Group Title: Agricultural research (Washington, D.C.)
Title: Agricultural research
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Title: Agricultural research
Uniform Title: Agricultural research (Washington, D.C.)
Physical Description: v. : ill. ; 25-28 cm.
Language: English
Creator: United States -- Science and Education Administration
United States -- Agricultural Research Administration
United States -- Agricultural Research Service
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Place of Publication: Washington D.C
Publication Date: June 2000
Frequency: monthly[1989-]
bimonthly[ former jan./feb.-may/june 1953]
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Subject: Agriculture -- Periodicals   ( lcsh )
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Agriculture -- Research -- Periodicals -- United States   ( lcsh )
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General Note: Description based on: Vol. 27, no. 7 (Jan. 1979).
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Volume ID: VID00035
Source Institution: University of Florida
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I "


Using Superplants

To Clean Up Our

Phytoremediation is an innovative use
of green plants to clean up our environ-
ment. The term comes from the Greek
word for plants ("phyto-") that can
detoxify, or remediate, soil or water con-
taminated with heavy metals or excess
Think of the industrial wastes, toxins,
and byproducts that emerge from our
daily activities-everything from sewage
sludge from cities to toxic heavy metals
from mines or factories to chemicals
from agriculture. Produced and used in
moderation and disposed of properly,
these compounds aren't a threat to hu-
man health or the environment.
What should we do, however, when
these materials accumulate in inappro-
priate places to levels that can be harm-
ful? Cleaning them up is a job for
In this issue, you'll read about the
work of Agricultural Research Service
plant physiologist Leon V. Kochian and
his associates at the ARS Plant, Soil, and
Nutrition Laboratory in Ithaca, New York
(p. 4). This laboratory was established
in 1940 with the mission of studying the
relationship between the soil-plant sys-
tem and the nutritional quality of plant
In keeping with its original mission,
the laboratory has also hosted research
that mapped the ability of soils to provide
essential nutrients such as selenium and
zinc to our foods. The soil maps are now
standard references that the food industry
uses to guide its actions.
Over the last 10 years, though,
Kochian has shifted gears a bit. He's
been studying the details of the processes
by which plants take up mineral nu-
trients-zinc, iron, manganese-from
the soil. One plant, alpine pennycress
(Thlaspi caerulescens) was chosen for
intensive study because it accumulates

tremendous excesses of some of these
elements-as much as 1,000 times more
than normal. This behavior has been
tracked to an alteration in nutrient uptake
and transport.
Normally, the activity of so-called
"transporter" proteins responsible for mi-
cronutrient uptake slows and eventually
turns off as the plant accumulates sig-
nificant levels. In this plant, however,
there is no such regulation, so it keeps
taking in more. Kochian is identifying
the genes involved in the hyperaccumu-
lation and hopes to transfer them to
larger, more suitable plants.
ARS agronomist Rufus L. Chaney, a
phytoremediation pioneer who published
the first paper on the subject in 1980, is
also working with alpine pennycress and
hopes to develop a commercial variety
of it. He has found it to be especially
good at removing zinc and cadmium
from soil (p. 6). Cadmium is a heavy
metal that is usually released by indus-
tries in conjunction with zinc. Chaney
has one pennycress that takes in 10 times
more soil cadmium than any other known
soil-cleaning plant.
Other ARS scientists nationwide are
applying the concept of phytoremedia-
tion to many different research problems.
Michael P. Russelle in St. Paul, Minne-
sota, has developed a novel alfalfa that
rapidly absorbs large amounts of
nitrogen-in its nitrate form-from soil
and water. He used the plant to success-
fully clean up a North Dakota site where
derailed tank cars spilled massive quan-
tities of liquid nitrogen fertilizer.
The plants' ability to tolerate what
they've taken in is equally important.
That's the focus of research by David W.
Ow at Albany, California. In hunting for
genes that are key to increased tolerance,
Ow has worked with Indian brown mus-
tard (Brassicajuncea) plants provided by
ARS colleague Gary S. Bafluelos at
Fresno, California.
Ow's team first moved mustard genes
into a simple-structured yeast, Schizosac-
charomyces pombe, so they could be

more easily copied and examined for
function. Now the scientists are in the
process of moving each of about 50
genes into another model plant, thale
cress (Arabidopsis thaliana), for more
detailed studies of their function in
plants. They have found that some genes
boost the test plants' ability to withstand
high levels of metals.
Bafuelos is working with central Cal-
ifornia farmers whose soils and recycled
irrigation water are overloaded with
selenium or boron-two salty contami-
nants that are all too common on the west
side of the state's famous central valley.
His experiments over the past 12 years
have shown that plants in the Brassica
family, like mustard and canola, thrive
on the selenium-laden soils and water.
Bafiuelos recently helped coordinate
production in California of another Bras-
sica not usually thought of as a phyto-
remediator-broccoli. The harvested
broccoli was shipped to ARS nutritionist
John W. Finley at Grand Forks, North
Dakota, for analysis to see whether it can
be used in a study of this veggie's health-
imparting benefits (p. 12).
Although the concept of phyto-
remediation is simplicity itself, this
research is slow, complicated, and pains-
taking. But compared to the very dis-
ruptive and expensive process of soil
removal and physical extraction of
contaminants, phytoremediation may be
the best alternative.
If successful, it will provide a low-
cost "green" technology for soil clean-
up that can be easily used anywhere
without special training or equipment.
An added benefit of phytoremediation is
that the plants-after pulling the con-
taminant from the soil-also serve as
ready-made storage containers for the
contaminant during shipment and sub-
sequent treatment.

John W. Radin
National Program Leader
Plant Physiology and Cotton
Beltsville, Maryland

Agricultural Research/June 2000

June 2000
Vol. 48, No. 6
ISSN 0002-161X

Agricultural Research is published monthly by
the Agricultural Research Service, U.S. Depart-
ment of Agriculture (USDA). The Secretary of
Agriculture has determined that this periodical is
necessary in the transaction of public business
required by law.
Dan Glickman, Secretary
U.S. Department of Agriculture
I. Miley Gonzalez, Under Secretary
Research, Education, and Economics
Floyd P. Horn, Administrator
Agricultural Research Service
Sandy Miller Hays, Director
Information Staff

Editor: Robert Sowers
Art Director: William Johnson
Photo Editor: Anita Daniels
Staff Photographers: Scott Bauer
Peggy Greb

(301) 504-1651
(301) 504-1659
(301) 504-1609
(301) 504-1607
(301) 504-1620

Information in this magazine is public property
and may be reprinted without permission. Non-
copyrighted photos are available to mass media in
color transparencies. Order by photo number and
date of magazine issue.
Agricultural Research magazine articles and
photographs are posted on the World Wide Web
monthly at
Subscription requests should be placed with New
Orders, Superintendent of Documents, P.O. Box
371954, Pittsburgh, PA 15250-7954. See back
cover for ordering information. Complimentary
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news media. Send requests or comments to:
Editor, Agricultural Research, 5601 Sunnyside
Ave., Beltsville, MD 20705-5130, e-mail
This magazine may report research involving pes-
ticides. It does not contain recommendations for
their use, nor does it imply that uses discussed
herein have been registered. All uses of pesticides
must be registered by appropriate state and/or
federal agencies before they can be recommended.
Reference to any commercial product or service
is made with the understanding that no discrimi-
nation is intended and no endorsement by USDA
is implied.
The U.S. Department of Agriculture (USDA)
prohibits discrimination in all its programs and
activities on the basis of race, color, national
origin, sex, religion, age, disability, political
beliefs, sexual orientation, or marital or family
status. (Not all prohibited bases apply to all
programs.) Persons with disabilities who require
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information (Braille, large print, audiotape, etc.)
should contact USDA's TARGET Center at
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To file a complaint of discrimination, write
USDA, Office of Civil Rights, Room 326-W,
Whitten Building, 1400 Independence Avenue,
SW, Washington, DC 20250-9410, or call (202)
720-5964 (voice and TDD). USDA is an equal
opportunity provider and employer.

