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HOUSEHOLD AND STRUCTURAL INSECTS
Fire Ant-Detecting Canines: A Complementary Method in
Detecting Red Imported Fire Ants
HUI-MIN LIN,
1,2
WEI-LIEN CHI,
2,3
CHUNG-CHI LIN,
2,4
YU-CHING TSENG,
1
WANG-TING CHEN,
1
YU-LING KUNG,
1
YI-YANG LIEN,
5,6
AND YANG-YUAN CHEN
1,7
J. Econ. Entomol. 104(1): 225Ð231 (2011); DOI: 10.1603/EC10298
ABSTRACT In this investigation, detection dogs are trained and used in identifying red imported
Þre ants, Solenopsis invicta Buren, and their nests. The methodology could assist in reducing the
frequency and scope of chemical treatments for red imported Þre ant management and thus reduce
labor costs and chemical use as well as improve control and quarantine efÞciency. Three dogs
previously trained for customs quarantine were retrained to detect the scents of red imported Þre ants.
After passing tests involving different numbers of live red imported Þre ants and three other ant
speciesÑCrematogaster rogenhoferi Mayr, Paratrechina longicornis Latreille, and Pheidole megacephala
F.Ñplaced in containers, a joint Þeld survey for red imported Þre ant nests by detection dogs and bait
traps was conducted to demonstrate their use as a supplement to conventional detection methods. The
most signiÞcant Þndings in this report are 1) with 10 or more red imported Þre ants in scent containers,
the dogs had ⬎98% chance in tracing the red imported Þre ant. Upon the introduction of other ant
species, the dogs still achieved on average, a 93% correct red imported Þre ant indication rate.
Moreover, the dogs demonstrated great competence in pinpointing emerging and smaller red im-
ported Þre ant nests in red imported Þre ant-infested areas that had been previously conÞrmed by bait
trap stations. 2) Along with the bait trap method, we also discovered that ⬇90% of red imported Þre
ants foraged within a distance of 14 m away from their nests. The results prove detection dogs to be
most effective for red imported Þre ant control in areas that have been previously treated with
pesticides and therefore containing a low density of remaining red imported Þre ant nests. Further-
more, as a complement to other red imported Þre ant monitoring methods, this strategy will signif-
icantly increase the efÞcacy of red imported Þre ant control in cases of individual mount treatment.
KEY WORDS red imported Þre ant, bait trap station, detection dog, odor recognition, Þre ant
detection
The red imported Þre ant, Solenopsis invicta Buren, an
exotic species that originated from South America,
was Þrst discovered in the United States in the 1920s.
Their spread to pan-PaciÞc countries such as Australia,
New Zealand, Taiwan, and China took place around
the early 21st century (Callcott and Collins 1996, ISSG
2010). Morrison et al. (2004) also predicted, based on
their dynamic ecophysiological model of colony
growth, the path of the red imported Þre antÕs future
invasions to parts of Asia, Africa, southern Europe, and
even to the PaciÞc island nations.
This notorious pest is capable of consuming a large
quantity of food during its rapid propagation, devas-
tating agricultural products, threatening the well-be-
ing of both livestock and humans, and seriously af-
fecting the native animal species in the invaded areas
(Adams 1986, Lofgren 1986, Allen et al. 1994).
The application of ant baits containing toxic chem-
icals or insect growth regulators (IGRs) over the in-
fested areas is one of the most widely adopted strat-
egies in red imported Þre ant management. Dust,
granule, or liquid insecticide intended for individual
mount treatments also provide a quicker option for
small-scale pest control. The red imported Þre ant
control support services in the United States have
promoted a methodology combining broad-spectrum
and single-nest treatment, known as the “two-step
method.”The two-step method is presently consid-
ered as the most cost-effective and environmentally
friendly approach for highly red imported Þre ant-
infested areas (Drees et al. 1998, 2000). However,
Drees reported that the overuse of the red imported
Þre ant pesticide “diazinon”produced massive
amounts of waste and water pollutants that failed to
1
Institute of Physics, Academia Sinica, Taipei, 128 Sec. 2, Academia
Rd., Nankang, 11592, Taiwan.
