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Open Access Research

Parasites of vectors - Ixodiphagus hookeri and its Wolbachia symbionts in ticks in the Netherlands

Ellen Tijsse-Klasen1, Marieta Braks1, Ernst-Jan Scholte2 and Hein Sprong1*

Author Affiliations

1 Laboratory for Zoonoses and Environmental Microbiology, National Institute for Public Health and Environment (RIVM), Bilthoven, The Netherlands

2 National Centre for Monitoring of Vectors (CMV), New Food and Consumer Product Safety Authority (nVWA), Dutch Ministry of Economic Affairs, Agriculture and Innovation, Wageningen, the Netherlands

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Parasites & Vectors 2011, 4:228  doi:10.1186/1756-3305-4-228

Published: 7 December 2011

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.

Conclusion

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.

Keywords:
Ixodiphagus hookeri; Ixodes ricinus; Parasitic wasp; Tick; Wolbachia