0023-6152

AA00697606

2340913

Although chemical insecticides have been used to control Diptera agricultural pests, because of characteristics of the pests that invade into soil or into the roots of plants to do harm over most of their larva developmental period, it is difficult to effectively control the pests using chemical insecticides, and biological control methods are necessary due to increases in the production of eco–friendly agricultural products. Therefore, this study conducted the survay of new control agent. In order to isolate Bacillus thuringiensis strains that show insecticidal activities against Diptera, B. thuringiensis strains were selected from soils from the streams in Yangyang, Gangwon Province, Saryang–do, Chuja–do, and Jeju–do (islands), which are main habitats of Diptera. In bioassays, isolate S11 and C55 showed high insecticidal activities not lower than 90% in both Lycoriella ingenua and Aedes albopictus larvae, and the selected strain S11 showed insecticidal activities not lower than 50% in Bradysia agrestis. In investigation of the insecticidal activities against L. ingenua larvae, strains S11 and C55 showed higher insecticidal activities than the control strain B. thuringiensis subsp. Israelensis which is widely used as a pesticide against Diptera. SDS–PAGE was performed to compare the δ–endotoxin protein characteristics of the two selected strains. Strain S11 showed three main bands at 150 kDa, 75 kDa, and 65 kDa, while strain C55 showed three main bands at 150 kDa, 70 kDa, and 25 kDa. In the digestion reactions with L. ingenua triturated solution, the strain S11 was digested to 75 kDa and 25 kDa to show bands while strain C55 showed a band at 25 kDa. The results of PCR of cry genes of the two strains indicated that both strains have cyt2Aa genes. In the plasmid DNA patterns, S11 showed a total of six bands and C55 showed a total of two bands.