Invasive Species Compendium

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Abstract

Induced gynogenesis in the silver barb (Puntius gonionotus Bleeker) and evidence for female homogamety.

Abstract

Diploid gynogenesis was induced experimentally in silver barb as the first step in a programme aimed at monosex ♀ production. Spermatozoa were exposed to UV light at a dose rate of 196 µW/cm2 for 0-32 min (0-376.3 mJ/cm2), using a sperm concentration of 8 × 108/ml. The optimum UV exposure for producing gynogenetic haploids when the irradiated spermatozoa was used to fertilize eggs was 1 min (11.8 mJ/cm2). Diploidization of the gynogenetic genome was achieved by cold shock of eggs, previously held at 29±1°C, at 2±0.1° for 10, 20 or 30 min or a heat shock at 40±0.1° for 1.0 min. A maximum survival rate of 61.3% viable diploid gynogenetic offspring (relative to survival of controls) was obtained using a cold shock of 2±0.1° for 10 min starting 1.5 min after fertilization. A total of 268 diploid gynogenetic fry from 10 ♀♀ were reared and sexed by histological examination of the gonads. With the exception of 4 undifferentiated fish, all the gynogenetic fish were ♀♀, in contrast to the controls, which had a mean of 54.6% ♀♀ (which was not significantly different from 50%).