Elm bark components and their potential influence on bark beetle feeding

Abstract

In order to better understand the chemical factors involved in the host feeding selectivity by Scolytus, components were extracted from elm bark and studied. Sampled trees were located in an elm stand that survived the Dutch twig elm disease pandemia, and from elm clones from throughout the Iberian Peninsula. The main samples studied were from Ulmus minor, and the other samples from U. pumila, U. laevis and several hybrids. The main compounds in the extracts obtained from current-year twigs were aliphatic hydrocarbons (particularly heptacosane and nonacosane) and from 2- to 4-year-old stems were triterpenes. Three of the triterpenes were identified for the first time in Ulmus (lupenol, alnulin, and ilexol) and two in Ulmaceae (moretenol and betulin). Differences occurred in the compounds isolated from U. minor from the two locations, and between species.