Supervisor: Professor Toomas Tammaru (University of Tartu)
Opponent: Stephan M. Blank, PhD (Senckenberg German Entomological Institute)
Although scientists have been describing biodiversity for more than 250 years, most of the species (probably 80-90%) remain unknown. Insects form the largest proportion of known and unknown macroscopic biodiversity. Nearly million insect species have been described, but the number of undescribed species could be ten times greater. Among the insects, order Hymenoptera (e.g. ants, bees, and wasps) is one of the largest, which also includes the sawfly genus Empria (60 species). Sawflies are plant feeding and caterpillar-like in the immature stage. Adults of Empria are small (4-9 mm) black insects. Characteristic of the genus are pale paired patches on abdominal terga, which makes it easy to distinguish from other sawflies. Species identification, however, is possible only using a microscope and usually penis valves need to be dissected from genital capsules of males and ovipositors from females. If this is done, the species identification is generally quite easy for anyone with a microscope, because the differences between penis valves and ovipositors of different species are usually obvious. It could be said that you simply need a gallery of penis valves and ovipositors to determine a species. The doctoral thesis includes a key to adults of Empria from eastern hemisphere (50 species) with photos of penis valves and ovipositors (corresponding information was already available for species of western hemisphere). There are 13 species new to science, 9 of which are still without a name. In addition, DNA sequence data from 46 species (including both hemispheres) was used to reconstruct the phylogeny of the genus. Future studies should describe the remaining unknown species and elucidate the host plants of all the species (unknown in more than half of the species). Closer look at Empria could also contribute to speciation studies, as there appear to be more or less continuous variation from highly distinct species to species pairs or groups with fuzzy species boundaries. Why is it necessary to know Empria species at all? The genus is not economically particularly important (couple of species in North America can be pests of strawberry), but from a scientific point of view the knowledge about it can be considered as a piece of a puzzle, assembling of which continuously improves our ability to make sense of the world.