Agricultural Research

Using Plants To Clean Up Soils 4

Kenaf and Canola-Selenium Slurpers 10

Colon Cancer Curbed by High-Selenium Broccoli 12

Temperature-Sensitive Medflies 14

Added-Sugar Intake on the Rise 17

Asian Longhorned Beetles 18

Predicting a Fat's Behavior in Food Products 22

Science Update 23

Cover: Plant physiologist Leon Kochian (left) and molecular biologist David Garvin
examine wheat plants of various genotypes being studied for aluminum tolerance.
Photo by Scott Bauer. (K8781-4)

In the next issue!

- Fescue toxicosis affects livestock cardiovascular, central nervous, and
endocrine systems. The effects occur after animals consume toxic alkaloids
produced by a fungus that lives within the tall fescue plant. A vaccine to
protect animals from the fungal toxins is being perfected.

A" St. John's-wort is one of the world's most widely used herbs for fighting
depression and other health problems. But the quality and potency of the
marketed herb are too variable. ARS scientists are developing tests and
procedures for analyzing and quantifying the amount of active ingredient in
the herb.

9 Standing crop residue prevents erosion, particularly from wind. Before
now, this plant material couldn't be measured very easily-until a
lightweight laser scanner was developed.

Agricultural Research/June 2000



clean up soils contaminat-
ed with heavy and toxic
metals, nature has ARS
plant physiologist Leon V.
Kochian to thank.
During 13 years of research at the U.S.
Plant, Soil, and Nutrition Laboratory at
Ithaca, New York, Kochian has become
an authority on mechanisms used by cer-
tain plants to take up essential mineral
nutrients and toxic heavy metals from
soils. He has also characterized strategies
some plants use to tolerate toxic soil
Kochian is an international expert on
plant responses to environmental stress,
plant mineral nutrition, and use of plants


. ... ....... ., -, ...

Could this be a job for soil-cleaning superplants? The lack of vegetation in the barren area
above is a result of the soil's high zinc content and low pH. This site in Palmerton,
Pennsylvania, was contaminated by a zinc smeltery operated from 1890 to 1980.

Fiant physiologist Leon Iocnian (rignt)
and Cornell University support scientist
Jon Shaff analyze compounds released
from sorghum roots.

to clean up or remediate soils contami-
nated with heavy metals and radio-
Besides providing important new in-
formation on how to use plants in this
practical way, Kochian's research may
also shed light on an important nutrition-
al concern: how to prevent toxic metals
from entering the food chain.
"One of the primary ways toxic heavy
metals, such as cadmium, get in food is
through plant uptake-the metal is taken
up by the roots and deposited in edible
portions," he says.
"Contaminated soils and waters pose
major environmental, agricultural, and
human health problems worldwide,"
says Kochian. "These problems may be
partially solved by an emerging new

"Green" Technology: Simple Concept
and Cost-Effective
Phytoremediation is the use of green
plants to remove pollutants from the en-
vironment or render them harmless.
"Current engineering-based tech-
nologies used to clean up soils-like the
removal of contaminated topsoil for
storage in landfills-are very costly,"
Kochian says, "and dramatically disturb
the landscape."
Kochian's cost-effective "green" tech-
nology uses plants to "vacuum" heavy
metals from the soil through their roots.
He says, "Certain plant species-known
as metal hyperaccumulators-have the
ability to extract elements from the soil
and concentrate them in the easily
harvested plant stems, shoots, and leaves.
These plant tissues can be collected,

Agricultural Research/June 2000



reduced in volume, and stored for later
While acting as vacuum cleaners, the
unique plants must be able to tolerate and
survive high levels of heavy metals in
soils-like zinc, cadmium, and nickel.
"Phytoremediation has been ham-
pered historically by our inadequate un-
derstanding of transport and tolerance
mechanisms," says Kochian. To address
this deficit, Kochian-working with
ARS research associate Deborah L.
Lethman, Cornell University postdoctor-
al associates Mitch Lasat and Paul B.
Larsen, and graduate students Nicole S.
Pence and Stephen D. Ebbs-has been
studying a unique and promising metal
hyperaccumulator. The plant is Thlaspi
caerulescens, commonly known as al-
pine pennycress.

"Thlaspi is a small, weedy member of
the broccoli and cabbage family,"
Kochian says. "It thrives on soils having
high levels of zinc and cadmium."
His lab has been trying to discover the
underlying mechanism that enables T.
caerulescens to accumulate excessive
amounts of heavy metals.

How Plants Clean Up
"Hyperaccumulators like Thlaspi are
a marvelous model system for elucidating
the fundamental mechanisms of-and
ultimately the genes that control-metal
hyperaccumulation," says Kochian.
"These plants possess genes that regulate
the amount of metals taken up from the
soil by roots and deposited at other
locations within the plant.
"There are a number of sites in the
plant that could be controlled by different
genes contributing to the hyperaccumu-
lation trait," says Kochian. "These genes
govern processes that can increase the
solubility of metals in the soil surround-
ing the roots as well as the transport pro-
teins that move metals into root cells.
From there, the metals enter the plant's
vascular system for further transport to
other parts of the plant and are ultimately
deposited in leaf cells."
Kochian's team has gained insights
into how, at the molecular level, Thlaspi
accumulates these metals in its shoots at
astoundingly high levels. "A typical plant
may accumulate about 100 parts per mil-
lion (ppm) zinc and 1 ppm cadmium.
Thlaspi can accumulate up to 30,000 ppm
zinc and 1,500 ppm cadmium in its
shoots, while exhibiting few or no toxic-
ity symptoms," he says. "A normal plant
can be poisoned with as little as 1,000
ppm of zinc or 20 to 50 ppm of cadmi-
um in its shoots."

The research also suggests an ap-
proach for economically recovering
these metals. "Zinc and cadmium are
metals that can be removed from con-
taminated soil by harvesting the plant's
shoots and extracting the metals from
them," he says.
After investigating the molecular
physiology of zinc hyperaccumulation in
Thlaspi, Kochian's group found that
several key sites for zinc transport were
greatly stimulated in this plant. To get at
the mechanism underlying the stimu-
lation, they cloned a zinc transport
gene-one of the first such accomplish-
ments achieved with any plant. This
breakthrough enabled the researchers to
discover that zinc transport is regulated


Alpine pennycress doesn't just thrive on
soils contaminated with zinc and
cadmium-it cleans them up by removing
the excess metals.

Agricultural Research/June 2000

differently in normal and hyperaccum-
ulator plants.
"In normal plants, the activity of zinc
transporter genes is regulated by the zinc
levels in the plant," he says. "In Thlaspi,
however, these genes are maximally ac-
tive at all times-independent of plant
zinc levels-until you raise the tissue
zinc levels to very high concentrations.
This results in very high rates of zinc
transport from the soil and movement of
this metal to the leaves."

