Analyse de la transmission des chromosomes surnuméraires chez Locusta migratoria migratorioides R. et F. (Orthoptera, Acrididae)

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Abstract
In a African grasshopper population of Locusta migratoria migratorioides reared in the laboratory, B chromosome transmission is analysed in progeny of pairs taken at random from the population. An accumulation mechanism of Bs exists in the females which presumably results from preferentiel segregation of the Bs in the female pronucleus. The analysis also shows B chromosome elimination during embryonic and larval development by means of mitotic non-disjunction: these non-disjunctions induce interfollicular variations in the number of Bs but all the cells of a follicle have the same number of Bs. The frequency of animals with B chromosome rises from 34% to 75% as the diurnal temperature rises from 27° C to 35° C. Thus frequency is controlled by genetic and environmental factors.