Russian and Finnish scientists look for reasons for the surprising rarity of the “secret” butterfly

Bear Menetrie (Arctia menetriesii) is an extremely rare species of butterfly that lives in intact taiga and mountain coniferous forests of Eurasia. An international team of entomologists has created a database that will help identify the factors that contribute to the extreme rarity and uniqueness of this species of lepidoptera. The description of the database is published in the highly rated scientific journal Scientific Data (https://www.nature.com/articles/s41597-022-01230-8), which belongs to the Nature Portfolio group.

Map with findings of the Menetrie bear and photos of some places where this butterfly was collected. The size of the circles indicates a possible error in the geographical indication of the place where the butterflies were collected.

Arctia menetriesii described by Russian entomologist Eduard Eversman in 1846 from a single specimen found in the mountains of northeastern Kazakhstan. The butterfly was named after Edouard Menetrier, a Russian scientist of French descent, one of the founders of Russian entomology.

As head of the international scientific team, director of the Academic N.P. Laverov of the Urals Branch of the Russian Academy of Sciences (Arkhangelsk), Corresponding Member of the Russian Academy of Sciences Ivan Bolotov, the main feature of the Menetrie bear is a very wide range along with exceptional rarity. It is common in man-made untouched forests throughout most of northern Eurasia – from Finland to Sakhalin, but can be found extremely rarely and almost by accident: it seems to evade humans.

According to the entomologists of the Laverov Center and the North (Arctic) Federal University (Arkhangelsk), this species reappears in places where it has been recorded about once every 50-100 years. Science does not yet have clear answers to the question of what such a phenomenon could be related to, but scientists are trying to solve this mystery.

From discovery and description Arctia menetriesii in the mountainous region of northeastern Kazakhstan, entomologists have never seen this species. In Finland, the bear’s range is located in the areas bordering Russia within a radius of about 50 km, where original forests have been preserved. It was in the Finnish taiga in 1913 that the second encounter with the rarest butterfly in the history of observations took place. During the whole observation period, seven findings were made in Finland and about 70 in Russia. Three finds are also known in the mountain ranges of northeastern China.

The vast majority of samples were collected by non-experts, so the scientists attracted collectors to form a database of the butterfly. The main idea was to collect all available data on such finds for the entire history of observations from 1846.

It is estimated that 10-15% of the finds, including collections in China, could not be left uncovered. The created database contains data for 78 samples collected.

– We believe that this data will serve as a basis for mathematical modeling that would answer questions about the reasons for the exceptional rarity of this species. Abroad it is called the mystical and legendary butterfly. All her encounters with one person are random. There is a belief among butterfly collectors that this is something like a blue bird: whoever finds it will be lucky, says Ivan Bolotov.

He is one of the few entomologists who was lucky enough to catch the Menetrier bear. This happened in the Pinezhsky refuge (eastern Arkhangelsk region) in 2005. According to the scientist, the butterfly has never been found in the neighboring forests of the Komi Republic, but in the eastern, undeveloped lands of the Northern Urals, it was recorded. A colleague and co-author of Ivan Bolotov, a researcher at the Institute of Aquatic and Environmental Problems of the Far East Branch of the Russian Academy of Sciences, Evgeny Koshkin has been hunting the Menetrie bear for about 30 years in remote areas of the Russian Federation.

Graph of the accumulated frequencies with the number of findings of the Menetrier bear by years.  Photographs of collection specimens of this species are also presented, including a butterfly from the collection of Eduard Eversmann (Zoological Institute of the Russian Academy of Sciences, St. Petersburg), according to which the species was described in 1846.

Graph of the accumulated frequencies with the number of findings of the Menetrier bear by years. Photographs of collection specimens of this species are also presented, including a butterfly from the collection of Eduard Eversmann (Zoological Institute of the Russian Academy of Sciences, St. Petersburg), according to which the species was described in 1846.

Externally Arctia menetriesii very different from related species. It has a catchy color – an orange background with patterns of black stripes and red spots. Theoretically, the Menetrie bear is inedible to birds: a glowing appearance should warn and repel birds and other hunters, as it resembles the color of a wasp. But scientists do not have absolute clarity about how the butterfly evolved, what factors influenced the color. Another interesting difference between the taiga winged bear: all its relatives are active at night and this species is active in the evenings, before dusk. Most of the finds were made near rivers, streams and lakes – for some reason, the butterfly is clearly attracted to water bodies.

Currently, the main part of insect species is rare, only a small number of species belong to the mass species. Scientists intend to use the Menetrier bear as a taxonomic model to help unravel the mechanisms that determine the super-rarity of a large number of butterfly species.

– Anthropogenic pressure on the natural environment is constantly increasing, natural ecosystems are being destroyed. Scientists are already talking about a “revelation” between insects. The data show that the biomass of insects has decreased by 2-3 times in the last 50 years in many parts of the world. And insects play a crucial role in ecosystems – they are food for birds, fish and animals, plant pollinators, organic matter destroyers and more. One way or another, humanity is heavily dependent on insects, which have begun to disappear catastrophically. This is not allowed. Therefore, rare species of insects require special attention, sums up Ivan Bolotov.

Article: Bolotov, IN, Gofarov, MY, Koshkin, ES et al. (2022). An almost complete database on the records and ecology of the rarest northern tiger moth from the 1840s to 2020. Scientific data, 9, 107. https://www.nature.com/articles/s41597-022- 01230-8

Information and photos are provided by the press service of the FITSKIA Ural branch of the Russian Academy of Sciences

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