It Even Works With Uranium
W. For soil contaminated with uranium,
Kochian found that adding the organic
.. acid citrate to soils greatly increases both
the solubility of uranium and its bioavail-
ability for plant uptake and translocation.
Though the concept of phytoremediation is simple, progress is limited by the complexity of Citrate does this by binding to insoluble
metal transport and tolerance mechanisms. Above, Cornell University research associate uranium in the soil.
Miguel Pineros (left) and plant physiologist Leon Kochian study some of these mechanisms "With the citrate treatment, shoots of
in corn. test plants increased their uranium con-

Today's "Phyto-miners" Rush to the Cry of E IT....LL ,;6,
"There's Metals in Them Thar Plants!" ,

Gold rush miners might ha\e been better off using plants
to find gold rather than panning streams for the precious
Early prospectors in Europe used certain w\eeds as
indicator plants that signaled the presence of metal ore. These
"eeds are the only plants that can thrive on soils \\ ith a high
content of heavy metals. One such plant is alpine penny-
cress, Thlaspi caerulescens. a wild perennial herb found on
zinc- and nickel-rich soils in many countries. This plant
occurs in alpine areas of Central Europe as well as in our
Rocks Mountains. Most varieties gro\% only 8 to 12 inches
high and have small. white flowers.
In 1998. ARS agronomist Rufus L. Chane\ and colleagues Agronomist Rufus Chaney examines
the roots of a metal-accumulating
in ARS. at the Uni\ersity of Mar;yland. and in England pat- Thlaspi plant in a growth chamber.
ented a method to use such plants to "ph\ to-mine" nickel.
cobalt. and other metals.

Agricultural Research/June 2000

centration to over 2,000 ppm-100 times
higher than the control plants," he says.
This demonstrates the possibility of us-
ing citrate-an inexpensive soil amend-
ment-to help plants reduce uranium
Recently, Kochian, with colleagues
Lasat and Ebbs, identified specific ag-
ronomic practices and plant species to
remediate soils contaminated with radio-
active cesium or cesium-137.
"Although the cause of cesium-137
contamination-aboveground nuclear
testing-has been reduced, large land
areas are still polluted with radiocesi-
um," Kochian says. "Cesium is a long-
lived radioisotope with a half-life of 32.2
years. It contaminates soils at several
U.S. Department of Energy (DOE) sites
in the United States. Projected costs of
cleaning up these soils is very high-
over $300 billion."
Phytoremediation is an attractive

Leon Kochian and ARS research associate
Deborah Lethman study electrophoresis
films to identify Thlaspi caerulescens genes
responsible for heavy-metal transport

alternative to current cleanup methods
that are energy intensive and very
In initial lab and greenhouse studies,
Kochian's team showed that the prima-
ry limitation to removing cesium from
soils with plants was its bioavailability.
The form of the element made it unavail-
able to the plants for uptake.
In a series of soil extraction studies,
Kochian's team found the ammonium ion
was most effective in dissolving cesium-
137 in soils. This treatment increased the
availability of cesium-137 for root up-
take and significantly stimulated radio-
active cesium accumulation in plant
Later, Kochian did field studies with
six different plant species in collabora-
tion with Mark Fuhrmann, a DOE scien-
tist at Brookhaven National Laboratory
in Upton, New York. They found sig-
nificant variation in the effectiveness of

ChaneN sa s bionining is the use of plants to mine valu- Chane. sa s that to make phyto-mining as \tell as ph- .,
able heavy -metal minerals from contaminated or mineral- toremediation worthwhile requires, at a minimum, a plant
ized soils, as opposed to decontanunating soils. \\ith %enr high annual intake of minerals, such as the high-
"The crops would be grown as ha\. The plants would be cadrmum-accumulating pennycress variety for which they
cut and baled after they'd taken in enough minerals." Chane. ha\e filed a patent application.
sai s. "Then they'd be burned and the ash sold as ore. Ashes "Better still, the traits of plants like penn cress could be 1
of alpine penn\cress gro\\n on a high-zinc soil in Penns I- incorporated into high-yielding commercial crop likecanola
\ania yielded 30 to 40 percent zinc-\\hich is as high as gro\\n for ha\." Chane sa\s.
high-grade ore. Electricity generated by the burning could His idea of the best h\ peraccumulators? "The\y'd have all
partial\ offset biominmn costs." the characteristics of a hay crop: They should be tall. high
USDA has signed a cooperate e research and development ~ wielding, fast gro\\ ing. easy to harvest, and deep rooted. And
agreement \% ith Viridian Environmental, a technology com- the\ should hold onto their mineral-rich leaves so they can
pans based in Houston. Texas. The CRADA in\olhes Scott be harvested along \\ ith the plant stems."-By Don Comis,
Angle at the University of Man land: Alan J.M. Baker at the ARS.
Uni'ersirt of Sheffield. United Kingdom: plant breederYin- Rith1s L. Chaney is at the USDA-ARS Environmental
Nling Li %\ ith Viridian: and a cooperator at Oregon State Uni- Chemi.\trr Laboratorv. Bldg. 007. 10300 Baltimore Ave..
\ersity. Viridian is funding the CRADA's ph\to-mining re- Beltsville. MD 20705-2350; phone (301) 504-8324, fa (301)
search and development to the tune of $I million over 5 ears. 504-5048. e-mail rchantr'

Agricultural Research/June 2000



Leon Kochian (left) and molecular biologist
David Garvin check wheat plants for
aluminum tolerance. Some wheat and corn
plants can tolerate aluminum by excluding
the metal from the root tip.

plant species for cleaning up contam-
inated sites.
"One species, a pigweed called Ama-
ranthus retroflexus, was up to 40 times
more effective than others tested in re-
moving radiocesium from soil. We were
able to remove 3 percent of the total
amount in just one 3-month growing sea-
son," says Kochian. "With two or three
yearly crops, the plant could clean up the
contaminated site in less than 15 years."
As a result of Kochian's findings,
DOE is performing pilot studies at
Brookhaven using this technology.

Aluminum Hurts Crops Worldwide
Kochian's lab is also working on find-
ing ways to grow crops on marginal lands
such as acid soils, where toxic levels of
aluminum limit crop production. Alumi-
num is the third most abundant element
in the Earth's crust; it is a major compo-
nent of clays in soil.
At neutral or alkaline pH values,
aluminum is not a problem for plants.

