When people think of Svalbard, they usually picture polar bears, reindeer, arctic foxes and barren tundra landscapes. Hardly anyone would suspect that aphids also belong among the inhabitants of the far north. Yet it is precisely these inconspicuous insects that are the focus of research by Prof. Karina Wieczorek from the Faculty of Natural Sciences at the University of Silesia.
To date, only three aphid species have been recorded on Svalbard: Sitobion calvulus, Acyrthosiphon svalbardicum and a species of the genus Pemphigus. They are among the northernmost known aphids on Earth and are found exclusively on the Arctic archipelago. This makes them endemic species that live nowhere else in the world.
Their extreme specialisation is particularly fascinating. Each of these aphid species is a so-called strict monophagous species and feeds exclusively on a single host plant. Without this plant, the insects could neither survive nor reproduce. Although the dwarf shrub Dryas octopetala – the silverweed – also grows in mountain ranges such as the Alps or the High Tatras, the Svalbard aphids are completely absent from these areas. It appears that, in addition to the host plant, other, as yet unknown environmental conditions must be met.
The search for these tiny insects is extremely laborious. The growing season on Svalbard lasts only from mid-June to the end of August. Within this short period, the aphids must feed, grow and reproduce. For scientists, this means hours of often fruitless searching in the tundra, during which every single host plant must be carefully examined.
During an expedition in August 2018, after intensive fieldwork, Prof. Wieczorek collected only around 100 females and 16 males. Among them were even three mating pairs, an exceptionally rare find that enabled the first detailed studies of the reproductive system of these Arctic specialists.
How the aphids originally reached Svalbard remains unclear to this day. Equally puzzling is why they are found exclusively in specific regions around two fjords. It is precisely these unanswered questions that make these tiny insects so fascinating to science.
Prof. Karina Wieczorek’s research impressively demonstrates that highly specialised organisms exist even in the most inhospitable regions of the Earth. Spitsbergen’s tiny aphids provide valuable insights into how insects adapt to extreme environmental conditions – and how sensitive such unique ecosystems might be to changes in the climate.
Rosamaria Kubny, PolarJournal