Malaise Traps in the Caucasus Reveal Dozens of Sawfly Species New to Georgia

A single summer of fieldwork in the forested hills of north-western Georgia has delivered one of the most striking boosts to insect biodiversity records in the Caucasus in recent years. Between June and August 2020, researchers deployed Malaise traps across six localities in the Tkibuli and Tsageri districts, collecting 388 sawfly specimens that turned out to represent 61 species. Of these, 29 species had never been recorded in Georgia before, pushing the country’s known sawfly fauna from 147 species to 183 in one stroke. The findings, published in the journal Caucasiana, underscore just how poorly documented the insect life of this mountainous region remains, even for relatively well-studied groups.

Sawflies, the members of the suborder Symphyta within the order Hymenoptera, are among the most overlooked of the plant-feeding wasps. Unlike their better-known relatives such as ants, bees, and predatory wasps, sawflies are defined by a broad waist connection between the thorax and abdomen and by the saw-like ovipositor that females use to slice into plant tissue to lay eggs. Their larvae, which often resemble caterpillars, feed on an extraordinary range of host plants, from ferns and mosses to grasses, shrubs, and hardwood trees. Because many species are tied to specific host plants, sawfly diversity can serve as a sensitive indicator of overall habitat complexity, making faunistic surveys of this group unusually informative for conservation planning.

The historical record of sawflies in Georgia is a story of fragmentary and often ambiguous documentation. Nineteenth-century authors routinely cited localities as vague as “Patria Caucasus” or “Transcaucasia,” making it impossible to determine whether a given type specimen actually originated from Georgia or from neighboring parts of the Russian Caucasus. The first real checklist of Caucasian insects, compiled by Radde in 1899, listed roughly 80 sawfly species for the region. Identification keys produced by Andguladze in 1957 and 1973 for Georgia, alongside Dadurian’s 1962 work on Armenia, eventually raised the Georgian tally by 105 species. Only this year, a survey of Kintrishi National Park in the country’s south-west added 42 species new to the national list. Before the present study, the accepted count stood at 147.

Against that backdrop, the new survey’s results are remarkable. The study area spans two administratively distinct districts roughly 40 kilometers apart, each with a distinct geological and ecological character. The Tkibuli district sits in the Okriba basin at around 600 to 800 meters above sea level, drained by the river Tkibula and rising to a maximum of 1,569 meters. The Tsageri district, by contrast, is built on Cretaceous limestone sculpted into sharp erosive and karst forms, riddled with caves and prone to landslides, with Paleogene and Neogene sandstones, clays, and conglomerates layered above, and culminating in Mount Tsekuri at 3,188 meters. In both districts the forest canopy is dominated by beech, hornbeam, chestnut, oak, maple, ash, and conifers such as spruce and fir, while the understory supports a rich array of deciduous and evergreen shrubs. Xerophytic vegetation clings to the southern-facing limestone slopes, and alder lines the moist riverbanks.

The trapping network spanned five altitudinal zones, from Katsunara at 550 meters up to Sakenebeli at 1,800 meters, with additional sites at Nalobievi (1,070 meters), Tsablanis Gora (1,470 meters), and Gabrichidzeebis Ubani in the Tkibuli district (780 meters). Malaise traps, the tent-like interception devices that funnel flying insects into a collecting bottle, were operated for varying lengths of time during the summer months. The authors are careful to note that the sampling was not designed to yield quantitative data: the traps missed the April and May activity peaks of many sawfly species, and the duration of operation varied between sites. The goal was a snapshot of regional diversity rather than a rigorous census, and the investigators flag this limitation explicitly in their analysis of abundance patterns.

Even so, the species list that emerged is rich in ecological and biogeographical interest. Among the 29 new country records are species with dramatically different distribution patterns. Aneugmenus padi, a fern-feeding species with a Holarctic range, was found at both Katsunara and the high Sakenebeli site. Empria tridens, a Palaearctic species whose larvae feed on Geum and raspberry, appeared at Nalobievi. Monostegia abdominalis, a species introduced from the Palaearctic to North America, turned up at 1,070 meters. Perhaps most intriguing are two stem-boring sawflies of the family Cephidae: Calameuta antigae, previously known only from Spain, and Calameuta gracilicornis, a Ponto-Caspian species. Their discovery in Tsageri suggests that C. antigae’s true distribution is considerably wider than the historical records imply, likely following a Ponto-Caspian–Mediterranean pattern that earlier sampling in western Europe simply failed to capture.

