2007년에 잣나무림에서 하늘소과, 바구미과, 나무좀아과에 속하는 천공성 딱정벌레 군집을 말레이즈 트랩을 활용하여 조사하였다. 하늘소류 15종 184 개체, 바구미류 17종 185개체, 6종 1,246개체의 총 1,615개체 천공성 딱정벌레가 채집되었고 우점종은 왕녹나무좀이었다. 개체수에 따 라 순위를 매겼을 때, 잣나무림에서 천공성 해충과 나무좀류 군집은 나무좀아과의 한 종에 의해 우점되어 생물다양성이 낮은 것으로 나타났다. 잣나 무림에서 간벌은 나무좀과 암브로시아좀류의 풍부도에 영향을 미쳐 특정 임분에서의 개체군들은 간벌 1년 후 밀도가 증가했으나 그 후 감소하였다.

Metam-sodium has been generally applied to control Pinus koraiensis, P. densiflora and P. thunbergii infected by pine wilt disease in the forest field of Korea. We determined the atmospheric concentration of nematocidal and insecticidal gaseous methyl isothiocyanate (MITC) and more volatile and toxic gaseous methyl isocyanate (MIC) in the metam-sodium fumigated fields depending on the distance from metam-sodium treated site, time and season by OSHA No. 52 method. Determined atmospheric MIC was below acute exposure limit (50 ㎍/㎥) and chronic exposure limit (1.0 ㎍/㎥) of EPA regulation in all detection point. In summer, the maximum of MITC and MIC was observed to 105.2 ㎍/㎥ in the 1st day and 0.41 ㎍/㎥ in the 4th day after metam-sodium treatment, respectively. On the other hand, in winter, the maximum of MITC and MIC was observed to 4.6 ㎍/㎥ in the 4th day and 0.52 ㎍/㎥ in the 5th day after metam-sodium treatment, respectively. Atmospheric concentrations of MITC and MIC were higher the closer to the metam-sodium treated site, but decreased below LOQ with distance (~ 50 m). This result showed that the reaction rate of metam-sodium to MITC is more affected by temperature and the translation rate of MITC to MIC is generally very low, regardless of season.

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.

To develop an empirical degree-day model for predicting the spring flight period of the bark beetle, Ips subelongatus Motschulsky, based on field observation, field studies were biweekly conducted in three Japanese larch (Larix kaempferi) forests in In-je, Korea from 2013 to 2014. To validate this degree-day model, we compared the model-predicted values with observed emergence data of I. subelongatus in 2015 spring at one of the sites. The flight period of over-wintering generation began on April and ended May, and flight of next generation lasted until October. The lower developmental threshold temperature (LDT) was estimated using spring emergence of I. subelongatus and field temperatures. Then a degree-day model was constructed, based on LDTs estimated from field observations data. The baseline temperature with the highest coefficient of determination was considered the LDT, and this was estimated to be 6.0℃. The explanatory power of the model was 88%. This model accurately predicted the flight of I. subelongatus in 2015 spring, as the estimated median flight dates was 1 days earlier than the corresponding observed flight date. The results of the goodness-of-fit test did not differ between observed and estimated values (ks = 0.21, P = 0.54).

The effects of thinning on community diversity of wood-boring beetles were examined in Japanese Larch (Larix kaempferi) forest in In-je, South Korea in 2013. Three study sites were selected and thinning in the plots was conducted in 2010, spring 2012, and autumn 2012, respectively. Wood-boring beetles were collected every week using the 12-unit Lindgren multi-funnel traps with pheromone lure (Ipsdienol +50/-50 40mg, Ipsenol +50/-50 40mg) from mid-April to early November. Total 5 families (Cerambycidae, Curculionidae, Dryophthoridae, Scolytidae, Platypodidae), 62 species, and 26,638 individuals were collected. Diversity indices were 2.08, 2.02 and 0.76, and evenness indices were 0.55, 0.49 and 0.19 in 2010, spring 2012 and autumn 2012 thinning area, respectively. Among wood-boring beetles, the number of species of bark and ambrosia beetles were accounted for 44.4, 41.9 and 46.3% in 2010, spring 2012 and autumn 2012 thinning area, respectively. The number of individuals of bark and ambrosia beetles were accounted for 86.9, 82.2 and 98.4% in 2010, spring 2012 and autumn 2012 thinning area, respectively. Our results showed that the density of wood-boring beetles was the highest in the most recent thinning area, suggesting that thinning timing can influenced on the abundance of bark and ambrosia beetles. Among them, Ips subelongatus, I. acuminatus, and I. sexdentatus are species that mainly attack Japanese Larch. Ips subelongatus emerged faster than others and was the most dominant species.

