WOLBACHIA IN A PREDATOR-PREY SYSTEM - 16S-RIBOSOMAL DNA ANALYSIS OF 2PHYTOSEIIDS (ACARI, PHYTOSEIIDAE) AND THEIR PREY (ACARI, TETRANYCHIDAE)

Using specific polymerase chain reaction (PCR) primers, the 5' region of Wolbachia 16S ribosomal DNA from the predatory mite Metaseiulus occ identalis (Nesbitt) and the twospotted spider mite, Tetranychus urtica e Koch, was amplified. Because they prey contains Wolbachia, a method to eliminate amplification of transient Wolbachia from the gut content s was necessary. We found that if the otherwise uninfected phytoseiid Amblyseius reductus Wainstein was fed spider mite prey containing Wolb achia, a positive PCR signal was detectable immediately after feeding, but not 4 h later. M. occidentalis remained positive for Wolbachia by the PCR even 48 h after feeding, although a stronger signal was prese nt at 24 h or less. Wolbachia DNA could be amplified from the predator 's eggs, suggesting it is transovarially transmitted and a stable symb iont in this predatory mite. All but 1 of the laboratory colonies of M . Occidentalis tested were positive for Wolbachia by the PCR, includin g those from other laboratories. One fresh collection of M. occidental is and their prey Panonychus ulmi (Koch) were tested immediately and a gain 5 d after collection from the field, but a positive PCR signal wa s never detected. A field-collected sample of T. urticae did not test positive for Wolbachia, although a Wolbachia-specific signal was detec ted in a population of the strawberry spider mite, T. turkestani Ugaro v & Nikolski, collected simultaneously from the same field. PCR produc ts from 1 adult female of the Russian Select strain of M. occidentalis , 60 eggs of the COS strain of M. occidentalis, and 1 male T. urticae were directly sequenced. Phylogenetic analyses placed them within the same clade as Wolbachia from insects, clustered together with type spe cies, Wolbachia pipientis Hertig, from Culex pipiens L. The Wolbachia from these mites was not similar to Wolbachia persica Suiter & Weiss f rom another acarine, the fowl tick, Argas persicus (Oken). The sequenc e similarity between the mite and insect Wolbachia provides more evide nce for the horizontal transfer of this microorganism between diverse arthropods.