Life cycle and phenology of an Antarctic invader: the flightless chironomid midge, Eretmoptera murphyi

Abstract

Knowledge of the life cycles of non-native species in Antarctica is key to understanding their ability to establish and spread to new regions. Through laboratory studies and field observations on Signy Island (South Orkney Islands, maritime Antarctic), we detail the life stages and phenology of Eretmoptera murphyi (Schaeffer 1914), a brachypterous chironomid midge introduced to Signy in the 1960s from sub-Antarctic South Georgia where it is endemic. We confirm that the species is parthenogenetic and suggest that this enables E. murphyi to have an adult emergence period that extends across the entire maritime Antarctic summer season, unlike its sexually reproducing sister species Belgica antarctica which is itself endemic to the Antarctic Peninsula and South Shetland Islands. We report details of previously undescribed life stages, including verification of four larval instars, pupal development, egg gestation and development, reproductive viability and discuss potential environmental cues for transitioning between these developmental stages. Whilst reproductive success is limited to an extent by high mortality at eclosion, failure to oviposit and low egg-hatching rate, the population is still able to potentially double in size with every life cycle. Electronic supplementary material The online version of this article (doi:10.1007/s00300-018-2403-5) contains supplementary material, which is available to authorized users.

Combining correlative and mechanistic niche models with human activity data to elucidate the invasive potential of a sub‐Antarctic insect

“…Larval instars dominate this species' biennial life cycle and encounter the full range of seasonal conditions. This is in contrast to adults, which typically live for just a few weeks during summer, and eggs, with oviposition to hatch periods of around a month in spring/early summer (Bartlett et al, ). Larval stages also act as ecosystem engineers, potentially releasing nutrient bottlenecks in currently nutrient‐poor habitats, and thus have a greater impact on the resident fauna and flora than adults (Hughes & Worland, ).…”

“…Larval survival levels were obtained from physiological experiments and arranged as maximum (90%-100%), very high (80%-90%), high (70%-80%), moderate (60%-70% and moderate to low (50%-60%) [Colour figure can be viewed at wileyonlinelibrary.com] F I G U R E 5 Sites vulnerability to the human-assisted colonization of the sub-Antarctic midge, Eretmoptera murphyi, in maritime Antarctica. This index accounts for the local human activity levels together with the local climatic suitability for the species at all ice-free sites [Colour figure can be viewed at wileyonlinelibrary.com] early summer (Bartlett et al, 2018a). Larval stages also act as ecosystem engineers, potentially releasing nutrient bottlenecks in currently nutrient-poor habitats, and thus have a greater impact on the resident fauna and flora than adults (Hughes & Worland, 2010).…”

“…In contrast, following its introduction to Signy I., the E. murphyi population, which has a dominant larval life stage spanning almost 2 years, has expanded locally in the vicinity of the original introduction site close to Signy Research Station. In particular, this species has expanded along well-used path routes suggesting an important element of human-assisted dispersal (Bartlett, Convey, & Hayward, 2018a;2018b;Bartlett, Convey, Pertierra, & Haiward, 2019;Hughes & Worland, 2010). This is a concern as Hughes, Worland, Thorne, and Convey (2013) calculated that in the area where the species occurs on Signy I., it is responsible for increasing litter turnover by up to almost an order of magnitude compared to that achieved by the entire native invertebrate community (see also Bridge & Denton, 2007;Montiel, 1998).…”

Surviving the Antarctic Winter—Life Stage Cold Tolerance and Ice Entrapment Survival in The Invasive Chironomid Midge Eretmoptera murphyi

“…For each temperature exposure, four replicates of five individual larvae (n = 20), and ten replicates of a single egg sac, were placed in a sealed Eppendorf tube with a thermocouple wire threaded through a small hole in the lid. The 10 egg sacs contained c. 630 eggs between them (based on Bartlett et al [27]). After each treatment, individuals were removed and placed in a petri dish containing moist Signy soil substrate and kept at control conditions in a dark refrigerator.…”

“…As with studies of the related Belgica antarctica [24][25][26], most physiological examinations of E. murphyi have been conducted on mature larvae-with the exception of two studies that examined desiccation and heat tolerance in eggs [27,28]. Thus, knowledge of the cold-tolerance abilities of different life stages remains limited.…”