Agricultural Research/June 2000

- -A .1 1C.. 1Vo1-1 1 1

However, in acid soils a form of alu-
minum-Al+3-is solubilized into a soil
solution that is quite toxic to plant roots.
For years, scientists have been baffled
by the causes of aluminum toxicity in
"Aluminum toxicity limits crop pro-
duction on acid soils, which cover well
over half of the world's 8 billion acres
of otherwise arable land, including about
86 million acres in the United States,"
Kochian says. "When soils become acid,
the toxic aluminum damages plant root
systems, which greatly reduces yields."
Kochian's research in collaboration
with ARS plant molecular biologist
David F. Garvin uses an interdisciplinary
approach integrating molecular, genetic,
and physiological research to provide
insights into how particular genetic types
of some plant species-including wheat,
corn, and sorghum-can tolerate high
levels of the metal in acid soils.
"We found that the root tip is the key
site of injury, leading to inhibited root
growth, a stunted root system, and re-
duced yields or crop failures from de-
creased uptake of water and nutrients,"
Kochian says.
"Aluminum triggers the release of
protective organic acids, specifically
from the root tip into adjacent soil. When
released, these acids form a complex
with the toxic aluminum, preventing the
metal's entry into the root. Wheat and
corn tolerate aluminum by excluding the
metal from the root tip," Kochian says.
Kochian is also conducting research
on an aluminum tolerance mechanism in
collaboration with plant molecular biol-
ogist Steve H. Howell of Boyce Thomp-
son Institute at Cornell, using thale cress,
Arabidopsis thaliana, a diminutive,
weedy member of the mustard family.
He and colleagues have successfully
identified Arabidopsis mutants that are
aluminum tolerant. Kochian is studying
differences between these mutants and a
wild type of Arabidopsis to identify the
molecular basis of tolerance.
The ultimate goal of this research is

to isolate the genes conferring aluminum
tolerance. It should then be possible to
improve the tolerance of relatively
aluminum-sensitive crop species, such
as barley, or to further enhance the toler-
ance of existing aluminum-tolerant
"One of the major goals for agricul-
tural scientists for the immediate future
is to increase food production to keep
up with an ever-growing world popula-
tion," Kochian says. "As much of the
world's best agricultural land is already
under cultivation or is being lost to in-
dustrialization, there is increasing
pressure for farmers to cultivate marginal
lands such as the huge expanses of acid
soils that are not currently used for
He continues, "Research aimed at
producing crop genotypes that tolerate
the suboptimal conditions of these mar-
ginal lands is one way global food pro-
duction can be increased significantly.
Being able to produce a wider range of
crop species with increased aluminum
tolerance will make a major contribution
to these efforts to cultivate marginal,

Leaves accumulate
metals and are har-
vested to prevent
soil recontamination.

Roots take up metals from
contaminated soils and
transport the metals to
stems and leaves.

stressed soil environments."
Besides helping farmers who grow
crops on acid soils, Kochian's phytore-
mediation research findings are used by
other scientists in government and aca-
demia and by environmental consultants,
government, and industry groups com-
plying with cleanup of contaminated
For his landmark phytoremediation
research, Kochian has received two
awards: in 1999, the U.S. Department of
Agriculture Secretary's Honor Award for
Environmental Protection and an award
as ARS 1999 Outstanding Senior Sci-
entist of the Year.-By Hank Becker,
This research is part of Plant Biolog-
ical and Molecular Processes, an ARS
National Program (#302) described on
the World Wide Web at http://www.nps.
ars. usda. gov/programs/cppvs. htm.
Leon V Kochian is with the USDA-
ARS Plant, Soil, and Nutrition Labora-
tory, Cornell University, Tower Rd.,
Room 121, Ithaca, NY 14853-2901;
phone (607) 255-2454, fax (607) 255-
2459, e-mail *

Agricultural Research/June 2000

Phytoremediation: Using Plants To Clean Up Soil

01 1

Kenaf and Canola-Selenium Slurpers


K enaf and canola plants do a
good job of cleaning up soil and
water contaminated with sele-
nium, Agricultural Research
Service studies in California
show. Besides helping detoxify water
and reclaim selenium-laden soil, canola
that's enriched with moderate levels of
selenium may provide a safe, nutritious
feed for livestock, according to prelimi-
nary ARS results.
Though selenium is an essential
micronutrient for humans and other
mammals, too much of it can harm
people and animals alike. Using kenaf
or canola for what's known as bio-
remediation-biological cleanup of soil
or water-could improve underground
water supplies destined for our homes
or could improve the safety of water that
ends up in ponds and lakes used by
Selenium-accumulating kenaf and
canola plants have value beyond envi-
ronmental cleanup chores. Kenaf, a fast-
growing, deep-rooted relative of okra
and cotton, makes a bright, high-quality
paper that resists yellowing. Better yet,
that papermaking doesn't require the
toxic chemicals needed for converting
wood pulp into paper.
What's more, kenaf can also be
processed into acoustic tile, cat litter,
bedding for horses or other animals,
composite board for construction, mats
for erosion control and grass seeding, or
pads for cleaning up chemical or oil
Canola, a member of the mustard
family, yields a healthful vegetable oil.
Forage made from the crop is a desir-
able feed for farm animals because it has
about as much protein as alfalfa, a pre-
mier forage and hay crop. And canola
plants first used to cleanse or detoxify
high-selenium soil or drainage water
might next be sold as a value-added feed
for livestock in regions where soils don't
provide enough of this nutrient.
"In the United States, selenium defi-
ciency is typically a bigger problem than

Soil scientist Gary Bailuelos evaluates canola plants grown for cleaning selenium-rich soils.
In studies on livestock, he is testing the potential use of high-selenium canola forage as feed.

selenium toxicity," says ARS soil scientist
Gary S. Bafuelos. "Selenium deficiency
is a major problem for livestock or wild-
life in at least 37 states and costs beef,
dairy, and sheep producers an estimated
$545 million in losses every year.
Ranchers in selenium-poor regions either
inject their animals with the mineral or
add selenium supplements to feed."
Bafiuelos, who is with the ARS Water
Management Research Laboratory in
Fresno, California, has not only scruti-
nized selenium uptake by kenaf and
canola, but has also looked at the
selenium-recycling prowess of other
cultivated crops, including grasses,
legumes, and even vegetables like broc-
coli, cabbage, Swiss chard, and collard
greens. And he has investigated the ability
of wild plant species like Indian brown
mustard to suck selenium from the soil.
The site of these experiments-Cali-
fornia's central valley-is America's

number one agricultural region. Ironi-
cally, growers there struggle with an
overabundance of selenium on the west
side and a paucity on the east.

Feeding Canola to Livestock
In collaboration with ARS soil sci-
entist Henry E Mayland at Kimberly,
Idaho, Bafluelos examined the effects
of feeding selenium-enriched canola to
lambs and dairy cows. Grower John E.
Diener of Red Rock Ranch in Five
Points, California, produced canola for
the experiment.
"Of course it's too early for us to rec-
ommend feeding of selenium-enriched
hay to livestock," cautions Mayland.
"But these preliminary results look
The study was likely the first to use,
as an animal feed or supplement, cano-
la that had been grown specifically for
the task of pulling naturally occurring

Agricultural Research/June 2000


Bafiuelos examines the effects of salt, boron, and selenium on the roots of kenaf. This crop is
much taller than canola and has a deeper root system for cleaning up soils.

selenium from the soil.
Half the animals in the tests were fed
canola that had been irrigated with high-
selenium drainage water (200 to 500
parts per billion). Water for irrigating the
canola fed to the other lambs and cows
had only 10 parts per billion selenium.
Ten lambs nibbled freshly harvested
canola for 7 weeks; eight dairy cows ate
dried, coarsely ground canola as part of
their total rations for 20 days. The
amount of selenium in canola was me-
ticulously measured to make sure it was
at a safe level-less than 5 milligrams
per kilogram of dry matter. That's the
equivalent of about a small pinch of se-
lenium in a bale of hay.
The scientists also checked selenium
levels in blood, cow's milk, and other
samples. "All of the animals," reports
Bafiuelos, "remained healthy throughout
the study. None showed signs of getting
too much selenium from the canola."

