title: The maternal transfer of bacteria can mediate trans-generational immune priming in insects.
abstract: Parents invest in their offspring by preparing them for defense against pathogens and parasites that only the parents have encountered, a phenomenon known as trans-generational immune priming. We investigated the underlying mechanism using the established lepidopteran model host Galleria mellonella. When larvae were fed with non-pathogenic bacteria, or the entomopathogenic species Pseudomonas entomophila and Serratia entomophila, the activity of lysozyme and phenoloxidase increased in the hemolymph, and immunity-related genes encoding antibacterial proteins such as gloverin were induced. Remarkably, the ingestion of bacteria by female larvae resulted in the differential expression of immunity-related genes in the eggs subsequently laid by the same females, providing evidence for trans-generational immune priming in G. mellonella. To determine the fate of these ingested microbes, the larval diet was supplemented with bacteria carrying a fluorescent label. We observed these bacteria crossing the midgut epithelium, their entrapment within nodules in the hemocoel, their accumulation within the ovary, and ultimately their deposition in the eggs. Therefore, we propose that trans-generational immune priming in Lepidoptera can be mediated by the maternal transfer of bacteria or bacterial fragments to the developing eggs.
authors.affiliation: Department of Applied Entomology; Institute for Phytopathology and Applied Entomology; Justus Liebig University; Giessen, Germany.
authors.forename: Dalial
authors.initials: D
authors.lastname: Freitak
authors.affiliation: Department of Applied Entomology; Institute for Phytopathology and Applied Entomology; Justus Liebig University; Giessen, Germany.
authors.forename: Henrike
authors.initials: H
authors.lastname: Schmidtberg
authors.affiliation: Department of Applied Entomology; Institute for Phytopathology and Applied Entomology; Justus Liebig University; Giessen, Germany.
authors.forename: Franziska
authors.initials: F
authors.lastname: Dickel
authors.affiliation: Institute of Biochemistry; Justus Liebig University; Giessen, Germany.
authors.forename: Günther
authors.initials: G
authors.lastname: Lochnit
authors.affiliation: Department of Entomology; Max Planck Institute for Chemical Ecology; Jena, Germany.
authors.forename: Heiko
authors.initials: H
authors.lastname: Vogel
authors.affiliation: Department of Applied Entomology; Institute for Phytopathology and Applied Entomology; Justus Liebig University; Giessen, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Vilcinskas
mesh_terms: D000818:Animals; D018988:Bacterial Translocation; D005260:Female; D007814:Larva / Q000254:growth & development* / Q000276:immunology / Q000382:microbiology; D008297:Male; D009036:Moths / Q000254:growth & development / Q000276:immunology* / Q000382:microbiology*; D011549:Pseudomonas / Q000276:immunology / Q000502:physiology*; D012705:Serratia / Q000276:immunology / Q000502:physiology*
keywords: Galleria mellonella; fitness costs; innate immunity; maternal inheritance; parental investment; trans-generational immune priming