Effect of temperature on sex and steroid hormones of purple mud crab, Scylla tranquebarica (Fabricius, 1798) during egg incubation, larvae rearing and juvenile production

The influence of temperature on sex determination has been reported previously on many crustaceans. The interpretability of temperature capability to regulate the steroidogenic pathway, which in turn governs the offspring sex of mud crab, still remains unclear. Thus, the aim was to determine the effects of temperature on sex percentage and steroidal pathway in purple mud crab, Scylla tranquebarica. In sex percentage analysis, the eggs (28°C and 30°C), larvae (28°C, 30°C and 32°C) and juveniles (26°C, 28°C, 30°C) were exposed to different temperatures. The results revealed that exposure to a higher temperature during larvae (32°C) and juvenile (30°C) stages probably initiated the maleness (58.7%) and femaleness (60.8%) mechanism respectively. In steroid hormone analysis, the eggs (26°C, 28°C, 30°C and 32°C), larvae (29°C, 30°C, 31°C and 32°C) and juveniles (26°C, 28°C, 30°C and 32°C) were exposed to different temperatures. The steroidal assay corroborated the results of the sex percentages, which found higher dihydrotestosterone (172.4 pg/g) and testosterone (580.2 pg/g) levels when the larvae were incubated at a higher temperature (32°C) while higher estrone (136.9 pg/g) and estradiol (540.7 pg/g) levels when the juveniles were reared at high temperature (30°C). In brief, the temperature plays a significant role to redirect the mud crab sex during the larval and juvenile stages.