This study examined the effects of environmental factors on the abundance of black pine bast scale (BPBS), Matsucoccus thunbergianae Miller and Park, in coastal disaster prevention forest stands composed mostly of Japanese black pine. Geographical factors, soil conditions and forest stand conditions were measured to evaluate the hazard rating for the occurrence of BPBS from 35 plots in the coastal forest stands. To assess the hazard rating, a combination of a self-organizing map (SOM), which classified the samples according to their characteristics, and a random forest model, which predicted the probability of the occurrence of BPBS from SOM results, was used in this study. Our results showed that major factors determining the abundance of BPBS were climate, tree size, and tree health. BPBS was more common in low latitude coastal forests, suggesting that warmer conditions were favorable to BPBS population buildup. Tree size also influenced the abundance of BPBS, which was higher in forests composed of larger trees (greater DBH). Finally, BPBS was also more abundant in areas with high soil salinity and clay-loam soil, and north-facing slopes where tree vigor was lower.

The species diversity of macrolepidoptera (larger species of moths) was surveyed using light traps at forests near the Forest Environmental Research Institute located in 9 provinces (Gyeonggi, Gangwon, Chungbuk, Chungnam, Jeonbuk, Jeonnam, Kyeongbuk, Kyeongnam, Jeju) in 2012. Sampling was conducted weekly or biweekly from April to October. Using light traps in 8 forests, 2,961 individuals belong to 530 species from 20 families were collected. The species richness between study sites ranged from 4 (Kyeongnam) to 258 (Chungbuk). Similarly, abundance was the highest at Gyeonggi (1,235 individuals) and lowest at Kyeongnam (11 individuals). Species diversity (H’) was the highest at Chungbuk (5.14) and lowest at Kyeongnam (1.29). Composition of macrolepidopteran species also changed seasonally, showing regional variations. Dominant species in 9 study sites were Lamoria glaucalis in Gyeonggi, Ivela auripes in Gangwon, Idiotephria amelia in Chungbuk, agrotis tokionis in Chungnam, Acosmeryx naga in Jeonbuk, Glyphodes perspectalis in Jeonnam, Spodoptera depravata in Gyeongbuk, Xestia dilatata in Gyeongnam and Lithosia quadra Jeju. Among the species, Ivela auripes, Lamoria glaucalis, and Glyphodes perspectalis were known to be sporadic forest insect pests. Therefore, continuous monitoring can be needed to prevent the potential outbreaks of such insect pests.

The dispersal distance and the flight behaviour of adult Platypus koryoensis were examined using mark-release-recapture experiment in central Korea in 2013. Sticky traps were attached to the trunks of oak trees toward release point and opposite direction up to 48.8m from the release point. For each direction, two traps were attached on upper (1.5m from ground) and lower (0.5m from ground) trunk. Platypus koryoensis which emerged within 24 hours were marked with fluorescent powder and released at 11:00 a.m. The number of recaptured beetles was counted after 30 and 90 minutes after release. The experiment was replicated three times on 20, 21, and 26 June. The numbers of beetles released were 299, 810, and 208, respectively. Recapture rates at 90 minutes after release on 20, 21, and 26 June were 0.09, 0.06, and 0.03, respectively. More than 85 percent of recaptured beetles were caught in 30m. The numbers of beetles caught by sticky traps in upper and lower trunk were not significantly different, indicating that P. koryoensis do not hover but just land and move to explore suitable for living site in trunk when they attack oak tree. The valley breeze which drive upward the valleys and mountain slopes in the daytime blew during experiment periods and maximum flight distance of P. koryoensis was 43m, even though the beetles flew against the wind.

The fall webworm, Hyphantria cunea (Drury) (Lepidoptera: Arctiidae), was originally distributed in North America and spread into central Europe and eastern Asia in the early 1940s. This species was first found in Seoul, Korea in 1958. In this study, the effect of temperatures on development in regional variation of the H. cunea was investigated. Local populations of fall webworm were collected in Goyang and Pusan, Korea and the larvae were reared on an artificial diet, incubated at seven constant temperatures of 17.5, 20.0, 22.5, 25.0, 27.5, 30.0 and 32.5℃ under the photoperiod 16L:8D. The average developmental periods decreased as the temperature increased at all stage in the Goyang population. The temperature dependent developmental rates in each stage were well described by linear and nonlinear Briere model in the Goyang population. The lower threshold temperature for development from egg to adult was 13.7℃ and all the eggs did not hatch at 32.5 ℃. Optimum temperatures for reproduction was 22.5℃, and average number of eggs laid by individual female at the temperature was 441.5±121.8. Developmental periods of larval and pupal stage in the Goyang population were not significantly different from those in the Pusan population at 25℃.

