Evidence of the Existence of Site-Specific Female Contact Pheromones Involved in the Sexual Interaction Behavior of the Pacific Whiteleg Shrimp Penaeus vannamei.

Simple Summary: If the existence of female sex pheromones in shrimp, Penaeus vannamei, is confirmed, they could be used to increase the larval production needed to supply shrimp farms worldwide. To gather more evidence of their existence, liposoluble compounds were extracted from the cuticle of different portions of the abdomen of adult females. These extracts were used to coat PVC tubes that were used as artificial females placed in tanks stocked with adult males. The males were monitored to determine if sexual behavior was displayed when in contact with the artificial females. The behavior observed in the shrimp males of this study provides evidence of the existence of sex pheromones located primarily in the ventral portion of the abdomen exoskeleton of shrimp females. Although the presence of female contact sex pheromones in P. vannamei has been hypothesized, to date its existence has not been proven. To gather more evidence of their existence, cuticular liposoluble extracts were obtained from the following samples of adult females to be used as the experimental treatments: (1) ventral exoskeleton of immature female (VI), (2) dorsolateral exoskeleton of immature female (DI), (3) ventral exoskeleton of mature female (VM), and (4) dorsolateral exoskeleton of mature female (DM). Polyvinyl chloride tubes (artificial females; AF) were coated with each extract and the behavior displayed by sexually mature males in contact with the AF was recorded and classified as follows: 0 = no response; 1 = contact; 2 = pushing; and 3 = prolonged contact (≥10 s). To test the hypothesis that the extracts collected from the ventral portion of the abdomen exoskeleton have a higher effect on the behavior of males than the extracts collected from the dorsolateral portion of the abdomen exoskeleton, the experiment was divided into two bioassays: Bioassay I (VI vs. DI) and Bioassay II (VM vs. DM). In each bioassay, all experimental treatments were significantly different (p > 0.05) from the CTL group (AF coated with hexane). Notably, the pushing behavior was significantly higher (p < 0.05) in the VI treatment compared to the CTL and DI treatment. These results provide evidence of the existence of contact female sex pheromones with sexual recognition function located primarily in the ventral portion of the abdomen exoskeleton of P. vannamei. [ABSTRACT FROM AUTHOR]