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Field Attraction of Termites to a Carbon Dioxide-Generating Bait in Australia (Isoptera)

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Abstract

termite bait stations with or without a cO2-generating bait (Focus termite Attractant, produced by Brotica, Inc., Fort collins, colorado, and distributed by Ensystex Australasia) were tested at tree and house locations in Australia. The termite species Coptotermes acinaciformis (Froggatt) (Isoptera: rhinoter - mitidae), Schedorhinotermes intermedius (Brauer) (Isoptera: rhinotermitidae), Microcerotermes turneri (Froggatt) (Isoptera: termitidae), and Nasutitermes exitiosus (Hill) (Isoptera: termitidae) discovered more monitoring stations when the cO2-generating bait was present, and also discovered the monitor - ing stations more quickly when the c O2-generating bait was present.
1
Field Attraction of Termites to a Carbon Dioxide-Generating
Bait in Australia (Isoptera)
by
Steve Broadbent1, Michael Farr2, Elisa J. Bernklau3, Matthew S. Siderhurst4, David
M. James5, & Louis B. Bjostad5
ABSTRACT
Termite bait stations with or without a CO2-generating bait (Focus Termite
Attractant, produced by Brotica, Inc., Fort Collins, Colorado, and distributed
by Ensystex Australasia) were tested at tree and house locations in Australia.
e termite species Coptotermes acinaciformis (Froggatt) (Isoptera: Rhinoter-
mitidae), Schedorhinotermes intermedius (Brauer) (Isoptera: Rhinotermitidae),
Microcerotermes turneri (Froggatt) (Isoptera: Termitidae), and Nasutitermes
exitiosus (Hill) (Isoptera: Termitidae) discovered more monitoring stations
when the CO2-generating bait was present, and also discovered the monitor-
ing stations more quickly when the CO2-generating bait was present.
INTRODUCTION
e economic impact of termites may exceed $11 billion each year in the
United States (Su 2002) and $40 billion worldwide (Wiseman & Eggleton
1994). e majority of damage to homes and other structures is caused by
subterranean termite species in the family Rhinotermitidae (Su 1990).
Baiting strategies for termite control have recently gained popularity due
to the withdrawal of chlordane, chlorpyrifos and other termiticides from
the market (Kard 1999, Su & Scherahn 2000). Current eorts are focused
on improving specic aspects of these systems, including the addition of at-
tractants and/or bait enhancers (Pawson & Gold 1996, Lewis et al. 1998,
Potter et al. 2001, Lax & Osbrink 2003). In a baiting system, the pesticide
is typically introduced into a station only aer termites are detected in that
1Ensystex Australasia
2Amalgamated Pest Control, ueensland, Australia
3Brotica, Inc., Fort Collins, CO
4Dept. of Chemistry, Eastern Mennonite University, Harrisonburg, VA 22802
5Dept. of Bioagric. Sci. & Pest Management, Colorado State University, Fort Collins, CO 80523
2 Sociobiology Vol. 48, No. 3, 2006
station, and depending on the species, weeks may pass before termites locate
a station and begin to feed (Lewis et al. 1998, Potter et al. 2001).
Baiting has been promoted as a more desirable method of termite manage-
ment. It is generally considered to more environmentally sound as baiting
uses very small amounts of insect specic toxicants that are administered
in stations that are targeted at the economically important termite species
only (i.e., it replaces the broad-scale application of liquid chemicals used to
poison the soil around a building). For baiting to work successfully, termites
must nd the bait stations so that the matrix with toxicant can be added for
termite consumption and transfer it back to the nest. ese requirements
are important, and a successful baiting program can take up to nine months
(e.g. 3-9 months Su, 1994; 7 months Tsunoda et al., 1998; 3-7+ months Su
& Scherahn, 2000), which is much slower than by other methods.
Carbon dioxide (CO2) has been reported as an attractant for the termite
species Reticulitermes avipes (Kollar) (Isoptera: Rhinotermitidae), R. vir-
ginicus (Banks) (Isoptera: Rhinotermitidae), and R. tibialis (Banks) (Isoptera:
Rhinotermitidae) in the United States (Bernklau et al. 2005). e most at-
tractive concentration of CO2 is 5 mmol/mol for R. tibialis and 10 mmol/mol
for R. avipes and R. virginicus. An attractant such as CO2 has the potential
to improve the eectiveness of termite baiting systems by reducing the time
interval between station placement and introduction of the pesticide.