2
These authors contributed equally to this work.
3
Working Dog Training School, National Pingtung University of
Science and Technology, 1, Shuefu Rd., Neipu, Pingtung, 91201, Tai-
wan.
4
Department of Biology, National Changhua University of Educa-
tion, 1, Jin-De Rd., Changhua City, 50007, Taiwan.
5
Department of Veterinary Medicine, National Pingtung Univer-
sity of Science and Technology, 1, Shuefu Rd., Neipu, Pingtung, 91201,
Taiwan.
6
Corresponding author, e-mail: yylien@mail.npust.edu.tw.
7
Corresponding author, e-mail: cheny2@phys.sinica.edu.tw.
0022-0493/11/0225Ð0231$04.00/0 䉷2011 Entomological Society of America
pass the state and federal discharge standards in the
United States (Drees 2003). Moreover, related re-
search revealed that contaminated drainage ditches
from the long-term insecticide applications might al-
ter the water quality of streams and rivers and affect
the aquatic communities (Heckman 1981, Liess and
Schulz 1999). Therefore, an accurate assessment of
the level of red imported Þre ant infestation is needed
before more precise insecticide treatments can be
applied as to reduce both the environmental and eco-
nomical costs associated with chemical control.
In monitoring red imported Þre ant, visual inspec-
tion, pitfall traps, and bait traps are the most common
methods adopted in detecting the red imported Þre
ant and determining the amount of treatment. For
large-scale investigations, satellite imagery, aerial im-
agery, or both are used to provide areawide images of
large red imported Þre ant mound distributions (Vogt
2004a,b). Yet, the nests are usually broken and lack the
obvious dune structures on sites where multiple red
imported Þre ant treatments have already been ap-
plied. Many of these areas consist of those that are less
tolerant to Þre ant infestation, i.e., places with signif-
icant human activities such as playgrounds, parks, hos-
pital, power facilities, and nurseries. Once treated
with pesticides and toxic traps, small amounts of nests
may still remain, whereas newer nests also can emerge
after treatment. On occasions, nests also are found to
be concealed in grass sods or outdoor electronic ap-
pliances. Such situations render the visual inspection
of red imported Þre ant tedious and rather useless. Bait
traps consisting of a food attractant inside a container
are not capable of locating the actual site of the
mounds because they are usually found by foragers;
instead, they merely show that red imported Þre ant
exists somewhere within the vicinity of the baits. Thus,
individual mound treatment cannot be applied efÞ-
ciently and accurately to attain rapid red imported Þre
ant control in such low nest-density areas. Thus, the
development of a practical method to rapidly locate
red imported Þre ant colonies in previously treated
areas is necessary as to avoid costs associated with
inaccurate and ineffective pesticide reapplications.
Animals rely heavily upon their delicate senses for
survival, such is the case with the dogÕs olfactory sys-
tem. Taking advantage of this trait, detection dogs are
often trained to search for objects or creatures such as
fruit, animal products, snakes, gypsy moths, termites,
bed bugs, and other organisms by tracking their
unique odors (Wallner and Ellis 1976, Welch 1990,
Engeman et al. 1998, Brooks et al. 2003, PÞester et al.
2008). Dogs have the great capability of accurately
locating concealed targets with their nose even when
it is wrapped in packages or enclosed in other mate-
rials (Brooks et al. 2003). We had demonstrated pre-
viously that dogs were able to pick up the scents of red
imported Þre ants (Huang et al. 2007). In Australia, off
leash Labrador retrievers also were trained to freely
search for red imported Þre ant nests in the Þeld with
satisfactory results (Corcoran and McNicol 2009).
In this report, three beagles were successfully
trained on leash to detect live red imported Þre ants
of varying quantity; discriminate them from other ant
species; and perform a detailed Þeld investigation of
emerging and small red imported Þre ant nests in a
pretreated outdoor area, which provided the ground-
work needed for the posttreatment of these individual
mounts.
