Throughout their evolution, humans have migrated to and colonized most regions of the world, with this movement drastically accelerating during recent centuries and decades through the development of new technologies and the globalization of trade and tourism activities (1). However, it was not until the last one to two centuries that humans started to have contact with Antarctica, and the continent remains the only one that has never had a native human population. Today, the Antarctic continent’s ecosystems remain amongst the least disturbed on Earth, with a long history of evolutionary isolation, and are characterized by low biological diversity, high levels of endemism and communities with low interspecific competition (2, 3). Its extreme climatic conditions and considerable geographic isolation have largely protected it against natural colonization processes (4–6), with no natural colonists known to have successfully established in Antarctica in the last one to two centuries of human contact with the continent and only two putative natural colonists in the sub-Antarctic since first human contacts in the Eighteenth Century (7).

Despite this level of natural protection, the combined effects of contemporary anthropogenic climate change and the growth of human activity on and around the continent are now facilitating the introduction of non-native species to Antarctica, highlighting the vulnerability of its ecosystems (7–13). Non-native species are recognized as one of the primary drivers of biodiversity loss globally, with their presence typically linked to the degradation of ecosystem health (14), and have been recognized as a particular threat to Antarctic terrestrial ecosystems (4, 8). They can lead to the introduction of new ecological functions and interactions, the loss of ecosystem services, the displacement of native species, and, ultimately, the extinction of native biota (15–19). Ecosystems characterized by low diversity and simple community structure, as is the case in Antarctic terrestrial ecosystems, are considered to be particularly vulnerable (10, 20).

Antarctic terrestrial biodiversity is characterized by a high degree of endemism, with terrestrial fauna consisting mainly of microarthropods (predominantly mites and springtails) and microinvertebrates (nematodes, tardigrades and rotifers) (3, 21, 22). Compared to other regions of the world, this biodiversity remains relatively unaffected by human activities. However, since the initiation of human contact with the sub-Antarctic in the Eighteenth Century, the Antarctic Peninsula in the early Nineteenth Century and the main body of the continent at the end of the Eighteenth and start of the Nineteenth Centuries, anthropogenic activities have contributed to a rapid increase in the arrival and establishment of non-native species across the region, with currently over 200 species established on the sub-Antarctic islands, at least 15 in the Antarctic Peninsula/maritime Antarctic, and records of many more arriving but not subsequently establishing, of which approximately 30% are insects (4, 10, 23, 24). The threats arising from non-native species establishment have raised considerable concern in the Antarctic Treaty Consultative Meetings (the governing mechanism of Antarctica under the Antarctic Treaty System) (8), as well as interest in the context of biological invasions. The Antarctic continent hosts only two native species of holometabolous insects, the winged Antarctic chironomid midge (Parochlus steinenii (Gercke, 1889)) and the wingless midge (Belgica antarctica Jacobs, 1900), the latter being paleoendemic to the Antarctic Peninsula and South Shetland Islands (23, 25).

In maritime Antarctica, which includes the Antarctic Peninsula (APR) and the Scotia Arc archipelagos of the South Shetland Islands, South Orkney Islands and South Sandwich Islands, one of the first reports of an established non-native invertebrate species was that of the midge Eretmoptera murphyi (Schaeffer, 1914) (Chironomidae, Orthocladiinae), native and endemic to sub-Antarctic South Georgia, on Signy Island (South Orkney Islands) (23, 26). It is thought to have been introduced in the 1960s as a result of plant transplantation experiments, although it was first observed and formally reported in the 1980s (27, 28). Its larvae are detritivorous, breaking down dead moss material, and recently being described as ecosystem engineers on Signy Island as they appear to be responsible for a nearly order of magnitude increase in the breakdown of moss peat and up to a five-fold increase in the release of available nitrogen (29). The dipteran Trichocera maculipennis Meigen, 1818 (Trichoceridae), a species whose larvae are detritivorous and also coprophagous, has been established with an increasing distribution on King George Island, South Shetland Islands, since the austral summer of 2006/2007 (30, 55, 56). Various species have been reported in synanthropic situations, generally associated with national research stations, either on single occasions or, in a small number of instances, becoming established on those stations for multiple years even in the face of eradication efforts, for instance, the fly of Genus Lycoriella on Australia’s Casey Station on the continental Antarctic coast (31). Most recently, the synanthropic presence of the food storage pest Plodia interpunctella (Indian meal moth) has been reported at Comandante Ferraz and Yelcho Stations in the South Shetland Islands and north-west Antarctic Peninsula (57, 58).

The aim of this study is to provide the first formal report of the presence of the non-native moth fly, Psychoda albipennis Zetterstedt, 1850 (Diptera, Psychodidae), in Antarctica, documented through repeated sightings during the austral summer seasons of 2019/20, 2021/22, 2022/23, and 2023/24 ( Figure 1 ).

This study presents the first report of a member of the family Psychodidae in Antarctica, Psychoda albipennis, with identification confirmed through both morphological and molecular methods. Some specimens of this species from Artigas and Escudero research stations in Antarctica were present in one of the two clades identified along with multiple sequences of European origin. The two clades containing Antarctic P. albipennis were clearly divergent, but more loci and sampling locations are required to confirm whether this is an indication of different source of species introduction.

