Résumé
The effects of Bacillus thuringiensis (Bt) Berliner on the termite Nasutitermes ehrhardti (Isoptera, Termitidae) were evaluated under laboratory conditions. From 55 Bt subspecies assayed in vivo under controlled conditions seven were found to be pathogenic in the subspecies yunnanensis, huazhongiensis, brasiliensis, colmeri and kurstaki (less than 72 percent of mortality), particularly sooncheon and roskildiensis (100 percent mortality at the seventh day after the bacteria application). The LC50 for subspecie sooncheon corresponded to 47x10(8),()66.2x10(6) and 5.1x10(5) cells/ml, at the third, fifth and seventh day, respectively. For the subspecie roskildiensis the LC50 corresponded to 30.8x10(5), 48.4x10(6) and 16.8x10(4) cells/ml, at the third, fifth and seventh day, respectively. The results show that the two most pathogenic subspecies effectively may be studied with regard to control the termite N. ehrhardti