Genetic basis of sterility in hybrid males from crosses of Glossina morsitans morsitans and Glossina morsitans centralis (Diptera: Glossinidae)

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Abstract
Glossina morsitans morsitans Westwood and Glossina morsitans centralis Machado carrying from one to three marker genes on each chromosome were hybridized. F1 females were backcrossed and the resulting backcross males were tested for their ability to inseminate and to fertilize both G. m. morsitans and G. m. centralis; these abilities were then related to the genetic constitution of each male. Hybrid males having an X chromosome from one subspecies and a Y chromosome from the other were sterile, as were about half the males having X and Y chromosomes from the same subspecies. There is weak evidence for autosomal involvement in hybrid sterility but this involvement is not through genetical recombination between the loci Ao and Xo, nor does it depend upon the number of autosomes from the same taxon as the sex chromosomes. Hybrid males descending from G. m. morsitans females could not fertilize G. m. centralis although they could inseminate them. F1 hybrid females had lower than expected intrachromosomal recombination in the X chromosome and in linkage group II, and hybrid females tended to use autosomes of G. m. centralis origin more frequently than chromosomes from G. m. morsitans. Models for evolution of the maternally inherited sterility factor(s) suggest that G. m. centralis is ancestral to G. m. morsitans. Use of hybrid males descending from female G. m. morsitans for genetic control of G. m. centralis is proposed.