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Keywords:

  • biochemistry;
  • invasive species;
  • natural resource management;
  • poison

Summary

  1. Top of page
  2. Summary
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References
  9. Biographies

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 suspension. Two species, the bacteria Micromonospora, and the actinomycete Streptosporangium, have not been previously reported for their defluorinating ability. These results indicate that defluorinating micro-organisms are present in soils in south-eastern Australia, 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 implications for the better informed use of 1080 in pest animal management programmes in south-eastern Australia.


Introduction

  1. Top of page
  2. Summary
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References
  9. Biographies

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 target 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, environmental 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-organisms capable of 1080 degradation may be found in the bait medium (Wong et al. 1991) and in the water and soil environment (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-eastern 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 defluorinating micro-organisms in soils from south-eastern Australia capable of environmental degradation may assist management to better determine any level of environmental impact. While chemical residue analysis of soil can assist to determining the environmental longevity of 1080, it does little to further understanding of the key decay mechanisms responsible for 1080 degradation. Further understanding of such processes can assist in developing strategies to reduce the probability of any long-term environmental persistence, and therefore, improve the sustainable use of 1080 products. Ultimately, 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 implication of this work for the sustainability of 1080 operations in south-eastern Australia, and the potential application of such findings to improve the safety of baiting campaigns.

Methods

  1. Top of page
  2. Summary
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References
  9. Biographies

Soil collection sites

Soils from Trangie Agricultural Research Station (TARS) (−31.9861°S, 147.9489°E) and Orange Agricultural Institute (OAI) (−33.3239°S, 149.0836°E) in New South Wales were collected to investigate the presence and capability of 1080 defluorinating soil micro-organisms. Trangie Agricultural Research Station is situated 5 km west of Trangie on the Central West Slopes and Plains and is predominantly composed of native grassland for grazing (Robards & Michalk 1975). The dominant soil group at TARS is red-brown earth (Downes & Sleeman 1955), which are a typical light textured soil of western New South Wales (Murphy & Eldridge 2000). The OAI is situated on the southern outskirts of Orange on the Central Tablelands and comprises mainly improved pastures for sheep and cattle grazing. The dominant soil at the site is a silty clay loam. Both sites are representative of farmland likely to undertake 1080 fox baiting in either region, although neither soil collection site was previously exposed to 1080.

Climatic data, including median annual, median monthly rainfall, and minimum and maximum average temperatures together with the actual rainfall that fell in the month before and during the soil collection period are shown in Table 1.

Table 1. Climatic data and long-term averages for the two soil collection sites, Orange Agricultural Institute (OAI) and Trangie Agricultural Research Station (TARS). The long-term annual median rainfall (mm) and annual mean daily minimum and maximum temperatures (°C) for OAI and TARS are presented with the rainfall (mm) for that fell in the month prior (October) and during the soil sample collection month (November) for each site in 2001. The long-term median average monthly rainfall and minimum and maximum temperatures are shown in parentheses
SiteAnnualOctoberNovember
 Median rainfall (mm)Mean daily min–max temperature (°C)Actual rainfall (mm)Mean daily min–max temperature (°C)Actual rainfall (mm)Mean daily min–max temperature (°C)
OAI985.97.1–17.794 (81.8)6.0–16.1 (6.2–20.7)44.3 (66)8.0–20.2 (11.1–24.2)
TARS470.510.6–24.348.9 (34.8)8.8–24.8 (10.1–25)19.6 (36.4)13.5–28.5 (13.3–28.2)

During the second week of November 2001, a 30-g soil sample was removed from 5 cm below the surface at three randomly chosen sampling positions in each site. Sampling sites at TARS and OAI were level open pasture paddocks with no livestock present. The soil samples were stored in individual 70-ml sterile containers for 5 months at 7°C until analysed.

