Feulgen hydrolysis and chromosome banding in Chilocorus (Coleoptera: Coccinellidae)

Prolonged Feulgen hydrolysis of chromosomes of Chilocorus orbus Csy. and C. stigma Say produces banding patterns that are the reverse of those revealed with quinacrine; brightly fluorescing regions are unstained, but nonfluorescent regions remain relatively darkly stained. This differential reactivity at hydrolysis times that otherwise yield intense Feulgen staining confirms the need for caution in the determination of DNA values with the Feulgen reaction in material with well-defined quinacrine bands. The coincidence of DNA-specific Feulgen bands with Q-, G-, and C-bands supports the view that, in Chilocorus at least, bands reflect differences in DNA composition along the chromosome.