Materials and Methods
Red Imported Fire Ants. Red imported Þre ants for
dog training were collected from mounds in Ching-Pu,
Taoyuan County, Taiwan. This was done by placing
pieces of tissue paper upon the disturbed mounds,
thereby allowing the collection of the ants that ag-
gressively swarmed the paper. The red imported Þre
ant populated paper was then transferred into plastic
zip-lock bags where the ants were subsequently anes-
thetized with CO
2
. The paralyzed ants were then
placed into a 50-ml capped tube with a square sieved
opening (1.7 by 1.7 cm) allowing the scent to perme-
ate out for dog training and testing.
Canines. Three neutered male beagles aged 6, 4, and
2 yr old were recruited in this investigation. They will
be referred to as dog A, B, and C, respectively. All
three dogs had previously received quarantine train-
ing to detect agricultural products in airport customs.
The dogs were then further trained for red imported
Þre ant detection and used in subsequent experiments.
In the red imported Þre ant training program, the dogs
were taught to inform their dog handler of red im-
ported Þre ant presence by sitting in front of the
discovered targets (passive response).
Indoor Training for Red Imported Fire Ant Odor
Recognition and Identification. Red imported Þre ant
odor recognition training was initiated indoors as a
precursor exercise for 2 wk. The purpose of the indoor
training was to avoid the inßuence of weather and
other extrinsic odors commonly encountered out-
doors. Considering quarantine issues and sample avail-
ability, only dead red imported Þre ants were allowed
in the indoor training. The indoor training consisted of
two steps: 1) ⬇50% of a set of tubes described previ-
ously were Þlled with ⬇100 previously frozen red
imported Þre ants. Each set was then hidden in a metal
can Þxed on a wooden board. The handler would lead
the dog to sniff the cans that contained the dead red
imported Þre ants and verbally encourage it to sit by
the cans; a food reward of two dog biscuit pellets was
given for correct responses. Simultaneously, the dogs
also were taught not to react to or sit by empty vials
through oral instructions. 2) To prevent dogs from
reacting to odors from non-red imported Þre ants, the
dogs were further educated to refrain responding to
tubes with ⬇100 frozen laboratory reared Solenopsis
germinata F., Anoplolepis longipes Jerdon, Polyrhachis
dives Smith, Crematogaster rogenhoferi Mayr, or Tet-
ramorium sp. 1. Before proceeding to the outdoor
training, the dogs are presented with sets of 30 tubes
each containing one to Þve tubes of dead red imported
Þre ants, they must consistently recognize at least 20
tubes of red imported Þre ants in total from all the sets
combined. In this case, the number of sets of 30 tubes
226 JOURNAL OF ECONOMIC ENTOMOLOGY Vol. 104, no. 1
presented can vary, but as long as the dog can suc-
cessfully identify 20 tubes in total of red imported Þre
ants in the duration of the tests, they are allowed to go
onto the next training exercise.
Outdoor Training for Red Imported Fire Ant Odor
Recognition and Identification. A set of tubes with
100, 50, 10, or no live red imported Þre ants were
buried in a lawn with the lids revealed above the
ground. Through the same methodology described
previously, the dogs were guided to detect the live red
imported Þre ant-containing tubes and to ignore the
empty tubes. To discriminate red imported Þre ant
odors from non-red imported Þre ant odors, 100 live
laboratory raised S. germinata, A. longipes, P. dives, C.
rogenhoferi, or Tetramorium sp. 1 were collected in
tubes and arranged randomly during the training.
Dogs were taught to only recognize red imported Þre
ants and to discriminate them from the non-red im-
ported Þre ant species as in the indoor training.
Field Training for Red Imported Fire Ant Nest
Detection. Initially, red imported Þre ant nests varying
in size were identiÞed in the Þeld by visual inspection.
As a warm up, each dog must accomplish two rounds
of outdoor live red imported Þre ant training, as de-
scribed above, for purposes of recalling their memo-
ries about the scents of red imported Þre ants. After
recollection of their red imported Þre ant odor mem-
ories, the dogs were guided to the general area to sniff
out red imported Þre ant nests and to sit by the targets.
