Geographic population structure of the specialist parasitoid, Hyposter horticola, and its hyperparasitoid, Mesochorus sp. cf. Stigmaticus, in the Åland Islands, Finland

Geographic population structure of the specialist parasitoid Hyposter horticola and its hyperparasitoid Mesochorus sp. cf. Stigmaticus in the Åland Islands, Finland.

 

Authors: Melaina Macone, Saskya Van Nouhuys and Raul F. Medina

 

The Glanville fritillary butterfly, Melitaea cinxia (Lepidoptera: Nymphalidae), is native to the Åland Islands (located between south-western Finland and eastern Sweden) and is the only known host for the specialist parasitoid, Hyposter horticola (Hymenoptera: Ichneumonidae).  H. horticola has a relatively high dispersal rate (dispersing  up to 5 km while seeking hosts).  Because H. horticola has a relatively high rate of dispersal, the Åland Islands are experienced as a single fragmented habitat due to the patchy distribution of M. cinxia.  H. horticola is host to the endoparasitic hyperparasitoid Mesochorus sp. cf. stigmaticus (Hymenoptera: Ichneumonidae).  M. stigmaticus is also able to hyperparasitize Cotesia melitaearum (Hymenoptera: Braconidae), the competitor of H. horticola.  In this study we are investigating the population structure of H. horticola and M. stigmaticus based on geographic distribution throughout the Åland Islands using AFLP markers.  We hypothesize that H. horticola populations will be lacking structure in their particular regions because of its relatively high gene flow.  Alternately, we hypothesize that M. stigmaticus will have a more structured population than H. horticola because of its generalist behavior that allows it to remain in one geographic region. Understanding the nature of population structure in parasitoids and their hyperparasitoids is crucial for designing conservation and biocontrol strategies.