Differences in laboratory performance between strains ofGlossina morsitans morsitansWestwood from Rhodesia and Tanzania and associated chromosome diversity

Abstract

AbstractA laboratory colony ofGlossina morsitans morsitansWestw. which originated from puparia collected near Kariba, Rhodesia was more productive than another colony which originated from Handeni, northern Tanzania; during 1975, the former produced an average of 5–9 puparia per female and the latter 3–6. Although mortality in the Tanzanian colony was somewhat higher than in the Rhodesian colony, the main reason for the lower productivity of the Tanzanian colony was the much poorer fecundity of the females. This was associated with abnormalities of the reproductive system. The differences in laboratory performance between the two stocks were probably a reflection of their genetic diversity. Thus the Tanzanian Y chromosome is metacentric compared with the almost acrocentric Y chromosome of Rhodesian males, and some individuals carry small metacentric supernumerary chromosomes which are not present in Rhodesian flies. Giemsa C-banding showed band differences between the chromosome complements of the two stocks. Probably the most important difference, revealed by polytene chromosome analysis, is a large inversion in the X chromosome of Tanzanian flies, which, together with at least one band difference, is fixed in the homozygous condition. The possible evolutionary pathways of these mutations are outlined and their significance is discussed in terms of their distribution in nature and of the performance of the two strains in the laboratory.