Attack pattern of Platypus koryoensis (Coleoptera: Curculionidae: Platypodinae) in relation to crown dieback of Mongolian oak in Korea.
The ambrosia beetle, Platypus koryoensis (Murayama), vectors the Korean oak wilt (KOW) pathogen, Raffaelea quercus-mongolicae K.H. Kim, Y.J. Choi, & H.D. Shin, in Korea, which is highly lethal to Mongolian oak, Quercus mongolica Fisch., and is considered a major threat to forest  ecosystem health. We characterized the attack pattern of P. koryoensis along the lower trunk of 240 Mongolian oaks in relation to tree decline symptoms on Mt. Uam in Gyeonggi-Do Province, Korea during June-July 2009. For each tree, we recorded diameter at breast height (dbh) (DBH) and  P. koryoensis entrance hole density at two heights along the lower trunk (near groundline and at 1.5 m above groundline) and on opposite sides (downslope side and upslope side). Trees were assigned to one of three dieback classes: 1) apparently healthy, no or practically no wilted foliage,  and no obvious platypodine frass near the base of the tree; 2) no or only partial wilting with obvious frass near the base of the tree; and 3) apparently recently killed by KOW with all foliage wilted and mostly retained with obvious frass near the base of the tree. As dieback class increased  from 1 to 3, P. koryoensis entrance hole density increased at all four trunk locations. Attack density was highest on the downslope side of the trunk near groundline, and principal component analysis indicated that this trunk location was the best indicator of tree dieback. In addition, DBH  tended to increase with dieback class suggesting that larger trees were infested first.
Division of Forest Disease and Insect Pests, Korea Forest Research Institute, Seoul, Korea.
Jung-Su
JS
Lee
Robert A
RA
Haack
Won Il
WI
Choi
D000531:Altitude; D000818:Animals; D017753:Ecosystem; D005247:Feeding Behavior; D007303:Insect Vectors / Q000382:microbiology*; D055155:Ophiostomatales / Q000502:physiology*; D010935:Plant Diseases / Q000382:microbiology*; D018547:Plant Stems / Q000382:microbiology / Q000502:physiology; D011157:Population Dynamics; D029963:Quercus / Q000382:microbiology* / Q000502:physiology; D056910:Republic of Korea; D014197:Trees / Q000382:microbiology / Q000502:physiology; D048889:Weevils / Q000502:physiology*