TRANSMISSION OF LEPTOGRAPHIUM-PROCERUM TO EASTERN WHITE-PINE BY HYLOBIUS-PALES AND PISSODES-NEMORENSIS (COLEOPTERA, CURCULIONIDAE)

Two weevils, Hylobius pales and Pissodes nemorensis, were studied as potential vectors of the fungus Leptographium procerum, the causal agent of procerum root disease. Transmission of the fungus to living trees was determined by caging field-collected and artificially contaminated H. pales and P. nemorensis on eastern white pine (Pinus strobus) seedlings for 24 hr and by caging artificially contaminated H. pales on 5-yr-old trees for 5 days. Feeding by artificially contaminated and field-collected adults of both weevil species resulted in transmission of L. procerum to eastern white pine seedlings and by artificially contaminated H. pales to 5-yr-old trees. To determine if transmission of the fungus during oviposition leads to contamination of the brood, field-collected adults of H. pales were allowed to oviposit on fresh white pine bolts. Oviposition by field-collected H. pales resulted in colonization of all of the bolts and contamination by L. procerum of 100% of the weevils that emerged over two subsequent generations. This study demonstrates the ability of H. pales and P. nemorensis to transmit L. procerum to seedling eastern white pines and the ability of H. pales to transmit the fungus to 5-yr-old eastern white pines. The contamination of weevils with L. procerum in eastern white pine bolts suggests that weevils may become contaminated during brood development in trees killed by the fungus.