attract Invasive Carp So Their Presence Can Be Readily Measured Using Environmental DNA

“…Further, there was a positive association between eDNA copy numbers and carp presence (total fish detections), suggesting eDNA might also be used for the quantification of aggregating carps. Although the PGF2α sex pheromone has yet to be tested with silver carp, it is highly likely that it could also be used on this invasive carp as it has proven to be highly attractive to them in small-scale laboratory tests [14,21]. Of course, large-scale tests of both of these stimuli must now be conducted in flowing river waters.…”

“…For the former, we tested a solution of 10 −9 M PGF2α (Cayman Chemical Co., Ann Arbor, MI, USA) [14,18]. For the latter, we created the pheromone complex following established protocols, which entailed implanting carp with PGF2α [18,19,21] and collecting holding water (Supplemental Data S1). The concentration of PGF2α in the mixture was determined to be 10 −9 M by mass spectrometry [11].…”

Herbivorous Grass Carp (Ctenopharyngodon idella) Exhibit Greater Olfactory Response to Amino Acids Than Filter-Feeding Bighead (Hypophthalmichthys nobilis) and Silver Carp (Hypophthalmichthys molitrix)

“…The invasion of bighead and silver carp into North American waters is of concern due to their negative impact on ecosystems by directly competing with native species for resources; this competition can cause a reduction in native fish diversity [2]. A variety of research has been conducted on food additives and compounds such as food cues (e.g., amino acids), pheromones, and alarm-eliciting compounds that could be used to attract and aggregate invasive carp for easier removal by managers [13][14][15]. This research is intended to inform the management of invasive carp control activities by the United States Fish and Wildlife Service, the Army Corps of Engineers, and multiple state agencies.…”