Abstract
Several levels of plant/insect-interactions on the basis of secondary compounds are
described and illustrated with some examples. Plant secondary substances, originally
accumulated for defense, are tolerated by adapted insects. Hence, plants have had
to accumulate new secondary constituents during evolution for their protection. Adapted
insects are able to use former plant repellents as attractants and, after collection
or sequestration, as allelochemicals for several purposes. Some insects produce substances
for defense that are structurally typical plant secondary compounds; in one case biosynthesis
and uptake from the host of the same substances occurs. It is concluded that secondary
metabolites are of great significance for the coexistence and biochemical development
of plants and insects.
1 Plenary Lecture given at the 36th Annual Congress of the Society for Medicinal Plant Research, Freiburg, Sept. 1988.
2 Dedicated to Professor Dr. R. Robert Hegnauer, Leiden, on the occasion of his 70th birthday on August 1, 1989.
