Oviposition Preference of Monochamus saltuarius (Coleoptera: Cerambycidae) for Different Host Species and Larval Development on Larix kaempferi and Larix gmelinii subsp. olgensis

This research aimed to investigate the oviposition preference of Monochamus saltuarius for different host trees and to determine whether it is capable of completing its life cycle in Larix kaempferi and Larix gmelinii subsp. olgensis. Male and female adults were placed in insect cages with the logs of Pinus tabuliformis, P. koraiensis, L. kaempferi, and L. gmelinii subsp. olgensis positioned in the four corners to determine the female beetles’ oviposition preference and the development of their offspring on the different host tree logs. First-instar larvae were also collected and introduced into logs of L. kaempferi and L. gmelinii subsp. olgensis to observe and measure their development. In addition, the phloem thickness, sapwood thickness, heartwood thickness, xylem density, and moisture content of these four host tree species were measured. The results showed that M. saltuarius larvae can develop into adults on L. kaempferi and L. gmelinii subsp. olgensis, but the lifespan and fecundity of adult M. saltuarius were lower than those observed for P. tabuliformis. In the choice test, females preferred P. tabuliformis to oviposit (75.44%), followed by P. koraiensis (12.86%), which showed less preference for L. kaempferi (5.99%) or L. gmelinii subsp. olgensis (5.71%). Phloem thickness and xylem density were significantly greater in the logs of L. kaempferi and L. gmelinii subsp. olgensis than in those of P. tabuliformis and P. koraiensis. M. saltuarius may feed on Larix species when food sources are scarce in forests. However, the likelihood of the beetle feeding on Larix species may decrease in the presence of favorable host species.