Ecology of Some Panorpa (Mecoptera, Panorpidae) Species from Several Regions of Russia

Abstract

Our study focuses on the investigation of the ecological aspects (seasonal dynamics, height distribution, and preference of biotopes) of six species within the genus Panorpa (P. alpina Rambur, 1842, P. cognata Rambur, 1842, P. communis Linnaeus, 1758, P. germanica Linnaeus, 1758, P. hybrida MacLachlan, 1882, and P. vulgaris Imhoff & Labram, 1845). The observed seasonal dynamics predominantly display a monovoltine nature. P. communis was active from the early days of May, with individuals persisting until the beginning of October. Conversely, P. vulgaris exhibits activity from the third decade of May to mid-September. P. hybrida manifests within a concise timeframe, observed from late May to late July. P. cognata demonstrates activity commencing in early May, with individuals observed until the end of September. Within forest environments, the highest population density of all species is concentrated at a height of 1.5 m above ground level, whereas the minimum population density is recorded at a height of 12 m above ground level. P. vulgaris demonstrates comparable abundance across heights ranging from 1.5 to 7.5 m, whereas P. hybrida exhibits uniform distribution solely at heights of 1.5 and 3.5 m. Furthermore, the abundance of P. communis surpasses that at other heights when observed at the height of 1.5 m. Panorpa specimens exhibit an absence in open ecosystems at heights of 8 and 10 m. The peak of population density for all species is consistently identified at heights of 2 and 4 m. The application of six diverse entomological methodologies leads to optimal outcomes. Our investigations reveal that P. communis, P. vulgaris, and P. hybrida display greater attraction to beer traps, while P. cognata exhibits a comparatively diminished propensity for such traps. P. cognata, in contrast, demonstrates a substantial presence in pan traps and pitfall traps. In Malaise traps, pan traps, and pitfall traps, five distinct species were captured, although with a species composition differing from alternative methods. To sum up, for the comprehensive study of Panorpa across an expansive geographical spectrum, it is judicious to integrate both net captures and the use of diverse trap types. In addition, it is necessary to explore all biotopes and tiers of the forest.

1. Introduction

Forest ecosystems are one of the most important and largest habitats of plants and animals; in many countries, they are places of regional biodiversity [1,2,3,4,5,6]. Over the past few centuries, with excessive anthropogenic load, forests have turned into managed plantations with a simple structure of stands. The constant degradation of forests affects the structure, composition, and diversity of forests, carbon stocks, functionality, and ecosystem processes. It is known that forest ecosystems contribute significantly to global carbon emissions [7,8,9]. There are not many intact natural forests, especially in Europe. These are mainly high-altitude and hard-to-reach areas, as well as protected areas [10,11,12,13,14,15,16]. Anthropogenic changes in landscapes strongly affect invertebrates, which causes a decrease in their numbers in forest ecosystems [1,17,18,19]. Unfortunately, many cases of recorded declines in insect abundance and biodiversity are often the result of limited research in small areas, a shortage of specialists, and a lack of funding [20,21,22]. Therefore, for a full-fledged analysis of biodiversity, it is necessary to eliminate these obstacles [23,24].

Among the many insect orders, there are several orders that do not differ in species richness. Among them, the order Mecoptera stands out, the taxa of which have a remarkable structure and behavior. In Russia, species from this order have not been studied enough, so many aspects of the biology of these species are still unknown to us. The largest family Panorpidae has about 500 taxa, distributed mostly in the Northern Hemisphere [25]. The larvae of Panorpidae live in the soil or on the surface of the soil and are mainly saprophages [26,27,28,29]. The objects of nutrition of adult individuals of Panorpidae are decomposing insects and plant remains and dead insects, with some species possibly being phytophagous [30,31]. The most remarkable thing about the biology of Panorpidae is the mating behavior of males. The males of many species may provide salivary secretions or prey to the female as a mating gift. Therefore, Panorpidae serve as model organisms for studying mating behavior [32,33]. Six species of Panorpidae have recently been described within the European part of Russia [34,35]. The purpose of our work was to study the distribution of species of the genus Panorpa within the European part of Russia on the basis of our own material obtained in recent years. The objectives of this study are: (a) to determine the seasonal activity of species; (b) to study the vertical distribution of species in forests and open biotopes; and (c) to explore the possibilities of using different types of sample collection to study species biodiversity.

