Oviposition sites constructed in Pinus densiflora phloem by Monochamus alternatus and Monochamus saltuarius (Coleoptera, Cerambycidae)

Monochamus alternatus Hope and M. saltuarius (Gebler) (Coleoptera: Cerambycidae) transmit Bursaphelenchus xylophilus causing pine wilt disease. They excavate a pit in the bark of pine trees, insert the ovipositor into the phloem through the pit, and oviposit. The size of oviposition sites in the phloem and positioning (array) of eggs in them were investigated to determine the size of bark samples to inspect B. xylophilus transmitted through the oviposition wounds. Both species constructed an oval, flat hollow as an oviposition site, in which there were 0-2 eggs for M. alternatus and 0-5 eggs for M. saltuarius. The mean length and width were 9.31 mm and 5.82 mm, respectively, for M. alternatus and 7.28 mm and 3.32 mm for M. saltuarius. The greatest length was 15.00 mm for M. alternatus and 10.10 mm for M. saltuarius. The distance from the ovipositor-inserted opening in the oviposition wound to the posterior end of egg increased with female body mass in both species. Each oviposition wound had one or two oviposition sites. Thus, the number of eggs per oviposition wound did not always represent the number of eggs deposited per oviposition behavior. Bark disks of >30 mm and >21 mm in diameter were suitable for inspecting the nematodes transmitted by M. alternatus and M. saltuarius, respectively.

Automated summary

Monochamus alternatus and M. saltuarius transmit Bursaphelenchus xylophilus causing pine wilt disease through oviposition wounds. The size of oviposition sites and the positioning of eggs were found to be related to the number of eggs deposited. Bark samples of specific diameters were suitable for inspecting the nematodes transmitted by each species.