Characterization of Wolbachia postica, the cause of reproductive incompatibility among alfalfa weevil strains

Wolbachia postica, which causes reproductive incompatibility between male western alfalfa weevils and female eastern or Egyptian weevils, was isolated by Renografin density gradients. Hybridization of DNA from this isolated microorganism with a mycoplasma-specific gene probe confirmed it is not a mycoplasma but a wolbachia. Polyclonal antibodies produced against inactivated Wolbachia postica showed high sensitivity in fluorescent light microscopy and immunoelectron microscopy. This antibody was specific for Wolbachia-infected adult weevil by immunoblots which were reliable and reproducible, and more sensitive than the Giemsa stain procedure. A 135-kDa protein detected in all weevils infected with wolbachiae appeared to be a good marker for the microorganism. This technique facilitates the detection of wolbachiae-infected male weevils. Dissection of the ovary was not required to analyze the female weevils.