An added bonus: An informal taste
test of milk produced by the canola-fed
cows indicated no detectable difference
in flavor. Plus the animals' weight
gains-essential to ranchers' profits-
were about the same, regardless of the
selenium content of the feed.
But what about the selenium that ends
up in the manure of animals that eat
higher-selenium canola? Results from an
earlier ARS study suggest that danger-
ously high levels of selenium are unlikely
to cycle into pasture plants from the
manure. That means the plants should
still be safe for animals to graze.
Selenium in cattle manure is pre-
dominantly of the organic forms that are
less available to plants than the inorganic
forms. That's according to an earlier
experiment reported by Husein A. Ajwa
at the Fresno lab, along with Bafiuelos
and Mayland. They used potted canola
and tall fescue plants grown in soils

treated with manure or other selenium

Big Kenaf
For the selenium-recycling study with
kenaf, Bafiuelos and co-researchers grew
some 120,000 plants on a 1-acre site near
Los Bafios, California. He performed the
kenaf analysis in collaboration with
Patrick T. Treffey of 3-Way Farms,
Watsonville, California; Charles G.
Cook, formerly with ARS; and David A.
Dyer of USDA's Natural Resources
Conservation Service.
The hardy plants shot up nearly 15
feet in only about 6 months. "Kenaf,"
says Bafiuelos, "took up at least 25 per-
cent of the soluble selenium to a depth
of about 3 feet. Canola, which has shal-
lower roots, used about 50 percent of the
selenium to a depth of about 2 feet."
Though kenaf is less tolerant than
canola of very salty drainage water, that
doesn't take this plant out of the running.
"Irrigation wastewater that's high in
selenium," Bafiuelos says, "isn't always
overloaded with other salts. Besides,
kenaf plants rapidly produce a tremen-
dous amount of biomass, meaning that
in a very short time you have a very big
plant cleaning up a lot of soil and water
for you."-By Marcia Wood, ARS.
This research is part of Water Quali-
ty and Management, an ARS National
Program (#201) described on the World
Wide Web at http://www.nps.ars.usda.
gov/programs/nrsas. htm.
Gary S. Baiuelos and Husein A. Ajwa
are in the USDA-ARS Water Manage-
ment Research Unit, 2021 S. PeachAve.,
Fresno, CA 93727; phone (559) 453-
3100, fax (559) 453-3122, e-mail
banuelos @
hajwa @ asrr
Henry F Mayland is at the USDA-
ARS Northwest Irrigation and Soils
Research Laboratory, 3793 N., 3600 E.,
Kimberly, ID 83341; phone (208) 423-
6517, fax (208) 423-6555, e-mail
mayland@ gov. *

Agricultural Research/June 2000

elenium. It's an essential trace
element that helps keep the
-immune system humming and
"l free radicals under control.
Recent evidence from human
41L studies suggests that the mineral reduc-
es the incidence of cancer when taken
in higher doses than most diets supply.
I OA CThat news has prompted increased
use of selenium supplements. Sales rose
from $60 to $66 million-a 10-percent
increase-between 1996 and 1997, ac-
cording to most recent statistics from
o 'tthe Nutrition Business Journal pub-
lished in San Diego, California.
The idea of selenium supplements
doesn't sit too well with nutritionists
Nulrilio t L&41a,] I s like John W. Finley and Cindy D. Davis
prepare., at the ARS Grand Forks Human Nutri-
ount th tion Research Center in North Dakota.
numbe o" They know the selenium salts in some

lesions in tissue supplements can be toxic when too
fro'i the much is ingested. On the other hand,
irstines of a "it's harder to get too much selenium
high-slt enasu through foods," says Davis.
broccoli and Different foods package selenium in
injected %%ith a~ different biochemical forms. And the
carcinogen, body uses these forms differently, ex-
plains Finley. An expert in selenium nu-
trition, he wants to find what form or
forms provide the widest range of
health-promoting properties-including
cancer prevention.

Broccoli's Got the Right Stuff
Recent research in Finley's lab is
demonstrating that high-selenium
broccoli may be the best source of an
anticancer agent. Other researchers dis-
covered that garlic stores selenium in a
form that appears to be most active
against cancer. And broccoli and brus-
sels sprouts also store selenium in this
form, known as selenium methyl seleno-
cysteine, or SeMSC. The body simply
snips the end off this amino acid to
produce the anticancer agent-methyl
Though garlic is higher in SeMSC,
most Americans are not likely to eat
enough of it to produce the desired

Agricultural Research/June 2000

effect, Finley notes. So his group has
focused on testing selenium-enriched
broccoli as a way to get effective levels
of SeMSC into the body.
Along the way, however, he learned
how animals and people metabolize other
food forms of the mineral. "It's a long
and tortuous path for the form of seleni-
um prevalent in grains and some meats-
selenomethionine-to get converted to
methyl selenol. It's easier for selenium
salts-the forms used in some supple-
ments-to get there. And it's only one
step for the form in broccoli," Finley
In a series of rat studies, Finley, Davis,
and former colleague Yi Feng, now with
the University of Louisville's medical
school, confirmed that differences in se-
lenium metabolism translated to differ-
ences in the risk of colon cancer. First,
they demonstrated that selenium salts-
both selenate and selenite-can prevent
the first of several steps that can lead to
cancer, whereas the grain form-seleno-
methionine-was ineffective.
Selenium salts reduced the number of
adducts in the rats' colons by 53 to 70
percent. Adducts are formed when a car-
cinogen binds to DNA, explains Davis.
"If the damage isn't repaired, it can lead
to tumor formation."
The researchers had beefed up the
rats' selenium levels through their diets
for several weeks. Then they injected the
animals with a potent carcinogen called
DMABP, for short. Their findings sup-
port those of others showing that selen-
ite protects against adduct formation in
rats' mammary cells.
The group got similar results when
they looked for a later stage of colon
tumor formation called aberrant crypts.
These are immature colon cells that have
gone awry. "Not all aberrant crypts
develop into cancer," says Davis, "but all
colon cancers begin as aberrant crypts."
Feng painstakingly counted the crypts
and found more in the animals fed
selenomethionine than in those getting
selenium salts.

s i- "

High-selenium broccoli is freeze-dried and
powdered before it is fed to rats. Above,
nutritionist John Finley holds one of the
rats and a sample of the enriched broccoli.

Beefed-Up Broccoli Works Best
The most exciting phase of this work
started in a Grand Forks greenhouse. The
researchers grew ordinary broccoli in
soilless media with added selenium to
observe uptake of the metal. Finley says
that studies show that broccoli grown in
the presence of selenium can accumulate
substantial amounts. Some commercial
broccoli grown in California has up to
50 times more selenium than normal, he
notes, because the irrigation water is nat-
urally high in the mineral. When Finley
analyzed his broccoli, however, he found
it had 100 to 200 times more selenium
than the California heads.
When the researchers pitted the high-
selenium broccoli against the salt form
selenate in rat studies, they made sure to
control for any beneficial effects of broc-
coli itself. The vegetable is high in anti-
oxidants and contains other substances
shown to be active against cancer. So
animals in each test group got ordinary
broccoli as well as the treatment.

