International Response under the Antarctic Treaty System to the Establishment of A Non-native Fly in Antarctica

Abstract

Antarctica currently has few non-native species, compared to other regions of the planet, due to the continent’s isolation, extreme climatic conditions and the lack of habitat. However, human activity, particularly the activities of national government operators and tourism, increasingly contributes to the risk of non-native species transfer and establishment. Trichocera (Saltitrichocera) maculipennis Meigen, 1888 (Diptera, Trichoceridae) is a non-native fly originating from the Northern Hemisphere that was unintentionally introduced to King George Island in the maritime Antarctic South Shetland Islands around 15 years ago, since when it has been reported within or in the vicinity of several research stations. It is not explicitly confirmed that T. maculipennis has established in the natural environment, but life-history characteristics make this likely, thereby making potential eradication or control a challenge. Antarctic Treaty Parties active in the region are developing a coordinated and expanding international response to monitor and control T. maculipennis within and around stations in the affected area. However, there remains no overarching non-native invasive species management plan for the island or the wider maritime Antarctic region (which shares similar environmental conditions and habitats to those of King George Island). Here we present some options towards the development of such a plan. We recommend the development of (1) clear mechanisms for the timely coordination of response activities by multiple Parties operating in the vicinity of the introduction location and (2) policy guidance on acceptable levels of environmental impacts resulting from eradication attempts in the natural environment, including the use of pesticides.

Can classic biological invasion hypotheses be applied to reported cases of non-native terrestrial species in the Maritime Antarctic?

“…Most of the non-native invertebrates (Diptera and Collembola) introduced to the continent also possess good cold-tolerance capabilities (Bahrndorff et al 2009, Bartlett et al 2019a, Liu et al 2020) that make them readily adaptable to their Antarctic environments (Worland 2010). In the case of the dipteran T. maculipennis, representing the latest threat, recent studies have confirmed the capacity of its larvae to withstand temperatures down to -5°C for short periods , while the northern boreal parts of its native distribution expose it to similar or more severe thermal stresses than characterize its establishment locations on King George Island (Remedios-de León et al 2021). As yet, nothing is known of the thermal tolerances of the non-native Acari (Table S5).…”

“…Moreover, a lag phase has been documented in the fly E. murphyi on Signy Island, which, 20 years after its presumed initial introduction, was present in an area of only 1 m 2 , but 30 years later now occupies an area of at least 35,000 m 2 (Bartlett et al 2020). The second introduced fly in Antarctica, T. maculipennis, has experienced a much reduced lag phase, being recorded in the vicinity of multiple research stations on Fildes Peninsula within 4-6 years of its first sighting, and most recently it spread ∼20 km to Arctowski Station in Admiralty Bay (Potocka & Krzemin ́ska 2018, Remedios-de León et al 2021). However, interpreting the factors influencing the range expansion of the latter species is complicated by the fact that it is still not confirmed whether it is established in the natural environment or only at research stations, although the former seems probable, or whether there was direct human involvement in the transfer of this fly between stations (Remedios-de León et al 2021).…”

“…The second introduced fly in Antarctica, T. maculipennis, has experienced a much reduced lag phase, being recorded in the vicinity of multiple research stations on Fildes Peninsula within 4-6 years of its first sighting, and most recently it spread ∼20 km to Arctowski Station in Admiralty Bay (Potocka & Krzemin ́ska 2018, Remedios-de León et al 2021). However, interpreting the factors influencing the range expansion of the latter species is complicated by the fact that it is still not confirmed whether it is established in the natural environment or only at research stations, although the former seems probable, or whether there was direct human involvement in the transfer of this fly between stations (Remedios-de León et al 2021). However, where a lag phase exists, it forms an escalating risk factor that reinforces the need for rapid response practices before the non-native species can effectively adapt or acclimatize to the new environment.…”

“…However, the high population density of H. viatica on Deception Island (Enríquez et al 2019) may suggest a competitive trait that gives this non-native species an advantage. It remains to be assessed whether morphological features (increased size) or the opportunistically synanthropic phenology of T. maculipennis provide it with unique capabilities in exploiting disturbed and human-altered Antarctic ice-free environments , Remedios-de León et al 2021. In this regard, it is worth mentioning that autofertility in alien plants and parthenogenesis in alien animals could also pose a competitive advantage over native species, but the expression of these reproductive strategies amongst some native species limits its novelty aspect.…”

“…Synanthropic species live directly in association with humans. The alien crane fly T. maculipennis may provide an example of this as, to date, all records of it reproducing in Antarctica involve human facilities, although this may also be a consequence of a lack of survey effort in the natural environment (Volonterio et al 2013, Remedios-de León et al 2021.…”