The reproductive barriers that prevent gene flow between closely related species are a major topic in evolutionary research. Insect clades with parasitoid lifestyle are among the most species-rich insects and new species are constantly described, indicating that speciation occurs frequently in this group. However, there are only very few studies on speciation in parasitoids. We studied reproductive barriers in two lineages of Lariophagus distinguendus (Chalcidoidea: Hymenoptera), a parasitoid wasp of pest beetle larvae that occur in human environments. One of the two lineages occurs in households preferably attacking larvae of the drugstore beetle Stegobium paniceum (“DB-lineage”), the other in grain stores with larvae of the granary weevil Sitophilus granarius as main host (“GW-lineage”). Between two populations of the DB-lineage, we identified slight sexual isolation as intraspecific barrier. Between populations from both lineages, we found almost complete sexual isolation caused by female mate choice, and postzygotic isolation, which is partially caused by cytoplasmic incompatibility induced by so far undescribed endosymbionts which are not Wolbachia or Cardinium. Because separation between the two lineages is almost complete, they should be considered as separate species according to the biological species concept. This demonstrates that cryptic species within parasitoid Hymenoptera also occur in Central Europe in close contact to humans.
Bibliographical noteFunding Information:
K.K. was financially supported by Landesgraduiertenförderung Baden-Württemberg. E.K. and M.P. received financial support by the partnership program of the Robert H. Smith Faculty of Agriculture, Food and Environment of The Hebrew University of Jerusalem (HUJI) in Rehovot with the Faculties of Agricultural and Natural Sciences of University of Hohenheim (UHOH), sponsored by the Ministry for Science, Research and the Arts of Baden-Württemberg. Strain DBrav was collected by Cornelia Gantert, strain GWpfo was collected by Steffi Niedermayer, and strain GWsat was kindly provided to us by Matthias Schöller and Sabine Prozell.
© 2019 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.
- Lariophagus distinguendus
- cytoplasmic incompatibility
- endosymbiotic bacteria
- parasitoid wasps
- sexual isolation