0023-6152

AA00697606

2340915

Recently, as the number of farms that cultivate crops using organic compost in greenhouses has been increasing in South Korea, the occurrence of Bradysia agrestis have been coming to the fore seriously. The larvae of B. agrestis appear in the roots of various crops because their host range is wide and they cause serious damage to the crops as they suppress the growth and defoliate the crops. Therefore, the search for new biological control agents was investigated. To screening new B. thuringiensis with high insecticidal activities against Diptera, three isolates that form spherical type crystals were selected from domestic soils. The LC95 value of B. thuringiensis strain CAB452, which is the most toxic to the larvae of Diptera B. agrestis among those three strains, was shown to be 4.4×107 (cfu/ml). SDS–PAGE was performed to identify the δ–endotoxin protein band pattern of B. thuringiensis strain CAB452 and the result indicated one main protein band of about 150 kDa. In order to investigate the proteins of the active toxin of this strain, this strain was treated with trypsin, which is a digestive enzyme, or B. agrestis larva triturated solution and as a result, one main band of about 50 kDa was shown under each of the two conditions. PCR analysis of the crystal proteins of B. thuringiensis strain CAB452 revealed two genes, cry4A and cry9D.