Red Pigments of Dactynotus rudbeckiae and D. ambrosiae[Homoptera, Aphididae]

Abstract

THE extensive investigations of Lord Todd and his colleagues¹ have shown that several related perylene-quinone pigments, the erythroaphins (Fig. 1), can be obtained from many aphid species; the two most completely investigated representatives, the erythroaphins fb and sl, are stereoisomers of the formula C₃₀H₂₂O₈. These pigments, however, are not present in the live insect, but are formed through post-mortem enzymatic transformations of yellow precursors, the protoaphins, which do not contain the perylene nucleus^1a. In the course of research on naturally occurring perylenequinones², we have investigated the pigments of two bright red species of-the aphid genus Dactynotus, since it seemed possible that their colour might be due to preformed perylenequinones. Earlier, Todd et al.³ had observed the occurrence of very small amounts of aphin pigments in D.jaceae; D. cirsii, however, was found to contain instead a red pigment which has not been described in detail but which, from its uncharacteristic absorption spectrum, is not a perylenequinone.