Isolation of micro-organisms

Isolation methods used to extract micro-organisms from each soil were heavily based on those used by Bong et al. (1979), Wong et al. (1992) and Twigg and Socha (2001). An enriched broth using deionised water containing 2 g/L KH2PO4 and 1 g/L (NH4)2SO4 was adjusted to pH 6.8 for bacterial incubations. For fungal incubations, the medium contained 0.2 mg/L CaCl2 and 10 mg/L FeSO4·7H2O and adjusted to pH 5.6. The broth media were sterilised by autoclave (121°C and 15 kPa for 15 min) and left to cool to <50°C before adding sterilised (by 0.22 μm Millipore filter) 1080 solution to make a final concentration of 20 mM 1080. This resulting solution was dispensed in 10-mL aliquots into 120-mL polycarbonate bottles before adding 1 g of air-dried soil from each sampling site to each bottle. Three replicates, representing the three individual soil samples, were undertaken for each site. Each bottle was incubated at 27°C on an orbital shaker (180 rev/min) for 10 days. A 100-fold dilution was then made from each of the culture broths and plated onto either nutrient agar (NA) for bacteria or potato dextrose agar (PDA) for fungi. Bacterial NA plates and fungal PDA plates were incubated at 27°C. Single colonies were subsequently subcultured onto NA or PDA as appropriate to ensure purity. Bacterial cultures were stored in (Pro-Lab Diagnostics, Round Rock, TX, USA) Microbank™ tubes at −80°C.

Whole-cell fatty acid profiles of the bacterial isolates, used to identify isolates, were determined using the Microbial Identification System (MIDI) (MIS; Microbial ID, Inc., Newark, DE, USA). Bacteria were grown on trypticase soya broth (BBLTM, BD, Franklin Lakes, NJ, USA) with agar (15 g/L) for 1 day at 27°C. Fatty acids were extracted and analysed using a Hewlett–Packard 6890 Gas Chromatograph. The extraction process followed the sample preparation procedures described in the MIDI Handbook. Fatty acid peak areas were identified with the peak-naming component of this system and quantified to develop a profile. The fatty acid profiles of the isolates were then compared with known reference strains in the MIS database, which generated a similarity index of how close the profiles of bacterial isolates were to the mean fatty acid composition of their nearest species match. The fungal species were identified using morphological characteristics as described by Domsch et al. (1993) and Pitt (2000).

Defluorinating activity of microbial isolates

The isolated fungal and bacterial species were assessed for their individual defluorinating ability when grown in a broth solution of 20 mM 1080 (as above) containing 10 g of sterile soil. This method quantifies defluorination of each isolate through measuring the concentration of the F ions in the broth that are released when 1080 is defluorinated. Soil was sterilised by autoclaving at 121°C and 15 kPa for 15 min on three successive days. To ensure that autoclaving did sterilise soil, two replicates of soil (autoclaved at 121°C for 15 mins on three successive days) from each site together with a broth solution of 20 mM 1080 solution were incubated for 7 days and plated onto NA and PDA. No micro-organisms were isolated from sterile soil incubations. Bacterial suspensions containing 1.5 × 109 cells/mL in 2 mL of sterile water were prepared from cultures <72 h old. Each 2-mL suspension was added to 20 mL of broth containing 20 mM 1080 in a sterile 120-mL polycarbonate bottle. Fungal suspensions were prepared by removing aerial mycelium from cultures <72 h old into 2-mL sterile water and adding this to 20 mL of broth containing 20 mM 1080 concentration. Two replicates were prepared for each isolate.

Bacterial and fungal media were incubated for 28 days at 27°C in an orbital shaker (220 rev/min). Each bottle was then centrifuged for 5 min at 22,400 g and the supernatant filtered using Whatman No. 4 filter paper. A 10-mL sample of the supernatant was added to 40 mL of deionised water for fluoride ion (F) measurement. The concentration of F was measured using a Thermo-Orion fluoride electrode (model 720A). Fluoride ions will bind to soil particles (Barrow & Shaw 1977) and consequently cannot be measured in the solution. The extent of the binding was calculated by measuring the F concentration of a sodium fluoride solution (Sigma Aldrich, Castle Hill, NSW, Australia), before adding 10 g of sterile soil. This suspension was then allowed to stand for 24 h before filtering through Whatman No. 4 filter paper and measuring F concentration. Additionally, background levels of free F in soil samples, 20 mM 1080 solution and deionised water were measured. The amount of 1080 defluorinated by each isolate was calculated by assuming that 380 μg of F ions are released when 20 mM 1080 is totally defluorinated (Twigg & Socha 2001). Final readings were adjusted for dilution factors, binding of F to soil (and filter paper) and background F levels in soil, water and 1080 solution.

The defluorinating activity of soil micro-organisms from each site was monitored after 7 days. Air-dried soil from each site (10 g) were added to 40 mL of deionised water and 20 mM 1080 and incubated at 27°C in an orbital shaker (220 rev/min) for 7 days. The amount of 1080 defluorinated by each soil sample was determined by measuring free F in each broth solution using a F electrode, and corrected for binding, background levels and dilution.

