Mutation "white pupae" in the integument of Ceratitis capitata affects both defense and melanogenesis.

Studying defense and melanogenesis processes in the cuticle of the "white pupae" (wp) and "dark pupae" (dp) mutant strains of Ceratitis capitata, we showed that both processes function equally well only in the cuticle of dp mutants, as in the wild-type cuticle. The cuticle of wp mutants lacks the ability to form Escherichia coli aggregates and to melanize in vivo. However, in this mutant, tyrosinase and dopachrome conversion factor activities, as well as melanin content and nonself-recognition proteins are expressed as in the wild strain. The present results indicate that the inability of wp mutant cuticle to immobilize E. coli seems to be due to lack of suitable site(s) on nonself-recognition proteins for adduct formation with tyrosine derivatives by the action of tyrosinase, and the inability to melanize, very probably due to deficiency of tyrosine derivatives (tanning precursors).