Focus Termite Attractant (produced by Brotica, Inc., Fort Collins, Colo-
rado, and distributed by Ensystex Australasia) is a granular formulation that
reacts in soil to generate CO2 in the optimum concentration range for termite
attraction (Bernklau et al. 2005). Focus Termite Attractant is a non-toxic
formulation composed of natural materials, and it contains no pesticidal
components. We tested Focus Termite Attractant in combination with
Exterra uarterra Termite Stations (Ensystex Australasia) to determine the
ability of the attractant to enhance the ecacy of bait stations by creating a
larger ‘footprint’ for termite discovery. Specically, we were interested in three
ecological eects, (i) the time required for station discovery, (ii) the number
of stations discovered, and (iii) the rate at which stations were abandoned
by termites.
MATERIALS AND METHODS
3
Broadbent, S. et al. — Attraction of Termites to a Carbon Dioxide in Australia
Trial sites were established in the vicinity of known termite activity and/
or colonies of the species Coptotermes acinaciformis (Froggatt) (Isoptera:
Rhinotermitidae), Schedorhinotermes intermedius (Brauer) (Isoptera: Rhi-
notermitidae), Microcerotermes turneri (Froggatt) (Isoptera: Termitidae) in
ueensland, Australia, and Nasutitermes exitiosus (Hill) (Isoptera: Termi-
tidae) in New South Wales, Australia. Exterra uarterra Termite Stations
(Ensystex Australasia) were placed equidistant around the termite colonies
in holes 10 cm diameter by 20 cm deep, prepared using a Jarrett auger. Due
to the dry conditions encountered, the soil around each hole was moistened
with 100 ml water. For the CO2-baited stations, Focus Termite Attractant
granules (5 g) were added to each hole prior to station placement. A minimum
distance of three meters was maintained between any control station and
any Focus-treated station to minimise the chance of the CO2 gradient from
a Focus-treated station impacting the results at a control station. Stations
were inspected weekly for the presence of termites. Each station contained
six Eucalyptus delegatensis R. T. Baker timber interceptors for feeding by the
termites.
Coptotermes acinaciformis
ree colonies of C. acinaciformis were located in trees in a residential
park in Deception Bay, ueensland. Four control and four Focus Termite
Attractant stations were placed on either side of each colony. Stations were
placed in a line running east to west with one meter between each series of
four stations on either side, and four meters separating the line of control
stations from the line of Focus Termite Attractant stations. At two trees the
control stations were placed to the north of the colony and at one tree they
were placed to the south of the colony.
Schedorhinotermes intermedius
A domestic residence in a leafy suburb in Upper Caboolture, ueensland,
was selected due to the known long-standing presence of S. intermedius in
the garden. Evidence of Schedorhinotermes activity was noted in the garden
though no termites could be located. Stations were placed at three meter
intervals around the home. Sides were selected randomly, two sides with
Focus Termite Attractant stations and two with control stations. Nine sta-
tions for each treatment were placed.
4 Sociobiology Vol. 48, No. 3, 2006
Microcerotermes turneri
An inspection also revealed the presence of Microcerotermes turneri in
a timber gate post at the front of the same property in Upper Caboolture,
ueensland. Four stations were placed, two on the nature strip and two
in the front garden, equidistant at 1.5 meters from the post infested with
Microcerotermes, with three meters between the control and Focus Termite
Attractant stations.
Nasutitermes exitiosus
A mound of N. exitiosus was located in a garden bed at a domestic residence
in Maitland, New South Wales. Six Focus Termite Attractant stations and
six control stations were placed on either side of the mound.
Statistical Analysis
T-tests were used to analyze dierences in termite presence among stations
that contained or lacked CO2 baits (SAS 2000).
RESULTS
Exterra uarterra Termite Stations containing Focus Termite Attractant
were located more oen and also more quickly than control stations for the
four termite species that were tested (Table 1, Table 2, Table 3, Table 4).
Coptotermes acinaciformis
Termites were found signicantly more oen in Focus-baited stations than
in control stations (Table 1, P<0.05, t-test). Termites located 10 of the 13
Focus-baited stations, but only located 3 of the 13 control stations (Table
1). Over the course of the 9 week study, termites were found in Focus-baited
stations on 68 occasions, but termites were found in control stations on
only 12 occasions (Table 1). Two of the Focus-baited stations were found
by termites within the rst week aer installation, but none of the control
stations were located by termites until 4 weeks aer installation. On average,
of the stations located by termites, Focus-baited stations were found aer 3.20
+SE 0.57 weeks, but control stations were found only aer 6.00 +SE 1.15
weeks. None of the stations were abandoned by termites once the termites
were rst observed in them.
