Profiling of methyl farnesoate in relation to female reproductive cycle in the freshwater crab, Travancoriana schirnerae Bott, 1969 (Crustacea: Gecarcinucidae)

ABSTRACT The sesquiterpenoid, methyl farnesoate, produced by the mandibular organ of decapod crustaceans has a variety of functions including the regulation of moulting, reproduction, morphogenesis, behaviour and osmoregulation. This study used gas chromatography and mass spectrometric analysis to measure the haemolymph concentration of methyl farnesoate during various developmental stages of the ovary of the edible freshwater crab Travancoriana schirnerae. The results revealed exceptionally low methyl farnesoate titres in the haemolymph during the avitellogenic and previtellogenic periods (5.7 ± 0.7 and 12.8 ± 1.3 ng/mL, respectively), reaching a peak in the early vitellogenic period (91.8 ± 3.8 ng/mL), followed by a significant fall during the middle and late vitellogenic stages (32.1 ± 2.3 and 22.1 ± 1.6 ng/mL, respectively). The progressive increase and decrease in the haemolymph titre of methyl farnesoate in accordance with the stages of the ovarian cycle clearly indicated the role of this hormone in growth and maturation of the ovary. Furthermore, administration of methyl farnesoate can be exploited as an alternate method to the traditional eyestalk ablation practised for inducing ovarian maturation and spawning.