Stilbenes from grapevine root: A promising natural insecticide against Leptinotarsa decemlineata.

Gabaston J, El-Khawand T, Waffo-Teguo P, et al. Journal of Pest Science. 2018;91(2):897-906. doi: 10.1007/s10340-018-0956-2.

Stilbenes are phenolic compounds which are produced in large amounts in vine and are involved in plant defence as phytoalexins. Oligomeric forms have recently proven to be the most active compounds against a wide range of parasites such as fungi, bacteria or algae. The aim of this study was to investigate the activity of a grapevine root extract which is a stilbene oligomer pool against Leptinotarsa decemlineata, a major pest of Solanaceae crops. Analysis by UHPLC-DAD-MS of the stilbene-enriched extract obtained from grapevine root (Riparia Gloire de Montpellier rootstock) highlighted twelve stilbenes at 25% (w/w). The major stilbenes found in root extract were isolated such as the tetramers vitisin B, vitisin A and hopeaphenol; the dimers ampelopsin A and E-ε-viniferin and the monomer E-resveratrol. The insecticidal effects of this extract as well as the main compounds were investigated against L. decemlineata larvae. The extract caused chronic toxicity, inhibited larval development and, to a lesser extent, inhibited food intake. The high concentrations of vitisin A and vitisin B in grapevine root contributed to this effect as they are the most toxic compounds. Outdoor pot experiments revealed the efficacy of stilbene-enriched extract with high mortality of L. decemlineata and protection of potato plants. The extract also revealed an absence of toxicity against non-targeted organisms such as earthworms (Eisenia fetida). Thus, these results strongly suggest that grapevine roots are a promising source of bioactive stilbenes for the development of natural insecticides.