Browsing by Subject "Stylops"

Twisted-winged parasitoids (Insecta: Strepsiptera) are parasites of other insects, which are characterized by complex life cycles and extreme sexual dimorphism. They have three endoparasitic larval stages. In most Strepsiptera only the motile first instar larvae and adult males are free living whereas the adult females are endoparasites during their entire life. The winged males slightly resemble flies, while females are neotenic. Around 630 extant Strepsiptera species are known but this is probably an underestimation since many species are cryptic. The genus Stylops, parasitoids of mining bees of genus Andrena, is one of the biggest genera of Strepsiptera. Until recently it was thought that only one species, Stylops melittae, occurs in Europe. Studies using DNA-methods revealed that it is in fact a species complex of 30 species. This study investigated which of these species occur in Finland. In addition, it was examined if the female morphology of the species could be used in species identification, since males are rarely found. Andrena host specimens were examined from three major entomological collections and the collecting data of the observed Stylops was recorded to a database. Suitable specimens were DNA barcoded and the acquired DNA barcodes were compered for the ones in databases (BOLD, GenBank). The females were separated from their hosts and photographed for the morphological examination using different imaging methods (focus stacking, SEM). Based on this study there are five species of Stylops in Finland instead of one as previously thought: S. thwaitesi, S. ater, S. japonicus, S. nevinsoni and S. spreta. In addition, there is one species, which is most likely undescribed. All females of these species can be identified based on their morphology. The results include summaries of each species containing information about their morphology, ecology, distribution and abundance. This study gives valuable new information about the twisted-winged parasitoids in Finland. The occurrence of the genus Stylops in Finland based on current taxonomy was examined for the first time. The study gave novel information about the distributions of Stylops-species. Deviating from previous information Stylops japonicus is also found in Europe. Furthermore, the study revealed new information about the host-parasite relationships of the species. Many of the Andrena host species had not been associated with certain Stylops species before. There has not been research focusing on Strepsiptera in Finland for a long time. The material collected for this study works as a good foundation for the possible future studies in Finland. The results were used in the 2019 Red List assessment and two of the Stylops species were in the Red List of threatened species.