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Hybridization between the freshwater prawns macrobrachium rosenbergii (De Man) and M. carcinus (L.)

Abstract:

The production of hybrids between Macrobrachium rosenbergii and other Macrobrachium species has great economical importance for aquaculture, but also has serious environmental implications when M. rosenbergii is present as an exotic species. In this study, intra- and interspecific crosses between M. rosenbergii and M. carcinus were carried out through natural mating and artificial insemination. For the natural crosses, a fertile female was placed inside an aquarium with a mature male and the behavior of animals was monitored. For the artificial insemination assays, male spermatophores were collected by electroejaculation and placed inside the sperm receptacle of a fertile female. The temperature was maintained at 27 ± 2°C during the study. Firstly, 62 and 45 natural intraspecific crosses were carried out in M. rosenbergii and M. carcinus, with larvae obtained from 32.3% and 57.8% of the crosses, respectively. Thirty-seven natural interspecific reciprocal crosses were also attempted but no mating occurred. A total of 57 and 39 intraspecific crosses were carried out by artificial insemination in M. rosenbergii and M. carcinus, obtaining larva from 22.8% and 41.0% of the crosses, respectively. Finally, 46 interspecific reciprocal crosses were also carried out by artificial insemination. Hybrid zygotes were produced in all the crosses, but embryo development did not progress further than the gastrula stage. This indicates the existence of both behavioral and postzygotic reproductive isolation barriers. These barriers could prevent the hybridization of these species in the natural environment. © 2003 Elsevier Science B.V. All rights reserved.