Tabanid spiroplasmas from France : characterization, ecology and experimental study

During 1989 and 1990, tabanid flies were collected from two different areas in Western France and assayed for spiroplasmas. From Central Britanny 62 flies of 9 different species yielded 20 spiroplasma isolates belonging to 6 different serogroups : VIII, XIV, XXIII, HYOS, TABS 1, TAAS. From Atlantic biotopes 81 flies of three different species yielded 58 isolates belonging mainly to serogroup IV, but also TABS 1, HYOS and XIV. All the 78 French isolates were able to multiply in vitro at 37° C.Of 240 flower or plant specimens tested from « Briere » none yielded spiroplasmas.81 animal sera from « Briere » were also examined. Using the Deformation test and 11 different spiroplasmas from honey bees, mosquitoes and tabanids, 61/76 bovine sera (or 80,3 %) were found to be positive but exclusively for the spiroplasma Ar 1357, a mosquito spiroplasma belonging to serogroup XVI3 and previously isolated in France from Aedes mosquitoes.At present we have no explanation for the paradoxical absence of antibody to tabanid spiroplasmas in cattle since all French tabanid spiroplasmas are able to multiply in vitro at 37° C and, at least for three isolates, in suckling mice.