title: Parasitic infection protects wasp larvae against a bacterial challenge.
abstract: Host antibacterial defense after Strepsiptera parasitization is a complex and rather unexplored topic. The way how these parasites interact with bacteria invading into the host insect during an infection is completely unknown. In the present study we demonstrate that larvae of the paper wasp Polistes dominulus are more efficient at eliminating bacteria when they are parasitized by the strepsipteran insect Xenos vesparum. We looked at the expression levels of the antimicrobial peptide defensin and we screened for the activity of other hemolymph components by using a zone of inhibition assay. Transcription of defensin is triggered by parasitization, but also by mechanical injury (aseptic injection). Inhibitory activity in vitro against the Gram positive bacterium Staphylococcus aureus is not influenced by the presence of the parasite in the wasp or by a previous immune challenge, suggesting a constitutive power of killing this bacterium by wasp hemolymph. Our results suggest either direct involvement of the parasite or that defensin and further immune components not investigated in this paper, for example other antimicrobial peptides, could play a role in fighting off bacterial infections in Polistes.
authors.affiliation: Department of Evolutionary Biology, University of Siena, via Aldo Moro 2, 53100 Siena, Italy. manfred_f@libero.it
authors.forename: Fabio
authors.initials: F
authors.lastname: Manfredini
authors.forename: Laura
authors.initials: L
authors.lastname: Beani
authors.forename: Mauro
authors.initials: M
authors.lastname: Taormina
authors.forename: Laura
authors.initials: L
authors.lastname: Vannini
mesh_terms: D000818:Animals; D023082:Defensins / Q000096:biosynthesis; D005260:Female; D020869:Gene Expression Profiling; D019476:Insect Proteins / Q000096:biosynthesis; D007814:Larva / Q000276:immunology / Q000382:microbiology / Q000469:parasitology; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA; D013211:Staphylococcus aureus / Q000254:growth & development* / Q000276:immunology; D014863:Wasps / Q000276:immunology / Q000382:microbiology* / Q000469:parasitology*
chemical_list: D023082:Defensins; D019476:Insect Proteins