Chromosome Study of Some Grasshopper Species from Different Localities in Central Ethiopia
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Date
2010-12
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Addis Ababa University
Abstract
Hitherto, around 200 grasshopper species have been recorded in Ethiopia. Despite the
diversity and economic importance of Ethiopian grasshoppers, the available information
on their taxonomy, distribution and ecology is meager, and no report on the karyology of
Ethiopian grasshoppers is available prior to this study. In this study, the karyotypes of ten
taxa identified to different taxonomic levels are described. The studied grasshopper
specimens were identified to belong to two families – Acrididae and Tetrigidae. Under
Acrididae six genera – Acanthacris, Paracinema, Gastrimargus, Acrotylus, Pardalophora
and Acrida were identified. Specimens of two additional taxa could not be identified
beyond the family level. The specimens under the family Tetrigidae were found to belong
to genus Paratettix. The grasshopper specimens were collected from eight localities in
central Ethiopia. Chromosome preparations were made from tissues of the whole gut, 6 –
8 hours after the colchicine injection. The tissue was grinded in hypotonic solution
(0.075M KCl). The suspension was centrifuged and the pellet was fixed in 3:1
methanol:acetic acid and followed by centrifugation. Air dry slide preparations were made
from cell suspension. In some case the testis was used for the preparation of meiotic
chromosomes following the same steps as in mitotic chromosome preparation. Slides were
stained in Giemsa stain. Basically, all the studied species (Acanthacris spp., Paracinema
tricolor, Gastrimargus spp., Acrida spp.-1, Acrida spp.-2, Acrotylus spp., Pardalophora
spp., and the two unidentified specimens) belonging to the family Acrididae showed
similarity in their karyotype, with all of them having 2n = 23 (22 autosomes + X) and 24
(22 autosomes + XX) telocentric chromosomes in male and female, respectively.
Paratettix spp. (family Tetrigidae) had a different chromosome number, that is, 2n = 20
telocentric chromosomes. Furthermore, Acanthacris spp. showed some numerical
instability of chromosomes in the mitotic and meiotic cells, and B chromosome like body
was found in the meiotic cells of this specimen. Apart from the gross Karyotypic
resemblance shown among the studied taxa of family Acrididae, slight variations in their
karyotype have been noted between taxa of acridid grasshoppers. Further studies of the
chromosomes of Ethiopian grasshoppers covering a wider geographic area and employing
new cytological techniques were recommended.
Keywords or phrases: Karyology, Central Ethiopia, Acridid grasshopper, Karyotypic
conservatism, chromosome
Description
Keywords
Karyology, Central Ethiopia, Acridid grasshopper, Karyotypic conservatism, chromosome