Schedorhinotermes intermedius
5
Broadbent, S. et al. — Attraction of Termites to a Carbon Dioxide in Australia
A Focus-baited station was the only station found to contain termites in
this test, and none of the 9 control stations were located by termites (Table
2). e Focus-baited station was located in Week 2 aer the stations were
installed. In Week 8 aer the experiment began, this station was found to
have been ooded by a broken pipe, and subsequent data was not available.
e station had not been abandoned as of the last reliable observation in
Week 7.
Microcerotermes turneri
A Focus-baited station was the only station found to contain termites in
this test, and neither of the 2 control stations were located by termites (Table
3). e Focus-baited station was located in Week 1 aer the stations were
installed.
Nasutitermes exitiosus
Table 1. Termite bait stations containing Coptotermes acinaciformis.
Stations Site Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Week 7 Week 8 Week 9
CO2 bait Tree 1 - - X X X X X X X
CO2 bait Tree 1 - - - X X X X X X
CO2 bait Tree 1 X X X X X X X X X
CO2 bait Tree 1 - - X X X X X X X
CO2 bait Tree 2 - - X X X X X X X
CO2 bait Tree 2 - X X X X X X X X
CO2 bait Tree 2 - - - - - - - - -
CO2 bait Tree 2 - - - - X X X X X
CO2 bait Tree 3 - - - - - - - - -
CO2 bait Tree 3 - - X X X X X X X
CO2 bait Tree 3 - - - - - - X X X
CO2 bait Tree 3 X X X X X X X X X
CO2 bait Tree 4 - - - - - - - - -
Control Tree 1 - - - - - - - X X
Control Tree 1 - - - - - - - - -
Control Tree 1 - - - - - - - - -
Control Tree 1 - - - X X X X X X
Control Tree 2 - - - - - - - - -
Control Tree 2 - - - - - X X X X
Control Tree 2 - - - - - - - - -
Control Tree 2 - - - - - - - - -
Control Tree 3 - - - - - - - - -
Control Tree 3 - - - - - - - - -
Control Tree 3 - - - - - - - - -
Control Tree 3 - - - - - - - - -
Control Tree 4 - - - - - - - - -
6 Sociobiology Vol. 48, No. 3, 2006
A heavy infestation of termites was recorded in one of the Focus Termite
Attractant stations 16 days aer installation (Table 4). A light infestation of
termites was recorded in one of the control stations on the same date. Further
inspections each week thereaer revealed that the termites remained in the
Focus Termite Attractant station, but the termites vacated the control station
the week aer they were detected and did not return. Aer six inspections,
the trial was terminated to allow elimination of the termite colony and safe-
guard the property.
Table 2. Termite bait stations containing Schedorhinotermes intermedius.
Stations Site Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Week 7 Week 8 Week 9
CO2 bait House - - - - - - - - -
CO2 bait House - - - - - - - - -
CO2 bait House - - - - - - - - -
CO2 bait House - - - - - - - - -
CO2 bait House - - - - - - - - -
CO2 bait House - - - - - - - - -
CO2 bait House - X X X X X X N/Aa N/Aa
CO2 bait House - - - - - - - - -
CO2 bait House - - - - - - - - -
Control House - - - - - - - - -
Control House - - - - - - - - -
Control House - - - - - - - - -
Control House - - - - - - - - -
Control House - - - - - - - - -
Control House - - - - - - - - -
Control House - - - - - - - - -
Control House - - - - - - - - -
Control House - - - - - - - - -
a In Week 8 aer the experiment began, this station was found to have been ooded by
a broken pipe.
Table 3. Termite bait stations containing Microcerotermes turneri.
Stations Site Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Week 7 Week 8 Week 9
CO2 bait House - - - - - - - - -
CO2 bait House X X X X X X X X X
Control House - - - - - - - - -
Control House - - - - - - - - -
7
Broadbent, S. et al. — Attraction of Termites to a Carbon Dioxide in Australia
DISCUSSION
We conclude that the CO2 gradient from each Focus-baited station eec-
tively created a larger ‘footprint’, and that the termites then followed the CO2
gradient to the station. For the four termite species tested, the presence of
Focus Termite Attractant in Exterra uarterra Termite Stations increased the
number of stations that were found by termites. Termites did not abandon
any of the bait stations once they located them, whether baited with Focus
Termite Attractant or not, except for one of the control bait stations that
was abandoned by Nasutitermes exitiosus aer a single week of occupancy
(Table 4).
e presence of Focus Termite Attractant also decreased the time required
for termites to discover the stations. is point is of particular interest in the
development of baiting system technologies, because it has been observed that
weeks may pass before termites locate a bait station and begin to feed (Lewis
et al. 1998, Potter et al. 2001). In the present study, two of the termite spe-
cies located Focus-baited stations within the rst week aer installation (C.
acinaciformis and Microcerotermes turneri), and the other two termite species
located the Focus-baited stations within the second week aer installation
(N. exitiosus and Schedorhinotermes intermedius). In contrast, control sta-
tions were never observed to contain termites for two of the species tested
(Schedorhinotermes intermedius. and Microcerotermes turneri), and required
a minimum of 2-4 weeks for the two termite species that did nd them (C.
