STUDIES ON MELANIN— IV 



The Origin of the Pigment and the Color Pattern in 

 the Elytra of the Colorado Potato Beetle 

 (Leptinotarsa decemlineata Say 1 ) 



DR. ROSS AIKEN GORTNER 



Introduction 



Among the more important problems in the study of 

 animal pigmentation is the question as to the origin of 

 the color pattern. Perhaps one of the most common of 

 the insects which has a definite color pattern is the Colo- 

 rado potato beetle (Leptinotarsa decemlineata Say), and 

 I have, therefore, investigated the origin of the color in 

 the elytra of this beetle, and have found a possible ex- 

 planation for the cause of the color pattern. 



I have already shown that in all probability the for- 

 mation of animal pigments is due to the interaction of 

 some chromogen and an oxidase of the tyrosinase type 

 (Gortner, 1910, 1911). I have found evidence which 

 leads me to believe that the same reaction produces the 

 pigment in the potato beetle, and that the color pattern 

 of the elytra is produced by the localized secretion of 

 chromogen. 



Historical 



In so far as I am aware the only work which has been 

 done on the nature of colors in Leptinotarsa has been re- 

 ported by Tower. In an article on " Colors and Color 

 Patterns in Coleoptera" (1903), Tower discusses the 

 origin of the pigment in the Colorado potato beetle, and 

 repeats his findings in a larger work, "An Investigation 

 of Evolution in Chrysomelid Beetles of the Genus Lep- 

 tinotarsa" (1906). The biological features of the latter 



'Prom the Biochemical Laboratory of the Station for Experimental Evolu- 

 tion. The Carnegie Institution of Washington. 



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