Ju-Hwan Han

Seasonal Occurrence and Morphological Measurements of Pine Sawyer, Monochamus saltuarius Adults (Coleoptera: Cerambycidae)

Abstract To investigate the seasonal occurrence of the pine sawyer, Monochamus saltuarius , its emergence rate was observed in pine log and Korean white pine log conditions after the logs were cut to a regular size and placed in a netted cage. Numerical measurement was also conducted for sex ratios, fresh weight, body length and width, head width, and length of adult antennae. In the Korean white pine logs, the first day of emergence occurred on May 2, the day of peak emergence observed on May 29, and the last day of emergence was on June 10. In the pine logs, the first day of emergence occurred on May 7, the day of peak emergence was observed on May 22, and the last day of emergence was on May 30. The period of seasonal occurrence observed for the pine logs was shorter than that of Korean white pine logs. Sex ratios were 0.58; the average fresh weights of males (331) and females (379) were 0.21 g and 0.23 g; body lengths were 17.6 mm and 18.4 mm; body widths were 5.47 and 5.81 mm; head widths were 3.30 mm and 3.42 mm; and antennal lengths were 40.28 mm and 26.40 mm, respectively. The ratio of the length of the antenna to the body length was measured to be 2.0 in males and 1.4 in females.

Possible Presence of Pheromone in Mating Behavior of the Pine Sawyer Monochamus saltuarius Gebler (Coleoptera: Cerambycidae)

Abstract The mating behavior of the pine sawyer, Monochamus saltuarius , is composed of two phases. The first phase is the female approach to pheromone-releasing males. When bioassayed by T-tube olfactometer, the female was moved toward the male and hexane extract of the male. The second phase is the male mounted the female to copulate after perceiving the contact pheromone being on the female body surface. When the hexane extract of the female body surface was applied onto a glass rod (dummy), the male showed the mating behavior to the dummy. The component of female body surface extract fractionated using a silicic acid column elicited mating behaviors of the males, and the other component by ether fraction was showed a high copulatory attempt. This study was discussed two-step functions of the pheromones in the beetle mating behavior.

Emergence Timing of the Pine Sawyer Beetle, Monochamus saltuarius (Coleoptera: Cerambycidae) by Tree Species

This study was performed to investigate the emergence timing and daily emergence from the different tree species logs (Korean white pine, Pine, and Japanese larch) at Cheongwon, Chungcheongbuk-do from 2006 to 2008. Pine sawyer adults began to emerge on early May (210th day) and finished on mid-June (420th day) in the Korean white pine and pine logs. However, pine sawyer adults began to emerge on mid-May (13th day) and finished late May (27th day) in Japanese larch logs, Japanese larch logs shows shorter emergence timing of pine sawyer adult compare to those of other two tree species. Emergence timing shows no difference between males and females. Sex ratios of emerged adult in 2007 were 0.55 from Korean white pine, 0.46 from Pine, and 0.59 from Japanese larch; it shows no difference among tree species. Female and male adults emerged throughout 24 hrs; 22.8% of the total adults emerged from 1214:00 (22.8%) and adults emerged lowest from 0608:00. Of the adults emerged from the logs, 98.9% was univoltine and the rest was biennial which emerged next year.

Feeding and oviposition preference of the Sakhalin pine sawyer Monochamus saltuarius (Coleoptera: Cerambycidae) for various tree species

Monochamus saltuarius was recently identified as an important vector of Bursaphelenchus xylophilus, the cause of pine wilt disease. In this study, M. saltuarius adults preferred different species of tree based on the longevity, ingested amount and wounded area that were determined for 90 d. Among eight tree species, the longevity of feeding by M. saltuarius was not significantly different except when feeding in Sciadopitys verticillata. However, the highest ingested amounts with the largest wounded areas were associated with Pinus koraiensis. The highest oviposition preference was in P. densiflora for the first 20 d. However, after 40 d, the oviposition highest preference was noted in P. koraiensis. For oviposition activities, M. saltuarius preferred the tree species in the following order: P. densiflora > P. koraiensis > P. rigida > Larix leptolepis. Although many oviposition scars were observed, M. saltuarius laid fewer eggs in P. rigida than other species of pine, which was related to the bark thickness. The oviposition frequencies were highest with bark 2.0–2.5 mm thick and with tree diameters of 110–130 mm. The current study increased understanding of the ecology of M. saltuarius by identifying specific tree preferences.

Electron Beam-Induced Sterility and Inhibition of Ovarian Development in the Sakhalin Pine Longicorn, Monochamus saltuarius (Coleoptera: Cerambycidae)

Abstract The Sakhalin pine longicorn, Monochamus saltuarius (Gebler; Coleoptera: Cerambycidae), is an insect vector of the pine wilt nematode (PWN), Bursaphelenchus xylophilus (Steiner et Buhrer) Nickle, and is widely distributed in central Korea. M. saltuarius is a forest pest that seriously damages Pinus densiflora (Siebold et Zucc, Pinales: Pinaceae) and Pinus koraiensis (Siebold & Zucc, Pinales: Pinaceae) forests. We examined the effect of electron beam irradiation on the mating, DNA damage and ovarian development of M. saltuarius adults and sought to identify the optimal dose for sterilizing insects. When the adults were irradiated with electron beams, both females and males were completely sterile at 200 Gy. In a reciprocal crossing experiment between unirradiated and irradiated adults, the reproductive ability of wild adults was recovered by crossing with wild adults even after crossing previously with sterile adults. When a pair of unirradiated adults (♀- × ♂-) and 10 or 20 irradiated adults (♀+ or ♂+) were kept together, the control effect was as high as 80∼90%. After electron beam irradiation at 200 Gy, the DNA of M. saltuarius adults was damaged, the ovarian development of female adults was inhibited, and the level of vitellogenin was significantly decreased compared with that in unirradiated female adults.These results suggest that pine wilt disease can be effectively controlled if a large number of sterilized M. saltuarius male adults are released into the field.