Seasonal Dynamics of Carabus Coriaceus Linnaeus, 1758 “Coleoptera, Carabidae” Activity in the Areal’s Eastern Part

INTRODUCTION

Coleoptera, Carabidae are widely distributed from the Arctic and alpine tundras to seacoasts, deserts, and rainforests, and they may be common in these environmental conditions [1-4]. They play a significant role in biocenoses as entomophages that regulate the number of terrestrial invertebrates, and they are considered economically useful: both imago and larvae destroy some pests of forestry and agriculture, limiting their numbers [5-8]. Carabidae is a convenient model object for ecological and faunal studies. This family is used for zoological diagnostics of soils, zoogeographic characterization of biocenoses, and assessment of anthropogenic impacts on the biocenosis [9-14].

Carabus species are large, often colorful, well-recognized, and well-studied members of the Carabidae. They are usually polyphagous predators that consume various invertebrates [15-17]. Some of them are common for forests. But there are species that can be rare, especially in conditions of severe anthropogenic pressure [7, 18-20]. Carabus (Procrustes) coriaceus Linnaeus, 1758 is a very large species of ground beetle with larval or imaginal diapause. The life cycle lasts one year and it is recyclic with autumn reproduction or obligately two-year recyclic with late-summer or autumn reproduction [21]. Females lay their eggs in September. Most larvae overwinter in the first and second stages. The species has a two-year development cycle [22]. The species is widely distributed in Europe [6, 22-26]. In some places, it is considered rare and is included in the lists of protected species [27-30]. The main factors leading to a low population of the species are habitat degradation (deforestation), the use of pesticides, and the weak ability of the species to settle. Recently, the areal has been described in detail within central Russia [31]. The eastern border of the species’ areal passes through the Chuvash Republic and the Ulyanovsk region. The Republic of Mordovia is located close to the eastern border of the species’ areal [32, 33]. The objective of the present study was to investigate the seasonal dynamics of Carabus coriaceus activity in the eastern part of its areal.

MATERIALS AND METHODS

The Republic of Mordovia is located in the center of the East European Plain between 42°11' and 46°45' East longitude and 53°38' and 55°11' North latitude. The Sura and Moksha Rivers (tributaries of the Volga and Oka Rivers, respectively) are the main rivers in the basin where the Republic of Mordovia is located. The territory of the republic is situated in the forest and forest-steppe zone of Central Russia. There are several small steppe areas within the territory. The eastern part of Mordovia is located in the northwest of the Volga Upland, and the western part in the Oka-Don lowland (Figure 1). In this regard, a variety of habitats is observed in the studied area. Boreal coniferous and mixed forests are common in the west, northwest, and north of the region [34]. Deciduous forests cover the central and eastern parts of the republic [12, 35]. Forest-steppe landscapes prevail in the east and south-east.

The collection was carried out using pitfall traps in different regions of the Republic of Mordovia in 2018-2019. The distribution of ground beetles was studied during 2008-2020. The pitfall traps consisted of plastic cups with a volume of 0.5 liters with a 4% formalin solution poured into them. In order to study seasonal population dynamics, traps were placed in the forests of the Mordovia State Nature Reserve in four localities (Temnikov district of the Republic of Mordovia) and the National Park “Smolny” in three localities (Ichalki and Bolshoe Ignatovo districts of the Republic of Mordovia). In each locality, there were 10 traps (from the end of April to September), which were installed in one line with a distance between them of 2-3 m. The evaluation of accounting results was expressed in dynamic density (ex./100 trap-days).

RESULTS AND DISCUSSION

The Republic of Mordovia is part of the range and is located close to the eastern border of the distribution of this species. The main biotopes of this species are forest edges, forest meadows, forest roads, and clearings in mixed and pine forests [33, 36]. Despite the fact that there are a lot of forests in the region, the findings of C. coriaceus are mainly confined to protected areas. In such conditions, the forest landscapes where C. coriaceus lives remain untouched.

Nevertheless, we note that the number of species in Mordovia State Nature Reserve was almost three times higher than the number of species from biotopes from the forests of National Park “Smolny”. The first protected area is protected for a longer time and all the landscapes have been untouched for more than 80 years. Ecosystems in the National Park “Smolny” have been protected for only 25 years, and before that, intensive forestry activities were carried out on this territory. It is possible that anthropogenic activity has caused some damage to the populations of C. coriaceus and they are now in the recovery stage.

The activity of ground beetles is influenced by several factors, including temperature, humidity, microclimatic conditions, etc. [37, 38]. The temperature has long been considered the most important abiotic factor affecting the activity of Carabidae [39, 40]. The seasonal and life-history fluctuations strongly influence the observed abundances and distributions of Carabidae in certain biotopes [1, 21, 41].

Seasonal activity of C. coriaceus began in late April-early May and lasted until mid-September – the first half of October (Figure 2). Only one peak of abundance was recorded, which occurred in the second half of July – August.