YU013 23ACQUISITION OF OPHIOSTOMA-QUERCUS AND CERATOCYSTIS-FAGACEARUMBY NITIDULIDS FROM O-QUERCUS-COLONIZED OAK WILT MATS

Field experiments were conducted to determine whether the frequency of Ceratocystis fagacearum and Ophiostoma quercus propagule acquisition by nitidulids visiting oak wilt fungal mats is affected by the presenc e of O. quercus on the mats. Augmentation sprays with O. quercus were used to achieve different levels of mat colonization by that fungus. T he extent of colonization by O. quercus 7 to 14 days after spraying wa s greatest for postmature mats with open cracks (>0.5 cm) observed on the spray date (P < 0.02). Specifically, all six subsamples assayed pe r mat for 16 of 18 open, O. quercus-sprayed, postmature mats yielded O . quercus. The frequency of nitidulids with O. quercus was also highes t (83%) for those collected from O. quercus-treated, postmature mats t hat were open on the spray date. The frequency of nitidulids with viab le C. fagacearum (88%), however, was also greatest for beetles from th e postmature mats. Thus, O. quercus colonization did not affect vector acquisition of C. fagacearum from the mats. In addition, O. quercus v ectored by nitidulids probably does not result in natural biological c ontrol of overland transmission of C. fagacearum at fresh wound surfac es on healthy oaks, as previously suggested.