[Distribution of Bacillus thuringiensis in soils of north and south of China].

221 isolates of Bacillus thuringiensis were isolated in 1491 soil samples from North and South of China. H-serotypes and larvicidal characters of all Bt isolates have been identified. The rate of Bt-harbouring soil sample and the rate of Bt isolates in Northeast and Neimeng were in 12.6% and 17.2% respectively. Predominant serotypes were H4, H10, H3, H13, H5 and H29. The most fertile Bt-harbouring area was the Heilongjiang Province with rate of Bt-harbouring sample of 21.4% and rate of Bt isolate of 29.4%. Rate of Bt-harbouring sample and rate of Bt isolate in Northwest area were 6.6% and 7.1% respectively. Main serotypes were H4, H5, H19, H10 and H3. In four provinces of Southern China, both rates above were 18.6% and 29.5%, but frequency of Bt distribution was varied seriously in different distinct. Predominant serotypes in soils from Southern China were H3 and H5. Results of bioassay showed that the percentage of strains high active to Heliothis armigera and Plogioidera versicolora were 1.6% and 1.1% in soils from North of China. In contrast to North of China, Bt strains active to H. armigera were 5.3% and none of Bt was effective to P. versicolora in South of China. A strain H27-05 was high toxic to H. armigera and showed temperate toxicity to P. versicolora.