Members of the genus Psychoda are commonly known as moth flies. They were observed for the first time in synanthropic locations around buildings of stations operated by two Antarctic national operators during the austral summer of 2021/22, with continued presence confirmed during the subsequent austral summers of 2022/23 and 2023/24 ( Figure 1 ). Psychoda albipennis is considered a globally cosmopolitan species, with the exception of Antarctica. It is a detritivorous species with saprophagous larvae and is often found in synanthropic locations and their environs (39, 40). It is often associated with humid or semi-humid environments (puddles, ditches, tree hollows) and in highly organic enriched environments such as drainage and wastewater treatment systems, consistent with the observations here in sewage treatment systems of Antarctic national operator stations ( Figure 2C, D ) (40, 41).

Psychoda albipennis is a holometabolous species, with a life cycle involving four stages (egg, larva, pupa, adult) the duration of which depends on environmental conditions (42, 43). While detailed studies of the life cycle of this species are not available, those of some congeneric species allow some inference to be made about factors underlying its successful establishment in Antarctica. Griffith and Gillett-Kaufman (44) indicate that females of P. alternata (Say, 1824) lay their eggs on moist soil or near pipes and sewage systems, as well as directly on fecal matter and decomposing plant material (41, 45). The larval stage is the longest, including four larval instars each with a duration of 9 to 15 d at 21°C (42). Both the eggs and larvae are capable of entering diapause, which could potentially enable P. albipennis to hibernate and survive the Antarctic winter. However, confirming this would necessitate physiological studies (40, 44). Moth flies are considered poor fliers. However, they are capable of short flights and can move up to 90 m from their emergence site, and can also be displaced up to 1.5 km by wind (40). In the context of their occurrence on/around research stations on King George Island, this highlights the risk of dispersal and colonization of natural Antarctic habitats, such as seal breeding, molting and resting areas, where the high density of organic matter and fecal matter present would provide an ideal food source.

Psychoda albipennis is not considered an exotic species elsewhere globally and there are no reports to date of its impacts on natural systems. However, understanding its biological characteristics can shed light on the risks this species may pose in Antarctica through introducing new ecological interactions and functions into such fragile ecosystems. Bartlett et al. (29) reported that the presence of the non-native chironomid, Eretmoptera murphyi, on maritime Antarctic Signy Island (South Orkney Islands) can strongly influence decomposition rates, with potential knock-on impacts on native plant and invertebrate communities. It can also cause a 4 to 5-fold increase in the availability of inorganic nitrogen in the habitats it occupies, highlighting the problems that can result from the introduction of new ecological interactions into Antarctic ecosystems.

The terrestrial arthropod fauna of the Antarctic continent consists predominantly of micro-arthropods with only two species of true Diptera, the chironomid midges Parochlus steinenii and Belgica antarctica (21, 26). The presence of non-native species, especially those that can overcome ecological filters (biotic and abiotic factors) and achieve biological functions (such as reproduction) (46), should be considered a threat to Antarctic ecosystems and their biological diversity (10, 47). Due to this threat, the development and implementation of policies to minimize the risk of further species being imported to Antarctica control those that are already established have been promoted. These include the adoption of strict regulations under the Protocol on Environmental Protection to the Antarctic Treaty (known as the Environmental Protocol and provision of detailed practical advisory guidelines through the COMNAP Non-Native Species Manual, such as the prohibition of the intentional introduction of non-native species (with exceptions subject to rigorous permits) and the promotion of scientific spaces with experts to develop strategies that help minimize the risks of accidental introduction to the continent (47–49).

The most effective (and cost-effective) goal of any biosecurity strategy should be to prevent the arrival of a non-native species in the first place (48, 50), To provide a solid foundation for any effective biosecurity system, timely information on newly arriving non-native species and those already present must be available (51). It is axiomatic that early detection is more likely to allow rapid and effective action to control the spread before an invasion becomes too extensive to be practically controlled (51, 52). However, despite the apparent widespread recognition of the threats to Antarctic ecosystems and species posed by the establishment of non-native species, several examples, even after the Environmental Protocol came into force, highlight that Antarctica remains far from being effectively protected today.

Although prevention and timely reporting are crucial for a rapid and effective response to the accidental introduction of exotic species, it is equally important for scientific and military bases in the area governed by the Antarctic Treaty to continually improve their wastewater treatment systems and disposal methods. This is essential to prevent leaks and discharges of inadequately treated organic or inorganic matter into the Antarctic environment. Such discharges can have implications for the health of Antarctic fauna, both marine and terrestrial (53). While it has not been proven that species introductions occur through this route, there is evidence suggesting that discharges contribute to the establishment and persistence of non-native species (30, 54).

In the current study, we present observations confirming the presence of P. albipennis in the Antarctic environment, both within the stations and in their immediate surroundings ( Figure 2C ). Additionally, ex situ observations of P. albipennis survival in mosses in natural environments not associated with scientific bases indicate that the species may have established and reproduced. This situation is of serious concern, as it may indicate that the species has a significant capacity for adaptation (physiological, genetic, morphological) and potential for establishment and invasion in other areas with environmental conditions similar to those of the Fildes Peninsula.