Five of the 13 known species of Mammomonogamus have been described in members of the family Felidae, including domestic cats, making felids the most frequent hosts of Mammomonogamus. The occurrence of Mammomonogamus in felids is geographically scattered and information on the life cycle and other aspects of infections is lacking. The paucity of data opens the questions on possible conspecificity of some of the described species of Mammomonogamus and on the existence of possible reservoirs for infections in domestic cats in geographically isolated endemic foci of infection. To test such hypotheses, we compared sequences of mitochondrial and nuclear markers obtained from Mammomonogamus adults or eggs collected from domestic cats in three geographically distant localities. Based on morphology, geographic origin and site of infection, the worms examined can be referred to as Mammomonogamus ierei and Mammomonogamus auris. Phylogenetic analyses of both mitochondrial and ribosomal DNA markers showed monophyly of the genus Mammomonogamus and suggested the existence of at least two species in cats. Review of the literature, the existence of several species and the discontinuous geographic distribution of Mammomonogamus infections in domestic cats suggest an historical spillover of infection from wild reservoirs, presumably wild felids.

Candidatus Midichloria mitochondrii is a maternally inherited bacterium of ticks with a unique intra-mitochondrial lifestyle. Here, we investigate on the evolutionary history of these associations and the degree of Midichloria–tick specificity. While previous surveys used the 16S rRNA gene as an exclusive molecular marker, we rather developed a multi-locus typing method based on four more variable housekeeping genes (groEL, rpoB, dnaK and ftsZ) and on one flagellum gene (fliC) present in Midichloria genomes. Using this method, multi-locus phylogenetic analyses revealed the structuring of a wide Midichloria genetic diversity into three distinct lineages associated with ticks. Overall, two distinct evolutionary strategies are obvious depending on lineage: two Midichloria lineages are generalists with infections acquired through horizontal transfers between distantly related tick species but one other Midichloria lineage rather show a high specificity degree to the Ixodes tick genus. This pattern suggests a capacity of certain Midichloria strains to maintain infections in only limited range of related tick species. These different infection strategies of Midichloria highlight an unexpected variability in their dependency to their tick hosts. We further conjecture that this pattern is also likely to indicate variability in their effects on ticks.

Behaviour manipulation imposed by parasites is a fascinating phenomenon but our understanding is still very limited. We studied the interaction between a virus and the parasitic wasp Leptopilina boulardi that attacks Drosophila larvae. Wasps usually refrain to lay eggs into already parasitized hosts (superparasitism avoidance). On the contrary, females infected by the Leptopilina boulardi Filamentous Virus (LbFV) are much more incline to superparasitize. Interestingly, the host-sharing induced by this behaviour modification leads to the horizontal transmission of the virus, thus increasing its fitness at the expense of that of the wasp. To better understand the mechanisms underlying this behaviour manipulation, we studied by RNA sequencing the meta-transcriptome of LbFV and the parasitic wasp both in the abdomen and in the head. We found that the abundance of viral transcripts was independent of the wasp strain but strongly differed between tissues. Based on the tissue pattern of expression, we identified a set of 20 viral genes putatively involved in the manipulation process. In addition, we identified a set of wasp genes deregulated in the presence of the virus either in the abdomen or in the head, including genes with annotations suggesting involvement in behaviour (i.e. Potassium-channel protein). This dataset gives new insights into the behaviour manipulation and on the genetic basis of superparasitism in parasitoids.