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Research article - Peer-reviewed, 2019

First evidence of Ixodiphagus hookeri (Hymenoptera: Encyrtidae) parasitization in Finnish castor bean ticks (Ixodes ricinus)

Sormunen, Jani Jukka; Sippola, Ella; Kaunisto, Kari Mikael; Vesterinen, Eero Juhani; Saaksjarvi, Ilari Eerikki


Ixodiphagus hookeri (Hymenoptera: Encyrtidae) is a parasitoid wasp specialized in parasitizing the larvae and nymphs of ticks (Acari: Ixodidae). As parasitized ticks die prior to reproduction, I. hookeri is seen as a prime biological control agent candidate. Despite this, little is known of their occurrence or ecology in northern Europe. The main aim of the current study was to determine whether adult wasps or parasitized ticks can be found from a tick-infested island in southwestern Finland, using field collections and molecular methods. Following the initial discovery of an adult I. hookeri female on Seili Island, we set out to collect further specimens via sweep netting and Malaise trappings between May and October 2017. Furthermore, 1310 Ixodes ricinus (1220 nymphs, 90 adults) collected from the island during 2012-2014 were screened for I. hookeri DNA using qPCR. Whereas no further wasp specimens could be collected via sweep netting or Malaise trappings, I. hookeri DNA was consistently detected in I. ricinus nymphs (annual minimum infection rates in 2012, 2013, and 2014: 2.3, 0.4, and 0.5%, respectively), whereas all adult samples were negative. Although the annually repeated detections of parasitized ticks suggest that the wasp inhabits the island, further field and molecular surveys are needed to more comprehensively determine the status and stability of the population.


Parasitism; Parasitization; Parasitoids; qPCR; Biological control

Published in

Experimental and Applied Acarology
2019, volume: 79, number: 3-4, pages: 395-404
Publisher: SPRINGER

Authors' information

Sormunen, Jani Jukka
Univ Turku
Sippola, Ella
Univ Turku
Kaunisto, Kari Mikael
Univ Turku
Vesterinen, Eero
University of Turku
Vesterinen, Eero
Swedish University of Agricultural Sciences, Department of Ecology
Saaksjarvi, Ilari Eerikki
Univ Turku

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