2. Materials and Methods

This research was conducted on the territory of the East European Plain (Figure 1). The plain is hilly with low altitudes above sea level. The largest and deepest rivers on the plain are the Volga and Don rivers. The East European Plain is located in a temperate continental climate, with the exception of the Far North. The continentality of the climate increases towards the east. The plain is affected by the transfer of air masses and cyclones from the Atlantic and the Arctic Ocean, as well as from the southern regions. A characteristic feature of the nature of the plain is the well-defined zonality of the landscapes (from tundra in the north to semi-deserts and deserts in the south). In the middle zone of the East European Plain, forest landscapes prevail. In the north is a dark coniferous taiga; in the south, there are mixed and then deciduous forests. Further south, they are replaced by forest steppes and steppes with fertile, mainly chernozem soils and herbaceous vegetation [36].

The sampling and identification of Panorpa species were carried out for the periods of 2008, 2009, 2011, 2015, and 2017–2023. Each of these methods is used in different ways in the study of the fauna and ecology of Panorpa. Usually, researchers use no more than two or three methods to obtain results. However, we believe that 2–3 methods of study are not enough to fully study the biodiversity of fauna and the ecology of individual species. Therefore, a wider range of trapping methods was used in our research [35]. Methods adhered to conventional practices, employing hand-held sweep-nets, light traps, pitfall traps, pan traps, Malaise traps, beer traps, and window traps [37,38]. The materials were collected from 16 regions in Russia. Most of the samples were identified by L. Dvořák, and voucher specimens are deposited in his private collection.

Seasonal population dynamics were discerned for four species, drawing upon a comprehensive dataset that considered findings from 2017 to 2023. Here, we used all the data obtained using all methods of study for all years of research. The investigation into the vertical distribution of species within forest ecosystems was concentrated in the Mordovia State Nature Reserve, located in the central region of European Russia. The vertical distribution of Panorpa in forest ecosystems was studied in the depths of the forest and at the edges. For this purpose, beer traps were used, which were located at a height of 1.5, 3, 7, and 12 m on large tree branches. These heights represent the levels from the surface grassy cover to the tree crowns. Beer traps were used throughout the warm season (from April to October). The methodology is described in more detail in previous publications [39,40]. The StatSoft STATISTICA 10.0.1011 software package was used to analyze statistical data.

3. Results

In the course of our research, we examined a total of 2250 specimens representing six species within the genus Panorpa (P. alpina, P. cognata, P. communis, P. germanica, P. hybrida, and P. vulgaris). Notably, P. communis exhibited the highest abundance with 1253 specimens distributed across 16 regions, followed closely by P. vulgaris, which accounted for 844 specimens in 15 regions. In contrast, P. alpina (17 specimens) and P. germanica (16 specimens) were observed in markedly lower numbers within three regions.

The seasonal dynamics of the species, as delineated from the dataset, were specifically traced for four species, revealing a pronounced monovoltine pattern characterized by a singular peak. Using P. communis as an illustrative example, its activity initiates from the early days of May and persists until the beginning of October (Figure 2a). The peak of abundance for P. communis occurs between mid-June and the first half of August.

The activity of P. vulgaris was noted to span from the third decade of May to mid-September, with peak abundance observed from the second half of June to the end of July (Figure 2b). The period of activity of P. hybrida was obtained from the end of May to the end of July (Figure 2c). The first individuals of P. cognata were documented from the onset of May, persisting until the end of September (Figure 2d).

Upon investigating the vertical distribution of four species within forest ecosystems, it was observed that P. communis predominates in these forests, with P. cognata occurring to a lesser extent (Figure 3). The predominance of P. communis over P. cognata in forests is clearly visible in the amount of studied material (170 versus 28 specimens, respectively). The highest overall abundance of all species was noted at a height of 1.5 m above the ground level, while the minimum abundance of all species was observed at a height of 12 m. Nevertheless, the distribution pattern varied for each species. P. vulgaris exhibited consistent abundance across heights from 1.5 to 7.5 m, while the distribution of P. hybrida individuals was consistent only at heights of 1.5 m and 3.5 m. The abundance of P. communis at 1.5 m exceeded that at other heights, but there were no differences in the number of species at heights of 3.5 and 7.5 m. Conversely, the abundance ratio of P. cognata skewed significantly towards lower heights, although the results concerning this species are not representative due to only 28 specimens being analyzed.

Divergent outcomes were observed in the investigation of the vertical distribution of Panorpa in open ecosystems at heights ranging from 2 to 10 m (Figure 4). Notably, no specimens of these species were detected in traps set at the heights of 8 and 10 m. P. hybrida was solely recorded at the height of 6 m. The remaining species (P. communis, P. cognata, and P. vulgaris) were encountered in traps set at the heights of 2 and 4 m. Remarkably, 83.3% of the total number of individuals were captured at the height of 2 m. For comparison, in forest ecosystems, only 37.1% of the total number of individuals were captured at the height of 1.5 m.

