Phytoecdysteroids and insect-plant relationships in the Chenopodiaceae

Abstract

The functions of phytoecdysteroids remain enigmatic. The favoured hypothesis is that they reduce the extent of invertebrate predation on plants containing them, but definitive evidence for this is currently lacking (Lafont et al., 1991). This is largely because there is presently no significantly detailed body of information about the identity and developmental titres of phytoecdysteroids for any one species of plant or any group of closely related species. One of the most effective ways of testing this hypothesis would be to establish from a normally phytoecdysteroid-containing plant species genetically stable lines with elevated or reduced phytoecdysteroid levels and to assess their relative susceptiblity to insect predation. However, prior to achieving this long-term goal, it would be necessary to identify an experimentally suitable species and ascertain as much as possible about the nature and distribution of phytoecdysteroids within the plants.