Genetics of hybridization of Glossina swynnertoni with Glossina morsitans morsitans and Glossina morsitans centralis.

Reciprocal crosses were performed with Glossina swynnertoni and Glossina morsitans morsitans and with G.swynnertoni and Glossina morsitans centralis, using strains that carried marker genes in all three linkage groups. Glossina swynnertoni males can inseminate, but not fertilize, G.m.morsitans; all other crosses produced some fertile females. Hybridization did not cause sex ratio distortion among F1 flies. Most F1 and backcross females were fertile, but all F1 males were sterile. Sterility among backcross males was also high (99% in Bx1, 85% in Bx2, and about 50% in Bx3 to Bx5). Chromosome transmission by hybrid females usually conformed to Mendelian expectations, but genetic recombination was lower than observed in G.m.morsitans. The reduction in fertility among backcross females was not associated with heterozygosity in any linkage group. Sterility among hybrid and backcross males was associated with heterozygosity of sex chromosomes and probably autosomes. The results support the systematic placement of G.swynnertoni closer to G.m.centralis than to G.m.morsitans.