Treatments consisted of daily doses
of either 0.1 or 1.0 mg of selenium per
kilogram of the rats' body weight, either
in the form of enriched broccoli or sel-
enate. The higher dose is representative
of the selenium level that reduced can-
cer risk in a human trial, Finley says.
After giving the animals DMABP,
Feng again looked for precancerous
aberrant crypts and for collections of
these cells, known as aberrant crypt foci.
High-selenium broccoli always resulted
in fewer precancerous lesions than
selenate did, says Finley-about one-
third fewer at the 1.0 mg/kg dose. And
the number of lesions decreased as the
dose increased.
The results were so promising that
Finley and Davis decided to repeat the
experiment. And they confirmed the
findings using a different salt-selenite
instead of selenate-and a single but
higher dose of selenium-2.0 mg/kg.
They also gave the animals a much more
potent carcinogen-dimethyl hydrazine
(DMH). Although it produced many
more lesions, the rats fed high-selenium
broccoli had half as many aberrant crypts
as the animals getting selenite.
"If there's a call to increase selenium
intake, we currently have few choices
other than high-selenium yeast or
selenium salts," says Finley. "Selenium-
enriched broccoli is a potential source of
the mineral in a highly effective form."
His group is looking for other potential
benefits of the enriched vegetable.-By
Judy McBride, ARS.
This research is part of Human Nu-
trition, an ARS National Program (#107)
described on the World Wide Web at http:/
/www. nps. ars.
John W Finley and Cindy D. Davis
are at the USDA-ARS Grand Forks
Human Nutrition Research Center, P.O.
Box 9034, University Station, Grand
Forks, ND 58202-9034; phone (701)
795-8353, fax (701) 795-8395, e-mail
jfinley @ gfhnrc.ars. usda. gov *

Agricultural Research/June 2000

For Males Only

T here are millions of these six-
legged bachelors in sunshine
states like California and Flori-
da. Because they're small and
unobtrusive, you're unlikely to
ever notice them. But their success in
the game of love helps protect your
favorite fruits and vegetables from
becoming an icky, maggoty mess.
What are they?
Temperature-sensitive lethal Mediter-
ranean fruit flies-or TSLs for short.
Through a bit of laboratory trickery, TSL
medflies that work outdoors are exclu-
sively males. All of them are sterile-
that is, infertile. Dropped from airplanes
to work in areas where invading med-
flies have been detected, the TSL med-
flies have an important assignment: Find
and mate with wild female Mediter-
ranean fruit flies.
These fertile females would like to
make a home for their offspring in warm-
weather states. When they mate with
sterile male medflies, however, no via-
ble offspring are produced. Deprived of
new generations of healthy young flies,
the population soon crashes.
Now, 6 years of tests by USDA scien-
tists and their colleagues in lush coffee
plantations of southwestern Guatemala
have shown that what's known as the
Toliman strain of TSLs do their job
anywhere from three to five times better
than conventional, mixed-sex strains.
Temperature-sensitive lethal medflies
get their name from the fact that high
temperatures can be lethal to eggs
containing TSL females. This genetic
quirk in females was discovered by
researchers working with the Inter-
national Atomic Energy Agency in
Vienna, Austria, about a decade ago.
The TSL trait allows mass-rearing of
medflies that are exclusively males. And
on a per-male basis, TSL males don't
cost any more to rear than standard,
mixed-sex strains of medflies. That saves
resources that would otherwise go into
producing the unneeded females. What's
more, not having sterile females to


Agricultural Research/June 2000


Male (brown) Using temperature-sensitive lethal
and female medflies, says ARS research geneticist
(white) med- Donald O. Mclnnis, is an effective,
fly pupae.
Pupae color environmentally friendly strategy that
was the basis helps reduce the need for chemical
of the old insecticides such as malathion. Medfly,
method of
methd of Ceratitis capitata, is one of the world's
males from worst insect pests of agriculture. It can
females, infest more than 250 different kinds of
fruits and vegetables and easily cost
millions of dollars to eradicate. If it were
to become established in California, for
example, this industrious, one-third-
inch-long insect could make a dent of
anywhere from $324 to $510 million in
the state's economy every year.

distract them once they are outdoors and
looking for wild, fertile females may be
a key to the TSL males' success.
To produce TSL males requires insec-
tary workers to bathe the white, banana-
shaped medfly eggs in 97 F water for
12 to 24 hours. That kills all the eggs with
female embryos inside but doesn't harm
those with males. Later, when they are
pupae-their final developmental stage
before becoming adult flies-the insects
are irradiated for several minutes to ren-
der them sexually sterile.

nia, mins inausrinous; on.ea- nrrrt .-nqg,: I np.g:';
could make a dent of anywhere frdm?$i324to $ :

million in the state's economy every, year. .:

Medflies ruin crops when fertile fe-
males use their tubelike ovipositors to
punch holes in the skin of a ripening fruit
or vegetable, then pump their eggs inside.
The eggs hatch and produce wiggly
medfly larvae that develop inside the
fruit, feeding on the flesh and making it
unmarketable. They eventually leave the
fruit, dropping to the ground to continue
their development into adult flies that
begin the cycle all over again.
McInnis, who is at ARS' U.S. Pacific
Basin Agricultural Research Center in
Honolulu, Hawaii, helped design the
pioneering tests of the Toliman TSL
medflies in Guatemala. He did the work
with David Lance of USDA's Animal and
Plant Health Inspection Service, for-
merly at Waimanalo, Hawaii, and now
at Cape Cod, Massachusetts; Pedro
Rendon and colleagues with APHIS in
Guatemala City, Guatemala; and co-
researchers from the government of
Rendon and staffers at the Inter-
national Atomic Energy Agency de-
veloped the Toliman TSL strain by
crossing the Viennese TSL flies with a
Guatemalan strain of medfly. Toliman
TSLs needed for the collaborative
research were produced at a medfly
factory in El Pino, outside Guatemala
City, Guatemala. APHIS and the Guate-
malan government run that insectary.
Native to Africa, medflies have lived
in Guatemala since at least the 1960s.
The El Pino factory can produce up to
about 50 billion medflies a year. Some
are released in Guatemala, forming a liv-
ing barrier that helps stop the species
from advancing north into the United
States. Other steriles are shipped to the
United States for use in regional wars
against medfly.
California, for instance, has an enor-
mous need for steriles for its ongoing
campaign in Los Angeles, Riverside,
Orange, and San Bernardino counties.
The state last year used 15 billion ster-
iles for this war on medflies. Florida has
a similar campaign and uses 70 million

Agricultural Research/June 2000


sterile medflies a week in a 500-square-
mile area.
The Guatemalan studies, begun in
1993, included the largest-ever outdoor
test of TSL medflies. For these rigorous
examinations of the insects' proficien-
cies, more than 120 million Toliman
TSLs and the lab's conventional "Peta-
pa" strain of neutered medflies were set
free in coffee fields.
As part of the experiment, research-
ers collected coffee berries that had been
visited by the female flies to determine
whether the hidden eggs were infertile.
In plots where the Toliman TSLs had
been released, the proportion of infertile
eggs to fertile eggs was from three to five
times greater than that of a standard lab-
reared strain.
The Toliman TSLs also scored high
in two other critical categories: field dis-
persal, or ability to roam throughout
fields instead of staying in one place, and
field survival, or ability to adapt to cli-
mate and other environmental conditions.
The ARS, APHIS, and Guatemalan in-
vestigators were the first to move TSLs
out of the lab and into mass production.

As a result of the team's exhaustive stud-
ies of Toliman TSLs, the El Pino fly fac-
tory is now planning to produce only this
top-performing strain.

