Abstract:
Methyl farnesoate (11:F), a hormone synthesized by the mandibular organ
(MO) of crustacean plays an important role in regulating moulting. By identifying a
practical and economic dosage, moulting estimated time without hyperecdysonism or
perturbation can be obtained. In addition, a wide range of commercial applications
such as propagation and soft-shelled production can also be developed. The objectives
of this study are to examine the effect of the MF hormone on orange mud crab, S.
olivacea in the aspects of moulting period, carapace width (CW) increment and the
survival rate. Samples were divided into three groups 'where control group (C) treated
with MF vehicle solvent (ethanol), Treatment l(Tl) treated with 3 µg of MF and
Treatment 2 with 9 µg of 11F in each crab per week. The experiment was lasted 100
days while the effect of MF on each aspect was observed and analyzed. In the aspect
of moulting period, administration MF had no effect in accelerating the moulting
period. In term of gender, 11F did have the tendency to accelerate moulting duration
in females (p = 0.018) but not in males (p = 0.18) however only females in Tl
significantly moulted faster than males (p = 0.00) while other groups did not show
any differences (p > 0.05). Female crabs have a positive response towards 11F in
accelerating moulting period with lower doses (3 µg) but it tends to inhibit the
moulting process in female crabs as the doses increased to 9 µg. Three different doses
of hormone did not cause a tendency to affect CW increment as there was no
significant observed in the increment (p = 0.274). In term of genders, female crabs
had significant difference (p < 0.05) in CW increment for C group and Tl but not in
T2 (p = 0.759). The effect of MF seemed not related to CW increment and may easily
be affected by external factors.