Infectivity of beetle spiroplasmas for new host species

Five beetle spiroplasmas, the Colorado potato beetlespiroplasma (CPBS, strain LD-1), the Cantharis carolinusspiroplasma (CCBS, strain CC-1), the Ellychnia corrusca fireflyspiroplasma (FS, strain EC-1), the Diabrotica undecimpunctatacorn rootworm spiroplasma (CRS, strain DU-1), and the Spiroplasmafloricola fall flower spiroplasma (FFS), all associated withbeetles, were fed to beetles (Maladera matrida and Carpophilushumeralis) and mosquitoes (Aedes aegypti and Culex pipiens). CPBSand CCBS were also injected into M. matrida. Attempts to recoverspiroplasmas from regurgitates and hemolymph were conducted 1–10days after their introduction. After day 1, orally administeredspiroplasmas could not be recovered from M. matrida beetles;however, at 2–5 days, four out of five spiroplasmas wererecovered from adult C. humeralis. Injected spiroplasmas survivedin the hemolymph of M. matrida beetles for a relatively longperiod (at least 22 days). All five spiroplasmas were recoveredfrom mosquitoes 1 day post feeding, but only two (CCBS and CRS)survived for five or more days. The results show short andvariable persistence in orally challenged non-host insects, withgeneral failure to pass the gut barrier. Such evidence should beconsidered when attempting to use these microbes in biocontrolprograms.