SEMIOCHEMISTRY OF CABBAGE BUGS (HETEROPTERA, PENTATOMIDAE, EURYDEMA AND MURGANTIA)

The semiochemistry of the common North American pest of crucifers, Mur gantia histrionica (Hahn) (the harlequin bug), and two related Europea n species, Eurydema ventrale L. and E. oleraceum L., was investigated. The metathoracic scent glands of these warningly-colored stink bugs ( Pentatomidae) are smaller than the scent glands of most cryptically-co lored pentatomids, and the secretions from the scent glands of Murgant ia and Eurydema species include two heretofore unknown natural product s: (2E,6E)-octadienedial and (2E,6E)-octadiene-1,8-diol diacetate. It also was discovered that when harlequin bug adults are squeezed, they expel a frothy fluid from the margins of the prothorax with a distinct ive odor due to the presence of 2-sec-butyl-3-methoxypyrazine and 2-is opropyl-3-methoxypyrazine. The presence of alkylmethoxyprazines in the expelled fluid of harlequin bugs extends the known distribution of th ese compounds to include the Heteroptera, and strengthens the argument that this class of pyrazines constitute a universal warning order equ ivalent to the color red as a visual warning signal.