Piles of rocks, soil mounds, or nests of non-red im-
ported Þre ant species were selected as negative con-
trols during the training. The dogsÕ false indications of
non-red imported Þre ant targets were discouraged
verbally by their handlers. To avoid being attacked by
red imported Þre ants, dogs also were trained to sit
away from detected nests right after snifÞng.
Each dog received2hofoutdoor training in addi-
tion to2hofÞeld training each day: one session in the
morning and the other session in the afternoon. The
whole process was completed within 2 wk. Alternate
training sessions prevented dogs from being bored and
distracted from the work, which could lead to lower
efÞciency during training. Field training also provided
more complicated situations that sharpened their ca-
pabilities to pick up more unpredictable scents of red
imported Þre ants. Before proceeding to the assays of
the dogsÕ ability in locating red imported Þre ants, they
must consistently recognizing a combined total of 10
tubes of red imported Þre ants out of sets of tests
consisting of 30 tubes in an outdoor setting, just as they
did before proceeding to the outdoor training.
Olfactory Detection of Varying Numbers of Red
Imported Fire Ants. Fifteen tubes of red imported Þre
ant were prepared as targets, in which three sets of Þve
tubes each contained 100, 50, and 10 live red imported
Þre ants. A further 45 empty tubes were used as non-
targets. Tubes were randomly selected and buried in
the ground in a line, 3 m away from one another with
their lids exposed to the air. Each dog was assayed with
the 60 (15 red imported Þre ants ⫹45 empty) tubes
once per day, for a period of 10 d. There were, in total,
50 chances for each of the 10, 50, and 100 red imported
Þre ant tubes to be recognized by each dog. “Positive
indication”was deÞned as a dogÕs correct response of
sitting by the target red imported Þre ant tubes. The
dogsÕ positive indication rates in discerning 100, 50, or
10 ant samples were compared with each other by the
MannÐWhitney Utest by using the online statistical
analysis package VassarStats as provided by Vassar
College (Lowry 2010).
Ability to Differentiate Red Imported Fire Ants
From Other Ant Species. To determine whether the
dogs would be confused by unfamiliar ant scents that
did not occur in previous training sections, and to
provide them with more chances to recognize other
non-red imported Þre ant scents, four sets of 12 metal
cans, each containing 10 Þeld-collected C. rogenhoferi,
P. longicornis, P. megacephala, or red imported Þre ants
were prepared as targets (red imported Þre ant) or
nontargets (non-red imported Þre ant species) as de-
scribed above. The metal cans were randomly selected
and arranged in a line three meters away from one
another. Each dogÕs distinction ability was assayed
with the 48 cans once per day for a period of 10 d.
There were, in total, 120 chances for the red imported
Þre ant tubes to be detected by each dog. “Indication”
was deÞned as a dog sitting in front of a can. The
Indication rates of the four species were compared
with each other by the MannÐWhitney Utest.
Searching for Emerging and Residual Red Im-
ported Fire Ant Nests in the Field Through Detection
Dogs Complemented by the Bait Trap Method. The
investigated site is a red imported Þre ant-infested
grassland of 6,160 m
2
located at the Taoyuan County
stadium in Taiwan; the stadium had been repeatedly
treated with pesticides and IGR baits for nearly 2 yr.
The ground in the area were without noticeable nest
mounds but contained previously surviving nests and
new emerging nests red imported Þre ant nests that
are hard to detect merely by eye. This grassland is thus
selected for a survey of residual and emerging red
imported Þre ant by detection dogs with the additional
help of bait trap data.
The grassland was equally divided into seven
smaller subareas, each ⬇880 m
2
. First, for bait traps,
⬇220 uncapped tubes containing potato chips were
distributed equally to each subarea (with 1,540 tubes
in total in the whole testing ground). After 2 h, the
tubes were collected and capped for further species
identiÞcation. The number and locations of the tubes
were then recorded.
Second, the dog handler led the dogs to search for
red imported Þre ant in the same area immediately
after the completion and removal of the baits traps.
