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Genetic control of hylemya antiqua ii: can inbreeding depression be a serious obstacle to the development of homozygous rearrangement lines

Entomologia experimentalis et applicata 1977 pp. 207-216
Delia antiqua, adults, chromosome translocation, egg hatchability, eggs, homozygosity, inbreeding, inbreeding depression, larvae, mortality, pests, pupae, sex ratio
In relation to the homozygosing of chromosomal translocations, eight control lines of Hylemya antiqua (Meigen) were maintained for three generations by full sib mating. During the course of inbreeding, several biological parameters were measured, namely egg, larval and pupal mortality, adult-mating propensity and adult sex ratio. In five of the lines there was a significant reduction in egg hatchability. The egg, larval and pupal mortality data were converted to k values in order to illustrate the relative importance of these three developmental stages. Larval mortality was the most significant contributor to fitness reduction. There was a gradual divergence of the k values for these three parameters as inbreeding progressed. No effect of inbreeding on mating propensity or sex ratio was demonstrated. The results are compared with the effect of inbreeding on fitness in other pest species, and wide differences in the response of different species became apparent. For Hylemya antiqua the total effect of three generations of full sib mating does not cause a very large reduction in fitness. As the degree of inbreeding necessary to produce a homozygous translocation line is less than that produced by three generations of full sib mating, it is concluded that inbreeding depression will not seriously interfere with the isolation of such rearrangement lines.