Pieris brassicae as laboratory of synthesis of new compounds with biological potential: interaction with Brassica oleracea var. costata and Brassica rapa var. rapa.

Interactions between insects and plants have been studied for a long time, showing beneficial
and deleterious effects for both organisms. A general overview about the relationship between
glucosinolates, flavonoids and insects will be presented. Several aspects of the complex interactions
established by cabbage white butterfly (Pieris brassicae L.; Lepidoptera: Pieridae) are also
considered. The larvae of this species constitute a frequent pest of some Brassica species, which
are an important way of subsistence in several countries. As insects are unable to synthesize 

phenolic compounds or their precursors, their presence in the different stages of P. brassicae life
cycle can only arise from the food it has ingested. Deacylation, deglycosylation and sulphating
steps are known to be involved in the metabolic process. Thus, with this study we intend to
demonstrate the possible use of P. brassicae as a source of compounds with interest for the
health, unusual in nature and hard to be synthesized in the laboratory. Two examples will be
presented: the sequestration of phenolics by P. brassicae larvae fed with tronchuda cabbage
leaves (Brassica oleracea L. var. costata DC) and kept without food for one hour, and the phenolic
profiles of P. brassicae at different development stages (larvae, exuviae and butterfly), its
excrements and its host plant Brassica rapa var. rapa L.