Insect cuticle is an extracellular matrix formed primarily from two different biopolymers, chitin and protein. During each molt cycle, a new cuticle is deposited simultaneously with degradation of the old cuticle by molting fluid cuticle degrading-enzymes, including epidermal chitinases (CHTs). Insect CHTs, belonging to family 18 glycosylhydrolase (GH18), have been classified into at least eleven subgroups based on phylogenetic analyses, and group I (CHT5) and group II (CHT10) epidermal CHTs present in molting fluid. In this study we report the physiological function of MaCHT5 and MaCHT10 in the Japanese pine sawyer, Monochamus alternatus. RNAi for either MaCHT5 or MaCHT10 resulted in larval-pupal and pupal-adult molting defects, in which the insects were unable to shed completely their old cuticle and died entrapped in their exuviae. Furthermore, TEM analysis revealed a failure of degradation of the old cuticle in both MaCHT5- and MaCHT10-deficient pharate adults. In the old pupal cuticle, the chitinous horizontal laminar and vertical pore canal essentially remained intact in the endocuticular layer. These results indicate that both CHTs are required for turnover of the chitinous old cuticle, which is critical for completion of insect molting. We also discuss the possible function of two spliced variants of MaCHT10, MaCHT10a and MaCHT10b.

본 연구에서는 생태모방적 관점에서 목질을 천공하는 송곳벌과 밑드리좀벌의 산란관의 형태적 특징을 비교하였다. 벌목에 속하는 송곳벌과 밑드리좀벌은 목질부를 천공하는 유사한 특징이 있으나 실체현미경, 전계방사형주 사전자현미경, 광학현미경을 이용하여 산란관의 형태적 특징을 관찰한 결과 두 종 간에 큰 차이를 보였다. 송곳벌의 산란관 말단은 등쪽과 배쪽에 모두 규칙적인 돌기가 발달하여, 회전형 드릴 비트와 흡사한 형태를 띤 반면 밑드리좀벌의 산란관 말단은 한쪽 방향에만 몇 개의 돌기가 있고 다른 부분은 매끄러워 마치 톱과 비슷한 형태를 보였다. 또한 얼룩송곳벌 산란관의 말단은 대칭적으로 4 등분으로 되어있다가 14번째 돌기를 지나면서 2 : 1 : 1의 비율로 3등분이 되는 반면, 밑드리좀벌 산란관의 말단은 2 : 1 : 1의 비율로 3등분되어 있음을 확인할 수 있었다. 또한, 송곳벌의 산란관의 중간을 수평으로 자른 단면구조에 서는 dovetail joint의 구조가 확인되었으며, 이를 통해 천공을 위해 수직 운동을 한다는 것을 확인할 수 있었다. 이러 한 두 종의 형태적 차이는 목질 부분을 먹이원으로 이용하는 송곳벌과 벌의 유충을 이용하는 밑드리좀벌의 생활방 식뿐만 아니라 계통분류학적 차이에 의해 기인한 것으로 사료된다. 끝으로, 산란관 말단 부분의 성분분석결과 두 종 모두에서 높은 강도의 특성을 부여하는 아연이 검출되었다. 이는 주로 목질을 천공하는 두 종의 생태적 적응 과정에 의하여 특이적으로 진화된 것으로 사료된다.

Host relationships between insects and plants are one of the major factor driving evolutionary diversification within terrestrial ecosystems. Beetles (Coleoptera) are the most diverse and species-rich group of insects, and a robust, time-calibrated phylogeny is fundamental to understanding macroevolutionary processes that underlie their diversity. Recently, many studies have been carried out about the relationships among those taxa according to the attention on co-evolution of phytophagous insects and their hosts, however, most of them focused on special taxa (family or genus level) of insects. In this presentation, we especially reviewed current trends of studies on interactions between coleopteran insects and host plant in the world and Korea for proposals of future studies.

많은 산림해충들은 목재검역에서 문제가 되고 있어 포스핀(PH3)을 이용하여 광릉긴나무좀, 왕녹나무좀, 노랑애나무좀의 성충에 대한 살충 활성을 조사하였다. 3종의 나무좀류에 대하여 99% 살충활성을 보이는 LCT값은 각각 3.192 (광릉긴나무좀), 0.994 (왕녹나무좀), 0.501 mg ‧ h/L (노랑애나무좀) 순으로 나타났다. 포스핀을 처리한 3종의 나무좀류는 시간이 지남에 따라 살충활성도 증가하였다. 특히 광릉긴나무좀에서 는 0.4 mg/L 이상의 농도에서 약제처리 7일 후에 100%의 사충률을 보였다. 이러한 결과로 볼 때 포스핀이 3종의 목재해충 성충에 대해 메칠브 로마이드의 대체훈증제로 이용될 수 있을 것으로 판단된다.

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.

Wood boring insects are the major problem of many industries, such as hardwood brokers, importers, merchants, and manufacturers of furniture. Phosphine (PH3) is highly toxic to insects and is known to penetrate treated material. In this study, effectiveness of PH3 which is altered methyl bromide, was examined with Monochamus saltuaris, Platypus koryoensis, Cryphalus fulvus, and Xyleborus mutilatus. Fumigation to M. saltuaris, P. koryoensis, C. fulvus, and X. mutilatus was carried in a desiccator (12L) at 20℃ for 24 h. As a result, LC99 of PH3 to M. saltuaris, P. koryoensis, C. fulvus, and X. mutilatus was showed 0.455 mg L-1, 0.804 mg L-1, 0.243 mg L-1 and 0.046 mg L-1 in a desiccator(12L) at 20℃, respectively. M. saltuaris, P. koryoensis, C. fulvus, and X. mutilatus 100 % mortality was showed in a fumigation chamber (10 m3 and 100 m3) at normal temperature. In these results indicates that PH3 described could be useful for fumigant agent of 4 species wood pests.

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.