THE CHEMISTRY AND SYSTEMATIC IMPORTANCE OF THE GREEN WING PIGMENT IN EMERALD MOTHS (LEPIDOPTERA, GEOMETRIDAE, GEOMETRINAE)

The green colour in the wings of Emerald Moths (Geometridae: Lepidoptera) was found to be caused by a single pigment, here termed geoverdin. Contrary to previous suggestions, it is not a bile pigment; there is some evidence that geoverdin is a derivative of chlorophyll. The pigment molecule is highly labile and eluded identification. However, after resolving problems of extracting this acid- and light-sensitive substance from the wing scales (inert, exocuticular structures), we found that profiling by thin layer chromatography (TLC) provided a sensitive and cost effective comparative technique for identifying the pigment in a wide range of Lepidoptera. With the possible exception of two genera, geoverdin occurs as the primary pigment only within the Geometrinae, although it exists in trace quantities in certain other Lepidoptera. Our comparisons suggest that the presence of large quantities of geoverdin in Geometrinae is an apomorphic character for the subfamily, although its occurrence in two anomalous genera suggests that it may not have evolved uniquely. More generally, we recommend the use of TLC profiling as an invaluable technique for systematic studies involving insect pigments.