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Title: MOLECULAR SYSTEMATICS OF BACILLUS POPILLIAE AND BACILLUS LENTIMORBUS, BACTERIA CAUSING MILKY DISEASE IN JAPANESE BEETLES AND RELATED SCARAB LARVAE

Author
item RIPPERE, K - VPI
item TRAN, M - VPI
item YOUSTEN, A - VPI
item HILU, K - VPI
item Klein, Michael

Submitted to: International Journal of Systematic and Evolutionary Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/27/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Larvae of the Japanese beetle and other scarabs are serious pests crops and turfgrass throughout the world. With increasing restrictions on the use of conventional insecticides, there is an interest in increasing the role of biological organisms in controlling damaging populations. Milky disease bacteria provide natural suppression of scarab larvae, but a better understanding of these bacteria is needed before their use can be expanded For the first time, we examined the molecular relationships of isolates of milky disease bacteria from around the world. We found that previous taxonomic schemes based on the presence or absence of a parasporal body, or protein crystal, may not be valid. DNA similarities and resistance of the bacteria to an antibiotic, vancomycin, suggest that new taxonomic relationships need to be considered. This study demonstrates the importance of molecular techniques, and establishes new groupings of the bacteria which can be examined for the biological control of scarab pests. This information will aid scientists interested in insect pathogenic bacteria here in the United States and abroad to better understand the biological and taxonomic relationship of the milky disease bacteria.

Technical Abstract: Bacillus popilliae and B. lentimorbus, causative agents of milky disease in Japanese beetle and related scarab larvae, have been differentiated based upon a small number of phenotypic characteristics, but they have not previously been examined at the molecular level. In this study, 34 isolates of these bacteria were examined for DNA similarity groups and by random amplified polymorphic DNA (RAPD) analysis. Three distinct, but related, similarity groups were identified; the first contained strains of B. popilliae, the second contained strains of B. lentimorbus, and the third contained two strains distinct from, but relate to, B. popilliae. Some strains received as B. popilliae were found to be most closely related to B. lentimorbus, and some received as B. lentimorbus were found to be most closely related to B. popilliae. RAPD analysis confirmed the DNA similarity results. Paraspore formation, believed to be a characteristic unique to B. popilliae, was found to occur among a subgroup of B. popilliae lentimorbus strains. Growth in media supplemented with 2% NaCI was found to be less reliable in distinguishing the species than was vancomycin resiistance, the latter present only in B. popilliae.