The effectiveness of Virkon® S disinfectant against an invasive insect and implications for Antarctic biosecurity practices

• Published in: Antarctic Science
• Main Authors: Bartlett, Jesamine C., Radcliffe, Richard James, Convey, Pete, Hughes, Kevin A., Hayward, Scott A.L.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2020
• Subjects: Antarc*; Antarctic; Antarctic Science; Signy Island
• Online Access: http://dx.doi.org/10.1017/s0954102020000413; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0954102020000413

Abstract The flightless midge Eretmoptera murphyi is thought to be continuing its invasion of Signy Island via the treads of personnel boots. Current boot-wash biosecurity protocols in the Antarctic region rely on microbial biocides, primarily Virkon® S. As pesticides have limited approval for use in the Antarctic Treaty area, we investigated the efficacy of Virkon® S in controlling the spread of E. murphyi using boot-wash simulations and maximum threshold exposures. We found that E. murphyi tolerates over 8 h of submergence in 1% Virkon® S. Higher concentrations increased effectiveness, but larvae still exhibited > 50% survival after 5 h in 10% Virkon® S. Salt and hot water treatments (without Virkon® S) were explored as possible alternatives. Salt water proved ineffective, with mortality only in first-instar larvae across multi-day exposures. Larvae experienced 100% mortality when exposed for 10 s to 50°C water, but they showed complete survival at 45°C. Given that current boot-wash protocols alone are an ineffective control of this invasive insect, we advocate hot water (> 50°C) to remove soil, followed by Virkon® S as a microbial biocide on ‘clean’ boots. Implications for the spread of invasive invertebrates as a result of increased human activity in the Antarctic region are discussed.