Table 4. Termite bait stations containing Nasutitermes exitiosus.
Stations Site Week 1 Week 2 Week 3 Week 4 Week 5 Week 6
CO2 bait Mound - X X X X X
CO2 bait Mound - - - - - -
CO2 bait Mound - - - - - -
CO2 bait Mound - - - - - -
CO2 bait Mound - - - - - -
CO2 bait Mound - - - - - -
Control Mound - - - - - -
Control Mound - - - - - -
Control Mound - - - - - -
Control Mound - - - - - -
Control Mound - - - - - -
Control Mound - X - - - -
8 Sociobiology Vol. 48, No. 3, 2006
acinaciformis and N. exitiosus).
e use of Focus Termite Attractant in association with Exterra uarterra
Termite Stations will provide added benets to pest managers using the
Exterra Termite Interception & Baiting System by detecting the presence
of termites within the vicinity of a property sooner. Early interception in a
Station further reduces the risk of termites entering a structure and enables
earlier placement of Requiem Termite Bait. Previous data has shown termites
are more likely to discover the Exterra uarterra Stations compared to other
commercial Stations due to the larger size and use of a more favored timber
source for the interceptors. Focus Termite Attractant will further enhance
the benets of the uarterra Stations.
ACKNOWLEDGMENTS
Matthew Camper assisted with the statistical analysis using SAS 2000.
is assistance is gratefully acknowledged.
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Of the more than 2,300 termite species in the world, 183 species are known to damage buildings and 83 species cause significant damage. Subterranean termites, including mound building and arboreal species, account for 147 (80%) of the economically important species. The genus Coptotermes contains the largest number of pest species (28), whereas the genus Cryptotermes, especially Cr. brevis, is the most widely introduced. The world-wide economic impact figure of termites is uncertain, but the control cost for termite pests in the United States was estimated at $1.5 billion annually in 1994. Because of differences in their life histories, control measures differ between subterranean and drywood species. Insecticide barriers are used for exclusion of soil-borne subterranean termites, whereas slow-acting baits are used for population control of subterranean termite colonies in and near structures. Whole-structure treatments (fumigation and heat), compartmental treatments (heat or cold), and local treatments (wood surface treatments or insecticide injection) are the primary tools for drywood termite control.
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A sensor consisting of a wooden monitor painted with a conductive circuit of silver particle emulsion was placed in a monitoring station to detect feeding activity of the subterranean termite Coptotermes havilandi Holmgren. Sensor accuracy was 100% 1 mo after installation, but 9 mo after sensor placement, the rate declined to 73%. After the detection of C. havilandi in the stations, baits containing the chitin synthesis inhibitor hexaflumuron were applied in five colonies, and four colonies were eliminated within 3-5 mo. Baiting could not be completed for the remaining one colony because the site became inaccessible.
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The Formosan subterranean termite, Coptotermes formosanus Shiraki is currently one of the most destructive pests in the USA. It is estimated to cost consumers over US dollars 1 billion annually for preventative and remedial treatment and to repair damage caused by this insect. The mission of the Formosan Subterranean Termite Research Unit of the Agricultural Research Service is to demonstrate the most effective existing termite management technologies, integrate them into effective management systems, and provide fundamental problem-solving research for long-term, safe, effective and environmentally friendly new technologies. This article describes the epidemiology of the pest and highlights the research accomplished by the Agricultural Research Service on area-wide management of the termite and fundamental research on its biology that might provide the basis for future management technologies. Fundamental areas that are receiving attention are termite detection, termite colony development, nutrition and foraging, and the search for biological control agents. Other fertile areas include understanding termite symbionts that may provide an additional target for control. Area-wide management of the termite by using population suppression rather than protection of individual structures has been successful; however, much remains to be done to provide long-term sustainable population control. An educational component of the program has provided reliable information to homeowners and pest-control operators that should help slow the spread of this organism and allow rapid intervention in those areas which it infests.