Escape pattern of the ambrosia beetle Platypus koryoensis (Murayama) based on individual gallery was investigated. The survey was conducted in four oak forests located in Chuncheon, Hanam, Paju and Seongnam, and escape patterns from individual gallery were surveyed using emergence trap attached at the entrances of galleries formed in 2010. The number of adults caught in each trap was periodically counted from May 2011 to September 2012. The adults ambrosia beetle was caught over two years after infestation. The escape patterns in the first and second year after infestation showed different types; in the first year, escape of adults from gallery was observed one or two times whereas escape from gallery was observed two times in the second year with variation in aspect of escape density and timing. Moreover, variations in escape pattern between trees or between galleries in the same tree was observed. Colonization success rate in living tree was higher than that of dead tree, but the number of progeny per gallery in living tree was lower than that of dead tree. Colonization success rate in the galleries of second year was lower than that of first year, but the number of progeny per gallery of second year was higher than that of first year.

The diurnal flight pattern of Platypus koryoensis (Murayama) was examined using sticky traps attached to the trunks of oak trees in central Korea in 2011. The flight activities of the beetle were estimated on the basis of 2-h interval trap catches from 05:00 to 17:00, between June 9 and July 21 (the peak flight period of the beetle). Peak flight time of the beetle ranged from 09:00 to 13:00, with variations due to the day surveyed and the facing slope. The flights began when the air temperature reached 16.7 °C, and the flights peaked when the air temperature was 23.6 °C. Flights were not observed during rainfall, suggesting that rainfall is one of the factors that influence beetle flight. The time of sunrise was not significantly correlated with the flight initiation time. The direction of flight along with the slope was changed bidirectional to unidirectional (movement from upslope to downslope) between 9:00 and 13:00.

Population dynamics of maize weevil, Sitophilus zeamais, and their parasitoids Anisopteromalus calandrae were examined while considering the spatio-temporal interactions using population modelling as a tool. The modelling of two species host-parasitoid systems identified the some factors concerning the long-term dynamics of interacting populations. In the single host system, the total density of S. zeamais increased exponentially and reached a saturated, asymptotic level with time. This stabilization in the density could be explained by the spatio-temporal dynamics among the patches. S. zeamais disperses continuously from patches of high density to those of low density. This density-dependent dispersal could be one of the mechanisms for stabilizing the S. zeamais population density. In the S. zeamais-A. calandrae system, both populations showed long-term coexistence. The long term coexistence could be attributed to spatio-temporal interactions of S. zeamais and A. calandrae resulted from dispersal of host and a non-random searching behavior of the parasitoid. Because such spatio-temporal variation in population dynamics, the overall host-parasitoid system may have been in a stable state, although the local population system in each patch was unstable.

The wood-boring and bark beetle (Cerambycidae, Curculionidae, Scolytinae) community in Korean white pine, Pinus koraiensis Sieb. & Zucc., forests was surveyed using Malaise traps in 2007. A total of 1,669 wood-boring and bark beetles were collected, including 193 cerambycids from 16 species, 221 curculionids from 21 species, and 1,255 scolydid beetles from 6 species, of which the dominant species was the ambrosia beetle Xyleborus mutilatus Blandford. Ranked by order of population size, the wood-boring and bark beetle community in Korean white pine showed high dominance by one species of Scolytinae, suggesting the community was unstable and had low biological diversity. Thinning in Korean white pine forests influenced the abundance of bark and ambrosia beetles, whose populations in particular stands increased 1 year after thinning, and then decreased the following year.

An ambrosia beetle, Platypus koryoensis, is a vector of Raffaelea quercimongolicae that is known to cause Korean Oak Wilt (KOW), one of the serious threats to forest healthy in Korea. To manage P. koryoensis properly, it is necessary to clarify flight period of the adult. This experiment was conducted to elucidate the relationship between temperature and the flight period based on field observation in three forests consisted of Quercus mongolica from 2007 to 2009 except winter season. Date of flight period for 50% (FP50) was estimated by the cumulative Weibull distribution model based on cumulative proportion of the adult density and air temperature. Relationship between site temperature and the date of FP50 of P. koryoensis was the most significant when temperatures below 6.5℃ were excluded, suggesting lower threshold temperature for the flight period based on the site temperature. The pooling cumulative proportion of flight period against degree days was well described by the degree-day model, which has explanatory power for the 89% of year and site variation in the flight period and predicted accurately the flight pattern in 2011.

