GENETICS OF A YOLK BODY-COLOR MUTATION IN PYRRHOCORIS-APTERUS (HETEROPTERA, PYRRHOCORIDAE)

A new body-color mutation, yolk body (yb), is described for Pyrrhocori s apterus. It causes a yolk-like coloration of all parts of the mutant body except the eyes, which remain red-pigmented as in the wild-type bugs. The body, particularly the forewings of older homozygous mutant adults, ranges from yolk-orange to orange-brick-red in color The yb tr ait is inherited as an autosomal recessive and exhibits complete penet rance and uniform expression in both sexes. Studies on the interaction between yb and 2 other autosomal recessive mutations, white (wh) and yellow (yw), revealed that yb is nonallelic to both of these mutations . It was shown that wh is phenotypically epistatic over yw, yw is epis tatic over yb, and that these mutations are not chromosomally linked. The relationship of the yolk-like coloration of the yb mutants to bios ynthesis of pteridines is discussed.