This study was conducted to examine the occurrence characteristics of pine trees infected by pine wood nematode in Gyeongsangbuk-do, Korea. Based on the GPS coordinate data of the infected trees at Yeongdeok-gun from 2013 to 2014 and at Andong-si in 2014, nearest neighbor analysis was conducted to analyze nearest distance between the infected trees. And the influence of geographical factors such as altitude, slope, and the distance from the road on the position of infected trees were identified. Our results showed that over 60% of the newly infected trees were found within 50m of the trees infected in previous year. Over 70% of infected trees occurred below 100m altitude in Yoeongdeok-gun whereas less 32% of total pine trees distributed below the altitude. 98% of the infected trees and 74% of total pine trees in Andong-si were found between 150 and 300m altitude, and altitudinal distribution of the infected trees was similar to that of pine forests. Only less 5% of infected trees found in the forests located below 5 degree of slope in Yeongdeok-gun whereas 18% of total pine trees existed in the areas. Over 50% of infected trees in the forests located from 10 to 20 degree of slope, and 47% of total pine trees were found in the forests located from 5 to 15 degree of slope. Most infected trees and total pine trees were found in the forests located below 15 degree of slope in Andong-si. Over 80% of the infected trees occurred within 1km of road in both study areas.

Ips acuminatus (Coleoptera: Curculionidae) is one of the potential pests of various species of pines. To investigate the effects of thinning on I. acuminatus and Stigmatium pilosellum (Coleoptera: Cleridae), known as a natural enemy of bark beetles, were examined in Korean pine (Pinus koraiensis) forest in Chuncheon, South Korea in 2014. Three study site were selected - two sites (western slope and southern slope) that thinning was conducted in early spring 2014 and a site without thinning within 5 years. I. acuminatus and S. pilosellum were collected every week or fortnightly using the 12-unit Lindgren multi-funnel traps with pheromone lure (Ipsdienol +50/-50 40mg, Ipsenol +50/-50 40mg) from May to early October. The densities of I. acuminatus, the dominant species of bark beetles, were maximum 8.4 ± 0.9 and 1.4 ± 0.4 individuals/trap/day at thinning site and non-thinning site, respectively. In case of S. pilosellum, the dominant species of Cleridae, its densities were 17.7 ± 2.4 and 2.6 ± 0.8 individuals/trap/day at thinning site and non-thinning site, respectively. I. acuminatus showed first emergence peak on June and second emergence peak on September, but S. pilosellum showed only one time emergence peak on June – the density of S. pilosellum increased along with the density of I. acuminatus (r = 0.66, p = 0.0365). Our results shows that thinning in Korean pine forest increases the densities of I. acuminatus and S. pilosellum, reflecting increase in their food resources available.