Stilbenes are constitutively accumulated in grape canes at a high concentration of about 10 g kg(-1) DW. Some of these compounds have antimicrobial activity and are involved in grapevine defence in leaves and fruits, acting as phytoalexins. In this work, we studied their insecticidal effects against Spodoptera littoralis larvae by using an extract from grapevine canes containing 27% (w/w) of total stilbenes and the major ones isolated from this extract (E-piceatannol, E-resveratrol, isohopeaphenol, E-epsilon-viniferin and E-vitisin B). The stilbenes isolated from the grapevine extract did not show any significant antifeedant effect or acute toxicity, but they did cause chronic mortality to the larvae population of an important polyphagous pest, S. littoralis. The tetramer, E-vitisin B, appeared to be the most effective compound with LC50 and LC90 values of 134 and 298 mu g cm(-2), respectively. Significant synergic relationships were found between some stilbenes, resulting in a significant increase in the insecticidal efficacy of the mixture of these substances. Taken together, these results suggest that grapevine canes are a good source of active substances for the development of botanical insecticides.Read less <