LOSS OF TREE VIGOR AND ROLE OF BORING INSECTS IN RED PINE STANDS HEAVILY INFESTED BY THE PINE NEEDLE GALL MIDGE IN KOREA

Abstract

Ten species of tree borers in 3 families [Asemum amurense, Pissodes nitidus, Shirahoshizo rufescens, Hylobitelus haroldi, Niphades variegatus, Hylastes parallelus, H. plumbeus, Hylurgops interstitialis, Tomicus piniperda, Cryphalus fulvus.] were collected from bait logs and dead trees in red pine forests infested by the pine needle gall midge, Thecodiplosis japonensis. They are secondary pests and played a minor role in causing tree mortality in the stands studied. Red pine stands with about 14 k.OMEGA. of cambial electrical resistance on an average in May were very vital; those with over 21 k.OMEGA. were in high mortality as a result of attacks by the pine gall midge.