Reticulitermes speratus (Kolbe) is economically important pest in East Asia including Korea, Japan and China where they infest wooden structures in urban areas. In this study, we report the first record of R. speratus speratus from Korea, which was verified using soldier morphology and molecular characteristics obtained from a mitochondrial gene. R. speratus speratus Kolbe, 1885 (Blattodea: Rhinotermitidae) are found in several provinces, mainly southern regions in Korea, whereas R. speratus kyushuensis are distributed throughout the country. Our morphological comparison showed that R. speratus speratus can be distinguishable from R. speratus kyushuensis by the ratio of the posterior postmentum width to length. In the molecular comparison, R. speratus speratus revealed genetic differences of 3.06% (range 2.60–4.10%) from R. speratus kyushuensis using cytochrome oxidase subunit II gene sequences.

세계화로 인해 교역 및 여행객의 증가로 외래 병해충의 유입이 증가하고 있고 이들의 유입 및 확산 경로 규명을 위하여 분자 유전학적 분석 방법이 이용되고 있는 실정이다. 본 연구는 외래 해충인 Reticulitermes kanmonensis의 유전적 특성을 분석하기 위한 18개의 초위성체마커(microsatellite)를 이용하여 총 16개 지역(전주, 김제1, 김제2, 군산1, 군산2, 서천, 완주1, 완주2, 완주3, 완주4, 익산1, 익산2, 논산, 일본1, 일본2, 일본3)의 흰개미 244개체를 분석하였다. 집단간 대립 유전자 패턴(allelic patterns)분석결과 일본3 지역의 유전적 다양성이 높게 나타났고 완주2 지역은 다른 지역에 비해 비교적 낮게 나타났다. 집단 간 유전적 거리(Genetic differentiation)는 평균적으로 0.163정도의 유전적 다향성 비율을 나타냈고, 서천과 군산2 지역이 0.048로 낮게, 서천과 일본2 지역이 0.442로 높게 나타나 서천과 군산2 집단이 유전적으로 가깝게 나타나고, 반면 서천과 일본2 집단과는 유전적으로 멀게 나타났다. STRUTURE 분석결과는 클러스터 집단 수가 6(k=6)일때 이상적인 집단 패턴을 나타내었고, 유전적 구조는 A그룹(전주, 김제1, 완주2), B그룹(서천, 군산1, 군산2), C그룹(완주1, 김제2), D그룹(논산, 익산1, 익산2), E그룹(김제1, 완주2, 완주3), F그룹(일본1, 일본2, 일본3)의 6가지의 패턴이 지역별로 분리되어 나타났다.

외래 병해충의 유입이 증가 하고 있고 이들의 유입 및 확산 경로 규명을 위하여 분자 유전학적 분석 방법이 이용되고 있는 실정이며, 본 연구는 외래 해충인 Reticulitermes kanmonensis의 유전적 특성을 분석하기 위한 초위성체마 커(microsatellite)를 문헌을 통해 탐색하였고, NGS(Next-Gen Sequencing) 기술을 통해 새로운 초위성체마커를 개발하였 다. 문헌을 통해 Reticulitermes속에서 개발된 마커29개와 NGS를 통해 선발된 25개의 마커를 탐색 하여, 이중 증폭 및 유용성이 있는 18개의 마커를 선정하였다. 선정된 단일 마커들을 이용하여 6개의 multiplex PCR set 및 증폭 조건을 수립하여 집단유전학 분석에 활용하고자 한다.

We have determined the mitochondrial genome of Reticulitermes speratus kyushuensis Morimoto, 1968. The total length of the R. speratus kyushuensis is 15,898 bp with 65.3% A + T content. It consists of 13 protein–coding, 22 tRNA, 2 rRNA genes and an A+T–rich control region. All the protein–coding genes used ATN as start codon. But the stop codons were TAA, TAG, and an incomplete termination codon (T) abutting an adjacent tRNA gene. The A+T–rich control region was 1,105 bp in length with 67.8% A + T content

Field surveys for the genus Reticulitermes were conducted from 2013 to 2014 in Korea, and the results were compared with published data of the genus Reticulitermes. Totally, two species, R. speratus kyushuensis and R. kanmonensis were collected from several provinces, and R.kanmonensis is newly confirmed as an unrecorded species in Korea. The R. speratus kyushuensis was mainly collected in various trees, showing 0-2% genetic divergences; whereas, the R. kanmonensis was collected in pine woods of western regions, Gunsan, Wanju, Iksan (Jeollabuk-do), and Seocheon (Chungcheonnam-do). In the morphological comparison, R. kanmonensis is distinguished from R. speratus kyushuensis by more than 15 setae on pronotum and reveals 7.0% genetic difference (in a mitochondrial COII gene) from R. speratus kyushuensis in the molecular comparison.