Dogs A and B were selected for the detection process.
Places containing ⬎10 red imported Þre ants were
deÞned as an ant nest. Sites of detected red imported
Þre ant nests (as opposed to forage tunnels) were
further veriÞed by shovel excavation or potato chip
bating, and the number of nests was recorded and
mapped on the same plot mentioned above.
The whole procedure ended in 7 d, with the
6,160-m
2
area fully investigated, resulting in a com-
plete map of the red imported Þre ant distribution as
February 2011 LIN ET AL.: FIRE ANT-DETECTING CANINES 227
revealed by the bait trap data combined with the nest
detection data from the dogs (Fig. 1).
For data analysis, a grid with cells of 2 by2mwas
superimposed onto the map of the surveyed area to
measure distances between the bait trapped red im-
ported Þre ant and their nest sites. Concentric circles
centered at red imported Þre ant nests with various
radiuses from 0 to 18 m were plotted at increments of
2 m. The larger the plotted circle area, the more
trapped red imported Þre ants were included within
its radius. The percentage of trapped red imported Þre
ants in each radius was then calculated from the num-
ber of trapped red imported Þre ants in each extending
radius over the total number of trapped red imported
Þre ants in the entire survey area. A logarithmic re-
gression curve of the accumulation percentage of red
imported Þre ants versus radii was generated to show
their correlation.
Results
Dogs’ Olfactory Ability in Discerning Various
Quantities of Red Imported Fire Ants. The experi-
mental data were separated into two parts and ana-
lyzed as follows: one part was the detection dogsÕ
reaction toward the tubes which contained 10, 50, or
100 live red imported Þre ants. Positive indications
were deÞned as when the dogs successfully located
the tubes containing red imported Þre ants. All three
trained detection dogs were capable of locating the
red imported Þre ant tubes, with an overall positive
indication rate of ⬎98% (Fig. 2). There were no sig-
niÞcant difference between dogs and their capabilities
of detecting 10, 50, or 100 ants (P⬍0.05; MannÐ
Whitney Utest). The other part was the results of the
detection dogsÕ responses to empty tubes. False pos-
itive indication is deÞned as when the dogs reacted to
empty tubes. In this category, the false positive indi-
cation rate was ⬍2% for each dog. We also observed
a lack of signiÞcant difference among the dogsÕ abil-
ities in detecting red imported Þre ants. Overall, the
results indicate that all three trained detection dogs
were able to detect red imported Þre ant populations
of ⬎10 ants. This threshold is preferable for locating
grouped red imported Þre ants or red imported Þre ant
nests rather than solo foragers.
Assessment of the Dog’s Ability to Distinguish Red
Imported Fire Ant From the Other Species. Four ant
species, C. rogenhoferi, P. longicornis, P. megacephala,
and red imported Þre ant, were prepared and tested.
Ten ants from each species were presented alive to the
detection dogs as described in Materials and Methods.
The general correct indication rate on red imported
Þre ant by the dogs was ⬇93%. This result is signiÞ-
Fig. 1. Distribution of bait trapped red imported Þre ants (open circles) and dog-detected red imported Þre ant nests
(closed squares) on the site of interest. The dotted line enclosed region illustrates the area that was searched using the
detection dogÐbait trap method.
Fig. 2. Positive indication rates of detection dogs for red
imported red ants (RIFA) in tubes containing 10, 50, and 100
ants. Positive indication rate is the mean percentage of pos-
itive indications over total indications by dogs. The result
shows no signiÞcant differences among the dogsÕ capability
in discriminating the varying quantities of ants (P⬍0.05;
MannÐWhitney Utest).
228 JOURNAL OF ECONOMIC ENTOMOLOGY Vol. 104, no. 1
cantly higher (P⬎0.05; MannÐWhitney Utest) than
the 4% from the dogsÕ response to other species (Fig.
3). The results revealed that, after training, the three
detection dogs had all acquired the capability to cor-
rectly differentiate red imported Þre ants from the
other local species of ants.
Detection Dog and Bait Trap Joint Field Survey.
