The Microgastrinae (Hymenoptera: Braconidae) of Germany

Höcherl, Amelie Cosima (2026): The Microgastrinae (Hymenoptera: Braconidae) of Germany: shedding light on a dark taxon through integrative taxonomy and DNA barcoding. Dissertation, LMU München: Faculty of Biology

Abstract

Insects comprise the bulk of terrestrial animal life and provide important ecosystem services, making their decline in the context of the ongoing biodiversity crisis particularly alarming. Despite dominating flying insect diversity, many small, hyperdiverse, and morphologically cryptic so-called ‘dark taxa’ are poorly understood and taxonomically neglected, even in relatively well-studied areas. The German Barcode of Life GBOLIII: Dark Taxa project set out to shed light upon selected dark taxa by applying DNA barcoding and training a new generation of taxonomists. This thesis is a result of the research conducted in the GBOLIII framework and focuses on the braconid wasp subfamily Microgastrinae. These wasps are highly diverse, with an estimated global diversity of 40,000–50,000 species compared to about 3,300 described species. Microgastrinae are koinobiont endoparasitoids of Lepidoptera larvae (caterpillars) and are often highly specialized on their hosts. The known German fauna of these wasps comprised 252 species at the beginning of this doctoral project. This work aimed to explore the biodiversity of Microgastrinae in Germany using DNA barcoding and integrative taxonomy. Three publications aimed to 1) Demonstrate the efficiency of new integrative taxonomy workflows for the German fauna, 2) Improve the accessibility of this dark taxon to a broader audience at a European scale, and 3) Apply and expand these objectives at a larger geographic scale for a taxonomic revision. In the first publication, efficient DNA barcoding workflows were applied within an integrative taxonomy framework, and 30 species were reported for the first time in Germany, thereby adding more than 10% to the known German Microgastrinae fauna. Information for four species was provided in a new Holarctic context, reporting them for the Nearctic or, respectively, Palearctic region, and 26 additional country records were added. Many species were linked with DNA barcodes for the first time, and new host-parasitoid associations were uncovered. All species treated were illustrated with high-quality photos, and integrative species concepts were discussed in detail. In the second publication, an illustrated key for the identification of the 20 European genera of Microgastrinae was provided. A brief review of 20th century progress on the group was given and morphological terms were explained and illustrated, with an emphasis on four different wing venation systems used by European authors. An outline of each genus was given, including information on biology, and some species difficult to place were highlighted. Available keys for species identification were referenced with comments, and attention was drawn to species more recently recorded or described. In the third publication, the approaches tested in Germany were applied and expanded in a larger geographic context. The genus Illidops Mason, 1981 was revised in the Holarctic region, which included the production of an identification key to all 33 Holarctic species. Illidops albostigmalis van Achterberg & Fernandez-Triana, 2017 was recorded for the Palearctic, and three new species, Illidops doreenae Höcherl & Fernandez-Triana 2025, Illidops oroseira Höcherl & Fernandez-Triana 2025, and Illidops stefanschmidti Höcherl & Fernandez-Triana 2025, were described. Many species were associated with new information, including photographs, DNA barcodes, and annotated translations of original descriptions from Russian. High-throughput sequencing of historical DNA and a first-glance, preliminary system for including poorly known species in taxonomic keys were applied to overcome challenges in Western Palearctic dark taxa. Representing a substantial increase in knowledge of the German, European, and Holarctic biodiversity of Microgastrinae wasps, these results also highlight the large diversity of this group. Estimates based on known Lepidoptera diversity indicate that the German fauna could comprise about 475 species. Overarching challenges hampering taxonomic progress were identified, such as the lack of a solid systematic basis for the group, the lack of host data, and historical backlog in the Western Palearctic. DNA barcoding has been demonstrated as an important method in mitigating some of these challenges through efficient workflows, integrative taxonomy, by analyzing historical DNA, and by facilitating international collaboration. The global knowledge gaps regarding Microgastrinae are alarming, as these wasps fulfill important ecosystem services through biological control and may, similar to their hosts, be strongly affected by insect decline. Methodologies and workflows proven here, combined with recent technological advancements applied at a large scale, are required to mitigate this critical lack of knowledge and shed light upon this dark taxon. This will benefit the inclusion of Microgastrinae in biomonitoring and conservation, as well as support much-needed fundamental and applied research of this fascinating group of parasitoid wasps. In conclusion, this research has demonstrated how efficient DNA barcoding workflows combined with integrative taxonomy can advance the knowledge of Microgastrinae wasps, providing a foundation to better understand the systematics of this dark taxon, its role in our ecosystems, and work towards including this group in biomonitoring and conservation efforts.

• Item Type: Theses (Dissertation, LMU Munich)
• Keywords: Dark Taxa, Integrative Taxonomy, DNA Barcoding, parasitoid wasps, Microgastrinae, Biodiversity
• Subjects: 500 Natural sciences and mathematics; 500 Natural sciences and mathematics > 570 Life sciences
• Faculties: Faculty of Biology
• Language: English
• Date of oral examination: 5. August 2026
• 1. Referee: Haszprunar, Gerhard
• Signature of the printed copy: 0001/UMC 32215