Eect of Imidacloprid Granules on Subterranean Termite
Foraging Activity in Ground-touching Non-structural Wood
Xing Ping Hu1*, Dunlun Song1,2 & Chip Anderson3
A eld trial was conducted to examine the impact of a new granular formula-
tion of imidacloprid on subterranean termite foraging activity and infestation
in ground-touching non-structural wood and the longevity of the eect. e
trial was carried out in an urban forest with high termite populations and a
oor relatively free from brush or deciduous ground cover. e percentages
of monitor wood blocks infested and having active termites were reduced to
< 8% and < 6%, respectively, while they were >50% and >33%, respectively
in population suppression. e estimated damage rates of monitor wood
blocks were also signicantly lower in treated than those in control plots.
e control eect can last for at least 7 months.
Keywords: granular termiticide, soil application, subterranean termite,
For more than six decades, soil treatment with liquid termiticides has been
the conventional technique for controlling subterranean termites (Forschler
1999). Even though baiting has become a popular termite control strategy,
two thirds of the treatments are soil applications of liquid termiticides and
more and more pest control companies are using new non-repellent termiti-
cides (Curl 2004).
Soil treatment with liquid termiticides protects structures against ter-
mite infestation by creating a chemical barrier around (and beneath, if it
is pre-construction treatment) the structures. During the post-treatment
1 Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36849. USA
2 Current address: Department of Entomology, China Agricultural University, Beijing, P.R. China
3Bayer Environmental Science, Professional Pest Management, 2 T. W. Alexander Dr., RTP, NC
* To whom correspondence should be addressed: Email: email@example.com
2 Sociobiology Vol. 50, No. 3, 2007
period, spot or localized treatments are oen needed due to disturbance of
the chemical barrier during reconstruction, add-on construction, structure
repair, landscaping, utility repairs or soil disturbance resulting in new termite
infestation. ese treatments are oen dicult to schedule and costly, be-
cause of the need for specic equipment and pulling technicians away from
In July 2006, a new ready-to-use granular formulation, Premise® Granules,
was approved by the EPA. Premise Granules are intended as a supplemental
treatment to be used with an approved, stand-alone termiticide. Premise
products have imidacloprid as active ingredient, a neonicotinoid that acts as
an insect-specic agonist of nicotinic acetylcholine receptors (Matsuda et al.
2001). As one of the non-repellent termiticides, Premise® (Bayer Environmental
Science) has registered as liquid, gel, and foam formulations.
During the second half of 2006, a eld trial was conducted to evaluate
the eect of Premise® Granules' broadcast application on reducing termite
foraging activity and the level of termite infestation of soil contacting non-
structural wood, as well as the longevity of the eect.
MATERIALS AND METHODS
Selection of test site
e experimental trial was conducted at the corner of an urban forest
park not frequented by visitors to satisfy the required minimum 6 months
with minimal disturbance. e main plants were pine trees and the oor was
relatively free from brush or deciduous ground cover. Pre-trial examination of
fallen logs and tree stumps revealed heavy active foraging populations of the
eastern subterranean termite, Reticulitermes avipes (Kollar). Termite species
were identied using keys to soldier and winged adult termites (Scherahn
& Su 1994).
A series of 12 plots were designed and randomly designated to 6 treated
and 6 untreated (control) plots. e plots were 74 m2 (6 × 24 m) each and
at least 15 m apart from each other.
Application of Premise® Granules
Premise® Granules (0.5% imidacloprid) were provided by Bayer Environ-
Hu, X.P. et al — Eect of Imidacloprid Granules On Termite Activity
mental Science (Research Triangle Park, Raleigh, NC, USA). Using a hand-
held rotary spreader (Scotts® handy Green II, Cinnaminson NJ), the product
was broadcasted evenly on the oor at the label rate of 1.8 lb product per
1,000 2 (= 816 g per 92.9 m2). As a result, each plot received 650 g product
containing 3.2 g active ingredient.
e trial was initiated May 19th (3 days aer a rainfall of 3.5 cm) and ended
December 2nd 2006. Immediately aer broadcast application, 8 southern yel-
low pine blocks (5 × 10 × 10 cm) were evenly distributed along the center
line and 0.25 m within the boundary of each plot. A brick was placed on top
of each pine block to secure its position. e pine blocks were monitored for
termite activities at bi-weekly intervals for the rst 4 months then monthly
through the next 3 months from May through December of 2006. During
visual observations, digital photos were taken to conrm observations when
it was necessary.
e following 3 variables were recorded: 1) the number of wood blocks
attacked by termites (regardless of the presence of termites); 2) the number
of wood blocks showing the presence of active termites; and 3) estimated
ASTM rating (ASTM 04.10, 2006) of wood blocks (10 = no damage; 9 =
trace feeding; 7 = moderate damage; 4 = heavy damage; 0 = destroyed). Data
were cumulative numbers because aer each monitoring, the wood blocks
were returned to their original locations.
e numbers were calculated as percentages that were arcsine-square root
transformed before data analysis. Signicant dierences between treatment
and control of the 3 variables were analyzed using the two-sample T test at
0.05 probability level (Statistix® 8 soware, Analytical Soware 2003).
