[Host selection of Oncopeltus fasciatus dall. (Heteroptera: Lygaeidae): Glycosides of asclepiadaceae the chemical basis for host specificity].

The host selection of O. fasciatus is based on typical glycosides sequestered from the Asclepiadaceae. Neither the genins - characterised as 15-oxasteroids - nor the sugars are phagostimulants. After the passage through the insect the glycosides exhibit their biological activity furtheron.