Problems with in vitro production of spores of Bacillus popilliae for use in biological control of the Japanese beetle

Abstract

Bacillus popilliae spores have been used in the United States for the biological control of the Japanese beetle for over 50 years. Lack of efficient sporulation in vitro has been a major limiting factor in expanding the use of this bacterium. Previously, commercial spore powders were produced by maceration of milky disease infected larvae containing large numbers of spores. Recently, (since 1985) a commercially available spore powder produced by a patented in vitro procedure has been marketed. However, most batches of the in vitro spore powder and primary fermentation products that we examined contained a bacterium identified as Bacillus polymyxa, but no B. popilliae. We also examined four cultures submitted to the American Type Culture Collection (Rockville, MD) at the time of patent application as representative sentative of the strains of B. popilliae produced in vitro. One of these, referred to as the preferred strain, was identified as B. polymyxa. The other ATCC strains were identical in their characteristics to Bacillus amylolyticus. Both B. polymyxa and B. amylolyticus spores, and in vitro-produced milky disease spore powder containing these bacteria rather than B. popilliae, caused no milky disease in Japanese beetle larvae. The patented procedure should be reexamined since there is no evidence that it is effective in producing infective B. popilliae spores.