An assessment of the genetic diversity and
structure within and among populations of wild pigs (Sus
scrofa) from Australia and Papua New Guinea
Species-specific visitation and removal of
baits for delivery of pharmaceuticals to feral swine
Additional toxins for feral pig (Sus scrofa)
control: identifying and testing Achilles' heels
BRENDAN D. COWLED
Invasive Animals Cooperative Research Centre, University of
Canberra, Canberra ACT 2601; the University of Sydney, School of
Veterinary Science, Sydney NSW, 2001, Australia
STEVEN J. LAPIDGE
Invasive Animals Cooperative Research Centre, University of
Canberra, Canberra ACT 2601, Australia
PETER ELSWORTH
Biosecurity Queensland, Robert Wicks Pest Animal Research Centre,
Inglewood, Qld 4387, Australia
Abstract
A literature review was conducted in order to identify unique
weaknesses in the physiology or metabolism of pigs that could be
targeted with specific chemicals (i.e. an ‘Achilles’
heel’ search). A promising weakness identified was the
species’ susceptibility to ethaemoglobin-forming compounds,
most likely related to their uniquely low levels of methaemoglobin
reductase. Further examination revealed that sodium nitrite is a
cost-effective, readily available methaemoglobin-forming compound
that is highly toxic to domestic pigs, which has caused numerous
accidental poisonings. Pen trials on pigs showed that sodium
nitrite delivered by gavage (>90 mg kg1) and freely consumed in
bait (>400 mg kg1) caused rapid and lethal rises in
methaemoglobin. Sodium nitrite appeared to be more humane than
currently used toxins, with deaths following bait consumption being
considerably quicker and with fewer symptoms (within 80 min of
clinical signs beginning; clinical signs including infrequent
vomiting, lethargy, ataxia and dyspnoea). The review also
identified a second deficiency in the metabolism of pigs, namely
high sensitivity to selective inhibition of cytochrome P450 liver
enzymes. This leads to potentially lethal interactions between
various drugs, such as two antibiotics, monensin and tiamulin. A
pen trial confirmed that the antibiotic combination in a single
gavage dose was reliably and rapidly lethal to pigs.
However, its utility as a pig toxin is low, because it was
unpalatable to pigs when delivered in bait and appeared to cause
pain and suffering (leading to the early termination of pen
trials). The findings presented here demonstrate the potential of
sodium nitrite as an additional feral pig toxin.
(WILDLIFE RESEARCH 2008, 35: 651-662. CSIRO
Publishing).
Vaccination of feral pigs (Sus scrofa)
using iophenoxic acid as a simulated vaccine
BRENDAN D. COWLED
Invasive Animals Cooperative Research Centre, University of
Canberra, Canberra ACT 2601, Australia
STEVEN J. LAPIDGE
Invasive Animals Cooperative Research Centre, University of
Canberra, Canberra ACT 2601, Australia
MICHELLE SMITH
Animal Control Technologies Australia P/L, PO Box 279, Somerton VIC
3062, Australia
Animal Control Technologies Australia P/L, PO Box 279, Somerton
VIC 3062, Australia
Abstract
Objectives
To develop an encapsulation method for delivery of vaccines to
feral pigs, and quantify the effect of iophenoxic acid on captive
feral pig blood iodine concentrations to assist in investigation of
factors affecting vaccine uptake.
Design and methods
Feral pigs were administered iophenoxic acid by oral gavage, and
consumption was assessed for different encapsulation methods in
baits. Blood iodine concentrations were monitored for eight days
after consumption. The relationship between dose rate, time since
dosing and blood iodine concentration was assessed for gavaged and
baited captive feral pigs. Wild feral pigs were baited with
PIGOUT® baits containing 20 mg of encapsulated iophenoxic acid
to simulate a vaccination program. Using knowledge from the pen
studies, bait uptake and factors affecting bait uptake were
investigated.
Results
Bait-delivered iophenoxic acid led to variable and inconsistent
changes in blood iodine concentrations, in contrast to pigs
receiving iophenoxic acid by gavage. This precluded accurate
assessment of the quantity consumed, but still allowed a
conservative determination of bait uptake. Iophenoxic acid in
smaller capsules was consumed readily. Increasing baiting intensity
appeared to increase bait uptake by wild feral pigs, and pigs of
varying sexes, ages and weights appeared equally likely to consume
baits.
Conclusions
Encapsulated liquids can be delivered to feral pigs within baits,
should the need to vaccinate feral pigs for fertility or disease
management arise. High baiting intensities may be required.