Twenty-Þve tubes of trapped red imported Þre ants
were captured by bait traps and 13 nests were located
by the dogs (Fig. 1). Besides this, we also found tubes
occupied by other non-red imported Þre ant ants, with
numbers from a few to hundreds depending on the
tubesÕ location and the geological distribution of the
different species of ants. The total number of tubes
with non-red imported Þre ants was estimated to
be ⬇30% out of the 1,540 tubes.
According to the logarithmic regression curve
(R
2
⫽0.976) showing the percentage of accumulated
bait trapped red imported Þre ant in the circled area
versus the radii, 60% of captured red imported Þre ants
were located within a 2-m radius centered at the
closest nest. As the radius extended to ⬇14 m, almost
90% of captured red imported Þre ant were included
in the circle. Thus, only ⬇10% of the red imported Þre
ants wandered to regions outside of the radius of ⬎14
m of the circle centered at the nearest nest (Fig. 4).
From the experimental results, it was concluded that
most of the red imported Þre ants (⬇90%) were
foraging within 14 m from the nests and that only
⬇10% red imported Þre ants foraged at distances fur-
ther than 14 m. The longest observed distance covered
by ants foraging from the nearest nest was ⬇26 m.
Discussion
All three trained dogs demonstrated high positive
indication rates (⬇98%) in detecting red imported Þre
ants. Their false positive rates on the empty tubes were
⬍2%. The indication rate on C. rogenhoferi, P. longi-
cornis, and P. megacephala were also ⬍4%. All these
results not only suggest the great capability of dogs for
locating red imported Þre ant but also met the re-
quired minimum acceptable detection threshold
among other insect detection dogs as suggested by
Brooks et al. (2003). In his report, the termite detec-
tion dogs had an accuracy of 95.93% in detecting east-
ern subterranean termites, Reticulitermes flavipes
(Kollar). Bed bug-detecting dogs showed an accuracy
of 97.5% in locating live bed bugs as well as a 90.0%
accuracy in locating viable bed bug eggs (PÞester et
al. 2008). A trained German wirehaired pointer could
search for screwworms, Cochliomyia hominivorax
(Coquerel), with 99% positive indication rate, and
three German shepherds were able to sniff out the
gypsy moth, Lymantria dispar (L.), egg masses with an
accuracy of 95% (Welch 1990, Wallner and Ellis 1976).
Many factors may affect the detection accuracy of
the dogs, ranging from the training protocols, equip-
ment, abiotic factors such as temperature and wind,
and the maintenance of the dogsÕ memories toward
speciÞc odors. The handlerÕs interpretation of the
dogÕs behavior as well as the length of dogÕs detection
time also contributed to their effectiveness (Wallner
and Ellis 1976, Welch 1990). Although all three dogs
received the same training process and maintenance
and were tested under identical conditions, dog CÕs
positive indication rates on red imported Þre ant ßuc-
tuated more than the other two dogs. Dog C was
observed to become easily excited whenever unfamil-
Fig. 3. Percentage of indication rates for the four ant
species by detection dogs. Indication rate is the number of
dog indicated tubes over the total tube numbers. Columns
represent the mean ⫾SD of 10 repetitive tests. The asterisks
indicate the signiÞcant difference between the non-red im-
ported Þre ant species and red imported Þre ants (P⬎0.05;
MannÐWhitney Utest).
y = 0.1538Ln(x) + 0.4985
rapped
reas
y()
R
2
= 0.976
100%
120%
( 13.6 , 90%)
mbers of t
in circle a
40%
60%
80%
% of nu
RIFA
0%
20%
0 2 4 6 8 10 12 14 16 18 20
Radius extended from dog detected ant nest ( m )
Fig. 4. Relationship between the dog-detected ant nests
and the bait-trapped red imported Þre ants (RIFA). Open
circles, percentage of trapped RIFA located in different radii
extended from the nests. An arrow indicates that 90% of
trapped RIFA were located within ⬇14 m from the nests.
