Role of fungal pathogen Ophiostoma novo-ulmi in semiochemical-mediated host selection by the native elm bark beetle, Hylurgopinus rufipes (Coleoptera: Scolytidae)

Dutch elm disease (DED) is caused by the fungal pathogen Ophiostoma novoulmi which is transmitted by the native elm bark beetle, Hylurgopinus rufipes. We have found that four semiochemicals [( - )-P-pinene, ( - )-a-cubebene, (+)-spiroaxa-5,7-diene and (+)- & cadinenel from diseased American elms, Ulmus americana, synergistically attract H. rufipes, and that their emission is up-regulated in elm trees inoculated with 0. novo-ulmi. The fungus thus manipulates host trees to enhance their apparency to foraging beetles, a strategy that increases the probability of transportation of the pathogen to new hosts.