title: Parasites of vectors--Ixodiphagus hookeri and its Wolbachia symbionts in ticks in The Netherlands.
abstract: BACKGROUND
  Ixodiphagus hookeri is a parasitic wasp of ixodid ticks around the world. It has been studied as a potential bio-control agent for several tick species. We suspected that the presence of Wolbachia infected I. hookeri eggs in ticks is responsible for incidental detection of Wolbachia DNA in tick samples.
  
  
  METHODS
  The 28S rRNA and 16S rRNA genes of a specimen of I. hookeri was amplified and sequenced. PCR on part of the 28S rRNA gene was used to detect parasitic wasp DNA in 349 questing Ixodes ricinus ticks from various sampling sites. Furthermore, the wsp gene of Wolbachia was sequenced from the I. hookeri specimen and a subset of ticks was tested using this marker.
  
  
  RESULTS
  Several sequences from tick specimens were identical to the Wolbachia sequence of the I. hookeri specimen. Ixodiphagus hookeri was detected in 9.5% of all tested ticks, varying between 4% and 26% depending on geographic location. Ten out of eleven sampling sites throughout the Netherlands were positive for I. hookeri. Eighty-seven percent of I. hookeri-positive but only 1.6% of I. hookeri-negative ticks were Wolbachia positive. Detection of I. hookeri DNA was strongly associated with the detection of Wolbachia in ticks.
  
  
  CONCLUSIONS
  This is the first reported case of I. hookeri in the Netherlands. Furthermore I. hookeri harbours Wolbachia species and is broadly distributed in the Netherlands. While detection of Wolbachia DNA in ticks might often be due to parasitism with this wasp, other sources of Wolbachia DNA in ticks might exist as well.
authors.affiliation: Laboratory for Zoonoses and Environmental Microbiology, National Institute for Public Health and Environment (RIVM), Bilthoven, The Netherlands.
authors.forename: Ellen
authors.initials: E
authors.lastname: Tijsse-Klasen
authors.forename: Marieta
authors.initials: M
authors.lastname: Braks
authors.forename: Ernst-Jan
authors.initials: EJ
authors.lastname: Scholte
authors.forename: Hein
authors.initials: H
authors.lastname: Sprong
mesh_terms: D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D020459:Genes, rRNA; D006927:Hymenoptera / Q000235:genetics / Q000254:growth & development / Q000382:microbiology*; D018884:Ixodes / Q000469:parasitology; D009426:Netherlands; D012339:RNA, Ribosomal, 28S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013559:Symbiosis; D020577:Wolbachia / Q000302:isolation & purification* / Q000502:physiology*
chemical_list: D001425:Bacterial Outer Membrane Proteins; D012339:RNA, Ribosomal, 28S; C112171:Wsp protein, Wolbachia