The Korean jewel beetle,
In the wild, it is rarely possible to find the adults of this beetle in Korea. In this study, the current status of the beetle is reported in relation to its host plant,
The field survey on the wild population of the beetle was carried out for five years from 2008 to 2012. The south western part of Korean peninsula was the main region of the survey. In each year, a 5-day field survey was performed at each month from June to September when is most likely time for adult emergence of the beetle in Korea. As well as the adult occurrence, the existence of the larvae inside the host plant was examined by carefully splitting the dead stems of
During the survey period, visual observation on the host plant was performed as well as its condition as a source food for the beetle. It is known that the larvae of the beetle only consume the dead stems of the host plant. Therefore, the existence of dead stems of the host plant is essential to beetle’s survival.
[Fig. 1.] The dead adult of Chrysochroa coreana found inside the decaying wood at the parking lot of Daeheung temple (DT) in Haenam, Korea in 2009.
HOST PLANT STATUS AND BEETLE POPULATION
The data collected from the survey were analyzed qualitatively on Table 1. Visual observation method was used to identify the existence of the adult beetle at the study site. When the dead corpse of the beetle was sighted, it was photographed and recorded as well. The existence of the larvae was examined by the splitting the dead stems of the host plant randomly at each study site.
As Table 1 shows, the beetles were found at DT and DR sites consistently during the study period. However, the live adults were not observed in 2010 and 2011 at these sites. Most of the host plant observed was long aged trees of more than 100 years old. Meanwhile, the beetles were found live at NT and ST sites in 2010 and 2011. It is not clear whether there is the dispersal of the beetle popula-tions
[Fig. 3.] The dead adult of Chrysochroa coreana found inside the decaying wood among the fire wood stack at the pension lodge near Daeheung temple (DT) in Haenam, Korea in 2011.
among the study sites during this period.
The host plants at the study sites usually suffered from the annual typhoons hitting Korean peninsula, resulting in the production of the broken stems. It is believed to be the main source of the beetle’s diet at larval stages. The relationship between the larval density and the quantity of dead stems was significant. DR site where the typhoon damage is most severe, the observation of the larvae was most frequent (Table 1).
Fig. 1 shows the finding of the dead adult beetle inside the dead stem of the host plant at DT site in 2009. Fig. 2 also shows the finding of the dead adult beetle along the seashore at DR site in 2011. At this time, larvae were found inside the broken stems of the host plant by the typhoon. Fig. 3 shows the file-up of the fire wood stack at DT site in 2011. The dead stems of the host plant,
[Fig. 4.] The dead adult of Chrysochroa coreana and the larvae found inside the dried wood at the wood stack in Naeso Temple (NT), Korea in 2012.
were found at the pension lodge near the entrance of the temple property. At this site, the larvae were also found inside the stem, but they were very small compared to those found from DT and DR sites.
[Table 1.] The occurrence of Chrysochroa coreana at each study site during the study period
The occurrence of Chrysochroa coreana at each study site during the study period
From the data collected from the study, the relationship was found between host plant management and the beetle survival. From visual observation, the beetles were best survived at the DR sites compared to other sites. The main difference between the two was human interferences on the dealing with the dead stems of the host plant. The old trees of