Hidden Fruit Fly Diversity Revealed in Georgia’s Protected Areas

Deep in the forests of Lagodekhi and the semi-arid floodplains of Vashlovani, two of Georgia’s most treasured protected areas, scientists have uncovered a hidden world of tiny vinegar flies that had never been systematically documented before. A new study published in the journal Evolutionary Systematics examined 407 drosophilid specimens collected from these two ecologically distinct landscapes, revealing 17 species and dramatically expanding what is known about the family Drosophilidae in the South Caucasus region. Among these, four species represent significant first records: two are entirely new to Georgia and two had never before been documented anywhere in Transcaucasia.

The research, conducted by entomologists working with specimens deposited in the Canadian National Collection of Insects in Ottawa, raises the number of drosophilid species known from Georgia from 25 to 29. It also presents an updated checklist of 35 species now recognized across the entire Transcaucasian region, which encompasses Georgia, Armenia, and Azerbaijan. This figure represents a substantial increase from prior knowledge, which had been largely inherited from Soviet-era surveys that treated the region’s insect fauna as part of a much broader territorial whole.

Drosophilidae, commonly known as small fruit flies or vinegar flies, is a family of true flies divided into two subfamilies, Steganinae and Drosophilinae, comprising more than 4,300 species across 77 genera worldwide. At least 860 species and 34 genera occur in the Palaearctic Region, which spans Europe, northern Asia, and parts of North Africa. These flies are of immense scientific importance: the genus Drosophila has served as a foundational model organism in genetics and evolutionary biology for over a century, while several species are significant agricultural pests or vectors of disease.

The two protected areas surveyed could hardly be more different from one another. Lagodekhi Protected Area, situated in eastern Georgia at coordinates 41.823°N, 46.272°E, lies close to the borders of Azerbaijan and Daghestan in Russia. Malaise traps were deployed at six different altitudes ranging from 666 to 2,559 meters above sea level, capturing species across a remarkable elevational gradient that encompasses humid mountain forest. Vashlovani Protected Area, located in the far southeastern corner of the country at 41.112°N, 46.646°E, sits near the Azerbaijani border in a semi-arid landscape. The collecting site was positioned at the Mijniskure camping ground on the floodplain of the Alazani River at just 97 meters above sea level.

Specimens were collected during two separate expeditions, one in 2014 and another in 2023, using Malaise traps that passively intercept flying insects. All material was preserved in 96% ethanol and shipped to the Canadian National Collection of Insects, where specimens were dehydrated, critical-point-dried, pinned or point-mounted, labeled, and databased. Duplicate specimens will be returned to Georgia. High-resolution photographs of body form and male genitalia were captured using a Leica DMC5400 color CMOS camera paired with Leica Application Suite X software, providing the detailed morphological documentation necessary for accurate species identification.

Among the most significant findings are two species newly recorded for Georgia: Hirtodrosophila confusa, a fungivorous fly known from Europe and the Mediterranean, and Lordiphosa fenestrarum, whose adults have been trapped using fermenting beer and oak sap. Both were found in Lagodekhi Protected Area. Equally notable are two species documented for the first time anywhere in Transcaucasia: Scaptomyza flava, a cosmopolitan leaf-miner that attacks various plants largely within the Brassica family, and Stegana nigrithorax, a species whose biology remains unknown but which has been recorded from the Russian Far East, Japan, Korea, Taiwan, and Europe.

The species list also includes several flies of considerable ecological and economic importance. Drosophila suzukii, commonly known as the Spotted Wing Drosophila, was recorded from Vashlovani. This highly polyphagous pest causes economically significant damage to fruit industries worldwide, with males recognizable by their spotted wings and females distinguished by a serrated ovipositor specialized for penetrating ripe fruits. Drosophila melanogaster, the celebrated laboratory model organism, was also documented, alongside Phortica variegata, a zoophilic fly that serves as a major vector of Thelaziasis, transferring the oriental eye worm Thelazia callipaeda to mammalian hosts through lachryphagous feeding behavior.

Several other species reveal fascinating ecological niches. Leucophenga maculata, whose females oviposit in mushrooms and whose males frequent dark, humid habitats, was found at both sites. Gitona distigma, commonly known as the drumstick pod fly, is considered a pest of Moringa in India. Scaptomyza pallida, whose larvae are frequently found on decaying plant material or as inquilines in mines dug by other insect pests, was among the most abundantly collected species across multiple altitudes and seasons. Mycodrosophila poecilogastra, another fungivorous species, was recorded from Lagodekhi at lower elevations.

The distribution patterns documented in this study reflect the biogeographic complexity of the Caucasus region, which serves as a bridge between Europe and Asia. Many species recorded here are widespread across the Palaearctic, while others show more restricted distributions. The updated Transcaucasian checklist reveals that some species are known from only one or two of the three countries, suggesting that further surveys in Armenia and Azerbaijan would likely reveal additional records. The Caucasus isthmus, with its dramatic elevational gradients and diverse vegetation zones, provides habitat for species with widely varying thermal and humidity preferences.

The researchers emphasize that their collection was assembled solely by means of Malaise traps, and they expect that many further species will be discovered if specifically designed traps baited with fermenting fruit are employed in future surveys. The likelihood that Chymomyza amoena occurs in Georgia remains high, given its documented presence in neighboring Daghestan and an unpublished observation of its presence near Tbilisi. As climate change alters habitats across the Caucasus and agricultural expansion brings human populations into closer contact with wild ecosystems, understanding the composition and distribution of even the smallest insects becomes increasingly important for predicting disease transmission, protecting crops, and conserving biodiversity in one of the world’s most biologically rich mountain regions.

Subject of Research: Drosophilidae survey in Georgia

Article Title: Drosophilidae ( Diptera ) of Lagodekhi and Vashlovani Protected Areas of Georgia (Sakartvelo), with a list of Transcaucasian species

Article References: Parchami-Araghi, M., & Japoshvili, G. (2026). Drosophilidae (Diptera) of Lagodekhi and Vashlovani Protected Areas of Georgia (Sakartvelo), with a list of Transcaucasian species. Evolutionary Systematics, 10(1), 55-62. https://doi.org/10.3897/evolsyst.10.183485

Image Credits: AI Generated

DOI: 10.3897/evolsyst.10.183485

Keywords: Drosophilidae, Georgia, biodiversity, invasive species, taxonomy, protected areas, Diptera, Lagodekhi, Vashlovani, Protected, Areas, Sakartvelo