To find an alternative for synthetic pesticides, methanol extracts from 69 plant samples were tested for their insecticidal activity against two spotted mite (Tetranchus urticae Koch). Seven plant extracts including Angelica japonica showed over 80% insecticidal activity at 5000 mg/L. Extract of Prunus armeniaca seed showed high insecticidal activity at 3000 mg/L. As a naturally occurring pesticide, P. armeniaca could be useful as a new botanic insecticide.

In organic Chinese cabbage fields, Commercial Bacillus thuringiensis products are used widely against diamond back moth, Plutella xylostella. We conducted the study to determine the effective spray-interval of commercialized B. thuringiensis against diamond back moth on Chinese cabbages. Chinese cabbage leaves were collected 0, 1, 2, 3, 6, 10days after treatment in first trial and 0, 2, 4, 7, 9, 11days after treatment. We compared the insecticidal property of sprayed B. thuringiensis and the density of it on surface of Chinese cabbages using collected leaves. The insecticidal property maintained high until nine days after commercial B. thuringiensis products sprayed.