SZ5.-= ai. Bwao 'n z. *.i.v
ME 17i.u.-. i
Technician Steven Tam checks medfly eggs
prior to heating them in a 97 F water bath
to kill the females.

Two major sterile-medfly factories in
Hawaii-one operated by APHIS and the
other by the State of California-also
plan to produce TSLs exclusively. In all,
they could provide more than 400 million
steriles a week for mainland campaigns.
Largely because of the impressive re-
sults of the Guatemalan field tests with
Toliman TSLs, other countries threatened
by medfly invasions are opting to use
TSLs in their own mass-rearing pro-
grams. Chile and the Portuguese island
of Madeira, for example, are already us-
ing strains of top-performing TSLs to
guard their crops against the ravages of
wild medflies.-By Marcia Wood, ARS.
This research is part of Crop Protec-
tion and Quarantine, an ARS National
Program (#304) described on the World
Wide Web at http://www. nps.ars. usda. gov
/programs/cppvs. htm.
Donald O. Mclnnis is at the USDA-
ARS U.S. Pacific Basin Agricultural
Research Center, 2727 Woodlawn Dr.,
Honolulu, HI 96822; phone (808) 988-
8232, fax (808) 988-7290, e-mail +

Agricultural Research/June 2000

Added-Sugar Intake on the Rise

o you forego that teaspoonful in your cereal or cof-
fee. But do you check the labels on processed foods
for sugar in other forms?
According to USDA's 1994-96 Continuing Survey
of Food Intakes by Individuals (CSFII), Americans
now average 20.5 teaspoons-nearly 3 ounces-of added
sugars each day. That's 68.5 pounds per year. And that figure
is probably low because of underreporting, says ARS food
scientist Shanty Bowman, who is with the agency's Community
Nutrition Research Group in Beltsville, Maryland.
Many processed foods and beverages PEGGYGREB (K8919-1)
contain added sugars-that is, those which
do not occur naturally in the foods them-
selves. These include white, brown, and
raw sugars; various syrups; dextrose;
fructose sweetener and liquid fructose; and
honey molasses.
"Many foods and beverages containing
high amounts of added sugars contribute
few nutrients," says Bowman. On the other
hand, those containing natural sugars, such
as fresh fruit and milk, are also rich in
vitamins, minerals, and other nutrients.
Based on U.S. food-supply statistics,
Bowman says added sugars have increased
in the U.S. diet 28 percent since 1982.
"About one-third of our added sugars come
from nondiet soft drinks," she says, based
on her analysis of the CSFII data. "Next .
are bakery products-cakes, cookies, pies,
and other pastries-which contribute about
13 percent."
She notes that fruit drinks, punches, and
ades also make a significant contribution, accounting for 10
percent of added sugars. Dairy desserts and candies each con-
tribute about 5 percent. "It's important for consumers to rec-
ognize that they get large amounts of added sugars through
processed foods and beverages," she emphasizes in a recent
issue of USDA's Family Economics and Nutrition Review (vol.
12, no. 2).

Children are more likely to have high intakes of added sugars,
whereas adults over age 40 are likely to have lower intakes.
Bowman notes that about one-third of children 2 to 5 years old
and one-half of those 6 to 11 fall in the group with the highest
She analyzed data from 14,709 individuals from age 2 to 90-
something and divided them into three groups based on the
percentage of total calories coming from added sugars. Group
1 got less than 10 percent of total calories from added sugars;
group 2 got between 10 and 18 percent; and group 3 more than
18 percent (see table below).
Bowman says group 3 had the lowest
intakes for all micronutrients-especially
vitamins A, C, B12, and folate and for the
minerals calcium, phosphorus, magnesium,
zinc, and iron. They also had the lowest
intakes of grains, fruits, and vegetables as
well as meat, poultry, and fish, and they
averaged the most calories. By contrast,
group 1 averaged the fewest calories but
had much higher intakes of protein and
fiber than group 3.
Added sugars and natural sugars are
listed together as "sugars" on the nutrition
labels. But interested consumers can scan
the list of ingredients to look for the pres-
ence of added sugars. Products having no
I added sugars or sugar-containing ingre-
dients may state that on the label in
accordance with Food and Drug Admin-
istration policy.-By Judy McBride, ARS.
This research is part of Human Nutri-
tion, an ARS National Program (#107) de-
scribed on the World Wide Web at
programs/appvs. htm.
Shanty A. Bowman is with the USDA-ARS Community Nu-
trition Research Group, 10300 Baltimore Ave., Bldg. 005, Room
125, Beltsville, MD 20705-2350; phone (301) 504-0610, fax
(301) 504-0698, e-mail *

Beverage Choice Patterns

Total calories


Fluid milk Fruit juices Soft drinks Fruit drinks
- -- - ----- ---O--Ounces ---- -----
6.6 3.6 1.0 0.4
6.7 2.9 5.7 2.2
5.2 1.9 16.6 4.8

Agricultural Research/June 2000


1 (<10%)
2 (10-18%)
_3 (>18%)

"" '.: ^ ''^^....^," .' ,: ." "" ;' .: ".' .

W: ., -

ontrol .
N w *i i 1 ^ -^^ *; ** '

*ii : :!' &'
:, ':,' monitoring the munching sounds
made by Asian longhorned beetles (ALB)
may help scientists home in on which
trees are infested. This is just one of sev-
eral new tactics that Agricultural Re-
search Service scientists are now explor-
ing to find ways to control these
wood-boring pests.
"Trees infested by the Asian long-
horned beetles were first found in the
United States in New York in 1996 and
then in Chicago in 1998," says ARS en-
tomologist Michael T. Smith. "Adult bee-
tles have also been intercepted at ports
in 17 states."
According to reports from USDA's
Animal and Plant Health Inspection
Service (APHIS), if this beetle spreads
unchecked, it could cause billions of dol-
lars in damage to ornamental trees and
forests and to the maple syrup, lumber,
and tourism industries.
Two highly prized and well-known ur-
ban parks in the United States-New
York City's Central Park and Chicago's
Lincoln Park-are presently at risk. Trees
bordering these parks or in very close
proximity have been found to be infest-
ed with ALB. While the infested trees

have been removed, there is concern that
the insects may have already spread to
other trees in the parks.
Smith, who works at the ARS Bene-
ficial Insects Introduction Research
Laboratory in Newark, Delaware, is fast
becoming one of the world's experts on
these pests. He has spent considerable
time over the past 2 years in interior
China, conducting collaborative field
studies with his Chinese colleagues on
key aspects of the beetle's behavior, as
well as its natural enemies. He and his
colleagues are simultaneously carrying
out additional studies here in the United
Native to China and Korea, Anoplo-
phora glabripennis causes widespread
mortality of poplar, willow, elm, and
maple throughout vast areas of China.
"Most of the damage can be found in
trees along streets, windbreaks around
agricultural fields, hedgerows, planta-
tions, and manmade forests," says Smith.
Together with the large number of
hardwood tree species thus far found
infested in the United States-maple,
elm, horse chestnut, and ash, to mention
a few-this beetle can probably survive

and reproduce in most sections of the
country where suitable host trees exist.
The adult-over an inch long-is coal
black with yellow or white spots and has
long antennae with white bands. A fe-
male beetle spends considerable time
chewing a small groove and hole through
the bark to the cambium. Then she
carefully inserts a single egg about the
size of a rice grain through the hole and
underneath the inner bark onto the outer
surface of the wood, or xylem. She plugs
the hole with digested wood known as
"Because of her efforts, young ALB
are safe and well hidden," Smith says.
He has documented female beetles
taking 50 to 72 minutes to complete egg-
laying. He is currently studying hours of
video data of this and other ALB
behaviors, so he considers these results
to be preliminary.
"Based on published Chinese re-
search, a female lays an average of about
35 eggs during her approximately 42-day
life. They hatch in about 11 days," he
says. "Then, the young grubs, or larvae,
start eating the tree's cambium, first
disrupting its nutrient-transporting