February 2011 LIN ET AL.: FIRE ANT-DETECTING CANINES 229
iar dogs other than dogs A and B were present, espe-
cially in the outdoor environment. Such behavior of-
ten distracted it from active searching and affected the
accuracy of detection. Behavioral corrections were
attempted but were unsuccessful. Considering this,
only dogs A and B were selected for the Þeld test of
investigating the red imported Þre ant nests at the
Taoyuan stadium.
The Australian canines were taken off their leashes
before searching and released to perform free search,
once the nest is found the dogs wagged their tails
excitedly at the site and were subsequently rewarded
with playtime consisting of catch and retrieve. Our
dogs however were trained to search for Þre ants while
being guided on leash by a handler; this gives the
handler more control over the speciÞc search area and
the search speed. It also prevents the dogs from getting
too close to the danger of Þre ant swarms and if
necessary, their mouths, noses, and paws can be in-
spected for red imported Þre ant immediately. Fur-
thermore, a food reward was given instead of playtime
after each successful detection, which ensures that our
dogs are well nourished and not too tired or overex-
cited from playing. Every dog was capable of working
for 4 h/d, dogs that worked over this time frame were
less motivated and easily distracted, hence leading to
lower detection rates.
Our Þeld investigation suggests that trapped red
imported Þre ant were not always adjacent to their
respective nests. Such phenomena could possibly lead
to an over estimation of the red imported Þre ant
distribution if the investigation was conducted merely
by the bait trap method. Therefore, in practice, ex-
cessive pesticides intended for individual mound
treatments could have been applied and unnecessary
labor costs would then incur as a result especially in
areas of low nest density. Oi et al. (2004) observed that
when red imported Þre ant nest densities are low (⬉15
nests per ha), ⬍30% of red imported Þre ant nests can
be detected by traps with attractants. Low efÞcacy of
bait traps implies that further improvements are
needed in detecting nests at low density locations.
Compared with the bait traps, the detection dog has an
overall positive indication rate of ⬎98% based on the
assay for olfactory detection of the various number of
red imported Þre ant, as shown in Fig. 2. Hence, they
are ideal for narrowing down the rough estimations
provided by the bait traps and would allow for more
accurate determinations of the speciÞc locations of
the individual nests. Once more precise nest site in-
formation has been obtained, the unnecessary costs
associated with overestimations of nests sites and over
applications of treatments can be avoided, allowing on
site or regional countermeasures to be applied more
efÞciently at the individual mound level as opposed to
inadequate area wide treatments.
Besides inspecting red imported Þre ants in the soil,
red imported Þre ant detection dogs are also readily
deployable to greenhouses, farms, container distribu-
tion centers, or ports-of-entry to examine the incom-
ing or outgoing products for any possible red imported
Þre ant infestation. Its wide array of applications has
the potential to improve the accuracy and reduce the
costs of red imported Þre ant quarantine programs
around the world.
This study was conducted to assess the trained dogsÕ
capabilities in detecting live red imported Þre ants as
well as their nest in the Þeld. The above-mentioned
results indicate that dogs can be trained to detect red
imported Þre ants, discriminate it from three other
species, and locate red imported Þre ant nests in the
Þeld. Of course, this methodology is by no means a
replacement to the conventional detection methods;
instead, the application of the red imported Þre ant
detection dogs is meant to act as a supplement to the
other red imported Þre ant inspection methods by
providing more accurate identiÞcations of hidden
nests.
Acknowledgments
We gratefully acknowledge James Ho (Wichita State Uni-
versity, Wichita, KS), Chin-Gi Huang (National Taiwan Uni-
versity, Taipei, Taiwan), and Xinyu Toby Huang (Cornell
University, Ithaca, NY) for valuable discussions. We also
thank Dong-Yi Huang (National Changhua University of
Education) for assistance in Þeld detection of red imported
Þre ants by bait trap stations and those who provided assis-
tance in this study. The great contributions of the lovely dogs
Snoopy, Giant, and Johnson in executing the experiment also
are deeply appreciated.
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Received 11 August 2010; accepted 3 October 2010.
February 2011 LIN ET AL.: FIRE ANT-DETECTING CANINES 231