Spatio-temporal distribution pattern of an ambrosia beetle, Platypus koryoensis (Murayama) which is vector of Raffaeleaquerci-mongolicae K.H. Kim et al, a causative agent for Korean oak wilt (KOW) was examined in the stand level. Spatial distribution of P. koryoensiswas influenced by their density. Relationship between degree of aggregation and density was positively correlated when the density was extremely low or high whereas the relationship was reverse when the density was intermediate. Patch of P. koryoensis formed around or near dead trees or partial dead trees, suggesting these trees indicated epicenter of P. koryoensis. Fraction of trees attacked by less than 100 individual of P. koryoensis in the stand per year increased abruptly whereas fraction of trees attacked over 1,000 individuals of P. koryoensis increased gradually. Our results showed that the dead trees would be an epicenter of P. koryoensis and the number of trees killed by the ambrosia beetle would be reduced by lowering total population of the ambrosia beetle around the epicenter.

The developmental time and survival of overwintering larvae of Monochamus saltuarius were studied at 7 constant temperatures (16, 20, 23, 25, 27, 30, 34℃), and a photoperiod of 16 : 8 (L : D) h. The total mortality of overwintering M. saltuarius was lowest at 27℃ (7%) and highest at 34℃ (93%). The total developmental time decreased with increasing temperature between 16℃ (49.48 days) and 34℃ (13.00 days). The relationship between the developmental rate and temperature was fitted by five nonlinear developmental rate models (Logan 6, Lactin 1, 2 and Briere 1, 2). The nonlinear shape of temperature development was best described by the Briere 1 model (r2=0.99). The developmental variation of overwintering larvae was well described by the three-parameter Weibull distribution model (r2=0.98). The temperature-dependent developmental models of M. saltuarius developed in this study could be used to predict emergence period of the adult, or to develop a population dynamics model of M. saltuarius.

The larval parasitoid, Bracon hebetor, attacks third or older larvae of indianmeal moth (Plodia interpunctella), which results in laying eggs or simply paralyzing the larvae. We studied the influence of the parasitoid’s attack on the larval development of indianmeal moth. The third larval instars of the same age were collected from the experimental colonies and each larva introduced in an acrylic cube (2 x 2 x 2 cm) treated with: 1) empty, 2) three rice grains, 3) three rice grains and a female parasitoid without ovipositor (by removing) and 4) three rice grains and a paralyzed larva. The larval activity in the experimental cube was photographed every five minutes until the larva died or pupated. Only the larvae in the cube with paralyzed larvae could pupate and emerge. The other larvae in the three treatments died before pupating, although the survival time was significantly different in relation to the treatment (F=5.27; df=2,14; P=0.019); the larvae in the empty cube had a shorter survival time than those in the rest of treatments. The results indicated that the paralyzed larvae could be fed by the health larvae and contribute to prevent population crush in the situation of food shortage with the presence of the parasitoids. The host parasitoid interaction between indianmeal moth and Bracon hebetor might not always be negative to the indianmeal moth population.

Dynamics of prey/host and predator/parasitoid interaction has been the main concern of the population ecology during the second half of the 20th century. Many theoretical and experimental studies have been conducted and discussed. The main questions were whether the interaction could be in stable state and whether the parasitoid/predator could regulate the host/prey populations, and if so at what levels. The questions are not yet solved, but some hypotheses have been presented that the prey/predator interaction could be in stable state, when both the predator and prey population are under intraspecific competition so that both populations could be limited at a low levels. This prerequisite, however, could not be easily satisfied in nature and several hypotheses have been discussed up to date. Biological control of pests, which is based on the predator-prey system dynamics, has not always been successful, because we do not understand the systems sufficiently. Thus, most successful cases of the biological control were dependent upon ‘trial and error’. But as the predator-prey system dynamics could be well understood in the future, more systemic control program of biological control could be possible. In this review, we analyzed the studies for biological control of pests in Korea based on 164 cases reported in the last forty years and will consider the future goal of the studies for more reliable control programs.

The effects of the genetically modified virus-resistant pepper (line: H15) and the Non-GM pepper (line: P2377) on the insect community in the pepper cultivation area were evaluated. Sampling was conducted using yellow sticky traps and pheromone funnel traps in Anseong and Deokso fields. Total number of insects caught on sticky trap were 3924 individuals at GM pepper and 3670 individuals at Non-GM pepper in Anseong and 2362 individuals at GM and 2528 individuals at Non-GM in Deokso, respectively. The total number of the insect individuals caught by sticky trap was not shown significant differences between GM and Non-GM pepper at Anseong and Deokso fields, respectively. The number of aphids per sticky trap ranged from 11.60±2.02 to 1.92±0.96 at Non-GM and from 11.56±2.15 to 0.33±0.23 at GM in Anseong, and from 2.78±1.22 to 0.11±0.08 and from 2.73±0.84 to 0.11±0.08 at Non-GM and GM pepper in Deokso, respectively. There were no significant differences in seasonal occurrences of aphids caught on sticky traps in GM and Non-GM pepper at both fields, and significant differences in aphids population density between Non-GM and GM were not observed.