Precipitation data were collected using a rain gauge installed at the test
site by taking a reading within 3 hours following a rainfall.
Summarized cumulative percentage of wood blocks showing symptoms
from termite attack (bars) and cumulative percentage of wood blocks show-
ing active termite infestation (lines) are presented in Fig. 1.
4 Sociobiology Vol. 50, No. 3, 2007
Premise® Granules treatment signicantly reduced termite attack compared
to control (F = 104.89, P > 0.05). In treated plots, only <5% of the monitor
blocks were attacked by termites, except for at the end of the trial (≈ 8%),
whereas in control plots, the percentage of attacked blocks increased during
the trial and eventually reached >50% when the trial was terminated.
Correspondingly, the reduction in termite foraging activity was also ex-
hibited by the signicant dierences between actively infested monitor wood
blocks in the treatment and control groups (F = 67.74, P < 0.05). Compared
to the increasing number of actively infested wood blocks from the control
group, the percentage from treated plots remained as low as < 2% during the
rst 5 months and only reached to about 6% at the end of the trial.
e eect of treatment also was evidenced by the cumulative estimated
damage rates, presented in Fig. 2. e damage was hardly visible during the
rst 2 months in both treated and control plots, but estimated damage rates
were signicantly lower in treated than control plots aer that (F = 66.8, P
Readings from the rain gauge showed very dry conditions from May 19th
Monitoring date (2006)
Fig. 1. Cumulative percentage of monitor wood blocks that were attacked by termites and had presence
of active termites in treated and control plots
Hu, X.P. et al — Eect of Imidacloprid Granules On Termite Activity
through August, with only 12.2 cm precipitation (3.5 months). Aer August,
the precipitation averaged 9.2 cm per month.
DISCUSSION AND CONCLUSION
is study indicates that broadcast application of Premise® Granules sig-
nicantly reduced termite foraging activity at the labeled rate, as low as 4.4
g active ingredient per 100 m2. e low termite activity before the middle
of July in both treatment and the control plots could be explained by the
extreme dry condition during that period. However, aer the middle of July
when termite activity in control plots began to increase signicantly, treated
plots retained a very low level of termite activity through the trial, even during
August when there was no rain in that month at all. ese results indicate that
Premise® Granules provided eective suppression of foraging termites last-
ing at least 7 months. Our results are similar to data generated from Georgia
(Bayer Environmental Science, unpublished) and agree with the report from
University of Florida (Oi et al. 2006) that Premise Granules proved eective
in suppressing termite foraging activity, even in extremely dry soil.
Monitoring date (2006)
Fig. 2. Cumulative estimated damage rates of monitor wood blocks in treated and control plots
6 Sociobiology Vol. 50, No. 3, 2007
e Premise® Granules are a ready-to-use product with favorable advantages
such as requiring no mixing or set-up time and stopping existing termite
infestation with minimal equipment. It is labeled to be applied to bare soil,
landscaped areas, turfgrass, mulched areas surrounding structures, and non-
structural wood-to-soil contact areas. Application of Premise Granules should
not be used as a stand-alone treatment but as supplemental spot treatments
for repairing isolated problems and as a perimeter application to suppress
foraging subterranean termite populations.
We thank Shizhu Li for technical assistance and eorts spent carrying
out the eld trial and collecting data, graduate students Franklin Quarcco
and Lavanya Polana for assisting laying out plots, and Johnny W. Todd for
providing access to a secured eld site. We would like to acknowledge Dr.
Charles Ray and Arthur Appel for critical comments and discussions of this
Analytical Soware 2003. Statistix® 8 soware. Tallahassee, FL.
ASTM 04.10 2006. ASTM book of Standards, 2006 Edition, Philodelphia, PA.
Curl, G. 2004. Pumped-up termite market. Pest Control. Technol. 32: 28-33.
Forschler, B.T. 1999. Part II: subterranean termite biology in relation to prevention and
removal of structural infestation. In: NPCA research report on subterranean termites.
Dunn Loring, VA. Pp. 31-51.
Matsuda, K., S.D. Buckingham, D. Kleier, J.J. Rauh, M. Grauso & D.B. Sattelle 2001.
Neonicotinoids: insecticides acting on insect nicotinic acetylcholine receptors. Trends
Pharmacol. Sci. 22: 573-580.
Scherahn, R.H. & N.-Y. Su 1994. Keys to soldier and winged adult termites (Isoptera) of
Florida. Fla. Entomol. 77: 460-474.
Oi, F. & J. Paige 2006. Impact of granular imidacloprid on subterranean termites. Presentation
D0381 at the5th Annual Meeting of the Entomological Society of America, December
10-13, Indianapolis, IN.