Transmission efficiency of the sigma virus in natural populations of its host, Drosophila melanogaster.

A study of the viral samples collected in French natural populations of Drosophila melanogaster since 1969, indicates that natural populations include, as expected, both stabilized and non stabilized infected individuals. In agreement with previous observations made on other characters of the virus, the viral samples collected appear to be homogeneous for the efficiency of the hereditary transmission. However, this efficiency is greater than the average value observed with virus perpetuated in infected laboratory fly strains. One sample collected in Gabon and three in the U.S.A. appear to differ from the French samples for one at least of the traits studied in these experiments.