Biodegradation of 1080: Testing soils in south-eastern Australia for sodium fluoroacetate-degrading micro-organisms By Matthew Gentle and Eric Cother Matthew Gentle is a Senior Zoologist with the Robert Wicks Pest Animal Research Centre, Biose- curity Queensland (203 Tor Street, Toowoomba, Qld 4350, Australia; Email: matthew.gentle@ daff.qld.gov.au) Eric Cother is a retired Princi- pal Research Scientist with the Orange Agricul- tural Institute, New South Wales Department of Primary Industries (1448 Forest Road, Orange, NSW 2800, Australia; Email: rncother@big- pond.com). The project arose from studies into the longevity of 1080 bait, to help improve the effectiveness and safety of fox management programs. Summary Sodium fluoroacetate (1080) is a vertebrate poison commonly used for the control of vertebrate pests in Australia. Long-term environmental persistence of 1080 from baiting operations has likely nontarget species and environmental impacts and is a matter of public concern. Defluorinating micro-organisms have been detected in soils of Western and central Australia, and Queensland, but not in south-eastern Australia. The presence or absence of defluorinating micro-organisms in soils from south-eastern Australia will assist in determining whether long-term environmental persistence of 1080 is or is not occurring. Soils from the Central West Slopes and Plains and Central Tablelands of New South Wales were sampled to investigate the presence and capability of 1080 defluorinating soil micro-organisms. Thirty-one species of micro-organisms were isolated from soils from each site after 10 days incubation in a 20 mM 1080 solution. Of these, 13 isolates showed measurable defluorinating ability when grown in a 1080 and sterile soil suspen- sion. Two species, the bacteria Micromonospora, and the actinomycete Streptosporan- gium, have not been previously reported for their defluorinating ability. These results indicate that defluorinating micro-organisms are present in soils in south-eastern Austra- lia, which adds weight to other studies that found that 1080 is subject to microbiological degradative processes following removal from the bait substrate. Soil micro-organism defluorination, in combination with physical breakdown and uptake by plants, indicates that fluoroacetate in soils and natural water ways is unlikely to persist. This has implica- tions for the better informed use of 1080 in pest animal management programmes in south-eastern Australia. Key words: biochemistry, invasive species, natural resource management, poison. Introduction Sodium fluoroacetate (1080) poison bait is widely used in Australia for the control of vertebrate pests such as the Feral Pig (Sus scrofa), European Rabbit (Oryctolagus cuniculus), Red Fox (Vulpes vulpes) and Wild Dog (Canis sp.) (APVMA 2008), and Australia is second only to New Zealand in the amount used per year (Eason et al. 2011). Baits need to retain a lethal dose of 1080 for a sufficient period to allow the tar- get animal to find and consume the bait (McIlroy et al. 1988). However, bait with long lasting toxicity will almost certainly provide a potential hazard to nontarget species (Twigg et al. 2000). Additionally, public concern about the use of 1080 for vertebrate pest control (Calver & King 1986; King et al. 1994; Williams 1994; O’Halloran et al. 2005) supports the need to investigate, among other things, envi- ronmental persistence of 1080. 1080 is highly water soluble and may leach from the bait material through the effects of rainfall (Wheeler & Oliver 1978; McIlroy et al. 1988). Micro-organ- isms capable of 1080 degradation may be found in the bait medium (Wong et al. 1991) and in the water and soil environ- ment (e.g. Bong et al. 1979; Parfitt et al. 1994). Defluorinating soil micro-organisms ensure that 1080 will not persist in the environment once removed from the bait (Twigg et al. 2000). Although studies have determined the presence of defluorinating microbes in soils of Western and central Australia (King et al. 1994; Twigg & Socha 2001; Twigg et al. 2001) and Queensland (Davis 2011), none have tested soils in south-east- ern Australia. Given the widespread use of 1080 in the eastern states for vertebrate pest management (Saunders & McLeod 2007), and the public concern with 1080 use, testing for the presence of defluori- nating micro-organisms in soils from south-eastern Australia capable of environ- mental degradation may assist manage- ment to better determine any level of environmental impact. While chemical residue analysis of soil can assist to deter- mining the environmental longevity of 1080, it does little to further understand- ing of the key decay mechanisms responsi- ble for 1080 degradation. Further understanding of such processes can assist in developing strategies to reduce the prob- ability of any long-term environmental per- sistence, and therefore, improve the sustainable use of 1080 products. Ulti- mately, it is useful to investigate the bacteria and fungi responsible for 1080 breakdown to ensure that long-term environmental persistence of 1080 does not occur. The aim of this study was to determine the presence and identification of any 1080 defluorinators in two soils from south-eastern Australia. We discuss the 52 ECOLOGICAL MANAGEMENT & RESTORATION VOL 15 NO 1 JANUARY 2014 ª 2013 Ecological Society of Australia doi: 10.1111/emr.12071 RESEARCH REPORT Ecological Society of Australia