G.K. Kyei-Poku
M Giladi
P Coghlin
O Mokady
E Zchori-Fein
K.D. Floate

House fly, Musca domestica L., and stable fly, Stomoxys calcitrans (L.) (Diptera: Muscidae) are 31 cosmopolitan pests parasitized by a guild of more than two dozen species of wasps. Several species of 32 these wasps have been commercialized, or are being studied for commercialization, as biocontrol agents. 33 Wolbachia bacteria are known to infect at least some of these wasps and are of interest because 34 infections can dramatically affect insect reproduction. A survey in this parasitoid-fly system detected 35 Wolbachia in 15 of 21 species of wasps and in three of nine species of flies parasitized by these wasps. 36 Phylogenetic analyses using wsp gene sequences identified single strain infections in infected species 37 with the exception of Spalangia cameroni (Pteromalidae), which contained infections of three strains. 38 Laboratory experiments using S. cameroni showed Wolbachia strain wScam1 to cause an incomplete 39 form of female-mortality (FM) type cytoplasmic incompatibility (CI). Crosses between uninfected female and infected male partners (& x %w 40 ) produced fewer progeny, which had a strong male-biased sex ratio. Crosses between & x %, &w x %w and &w 41 x % produced more progeny, which had a female-biased sex 42 ratio. Of particular interest was the finding that developmental times of progeny were increased when the 43 paternal parent was infected with Wolbachia, regardless of the infection status of the maternal parent. 44 This finding is unexpected because progeny of uninfected females do not harbour Wolbachia. To our 45 knowledge, this is the first report of Wolbachia in the male parent affecting the developmental time of F1 46 progeny. Collectively, these findings emphasize the prevalence and consequences of Wolbachia in the 47 guild of wasps parasitic on filth flies. It is hoped that future studies of Wolbachia in this guild will facilitate 48 the use of these wasps as biocontrol agents of house fly and stable fly.