Several other new records carry practical significance. Pristiphora tibialis, originally a Nearctic species, was introduced to Europe together with its host plant, black locust (Robinia pseudacacia), and is described as invasive in the Caucasus. Its capture at the Tkibuli site confirms that this exotic pest is now established in Georgian forests. Priophorus compressicornis, a Holarctic species recorded as a frequent pest of birch, cotoneaster, cherry, rowan, hazel, and rose, was also present. The distinction between native diversity and invasive arrivals is important for forest managers: the same traps that documented vulnerable native lineages also registered the expanding footprint of globally distributed species that hitchhiked on ornamental and plantation trees.

The survey also required careful taxonomic housekeeping. Two species, Macrophya duodecimpunctata and Tenthredo maculata, were listed in the Georgian Biodiversity Database on the basis of a 1996 publication by Zhelochovtsev and Zinoviev that provided no examined material, voucher specimens, or references. Because those database entries could not be substantiated, the authors treat both species as new country records, supported this time by physical specimens with precise coordinates, dates, and altitude data. A third species, Pristiphora pallidiventris, was similarly relisted after its database record was found to rest on an erroneous citation. Nomenclature throughout follows the latest monograph of European sawflies by Lacourt, with special attention to the revised classification of the subfamily Nematinae proposed by Prous and colleagues, and identifications were cross-checked against reference material in the Hungarian Natural History Museum in Budapest.

Within the dataset, the altitudinal distribution of specimens shows a clear mid-elevation peak. Of the 388 individuals, 40 percent, or 155 specimens representing 39 species, were collected at 1,070 meters, the highest diversity and density of any altitude band. Numbers and raw species richness fall off on either side: 16 individuals and 9 species at 550 meters, 121 individuals and 28 species at 780 meters, 74 individuals and 15 species at 1,470 meters, and just 22 individuals and 7 species at 1,800 meters. The authors caution that this pattern cannot be taken as a statistically valid description of how sawfly diversity changes with elevation, because sampling intensity was itself higher at the most productive sites and the trapping window missed the main spring activity period. Still, the mid-elevation concentration is consistent with the idea that transitional forest zones, where lowland and montane vegetation intergrade, offer the greatest variety of larval host plants.

Perhaps the most consequential comparison in the study concerns the difference between Georgia’s two sampled regions. The present survey captured 61 species in north-western Georgia during a single, suboptimal season, whereas an entire year of extensive Malaise trapping in the Kintrishi Protected Areas of south-western Georgia yielded only 65 species. The implication is that north-western Georgia, with its karst landscapes, limestone slopes, and mixed beech-conifer forests, supports substantially higher sawfly diversity than the south-west, and that the national list of 183 species remains a substantial underestimate. The authors conclude that, given the sparse and sporadic history of sawfly research in the country, the true number of Georgian species is expected to be significantly higher. For a region that sits at the crossroads of Europe and Asia and harbors deep relict lineages of temperate forest biota, that gap represents not a deficit of nature but a deficit of eyes on the ground, and every future trapping season is likely to keep rewriting the map of Caucasian insect life.

Subject of Research: Faunistic survey of sawfly (Hymenoptera: Symphyta) diversity in north-western Georgia

Article Title: Sawflies ( Hymenoptera : Symphyta ) from North-Western Georgia (Sakartvelo)

Article References: Japoshvili, G., & Haris, A. (2022). Sawflies (Hymenoptera: Symphyta) from North-Western Georgia (Sakartvelo). Caucasiana, 1, 41-49. https://doi.org/10.3897/caucasiana.1.e83640

Image Credits: AI Generated

DOI: 10.3897/caucasiana.1.e83640

Keywords: sawflies, Symphyta, Hymenoptera, Georgia, Caucasus, biodiversity, Malaise traps, new country records, entomology, Tsageri, Tkibuli, invasive species