Numerous insects live in forests as a component of forest ecosystem. Forest insect pests are defined certain insects when they adversely affect ecological, economic, and social values that we associate with forest. Kinds of forest insect pests are continually changed as a result of change of forest ecosystem and the introduction of foreign alien insect pests. Forest pest management is the maintenance of destructive insects at tolerable levels by the planned use of a variety of preventive, suppressive, or regulatory tactics and strategies that are ecologically and economically efficient and socially acceptable. However, the system of forest pest management is slighly different according to the nation and case of insect pests. Currently, the most important insect pests of Korea are Monochamus beetles and Platypus koroensis, which are insect vectors of pine wilt disease and oak wilt disease, respectively. Major forest insect pests are Thecodiplosis japonensis, a gall maker of pine needle and sapsucking insects such as black pine bast scale, Matsucoccus thunbergianae, Corythucha ciliata, Lycorma delicatula. Defoliating insects, such as Dendrolimus spectabilis, Hyphantria cunea, Agelastica coerulea, Acantholyda parki, and phloem boring insects, such as Tomicus piniperda and Ips bark beetles are also regarded as major forest insect pests. Management of forest insect pests are different from kinds of insect species. Control methods currently used are as follows; (a) Chemical control : ground and aerial spray of low-toxicity insecticide, trunk injection of systemic insecticide, fumigation, etc. (b) Biological control : release of parasitic wasps, use of Beauveria bassiana. etc. (c) Physical or mechamical control : burn, crush, etc. (d) Silvicultural practice : salvage cutting, clear cutting and reforestation, breeding of resistant trees, etc.

Pine wood nematode, Bursaphelenchus xylophilus, is a causative organism to induce pine wilt disease in many varieties of pine trees. Until 2006, Monochamus alternatus had been known as the only insect vector of pine wood nematode in Korea which targeted on Pinus densiflora (Japanese red pine) and P. thunbergii (Japanese black pine). However, pine wilt disease was also reported from Korean pine tree (Pinus koraiensis) in 2006 and we found another insect vector, M. saltuarius, was involved to transmit pine wood nematode. Both Monochamus species were confirmed to transfer pine wood nematode to their hosts but, there is no detail information about other transmitted nematode. Especially Bursaphelenchus mucronatus is common species transmitted by Monochamus species which is morphologically closed to B. xylophilus. Moreover B. mucronatus have two genotypes; one is East Asian type and the other is European type. Both genotypes of B. mucronatus were found in Korea but, the host and vector information related to the genotypes of B. mucronatus was not clear. Monochamus saltuarius was collected from three different geographical locations and nematodes were extracted and identified. For the identification of the juveniles, nematode DNA was extracted and ITS-RFLP analysis was done by PCR and gel electrophoresis. The selected enzymes were Hinf I, Alu I, Msp I, Hae III, Rsa I. Most of Bursaphelenchus species carried by M. saltuarius, which collected from pine wilt disease-free area, was determined as European type of B. mucronatus. We will compare the nematode species and genotypes carried by M. alternatus and M. saltuarius. In addition the rate of nematode carrying insect and the average number of nematode per single insect will be counted and compared.

Pine wood nematode(PWN), Bursaphelenchus xylophilus, is a causal organism to induce pine wilt disease in many varieties of pine trees. PWN is mainly distributed in the East Asia including Japan, China, and Korea, but it was originally imported from the North America of the West. Over 70 species of Bursaphelenchus have been reported, but they are morphologically similar to each other. In Korea, only two species of Bursaphelenchus xylophilus, B. mucronatus (both Asian type and European type) have been reported however, a recent survey showed the distribution of extra species of Bursaphelenchus in dead trees. Three isolates, BSPD-1, BSPD-2, and BSPL-1, were identified as Bursaphelenchus thilandae, B. hylobianum, and B. doui, respectively, which was determined by both morphological and molecular biological characteristics. Both BSPD-1 and BSPD-2 were originally collected from Pinus densiflora in Namyangju and BSPL-1 came from Liriodendron tulipifera in Wanju. The morphology of each species were compared from the original descriptions focusing on male spicule and female tail and reproductive organ. A molecular diagnosis method, ITS-RFLP was applied to confirm morphological identification. Genomic DNA was extracted from a single individual nematode and ITS DNA was amplified by PCR. Amplified ITS was digested by 5 different restriction enzymes (Rsa I, Hae III, Msp I, Hinf I, and Alu I) and provided a discriminatory profile for different species of Bursaphelenchus. The three species, B. thilandae, B. hylobianum, and B. doui, are all unrecorded species in Korea.

Pine wilt disease (PWD) is one of the most serious forest tree diseases and now the damaged area covers 7,877 ha and more than 60 cities in Korea. The causal agent of PWD, Bursaphelenchus xylophilus is transmitted by the insect vectors, pine sawyers (Monochamus spp.). Spread of PWD damage and control effect for PWD are directly related to dispersal potential of Monochamus spp. vectors. Recently, harmonic radar technology has been applied as a means for tracking individual dispersal of tagged insects. Tracking insects with harmonic radar system is similar to a mark-and-recapture technique, in which an organism is tagged, released, and recaptured. Our objective is to develop a harmonic radar tracking system by using lightweight tags to investigate dispersal of Monochamus spp., insect vectors. The harmonic radar system consists of two parts: a commercially available, light-weight (1.6 kg), handheld transceiver (RECCO Rescue System) and a small tag that reflects the transceiver signal (917 ㎒) at harmonic frequencies (1,834 ㎒). A tag consists of a miniature diode (Toshiba ISS350) with wires (36-gauge tinned copper) soldered using conductive epoxy on each side to produce a dipole antenna. These tags were evaluated in an open field to assess their maximum detection range, and at tag length of 13 ㎝, the tag was detected at >100 m.