Abstract
The aim of the project is to elucidate how parasitoid females localize and identify bark beetle brood, late instar larvae and pupae in or beneath the bark before their oviposition. This localization can be divided into 3 phases: 1) identify a group of bark beetle attacked trees; 2) identify a suitable bark beetle attacked tree and land on this tree; 3) the parasitoid female should localize and identify the bark beetle brood, and oviposit, she lays one egg per host. Earlier research has shown that oxygenated monoterpenes and aromatics, can guide the parasitoid females through phases 1 and 2. This project will concentrate on phase 3, the host identification, after the female has landed on the tree. The strategy of the project is to identify the involved semiochemicals by a combination of chemical and electrophysiological analytical methods. The selective electrophysiological method gives information of which compounds the parasitoid females can identify, while the combined gas chromatography and mass spectrometry is used for chemical identification. Comparisons between active 'hot-spots' and non-active controls from the same tree, will be preformed to isolate the active compounds. Identified and likely candidates for the host identification will be tested in bioassays in the laboratory and in the field. The project will also try to elucidate the source of these volatiles, as it is not necessarily compounds produced by the bark beetle brood that attracts the parasitoid females.
Sweden