SPIROPLASMA LEPTINOTARSAE SP-NOV, A MOLLICUTE UNIQUELY ADAPTED TO ITSHOST, THE COLORADO POTATO BEETLE, LEPTINOTARSA-DECEMLINEATA (COLEOPTERA, CHRYSOMELIDAE)

Spiroplasma strain LD-1(T) (T = type strain), which was isolated from the gut of a Colorado potato beetle (Leptinotarsa decemlineata) larva collected in Maryland, was serologically distinct from other spiroplas mas. Similar isolates were obtained from other L. decemlineata specime ns collected in various parts of North America, in Poland, and in othe r eastern European countries and from Leptinotarsa texana specimens co llected in Texas. Cells of strain LD-1(T), which in early passages wer e spiral, exhibited exceptionally rapid translational motility. This r apid motility and the spiral shape were lost after extended passage in culture, The organism required serum for growth. Originally isolated in coculture with insect cells in DCCM medium, strain LD-1(T) adapted to several media in the absence of cocultured cells. Use of anaerobic conditions allowed primary isolation in a variety of media. The organi sm did not grow in serum-free media containing 2% serum fraction, Opti mal growth in M1D medium occurred at 30 to 37 degrees C (doubling time , 7.2 h). On solid M1D medium containing 2.0% Noble agar (pH 6.25) at 30 degrees C, strain LD-1(T) produced discrete colonies with numerous satellites. Strain LD-1(T) hydrolyzed arginine, but did not utilize ur ea; there was evidence of weak fermentation of glucose, The guanine-pl us-cytosine content of the DNA was determined to be 25 +/- 1 mol%, and the genome size was 1,085 kb. The results of extensive studies of the ecology of this spiroplasma suggest that it is host specific for Lept inotarsa beetles, Strain LD-1 (= ATCC 43213) is designated the type st rain of a new species, Spiroplasma leptinotarsa.