D-limonene oil also known as orange oil is not orange
juice. It is a material (terpene) extracted from the citrus rind. The
citrus is juiced and the oil is pressed and separated. Then distilled
into a solvent with essence of orange. D-limonene is a low toxic (5,000mg/kg)
yet volatile hydrocarbon. It is not nontoxic. It is also a marine pollutant.
Primarily, d-limonene oil has been used as an industrial solvent and
paint additive. The most recent uses of D-limonene are as a pesticide.
Many companies are making egregious and undocumented claims of "non-toxic
control of termites", "whole structure treatment" and
"the fumes penetrate the wood". None of these claims can be
backed by scientific evidence. In fact, there is no empirical scientific
data currently available on the efficacy of orange oil as a treatment
for drywood termites.
How is orange oil used to treat dry wood termites?
First
of all, d-limonene, is aromatic, with some absorbing qualities. There
is no scientific evidence indicating that it "penetrates the wood
to kill termites as some advertisements claim. "Of course anything
other than direct contact would result in no mortality of I. minor.
At best it is a very, very local fumigant (a few centimeters) when high
vapor concentrations are present in closed galleries."( Dr. Rudolf
H. Scheffrahn University of Florida).
Unpublished research has determined that injecting d-limonene
oil into termite galleries can kill dry wood termites. The problem with
this method is, drill and injection is a random, localized treatment
and not whole structure. The limitations would include the many "inaccessible
areas" common in most structures and detection.
Detection
Detecting live termite infestations is critical for efficacy of spot
treatment with d-limonene or any other product. One cannot inject a
liquid into solid wood; the liquid would have to be injected into a
termite gallery. If there happens to be termites it that gallery, orange
oil as a contact poison would offer reasonable control (UC Davis IPM
2006). Undetected termites will not be treated. The elusive drywood
termite cannot be detected in wood by the naked eye. There are devices
on the market for detecting termites. They include: Acoustic Emission
Devices (Termite Tracker), odor detectors and fiber optics. "These
devices are expensive, lack adequate field studies and are rarely used"
(Lewis, Vernard 2002 Drywood Termite Pest Notes). However, Dow Chemical
has published studies on Acoustic emission devices: They worked with
PCOs in actual field situations. Thoms, 2000. Fla Entomol. 83:64-74.
They used acoustic detectors to evaluate the treatment of drywood termites
with spinosad. They found better than 90% mortality at 89% of the sites.
No tests were done with d-limonene. Because of design and intent of
an infested structure, termite galleries can extend into wood framing
behind sheetrock or tiled walls. This condition would create inaccessible
areas for treatment and detection. Subsequently, one would have to gain
access to infested areas by removing wall covering or other expensive
renovation. In addition, orange oil offers no residual qualities (<24hours).
Termites will not feed on wood treated with any type of oil (Rust, UC
Irvine) these conditions could allow termites to move to other areas
of the structure.
Is orange oil magic?
Orange oil can kill termites. It is considered a low toxic
product and efficacious when used under optimum conditions. It is definitely,
not magic and not the best product on the market. "There are no
residual qualities, has odor that lingers that many people do not habituate
to, flammable, and, as an organic solvent, will damage many painted
and finished surfaces. (dr. schefferhan)
Unlike heat treatments, the electro gun, and low toxic, non repellent
liquid residuals that went through rigorous independent university studies
(,Vernard R. Lewis, Michael I Haverty) there is no empirical data or
published reports on the efficacy of Orange oil. Dr. Michael Rust of
UC Irvine and Dr. Rudolf Scheffrahn of University of Florida have done
some independent testing. The below is their response to customer Molly
M. of Sebastopol
From Dr. Michael Rust of UC Riverside:
I don't know of any published studies regarding d-limonene
against drywood
termites. We have done some laboratory testing, but it is not complete.
The
d-limonene will kill termites on contact, but has very little residual
effect (< 24 hours). Termites will not feed on wood treated with
oils
including olive oil, canola oil, ect. We don't know how far the effect
extends.
The problems with localized chemical treatments are the
detection and
treatment of individual colonies. If colonies are not detected or
inaccessible, they will not be killed by injecting chemicals. In widespread
infestations, the fumigant (Vikane or sulfuryl fluoride) or the heat
treatment is probably a better option.
Without the scientific studies, it comes down the buyer
beware.
Unfortunately, the companies that registered the d-limonene were not
required to produce field efficacy data to get it approved.
Mike Rust
"Limonene is a contact poison to termites. The issue is that if
the colony
or colonies are not accessible to treatment with limonene, there will
be no
success. On the other hand, the fumigant will kill termites in all parts
of
the structures. What are your objections to fumigation? Maybe those
can be
addressed to determine your best option."
Rudolf H. Scheffrahn
Professor of Entomology
University of Florida
Orange alone is not Green
The Pest control industry should be proud of recent innovations and
less toxic treatment methods. There is no need to misrepresent products,
use unreasonable scare tactics and resort to questionable and even illegal
claims. Being "green" is much more complex than a "one
size fits all" approach in dealing with termites. Every situation
is different and control would have to be accomplished in a "prescribed"
manner. Integrated pest management (considered a green approach to pest
control) is an inclusive process focusing on not only the pest problem
but also the issues regarding "the reason" for the problem.
Hence, coming up with permanent or long-term reduction in the target
pest population. These solutions may involve habitat modification, structural
modification, physical control, cultural control and judicious use of
pesticides. Treatment also involves understanding the biology of the
pest and a working relationship with a proactive homeowner.
There is strong public interest in reducing the presence
of pesticides in our environment. People are demanding less exposure
to all types of toxicants, not just pesticides. By providing accurate
information, and excellent customer service, pest management professionals
will best represent our industry.
UC Davis IPM program
Pest Control Operators of California
Evaluation of Six Techniques for Control of the Western Drywood Termite
(Isoptera: Kalotermitidae) in Structures Vernard R. Lewis and Michael
I. Haverty Alternative Control Strategies for Termites Vernard R. Lewis
Rudolf H. Scheffrahn, Professor of Entomology University of Florida,
non-published studies on orange oil
Michael Rust, UC Irvine
Florida Chemical Co Inc.
Bill Mashek
BS, Biology, Teaching Credential Dominican University, Advanced Urban
Integrated Pest Management graduate, Perdue University
Principal, Northwest Termite and Pest Control Inc. Specializing in least
toxic termite and pest control.
www.Northwesttermite.com
These
versatile products qualify as exempt from Federal registration. All
EcoEXEMPT® products are USDA NOP (National Organic Program) compliant.
The performance and application costs are comparable to conventional
pesticides, and have a pleasant botanical fragrance.
Nisus'
mission is to provide homeowners, Pest Management Professionals
(PMPs), and distributors with strong, effective products that kill
unwanted pests while providing the lowest possible impact to the
environment.
