Litopenaeus vannaemei is one of the most important aquaculture species at international level, so it is necessary to continue with the development of biotechnologies that allow optimization of larval production in an efficient and sustainable way. Within the lines of research that can contribute to this objective, sexual pheromones are one of those with the greatest potential; however, although the existence of two types of female sex pheromones in this organism (distance and contact) is hypothesized, to date their existence has not been proven. In this work, the detection of the contact female pheromone involved in the reproductive process of this important specie was carried out for the first time.
For this purpose, the behavior presented by sexually mature males against "artificial females" previously treated with liposoluble cuticular extracts of mature and immature females was observed and classified. The treatments tested were: (1) ventral exoskeleton of immature female (EVHI), (2) dorsolateral exoskeleton of immature female (EDHI), (3) ventral exoskeleton of mature female (EVHM) and (4) dorsolateral exoskeleton of mature female (EDHM). The experiment was divided into two bioassays: 1) extracts from immature females and 2) extracts from mature females; each with two treatments and one control (hexane), evaluated in 15 replicates per treatment. The behavior was classified according to the following grades: 0 = no response; 1 = contact; 2 = push and 3 = prolonged contact (≥ 10 s). The association between each behavior presented and between the different treatments was determined using Barnard’s exact test; if any behavior was presented more than once in at least one replicate, a one-way ANOVA was performed to determine if there were differences in the number of times each behavior occurred. In addition, the total bioactivity presented was evaluated with the Kruskal-Wallis test.
Figures 1 and 2 show the results obtained in terms of total bioactivity, finding a significant association between the reproductive behavior of L. vannamei and the different extracts tested. The results show sufficient evidence to determine the existence of a contact female sex pheromone with sexual recognition function