The Japanese termite, Reticulitermes speratus Kolbe, is distributed in Korea widely. Although, termites are not currently a great problem in Korea, it might be increased commercial losses from imported timber. Phosphine (PH3) is very effective fumigant and is widely used to control pests. Oxygen treatment was found to enhance phosphine toxicity and reduce fumigation time against various life stage of insects. In this study, we determined efficacy of oxygenated phosphine fumigation for controlling R. speratus. Fumigation to adults of R. speratus was carried in a desiccator system at 20.9% (normal), 50% and 80% of oxygen concentration for 24 h. Fumigations under higher oxygen levels greatly increased phosphine toxicity to R. speratus. Mortality of termite was increased 15.0% and 16.2% in the 50.0% and 80.0% oxygen concentration with 0.25 mg L-1 phosphine at 5℃, respectively. 100% mortality was determined in 80.0% oxygen concentration with 0.5 mg L-1 phosphine at 5℃. Oxygenated phosphine fumigations have marked potential to improve insecticidal efficacy against R. speratus. These results merit further study as potential fumigant for control of wood destroying pests.

Subterranean termites bring enormous damages on wooden buildings and cultural properties (e.g., ancient temple, historical documents). Due to temperature increase in climate, there is a strong potential for termites to disperse in temperate zone widely. Since subterranean termites construct complex nests, diverging vertically from the horizontal network, we measured “movement efficiency” to address how fast termites pass through the tunnels in different slopes. Artificial tunnels were constructed on observation arena (curvature of 3cm) across different slopes (20o, 40o and 60o between the plate and ground). The passing time of the tunnel by single individual was subsequently measured. When the angle was 20o, there was no significant difference in movement efficiency (7.37 ± 1.07sec) compared with the case without slope (7.84 ± 1.35sec). As the angle was further increased, however, passing time increased. The mean time was approximately 8.79 ± 2.45sec and 14.83 ± 2.479sec at angles 40o and 60o respectively. It was also noteworthy that the termites showed the tendency to avoid entering into the tunnel. Optimization in nesting was further discussed between cost (i.e., energy requirement) and benefit (i.e., foraging efficiency) in tunnel construction.

Part of a field survey to assess the extent of damage by termite (Reticulitermes speratus kyushuensis Morimoto), termite samples were collected from various locations of Korea from 2009 to 2011. During the study period, we firstly discovered Reticulitermes species on Jeju island, and partial sequences of mitochondrial COII gene, which is proved useful to study phylogenetic relationships of termites were investigated. Also, morphological characteristics of the collected samples were compared with previous reports. According to the result of taxonomic study and comparative sequence analysis, it was identified as Reticulitermes speratus kyushuensis Morimoto, and this is first report of R. s. kyushuensis from Jeju island in Korea which can be used as estimation of population structure and tool of control strategy.

Methyl bromide (MB) is a widely used fumigant in most of the countries for quarantine purpose. However, MB has been phasing out and under control in many countries because it is listed as an ozone-depleting substance under the Montreal Protocol. In this study, we have investigated the effectiveness of phosphine fumigation on wood pests for developing an MB alternatives. We evaluated two bioassay methods; wooden cube (10×10×10 cm) and normal fumigation procedures in comparison with effectiveness of phosphine (PH3) penetrations into the timber block. Fumigation to adults of Reticulitermes speratus was carried in a desiccator system for 24hr at 5 and 15 ℃. As a result, LC99 of PH3 to R. speratus in wooden cubes and insect breeding dish at 5℃ was 0.183 and 0.177 mg L-1, respectively. LC99 of PH3 in wooden cubes and insect breeding dish at 15℃ was 0.077 and 0.078 mg L-1, respectively.

Field survey to estimate extent of damage to Reticulitermes species were conducted from 2009 through 2011 in the various locations of Korea. We discovered Reticulitermes species from three different locations of Jeju island. Partial COII sequences of mt DNA and morphological characters were collected and compared with previous reports. As result of comparative sequence analysis and taxonomic study, it was identified as Reticulitermes speratus kyushuensis Morimoto 1968 and this is first report of Reticulitermes speratus kyushuensis from Jeju island in Korea which can be used as estimation of population structure and tool of control strategy.