Interesting results were obtained when comparing the habitats of two closely related species (P. hybrida and P. communis). The syntopic occurrence of both species constitutes 29% of the total (Figure 5). The data, obtained from beer traps adept at capturing these species (as discussed below), show that P. vulgaris/communis seldom co-exist in the majority of localities, underscoring the microhabitat preferences of each species.

Our analysis scrutinized the occurences of different Panorpidae species in various trap types (Figure 6).

In our investigation, P. communis, P. vulgaris, and P. hybrida displayed heightened responsiveness to beer traps, while P. cognata exhibited relative rarity in such traps (these outcomes are naturally influenced by the abundance of each species in the studied regions). P. cognata was well-represented in pan traps and pitfall traps. Malaise traps, pan traps, and pitfall traps captured five species, although the species composition in these traps varied. All Panorpa were captured using entomological nets and hands, marking this method as the most optimal for studying the fauna of these species. P. alpina and P. germanica were infrequent, found in modest numbers in window traps, pitfall traps, and hand-held sweep-nets (P. germanica was also captured in pan traps).

4. Discussion

As a result of our research, six species of Panorpa have been identified (P. alpina, P. cognata, P. communis, P. germanica, P. hybrida, and P. vulgaris). The most common species with a wide range of habitats was P. communis. The rarest species with local distribution in a few regions were P. alpina and P. germanica.

P. communis is the most common species in Europe. Its seasonal activity has been studied in many countries. Comparable patterns were observed in other regions, such as England, where P. communis adults have been documented from May to September, with a concentration from late May to late July [41]. Additional reports [42] indicated that its activity spans from late May to early August. In a moss forest near Neuershausen, Germany, P. communis was recorded from late April to early September [43]. French forests exhibited peak abundance in traps during June [44]. Further geographic variations include the Czech Republic, where the species was active from May to September [45], and Slovenia, where activity extended from May to September [46]. In Germany, P. vulgaris displays activity from late April to early September [47], while alternative sources [48] suggested activity extending from late May to late August. In the Czech Republic, activity is usually from mid-May to the end of August, with an exceptional observation from early October. P. hybrida exhibited a brief activity period, ranging from late May to late July, with the highest abundance recorded from mid-June to the first half of July. It is plausible that this species undergoes a rapid emergence, with adults exhibiting activity for a short duration before their subsequent decline. In the Czech Republic, the species was similarly active, occurring exclusively from May to July [45], but one record was published from a beer trap installed between the 28th of July and the 15th of August [49]. The peak of active adults for P. cognata was recorded from late June to the middle of July. In England, the phenology of P. cognata adults aligns with other species of the genus, but it exhibited a later peak in adult abundance, occurring in July to August, a period when other species were in decline. It is postulated that P. cognata had a shorter season of activity that concludes earlier than P. germanica [41]. In Germany, P. cognata typically emerged in June–July [43,48], and it appears as one of the last species to be observed, with potential sightings extending into late summer, including the latest recorded find in early September [48]. In Slovenia, its activity spans from May to September [46]. In Czechia, this species was also recorded mainly in July and August, with the first records in May and the last in October [50].

Based on the discovery of individuals from two species, P. communis and P. cognata, during late autumn and early spring, it can be inferred that some adults from these species successfully overwinter. The phenology of Panorpa depends on temperature, influenced by the sun’s altitude and the intensity of solar radiation [43]. Under favorable temperatures, a second generation may emerge in late summer [51]. Some authors believe that P. communis might exhibit a facultative second generation in August [52,53], a possibility that aligns with our observations.

Unfortunately, the vertical distribution of Panorpa has been studied to a lesser extent than their seasonal activity. Therefore, it is difficult to compare the results we have obtained. In France, the authors observed the highest abundance of P. germanica and P. communis in tree canopies rather than in the ground layer [44]. However, they attributed this shift in spatial niche to closed plantings where herbaceous and shrubby tiers were poorly developed, compelling adults to seek food in the forest canopy [44].

P. hybrida has historically not been regarded as a distinct species from P. communis. Nonetheless, Sauer and Hensle [47,54] discerned differences between these species, frequently found in syntopy. Their assessment encompassed distinctions in ecology, ethology, reproductive isolation, and morphology. Molecular investigations, such as those conducted by Hu et al. [55], corroborate the existence of species-level distinctions. Earlier studies [34,56,57] have underscored the prevalence of P. hybrida in Eastern Europe, with its abundance increasing in an eastward direction. The results obtained by us confirm the data [47,54] on the different preferences of biotopes for these close species.

