The present thesis consists of two main parts: 1) field survey results on a parasitroid of the two Monochamus vector species of the Pine Wilt Nematode (PWN) in South Korea and 2) a study on biology of the parasitoid to evaluate the potential as a viable biological control agent through in-door breeding.
The field survey, using the sentinel logs to attract the parasitoid, was conducted in Pohang, Gyeongsangbuk-do, South Korea from 2018 to 2020 in order to elucidate ecological and biological characteristics of Cyanopterus flavator (Fabricius), a larval ectoparasitoid of two cerambycid vectors of PWN, namely M. alternatus Hope and M. saltuarius Gebler. The average parasitism rate of C. flavator in M. alternatus was 6.33 ± 6.21% (max: 28.44%, min: 0.63%) on M. alternatus, and 1.04 ± 8.91% (max: 24.46%, min: 0.54%) on M. saltuarius. And it was confirmed that the parasitism rate of C. flavator during peak season and when larva of M. alternatus live under the bark were similar. Also, it was confirmed that the height with the highest parasitism rate of C. flavator and the height with the highest density of M. alternatus larvae in the pine tree was similar. The results of this study will be used as helpful information to determine the release timing and height of C. flavator.
An indoor rearing experiment of C. flavator was conducted to investigate the mass-rearing possibility, development, and oviposition characteristics. As a result, the average period from egg to adult was 23.24 days, 16.96 days, and 13.24 days at 20℃, 25℃, and 30℃, respectively. The average mating male longevity was 56.67 days, 41.17 days, and 40.5 days at 20℃, 25℃, and 30℃, respectively. The average mating female longevity was 60.83 days, 49.67 days, and 57.83 days at 20℃, 25℃, and 30℃, respectively. The average parasitism rate was 17.05%, 18.24%, and 23.62% at 20℃, 25℃, and 30℃, respectively. It is most effective to breed C. flavator using M. alternatus at 30℃. This rearing information should be helpful in developing future biological control programs for vectors of pine wilt disease.