The Subarctic A. frigida Species has
Disappeared in Europe; Is it the Effect
of Global Warming?
Zakharov Ilia A*
Vavilov Institute of General Genetics, Russia
Submission: September 19, 2022; Published: November 23, 2022
*Corresponding author: Zakharov Ilia A, Vavilov Institute of General Genetics, Moscow, 119133, Russia
How to cite this article: Zakharov Ilia A. The Subarctic A. frigida Species has Disappeared in Europe; Is it the Effect of Global Warming?.s Int J Environ Sci Nat Res. 2022; 31(3): 556315. DOI 10.19080/IJESNR.2022.31.556315
The composition of populations of beetles of the Adalia genus in the northern regions of Europe and Siberia has been investigated. In Europe, the subarctic species Adalia frigida is currently not found; it has been replaced by the species Adalia bipunctata, common for the temperate zone of Eurasia. The change in the composition of ladybird populations is considered to be a consequence of global warming.
Keywords: Adalia bipunctata; Adalia frigida ; Climate; Global warming; Temperature
Three species of ladybirds belonging to the Adalia genus are found in Europe, in temperate and Mediterranean climate zones: A. bipunctata (L.), A. decempunctata (L.), A. conglomerata (L.) (the latter species is rare) . In addition to these three species, as well as A.alpina Villa and A.revelierie Muls. (in the Alpine zone and on the islands of the Mediterranean Sea, respectively), G.G. Jacobson also notes A. frigida Schneid as a species distributed in the north: in Norway, Sweden, Lapland, Kola Peninsula, near the Pechora River . S.M. Iablokoff-Khnzorian  considers this species as a form of A. bipunctata .
To clarify the taxonomic status of A. frigida species, the nuclear and mitochondrial DNA of some individuals of this ladybird species compared to other Adalia species were analyzed. The results of studies indicated that A. frigida was an independent species, although being very close to A. bipunctata .
This study presents the results of observations over the past 40 years on the distribution of A. frigida in northern Europe and Siberia, showing that this ladybird species has practically disappeared in Europe and has been replaced by A. bipunctata, which is considered to be the consequence of global warming/.
Ladybirds of the Adalia genus were sampled in August (in Transbaikalia in September) at the stage of imago and pupa. In the latter case, adult ladybird beetles were bred under laboratory conditions.
All sampling of ladybird beetles was conducted in the cities; outside the cities, especially in the northern regions, the species of Adalia genus were practically not found. Ladybird beetles were collected on willows (Salix sp.), elms (Ulmus sp.), Tatar honeysuckle (Lonicera tatarica), and in Alta (Norway) they were collected on bird cherry (Prunus padus).
Individuals of the A. frigida and A. bipunctata species are clearly distinguished by the pattern on the elytra. The ladybird beetles of European populations of A. bipunctata species are represented by two forms: with red elytra and one black dot on each elytron, and with black elytra and red spots. A. frigida ladybird beetles have five black spots on the red elytra, in two rows (3+2), the spots often merge and are often surrounded by light halos.
The Table 1 shows the places where A. frigida ladybird beetles were found, as well as the areas where the presence of this species could be expected (Scandinavia, Kola Peninsula). The northernmost points surveyed were the polar cities of Alta in Norway and Murmansk in the Russian Federation. The southernmost point was Ulan-Ude in Transbaikalia, where individuals with a pattern on the elytra characteristic of A. frigida species were occasionally found in a very polymorphic population of the A. bipunctata fasciatopunctata subspecies.
The results of studies show that after 2005 A. frigida ladybird beetles were not found anywhere in Europe. In Arkhangelsk in the 1980s, A. frigida was the predominant species, after 20 years it was in the minority, and since 2010 it had not been found even once.
The results of crossing between A. frigida and A. bipunctata species demonstrated that the hybrids of the first generation showed signs of A. bipunctata. Segregations in the backcross and in the second generation indicated that the elytral pattern characteristic of A. frigida species was determined by an allele that was recessive to the alleles of A. bipunctata, which determined the coloration and pattern on the elytra typical of this species (the data will be presented in another publication).
The current absence of A. frigida species in Scandinavia and the Kola Peninsula, i.e., in the regions included in its habitat , and the disappearance of this ladybird species in Arkhangelsk after 2005 are considered to be a consequence of global warming. A. frigida species has been replaced by another species, A. bipunctata, inhabiting territories with temperate climate.
It is known that over the past four decades (1979-2021) the
increase in the average annual temperature in the Arctic, in the
sector from Svalbard to the Novaya Zemlya Islands, was about
1.25о per decade .
In Arkhangelsk, where A. frigida ladybird beetles have disappeared, the average annual temperature increased from 0.7о in 1979 to 2.8о in 2021. The average annual temperatures of the three decades, in which the sampling of coccinellids was conducted, increased as follows: +1.20о during 1981-1990, +1.44о during 1991-2000, +1.97о during 2001-2010 .
Under the conditions of global warming, the area of A. bipunctata habitat expanded, and in the subarctic territories, this species replaced the A. frigida species that previously inhabited them.
There could be two mechanisms of such substitution: the reproductive advantage of A. bipunctata during global warming compared to the more “cryophile” A. frigida ladybird species and the displacement of the latter, or genetic mergence. The ladybird beetles of these two species are freely crossed and their hybrids are fertile, and the pattern on the elytra, which is the diagnostic feature distinguishing these two species, is represented by dominant variants of A. bipunctata. Accordingly, hybrids of the first generation look like A. bipunctata, and in subsequent crossings of hybrids with each other and with individuals of both parental species, the offspring will also be phenotypically similar to A. bipunctata species in most cases.