Typically, Panorpa specimens are collected in shaded and moistened biotopes, often amidst dense vegetation or within forests. Adults of Panorpa are also encountered on a diverse range of plants, including hedges and trees [42]. While they are occasionally found in areas with more solar exposure, these locations still maintain high humidity levels due to their proximity to swamps, lakes, reservoirs, or rivers [58]. Nonetheless, distinct preferences in biotopic distribution exist among species. For instance, P. vulgaris is discovered in drier habitats exposed to the sun, aligning with previously reported habitat preferences for this species [54,59,60]. In Germany, the habitat of P. communis encompasses cool, humid environments with low microclimatic fluctuations [54]. According to our data, P. communis was widely distributed, occurring in various biotopes, both natural and anthropogenically altered. It exhibits a preference for forest ecosystems, frequents meadows, is less common in pastures, and tends to avoid open dry ecosystems. P. cognata inhabits dry, predominantly southern, or warm-friendly localities such as forest edges and thickets of shrubs [48]. In the Czech Republic, P. cognata prefers rather open and slightly shaded areas such as lowland and hilly habitats, especially meadows with thermophiles, grass, and herbaceous vegetation, and scattered solitary massive trees, as well as the edges and interiors of light forests and xerothermic grass orchards. It does not avoid wetter meadows and coastal habitats as long as these places are warm enough [50]. In England, it has been found in moist forests and meadows with tall vegetation [41]. In the central region of Russia, P. cognata is more frequently encountered in open biotopes, such as wet meadows and forest edges, as supported by the findings of studies conducted in both forested and open ecosystems.

There are indications that certain Panorpa species thrive in disturbed areas resulting from events such as fires or other natural disasters [61]. Notably, catastrophic fires occurred in the Mordovia State Nature Reserve in both 2010 and 2021, extensively impacting the region. In the aftermath of the 2010 fires, no Panorpa individuals were detected in the burned areas even nine years later; their presence was only confirmed in control plots [62]. Similarly, following the 2021 fire, it was observed that no Panorpa specimens were captured in the areas affected by the blaze the following year [63].

Based on the abundance of samples acquired through beer traps, it can be inferred that Panorpa species effectively forage on fermented and decomposed substrates, exhibiting an active attraction to beer traps. Notably, this method has been used across various countries for collecting diverse Panorpa species [49,56,64,65,66]. Nevertheless, its application is constrained by the requisite human presence and proves less effective for large-scale geographical and environmental studies. In all instances, four species were captured, most prevalent in the central region of European Russia—P. hybrida, P. vulgaris, P. cognata, and P. communis. Notably, P. hybrida was minimally captured in pan traps (and not at all in window traps). Mecoptera exhibit an affinity for yellow traps, which are commonly used to capture them [53,67]. The green color of certain traps resembles the color of the foliage that attracts diverse guilds of phyllophagous insects and presents a favorable hunting ground for Mecoptera [44]. While pollen, leached plant juices, and secretions from various invertebrates are considered minor constituents in the Panorpidae diet [26], numerous observations suggest that Panorpidae species frequently forage on flowering plants [42,68,69,70,71,72].

Consequently, for comprehensive studies of Panorpa across an expansive geographical region, it is advisable to employ a combination of netting and diverse trap types. This approach facilitates not only the examination of fauna but also the identification of species’ phenological characteristics, biotopic preferences, and certain facets of their biology.

5. Conclusions

In our investigation, we delved into the ecological nuances of six species within the Panorpa genus (P. alpina, P. cognata, P. communis, P. germanica, P. hybrida, and P. vulgaris). The seasonal dynamics of these species predominantly exhibit monovoltinism. P. communis displayed activity from the early days of May, persisting until the beginning of October. Notably, P. vulgaris exhibited activity from the third decade of May to the middle of September, while P. hybrida manifested a brief period of activity, spanning from the end of May to late July. P. cognata, on the other hand, commenced its activity at the beginning of May, with individuals observed until the end of September. Within forested habitats, the highest species abundance was noted at the height of 1.5 m above the ground level, with a minimum occurrence observed at the height of 12 m above the ground level. However, each species displayed distinct vertical distribution patterns. In contrast, the vertical distribution of Panorpa in open ecosystems diverged, with no specimens recorded at heights of 8 and 10 m. P. hybrida was exclusively documented at the height of 6 m. The peak abundance for all species was consistently observed at heights of 2 and 4 m. The application of six diverse entomological methodologies leads to optimal outcomes. Variations in the efficacy of these methods were discerned for each species. P. communis, P. vulgaris, and P. hybrida were notably attracted to beer traps in our studies (these results are influenced, of course, by the abundance of each species in the studied regions), whereas P. cognata exhibited relative scarcity in such traps. Pan traps and pitfall traps proved effective for capturing P. cognata, whereas the species composition in Malaise traps, pan traps, and pitfall traps differed from other collection methods. All methods were used to capture the four species most prevalent in the central region of European Russia, which are P. hybrida, P. vulgaris, P. cognata, and P. communis.