Role of methyl farnesoate with Ca(OH)2or EDTA on growth of male crab Ozithelphusa senex senex

Abstract

The world's crustacean aquaculture industry facing many problems including limited production of quality protein. Growth induction a method of increasing yield of crustacean protein is in focus by the scientists. Administration of methyl farnesoateaknownproven method of crustacean growth induction is in practice. The present investigation focused to elucidate themolt induction frequency of MF alone and MF in Ca(OH)2 or EDTA medium in male crab Oziothelphusa senex senex(O. senex senex). The optimum concentration of MF for effective molt induction was found as 10-8 moles/crab out of three concentrations tested (10-9, 10-8 and 10-7 moles/crab every alternative day during experimentation) in the male crab O. senex senex and is used for further testing.Further, male crabs were maintained MF alone(10-8 moles/crab) and MF (10-8 moles/crab) in Ca(OH)2(1.4 mM) and EDTA (5 mM) medium and tested for molt induction on 7th, 14th, 21st and 28th day of experiment.Concurrent control with vehicle administration and eyestalk ablated (ESX; a positive control) groups were also maintained along with experimental groups. Concurrent controls were found in intermolt C4 stage during experimentation. Mortality was found in ESX group males, some are entered into different premolt stages and molted (on day 21 and 28) during the experimentation. On 7th day MFaloneinjected crabs were observed in premolt D1 (66.66%) and D2 (33.33%). MF injected and maintained in Ca(OH)2 medium were in D1 (55.55%) and D2 (44.44%) stages. Intermolt stage C4 (44.44%) and premolt stage D1 (55.55%) were observed in crabs received MF and maintained in EDTA medium on 7th day of experiment. MF alone received males, found in intermolt D2 (44.44%), D3 (33.33%), and molted were 22.22%. Crabs received MF and maintained in Ca(OH)2 medium were observed in late premolt stages D3 (44.44%), D4 (22.22%) and 33.33% were molted. Premolt stages D1 (55.55%) and D2 (44.44%) were observed in crabs injected with MF and maintained in EDTA medium on 14th day of experiment. MF alone injected crabs were found inpremolt stage D3 (33.33%), D4 (33.33%) and molted (33.33%). Crabs injected with MF and maintained in Ca(OH)2 medium were in late premolt D4 (44.44%) stage and 55.55% were molted on day 21. Premolt stages D2 (33.33%), D3 (33.33%) and molted (33.33%) were observed in MF injected and maintained in EDTA medium males on 21st day. MF alone injected males was found in premolt stage D3 (44.44%) and 55.55%molted. Observed 100% molt in animals received MF and maintained in Ca(OH)2 medium on day 28 of experiment. Premolt stage D3 (22.22%), D4 (33.33%) and molted (33.33%) crabs were observed in MF injected and maintained in EDTA medium on 28th day of experiment. It is evidenced that MF injected male crabs maintained in Ca(OH)2 medium is more effective for molt induction in crab O. senex senex.