Catecholamines in the cuticles of four strains of the german cockroach Blattella germanica (L.) during sclerotization and melanization

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Abstract
Catecholamines were extracted from the cuticles of four strains of the cockroach Blattella germanica at different times 48 h after adult ecdysis and analyzed by reverse phase HPLC with electrochemical detection. The wild (VPl), black (Bl), orange (or), and yellow (y) phenotypes differ in cuticular pigmentation, particularly in the extent of melanization. N‐β‐Alanyldopamine (NBAD) and N‐β‐alanylnorepinephrine (NBANE) were major o‐diphenolic compounds in extracts from cuticle of all strains during the main period of sclerotization. N‐Acetyldopamine (NADA) and N‐acetylnorepinephrine (NANE) were minor the first day after ecdysis, but accumulated to higher levels thereafter. Dopamine (DA) concentrations were higher in the darker pigmented cuticles of strains Bl and or than in the lighter‐colored cuticles of strains VPl and y. Extractable DA rapidly increased in VPl, Bl, and or cuticles shortly after ecdysis, reached peak levels 6–24 h later, and then decreased after melanization. Only small amounts of DA were detected in strain y cuticle, whereas NBANE concentrations were very high. Therefore, high DA levels in cuticle are correlated with melanization that occurs during the first few hours after adult ecdysis, whereas sclerotization is correlated with high levels of the N‐β‐alanylcatecholamines. Sclerotization appears to be delayed in strain Bl, since only low concentrations of the N‐acylated catecholamines accumulate until after melanization is completed.