Results

  1. Top of page
  2. Summary
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References
  9. Biographies

Binding of F to soil and background levels in 20 mM 1080 and deionised water

When added to a solution containing sterile soil, a substantial amount of free F was unable to be recovered. The mean levels of free F ions detected after adding 220–260 μg of F to 10 g of soil was 57.5 ± 2.8% (SD, n = 3) for TARS and 32.2 ± 5.9% (SD, n = 3) for OAI. The concentration of F in deionised water (0.0116 ± 0.003 μg/L SD, n = 3) and 20 mM 1080 solution (0.0374 ± 0.006μg/L, SD, n = 3) was low but all measured concentrations were nevertheless adjusted for these values.

Isolation of micro-organisms

A total of 31 species of micro-organisms were isolated from soils from each site in the presence of 20 mM of 1080 after 10 days incubation. Of these, five isolates of bacteria and two actinomycetes from TARS, and two species of bacteria from OAI degraded 1080 when incubated for 28 days with 1080 as the sole carbon source (Table 2).

Table 2. The mean percentage of 1080 (two replicates) defluorinated by bacteria and actinomycetes (*) isolated from soil at Orange Agricultural Institute (OAI) and Trangie Agricultural Research Station (TARS) in a 20 mM 1080 solution with 10 g of sterile soil incubated for 28 days at 27°C. The mean concentration of fluoride ions (Mean F conc.) and 1080 (%) defluorinated by microbes is corrected for defluorination without micro-organisms, as indicated by the difference between recorded F levels and background and control F levels (OAI and TARS)
Micro-organismFatty Acid Similarity indexSiteMean F conc. ± SD (μg/L)1080 (%) defluorinated by microbesTotal 1080 (%) defluorinated
ControlTARS00
ControlOAI0.2207.3
Alcaligenes paradoxus 0.267TARS0.161 ± 0.0366.810.0
Alcaligenes paradoxus 0.578TARS0.298 ± 0.02815.418.6
Alcaligenes paradoxus 0.441TARS0.1870 ± 0.1468.511.7
Arthrobacter oxydans 0.01TARS0.0873 ± 0.00122.35.5
Bacillus megaterium 0.695TARS0.0826 ± 0.03572.05.2
Bacillus megaterium 0.884TARS0.0925 ± 0.02342.65.8
Bacillus megaterium 0.884TARS0.0540 ± 0.00110.23.4
Bacillus thuringiensis kurstakii 0.807TARS0.0711 ± 0.02041.24.4
Burkholderia cepacia (n = 1)0.295OAI0.44914.328.1
Micromonospora carbonacea (n = 1)0.01OAI0.3578.522.3
Micromonospora carbonacea (n = 1)0.212TARS0.9742.96.1
Possible Streptosporangium sp.*TARS0.1102 ± 0.01463.76.9
Unknown*TARS0.07631.64.8

Defluorination by isolates

Thirteen isolates showed measurable defluorinating ability when grown in a 1080 and sterile soil suspension. Ten of these isolates were found only in the TARS soil, and one only from OAI, and one species was common to both sites. The bacteria defluorinated an average of 5.8 ± 5.1% (SD, range = 0.2–15%) of added 1080 and the actinomycetes averaged 2.6 ± 1.1% (SD, range = 1.6–3.7%). The isolates from TARS averaged 4.6 ± 4.8% (SD) defluorination and 11.4 ± 4.1% (SD) at OAI.

There was a difference in the defluorinating ability of nonautoclaved soil from both sites. TARS samples showed considerable defluorinating ability, with 43.0 ±20.1% (SD, n = 2) of added 1080 degraded within 7 days. However, the amount of F released from the soil at OAI did not exceed the amount released by the sterile soil control after 7 days.

Discussion

  1. Top of page
  2. Summary
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References
  9. Biographies

Thirteen isolates of micro-organisms (fungi, actinomycetes and bacteria) capable of defluorinating 1080 were isolated from soils in the Central Tablelands and Western Slopes of New South Wales. This is the first confirmation of soil defluorinators from south-eastern Australia; previous studies have shown that such organisms are present in central (Twigg & Socha 2001), Western Australian (Wong et al. 1991; King et al. 1994) and Queensland soils (Davis 2011). In central Australia (Finke Gorge), soil samples contained 24 species of micro-organisms capable of defluorinating 1080 (Twigg & Socha 2001), while in Western Australia, 20 defluorinating species have been isolated (Wong et al. 1991). Only one bacteria Burkholderia sp. was isolated from soils in eastern (Brisbane) and western (Aramac) Queensland (Davis 2011). Because the relative abundance and activity of micro-organisms, and hence probability of isolation, may vary with soil conditions, including moisture and organic matter (Clark 1967), it is likely that the number of species isolated will vary according to seasonal conditions (see Twigg & Socha 2001) in addition to region. This variation in the number of species isolated between these studies is therefore likely to represent the soil conditions at the time of collection in addition to the number of species actually present in each area.