(AUSTRALIAN VETERINARY JOURNAL 86:1 and 2, January, February
2008).
Feral pig population structuring in the rangelands of
eastern Australia: applications for designing adaptive management
units
BRENDAN D. COWLED
Invasive Animals Cooperative Research Centre, University of
Canberra, Canberra ACT 2601, Australia.
JACLYN ALDENHOVEN
Centre for Advanced Technologies in Animal Genetics and
Reproduction (Reprogen), Faculty of Veterinary Science, University
of Sydney, Sydney NSW 2006, Australia.
INAKWU O.A. ODEH
Faculty of Agriculture, Food and Natural Resources, University of
Sydney, Sydney NSW 2006, Australia.
TOM GARRETT
Queensland Macropod & Wild Game Harvesters Assoc Inc., 1 Creek
Street, Amby QLD 4462, Australia.
CHRIS MORAN
Centre for Advanced Technologies in Animal Genetics and
Reproduction (Reprogen), Faculty of Veterinary Science, University
of Sydney, Sydney NSW 2006, Australia.
STEVEN J. LAPIDGE
Invasive Animals Cooperative Research Centre, University of
Canberra, Canberra ACT 2601, Australia.
Abstract
Feral pigs (Sus scrofa) are an invasive species in
Australia. Their negative impact on conservation values has been
demonstrated, and they are controlled in many areas in the
rangelands of Australia. However, they are usually controlled over
small, often ad hoc management units (MUs), and previous research
has revealed that these MUs can be inadequate. Understanding feral
pig population structuring can aid in the design of appropriate
MUs. This study documents an approach to improving MUs for feral
pig control in the rangelands of Australia. Feral pigs from a
500,000 km2 region were genotyped with 13 polymorphic markers.
Genetic analyses were used to identify population structure.
Identified sub-populations were then related to geographical and
environmental gradients with geographical information systems,
regression analysis and with canonical correspondence analysis.
Five sub-populations were identified. These were moderately
differentiated, with relatively high migration rates. Two
sub-populations in drier, lower elevation areas overlapped, due to
extensive migration, probably along the large, inland rivers and
flood plains. Sub-populations in higher rainfall environments
appeared less likely to migrate. Sub-population differentiation was
also dependant on distance, indicating isolation by distance was
present. A case study applying an adaptive MU to a previously
controlled area is presented. Generally, however, MUs for feral pig
control for natural resource protection and endemic disease
eradication in the rangelands should take into account geographical
size, but also geographic features, especially major rivers in
low-rainfall areas.
(CONSERVATION GENETICS 9: 211-224 2008)
Measuring the Demographic and Genetic Effects of
Pest Control in a Highly Persecuted Feral Pig
Population
BRENDAN D. COWLED
Invasive Animal Cooperative Research Centre, Canberra, ACT 2601,
Australia
STEVEN J. LAPIDGE
Invasive Animal Cooperative Research Centre, Canberra, ACT 2601,
Australia
JORDAN O. HAMPTON
School of Veterinary and Biomedical Sciences, Murdoch University,
Western Australia 6150, Australia
PETER B. S. SPENCER
School of Biological Sciences and Biotechnology, Murdoch
University, Western Australia 6150, Australia
Abstract
Substantial efforts have been made to identify the most
effective practices for the control and management of invasive
vertebrate pest species, such as the feral pig (Sus
scrofa). We investigated the demographics, abundance, and
molecular ecology of a persecuted feral pig population that was
subjected to control. We then applied methodologies to determine if
we could retrospectively quantify any changes in the population
structure or dynamics of these pigs. Feral pig demographic and
abundance parameters indicated that in this population of feral
pigs, there were very few detectable changes between the two aerial
culling years. We observed this despite environmental conditions
being optimal for control. Genetic results indicated that pigs
culled in the latter 2004 cull were genetically identical to those
pigs that inhabited the area a year earlier. The genetic
population was geographically larger than the sample area.
These findings indicate that the recovery in feral pig density
witnessed in the controlled area was not a result of re-invasion
from a separate, genetically distinct population, but rather, it
was the result of re-invasion from feral pigs outside the study
area but within the same genetic population. Importantly, we were
unable to detect any recent genetic bottlenecks. This approach has
considerable potential for auditing the effectiveness of control
programs of pest species and assessing the feasibility of impacting
upon or locally eradicating many other free-ranging pest species.
