Field survey were conducted in to evaluate the insect damage to growing Lemonbalm(Melissa officinalis). Lemaonbalm, belonging to the Lamiaceae family, is a smelling perennial shurb which is possible to grow in Korea. To date, there has been minimal research regarding plant culture, pest insect occurrence and management research about herbal plants in Korea. Meanwhile, it grows for processed food and cosmetics in Jellabukdo, and necessity to pest management is on the rise. Chrysolina exanthematica(Coleoptera: Chrysomelidae) was realized not pest but general insect in Korea. But, in this survey, it is found to pest about lemonbalm. Damage period was concentrated in April. Rest period was decreased in density. At size of Chrysolina exanthematica, larva is 7.0*3.6mm, pupa is 8.3*5.3mm, and adult is 9.7*6.7mm. In farm surveying about Chrysolina exanthematica host preference of 5 species herb plants, Lemonbalm has great preference but, Oregano has no preference. Surveying leaf damage about 6 species in Lamiaceae family in lab., Lemonbalm belonging to Melissa genus has great damage, Some species in Mentha genus have little damage. And, Oregano in Origanum genus no damage. In Growth characteristics of healthy and damage plant, plant length on damage plant is decreased 41.3%, number of tiller is decreased 67%. Fresh and dry plant weight of damaged plant is decreased 66.7%, 64.2% compared with healthy plant. Because damage of insect can influence on plant main contitutents, we analysed the constitutent parts of extracts from supercritical fluid extraction system using gas chromatography/mass spectrometer.

This study was conducted to develop the economic threshold for the diamondback moth (Plutella xylostella (L.) on Leaf Broccoli (leaf vegetable) in 2007. To investigate the relationship between initial density of diamondback moth larvae and broccoli leaf yield, experimental plots with five treatments (0, 0.5, 1.0, 2.0, 4.0 larvae per plant) as initial density were established. We inoculated larvae in chesses cloth covering to survey larvae density change. When grown to eat, leaves of broccoli were harvested by periods. 60-70% of larvae were removed whenever we picked the leaves. High levels of larvae were associated with significant reductions in leaf yield. There were 85%, 64%, 58%, and 56% yield reductions from the diamond back moth larvae density in 0, 0.5, 1,0, 1.5, 2.0 per plant, respectively 25days after larvae inoculation. The regression equation used to predict leaf yield based on the number of initial larvae density per a plant was y=1635-393x(R2=0.79***). The economic injury level of diamondback moth on leaf broccoli was 2-3 larvae per 10 plants for a damage level of 5%. The economic thresholds was 1-2 larvae per 10 plants. Thus, the diamond back moth management should be initiated 1-2 larvae occurrence per plant.