Previous studies have found that the common soil fungus Fusarium, in particular Fusarium oxysporum, appears to be the most efficient microbial defluorinator (Wong et al. 1991, 1992; Walker 1994; Twigg & Socha 2001). Fusarium oxysporum is reportedly ubiquitous in soils in Australia and New Zealand (Burgess et al. 1988) although it was not isolated in this study. Although the environmental conditions at the time of study may be partly responsible, the failure to isolate Fusarium on 1080 medium suggests that other species may be better adapted to defluorinating 1080 under the climatic conditions of south-eastern Australia. Importantly, this would suggest that the micro-organisms identified in this study would be more suitable for use in bioremediation in south-eastern Australia than Fusarium. Furthermore, it reinforces caution in generalising the findings from studies under different climatic conditions and highlights the value in investigating defluorinating isolates under a range of environmental conditions in Australia.

The bacteria Alcaligenes, Bacillus and Burkholderia are known to occur in Australian and New Zealand soils and have been previously reported for their defluorinating ability (Bong et al. 1979; Wong et al. 1992; Meyer 1994; Walker 1994; Twigg & Socha 2001; Davis 2011). Alcaligenes and Bacillus are often involved in bioremediation, where their degrading capacity is used for environmental cleanup of chemically contaminated sites (Paul & Clark 1996). However, Micromonospora, and the actinomycete Streptosporangium have not been reported in earlier studies. The rate of defluorination also varies considerably between species (King et al. 1994) and isolates of the same species, as observed in this study.

Although this study was based on established microbiological isolation and identification techniques (see Bong et al. 1979; Wong et al. 1992; Twigg & Socha 2001), there are some caveats. Defluorination rates were difficult to quantify; sterile soil incubations (negative controls) indicated that some defluorination was occurring without micro-organisms, as also reported by Twigg and Socha (2001). Wong et al. (1991, 1992) also reported that many isolates (48–85%) capable to defluorinating 1080 solution were unable to defluorinate 1080 in the presence of sterile soil. The defluorinating ability of nonautoclaved soil was only measurable in the TARS soil; the amount of F released from the OAI soil did not exceed the amount in the sterile soil control. Additionally the measured defluorinating ability of individual isolates was variable, As a result, the defluorination rates of the soils and isolates identified in this trial should be confirmed in the presence of 1080 without sterile soil, with greater precision, to improve results.

Despite difficulties in accurately quantifying defluorination, our results confirm that soils at TARS and OAI contain 1080-degrading micro-organisms. The incubation of species utilising 1080 as the sole carbon source and measurable defluorination rates of species isolated from OAI and TARS soil demonstrate that such organisms are present. Secondly, the results from trials demonstrating the degradation of 1080 in fox baits at OAI (Saunders et al. 2000) and TARS (Gentle et al. 2007) strongly suggest that microbes are largely responsible. The rapid degradation of buried Foxoff® (Animal Control Technologies, Somerton, Australia) fox baits relative to shelf stored Foxoff® (Saunders et al. 2000) suggests that these micro-organisms are likely to be sourced from the soil environment. Despite the inability to quantify the rate of 1080 degradation in the OAI soil samples, the strong circumstantial evidence indicates that the soil at OAI has defluorinating ability.

The measured defluorinating ability of nonautoclaved TARS soil suggested 8.7 ± 0.8% of added 1080 was defluorinated within 7 days at 27°C. This is comparable to the results of Twigg and Socha (2001) who found that between 10–50% defluorinated within 12 days at 27°C in soils from central Australia. Despite differences in the time periods reported the defluorination in this study appears to be less than in other studies; Parfitt et al. (1994) found that in New Zealand silt loams 50% of added 1080 was defluorinated within 10 days at 23°C, and Wong et al. (1992) found that up to 70% was defluorinated in 9 days (at 28°C day and 15°C night) in Western Australian soils. Differences between these rates may be partly due to methodological discrepancies (i.e. incubation temperatures and periods) and highlight the difficulty in generalising results between studies. Furthermore, such differences highlight the variability as expected from variations in soil composition, soil biota and environmental conditions (King et al. 1994). Only when such variables are accounted for in a replicated, multiple-variable experiment can adequate comparisons be made.

