Spontaneous recombination between wp+ the translocation breakpoint in the t: Y(wp+)30c genetic sexing strain of ceratitis capitata (wied.)

Abstract

The frequency of male recombination (r) between the translocation breakpoint, the wp+ gene, the selection coefficient (s) against wp/wp, in the genetic sexing strain T:Y(wp+)30C of the Mediterranean fruit fly Ceratitis capitata (Wied.) were measured in population experiments over 11 generations. The population was 50 females, 50 males in the first generation, after which 150 pupae were used to start each subsequent generation. A computer program was used to estimate values of r, s. The best fit to the observed data was obtained when r= 0.14 ± 0.04 per cent, s= 26.0 ±2.7 per cent. Using these estimated values, predictions were made on the frequency of brown females, white males for up to 100 generations. The frequency of white males was predicted never to exceed 0.5 per cent, to be reached after 25 generations, while the frequency of brown females was expected to exceed 33 per cent after 25 generations. Published data on the mass reared T:Y(wp+)30C strain, maintained with a population size of 240, 000 adult flies, were subjected to the same analysis, indicating a higher value of s (38.0 ± 3.2-52.0 ± 0.3 per cent) under these conditions, but a similar value of recombination. Again, the frequency of white males was predicted never to exceed 0.5 per cent as a result of recombination. When analysing published data on T:Y(wp+)101, another genetic sexing strain, a lower stability was indicated, i.e. a more rapid generation of brown females, white males than in T: Y(wp+)30C. No suitable values of s, r could be calculated from the T:Y(wp+)101 data. It is concluded that outside contamination had probably occurred in the latter strain during both periods when it was mass reared. © 1993 The Genetical Society of Great Britain.