An eye color mutant (tan) in the tsetse fly, Glossina palpalis palpalis (Diptera: Glossinidae)

Abstract

A nondeleterious eye color mutant, tan, is described as the first visible mutant in Glossina palpalis palpalis (Robineau-Desvoidy). The locus for tan is on the X chromosome approximately 24 recombination units from the locus for testicular esterase (Est-t). Homozygous (tan/tan) females and hemizygous (tan/Y) males have compound eyes and ocelli that are pink (instead of dark brown) while the flies are alive but these fade to a tan color after death. No other differences in physical appearance of flies were found. General bionomic features of tan flies are not significantly different from those of wild-type flies. The mutant flies have a lower propensity for mating than do wild-type flies in the laboratory and there is assortative mating. Approximately half the offspring produced by tan females, which had mated twice, are sired by the second mate. Wild-type and tan adults excrete kynurenine and both types have tryptophan oxygenase and kynurenine formamidase. The lesion causing the abnormal eye color in the tan mutant appears to occur late in the metabolism of tryptophan to xanthommatin, possibly at the level of retention of xanthommatin in the eyes. Key words: eye color mutant, Glossina.