The history of management of each site was unlikely to affect the composition of soil defluorinators. Historically, 1080 fox baits were laid at the OAI and TARS sites as part other studies (Saunders et al. 2000; Gentle et al. 2007) and immediately prior to soil collection (October 2001), but soil samples were collected from separate areas to those exposed to 1080.

The identification of micro-organisms capable of defluorination may offer advantages in addition to reassurance of environmental degradation of 1080. If increased longevity is required, meat baits could be dried, or bacteriostats (e.g. mercuric chloride) and fungistats (e.g. paranitrophenol) added to retard microbial growth and hence defluorination (Thomson 1986; Wong et al. 1992). An understanding of the organisms responsible will assist in selecting appropriate retardants or strategies for use. Alternatively, where swift degradation is required, there may be potential to add defluorinating micro-organisms to detoxify a bait after an appropriate period (Wong et al. 1991), or improve soil, bait or bait presentation conditions (e.g. moisture, aeration, temperature) to encourage microbial colonisation and growth (Clark 1967; Wong et al. 1992). The results indicate that the defluorinating ability of any one isolate is limited, suggesting that adding a ‘mixture’ of defluorinating isolates would be more effective than inoculating with any one specific isolate. Such strategies to increase 1080 degradation may have practical applications to improve the safety of baiting campaigns. While bait uptake rates can be considerable (e.g. 82%; Carter & Luck 2013), usually many baits remain untouched at the completion of a baiting campaign. Additionally, foxes will cache baits (Saunders et al. 2000) resulting in baits that cannot be retrieved remaining a threat to working dogs and other vulnerable nontarget species. Encouraging 1080 defluorination would therefore be favourable where long-term hazards from toxic baits are highly undesirable, or periods where shorter withholding periods for working dogs is required.

Identifying microbes that defluorinate 1080 has also potentially important applications in other fields. Inoculation of ruminants with bacteria genetically modified to defluorinate has been suggested as a means of preventing fluoroacetate poisoning of domestic ruminants (Gregg et al. 1994). Research is continuing to identify potential candidate species from the environment (Davis 2011; Camboim et al. 2012a,b) and the potential of the two bacteria species identified in this study should be further investigated.

The objective of this study was to investigate the presence of 1080 defluorinating micro-organisms present in the soil in south-eastern Australia. The results are the first to show the existence and identity of defluorinating micro-organisms present in the soils on the Central Tablelands and Western Slopes of New South Wales using published methods. These findings have important implications for the sustainability of baiting operations by indicating the presence and preliminary identities of a number of defluorinating bacteria and fungi in the soils of south-eastern Australia. This provides strong indication that 1080 is subject to microbiological degradative processes in this environment following removal from the bait substrate. Such soil micro-organism activity, in combination with uptake from plants and physical breakdown from ultra-violet radiation and heat, indicates that prolonged persistence of fluoroacetate in soils and natural waterways is unlikely to occur (Parfitt et al. 1994).

The results of this study also suggest the likelihood of longer term environmental persistence of fluoroacetate is low, helping to support the continued, sustainable use of 1080 for pest animal control in south-eastern Australia.

Acknowledgements

  1. Top of page
  2. Summary
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References
  9. Biographies

We sincerely thank Ipek Kurtboke for assistance in identifying the actinomycetes and Laurie Twigg for technical advice. Thanks to an anonymous referee for comments that helped improve the manuscript. This study was funded by New South Wales Department of Primary Industries, the University of Sydney and the Pest Animal Control Co-operative Research Centre.

References

  1. Top of page
  2. Summary
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References
  9. Biographies
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Biographies

  1. Top of page
  2. Summary
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References
  9. Biographies
  • Matthew Gentle is a Senior Zoologist with the Robert Wicks Pest Animal Research Centre, Biosecurity Queensland (203 Tor Street, Toowoomba, Qld 4350, Australia

  • Eric Cother is a retired Principal Research Scientist with the Orange Agricultural Institute, New South Wales Department of Primary Industries (1448 Forest Road, Orange, NSW 2800, Australia ). The project arose from studies into the longevity of 1080 bait, to help improve the effectiveness and safety of fox management programs