(JOURNAL OF WILDLIFE MANAGEMENT 706):16901697; 2006).
Using Baits to Deliver Pharmaceuticals to
Feral Swine in Southern Texas
TYLER A. CAMPBELL
United States Department of Agriculture, Animal and Plant Health
Inspection Service, Wildlife Services, National Wildlife Research
Centre, Texas Field Station, Texas A&M University-Kingsville,
Kingsville TX, USA
STEVEN J. LAPIDGE
Invasive Animals Cooperative Research Centre, Unley, South
Australia, Australia
United States Department of Agriculture, Animal and Plant Health
Inspection Service, Wildlife Services, National Wildlife Research
Centre, Texas Field Station, Texas A&M University-Kingsville,
Kingsville TX, USA
Abstract
Few studies have evaluated oral delivery systems of
pharmaceuticals (e.g., vaccines, fertility control agents, and
toxicants) to feral swine (Sus scrofa) in the United
States. Our objective was to assess, through a field trial, the
percentage of feral swine and non-target animals that remove and
consume baits intended to transport pharmaceuticals to feral swine
in southern Texas. We hand-placed 1,178 iophenoxic acid (IA)marked
baits distributed over 1,721 ha (68 baits/km2) in April 2005 and
monitored species-specific bait removal and consumption using track
stations, automated camera systems, and serum IA values from
captured animals. Ninety percent of baits were removed after 72
hours. For baits for which we determined the species that
definitely or likely removed bait using track stations and cameras,
51% were taken by raccoons (Procyon lotor), 22% were taken
by feral swine, and 20% were taken by collared peccaries
(Tayassu tajacu). We found elevated serum IA values in 74%
of trapped feral swine, 89% of raccoons, and 43% of opossums
(Didelphis virginiana). Our oral delivery system was
successful in marking a substantial proportion of feral swine.
However, our observed removal rates suggest that the majority of
the baits were taken by non-target species and, therefore,
unsuitable for most pharmaceutical applications in their current
form.
(WILDLIFE SOCIETY BULLETIN 34(4):000000; 2006)
Efficacy of manufactured PIGOUT baits for
localised control of feral pigs in the semi-arid Queensland
rangelands
BRENDAN D. COWLED
Pest Animal Control Cooperative Research Centre (now Invasive
Animals CRC)
EDDIE GIFFORD
CSIRO Sustainable Ecosystems, GPO Box 284, Canberra ACT 2601,
Australia
MICHELLE SMITH
Animal Control Technologies Australia P/L, PO Box 279, Somerton VIC
3062, Australia
Animal Control Technologies Australia P/L, PO Box 279, Somerton
VIC 3062, Australia
STEVEN J. LAPIDGE
Invasive Animals Cooperative Research Centre, University of
Canberra, ACT 2601, Australia.
Abstract
Conservative population declines of 73% were recorded in three
independent feral pig populations in Welford National Park,
Queensland, when PIGOUT baits containing 72 mg of sodium
fluoroacetate were used in a baiting program following prefeeding.
Declines were measured using a prebaiting population census with
remote cameras, followed by carcass recovery. The knockdown of
susceptible feral pigs may have been higher than this, since any
carcasses not recovered reduced the recorded efficacy. In addition,
feral pigs know to have left the baiting area after trapping and
telemetry-tagging, and subsequently not exposed to toxic baits,
were included in the analysis.
The use of remote cameras and carcass recovery appears to be a
relatively accurate means of recording localised declines in feral
pig populations. This method is applicable only when carcass
recovery is possible, such as in open areas in the semi-arid
rangelands. A decline of 86% of radio-tagged feral pigs
attending bait stations was also recorded. Camera observations
revealed no non-target consumption of baits. Measurement of
sodium fluoroacetate contaminated tissues from feral pigs showed
that residues were too low to present a significant risk to
recorded scavenging animals in the area. Some feral pigs vomited
before death, with vomitus containing sodium fluoroacetate poison
at high concentrations. No vomitus was consumed by non-target
species. Almost all feral pigs were killed relatively rapidly after
ingestion of sodium fluoroacetate and the signs observed in a small
number of poisoned feral pigs did not indicate a significant
welfare concern.
(WILDLIFE RESEARCH 33, 427-437 2006) CSIRO
Publishing www.publish.csiro.au/journals/wr
Attractiveness of a novel omnivore bait,
PIGOUT, to feral pigs (Sus scrofa) and assessment of risks
of bait uptake by non-target species
BRENDAN D. COWLED
Pest Animal Control Cooperative Research Centre (now Invasive
Animals CRC)
STEVEN J. LAPIDGE
Invasive Animals Cooperative Research Centre, University of
Canberra, ACT 2601, Australia
MICHELLE SMITH
Animal Control Technologies Australia P/L, PO Box 279, Somerton VIC
3062, Australia
LINTON STAPLES
Animal Control Technologies Australia P/L, PO Box 279, Somerton VIC
3062, Australia
Abstract
Following a bait-preference pilot study on captive feral pigs, a
series of field studies assessed the attractiveness and
target-specificity of a prototype manufactured feral pig bait
(PIGOUT). Two promising test baits and fresh meat reference baits
were biomarked with iophenoxic acid and aerially distributed in
100-km2 blocks of land infested with feral pigs in western
Queensland to assess field uptake and target-specificity without
prefeeding.
Uptake was assessed by measuring blood iodine levels in aerially
shot feral pigs. In all, 80% of feral pigs sampled in a non-toxic
PIGOUT-baited area had significantly elevated blood iodine,
compared with 52% of sampled feral pigs in a meat-baited area
(although slightly different baiting strategies were employed). No
age or sex bias was evident in PIGOUT-consuming feral pigs.
No monitored manufactured baits were consumed by non-target species
in 500 bait-nights. Attractiveness and target-specificity
trials of ground-laid, unfenced PIGOUT baits compared with
reference baits were subsequently undertaken in several regions of
eastern Australia. Results showed that PIGOUT was consumed readily
by feral pigs at all sites, and that it offered significant
improvement in target specificity when compared with unfenced wheat
or meat baits. However, the baits were consumed by small numbers of
macropods, birds and possums. Available evidence indicates
that the target-specificity of PIGOUT bait is highest in the
rangelands, reducing slightly in temperate areas and subalpine
forests, where abundance of small animals is higher.
(WILDLIFE RESEARCH 33, 651-660 2006) CSIRO
Publishing www.publish.csiro.au/journals/wr
An assessment of the genetic diversity and
structure within and among populations of wild pigs (Sus
scrofa) from Australia and Papua New Guinea
P.B.S. SPENCER
School of Biological Sciences and Biotechnology, Murdoch
University, Murdoch WA 6150, Australia
J. HAMPTON
School of Biological Sciences and Biotechnology, Murdoch
University, Murdoch WA 6150, Australia
S. J. LAPIDGE
Invasive Animals Cooperative Research Centre, University of
Canberra, Canberra ACT 2617, Australia
J. MITCHELL
Queensland Department of Natural Resources and Water, PO Box 187,
Charters Towers QLD 4820, Australia
J. LEE
Australian Quarantine and Inspection Service, PO Box 96, Cairns
International Airport, Cairns QLD 4870, Australia
Species-specific visitation and removal
of baits for delivery of pharmaceuticals to feral
swine
TYLER A. CAMPBELL AND DAVID B. LONG
United States Department of Agriculture, Animal and Plant Health
Inspection Service, Wildlife Services, National Wildlife Research
Centre, Texas Field Station, Texas A&M University-Kingsville,
Kingsville TX, USA
Abstract
Within the domestic swine industry there is growing trepidation
about the role feral swine (Sus scrofa) play in the
maintenance and transmission of important swine diseases.
Innovative disease management tools for feral swine are
needed. We used field trials conducted in southern Texas from
February to March 2006 to compare species-specific visitation and
removal rates of fish-flavored and vegetable-flavored baits with
and without commercially available raccoon (Procyon lotor)
repellent (trial 1) and removal rates of baits deployed in a
systematic and cluster arrangement (trial 2). During trial 1, 1)
cumulative bait removal rates after four nights ranged from 93% to
98%; 2) bait removal rates by feral swine, raccoons, and collared
peccaries (Pecari tajacu) did not differ by treatment; and
3) coyotes (Canis latrans) removed more fish-flavored
baits without raccoon repellent and white-tailed deer removed more
vegetable-flavored baits without raccoon repellent than expected.
During trial 2, feral swine removed fish-flavored baits distributed
in a cluster arrangement (eight baits within 5 m2) at a
rate greater than expected. Our observed bait removal rates
illustrate bait attractiveness to feral swine. However, the diverse
assemblage of omnivores in the United States compared with
Australia where the baits were manufactured adds complexity to
the development of a feral swine-specific baiting system for
pharmaceutical delivery.