Agricultural Research/June 2000


Above, an Asian

longhorned beetle adult

crawls on a cross section

of a tree damaged by

larvae of the species.

vessels. After shedding their skin twice,
the larvae start boring into the wood of
the tree, gnawing into the tougher, water-
transporting vessels deeper inside."
So far, the only solution has been to
cut down and remove infested trees. In
the U.S. eradication program, infested
trees are also chipped into tiny pieces
after they are taken down. Chips are
sometimes even incinerated.
A method for detecting and monitor-
ing adult ALB is needed. One such meth-
od may be a pheromone lure-a scent
produced by one sex to attract the other.
Last May, ARS entomologist Jeffrey
R. Aldrich and chemists James E. Oliver
and Aijun Zhang of the ARS Insect
Chemical Ecology Laboratory in Belts-
ville, Maryland, isolated, identified, and
synthesized two compounds from quar-
antined ALB as potential lures. In
preliminary laboratory tests, these com-
pounds appeared to stimulate flight and
walking in both sexes.
However, field tests in China last July
failed to demonstrate that the beetles are
attracted to either compound. Additional
field tests are planned. Stephen A. Teale,
an entomologist at State University of

New York-Syracuse, has been working
for more than 2 years on this as well. He
has isolated several compounds that he's
been testing in China.

How Do You Detect Them?
Detection of ALB-infested trees has
largely depended on visual examination
of trees. Trunks are checked for insects
and telltale signs-a small slit left by the
female when she lays an egg, sawdust or
sap coming from this slit, or dime-sized
holes made by new adults emerging from
the tree, says Smith.
APHIS estimates that inspectors
identify only about one-third of the
beetle-infested trees in situations where
inspectors stand below and use binoc-
ulars to examine the trees. This has been
the primary method used since 1996 in
the New York infestation.
In Chicago, cherry pickers and tree
climbers have been used to detect infest-
ed trees, and APHIS has reported im-
proved detection efficiency from this
method. The procedure, however, is quite
costly and time-consuming.
Smith has been working with Teale
to find a better system for detecting in-

fested trees. They're developing an
acoustic beetle detector that homes in on
the beetle's munching sounds as they
"The pest spends most of its life-
about a year-as a larva inside a tree be-
fore emerging as an adult. We're work-
ing on a device that can pick up the
sounds of tunneling larvae," says Smith.
So far, they've successfully recorded
the beetles within standing live poplar
and willow trees in China. These record-
ings were made under fairly noisy con-
ditions to better simulate those under
which this system is needed to operate
in the United States.
In addition, successful recordings
were made of ALB feeding up to 6.5
yards away from the recording device.
"This will be particularly important
since one of our goals is to provide a
tool that inspectors could use to check
trees without initially having to climb
them," he says.
To distinguish beetle-chewing sounds
from various environmental noises,
Smith and Teale are working with a
specialist on a feeding-noise recognition
system. "It would generate an acoustic

Agricultural Research/June 2000


fingerprint of the beetle as the
larvae feed on the two tree
tissues they commonly in-
habit-inner bark and inner
wood," he says. "Besides re-
cording the chewing sounds of
the beetles, we will be re-
cording and developing an
archive of the insect-munching
sounds created by other chew-
ers that also inhabit trees
commonly infested by the
If successful, Smith and
Teale hope that by early this fall Entomo
they will have a functional pro- produce
an infes
totype system for identifying
ALB-infected trees by the
chewing noises coming from

Other Control Tactics
Smith is also examining the biology
of invasion for this beetle, which includes
studies being conducted under natural
field conditions in China in cooperation
with Gao Ruitong and Li Guohong of the
Chinese Academy of Forestry in Beijing,
"We hope to find exploitable nicks in
the pest's armor-points in its life cycle
we can take advantage of-to develop
eradication or management tools," he
First, he is studying the behavior of
adult beetles while they inhabit the tree,
including how male and female beetles
find, recognize, and mate with one
another and the steps leading to egg
laying, feeding (by adults), and host tree
To date, Smith has uncovered new in-
formation never before recorded on ALB
behavior, as well as identified several
behaviors that are potentially exploitable
for eradication or management.
Second, by observing the beetles'
flight behavior in a single flight, he is
assessing their ability to fly (distance,
rate, in-flight orientation, etc.).

logist Michael Smith patiently listens and records so
:d by Asian longhorned beetle larvae as they feed wil
ted willow tree in Gansu Province, China.

"Thus far, preliminary data analysis
indicates that the average distance a
beetle flies in a single flight is about 50
yards," Smith says. "However, since
single flight distance may be largely
influenced by the distance between trees
within the landscape, this may under-
estimate the average single flight dis-
tance in urban landscapes where trees are
more widely spaced. Our data show that
ALB are capable of single flights of over
437 yards."
Third, Smith is also studying popula-
tion dispersal behavior under natural
field conditions in China. He wants to
show how groups of ALB move over an
entire season (in multiple flights).
"We're uncovering new information
on the potential rate of population
spread," says Smith. "It's particularly im-
portant that we conduct our initial stud-
ies in areas where the trees are spaced
about the same as they are in the areas
infested in the United States."
The immediate use of this information
is to help APHIS, which oversees the
ALB eradication program, establish the
outer boundaries of its quarantined areas,
as well as predict the direction and rate
of spread from infestations in New York
and Chicago.

Results from these studies
will also be used by ARS ento-
mologist Jay S. Bancroft at the
Newark laboratory to develop
models for predicting ALB
population dispersal within var-
ious landscapes-such as
parks, woodlots, plantations,
and forests-that are at risk
within the United States, ac-
cording to Smith.
"While this is the first year
.i of our multiyear study, pre-
Sliminary dispersal results indi-
,unds cate that adult beetles are
thin stronger flyers than previously
thought," says Smith. "Prelim-
inary analysis indicates that
they are capable of dispersing
an average of 328 yards over an
entire season. However, the maximum
dispersal distance recorded in this study
was over 1,530 yards." The study will be
repeated in the year 2000.
A recent report listed the ALB flight
distance as only 40 to 50 feet. Referring
to this report, Smith says, "based upon
our 1999 studies of both population dis-
persal and individual flight behavior,
ALB is certainly capable of dispersing
or flying well beyond 50 feet." He is ap-
prehensive that these flight distances
underestimate the insects' flight ability
or range.
To complement these field studies, lab
studies of key aspects of ALB biology
are being carried out with Smith's ARS
biological technician Joseph M. Tropp
at Newark.
"These studies will provide new infor-
mation on the daily reproductive capacity
of adult female beetles over their life
span," Smith says. This is particularly im-
portant in light of the beetle's host-tree
preference and the select group of tree
species found infested in the United
Finally, ARS entomologist Keith R.
Hopper at the Newark laboratory, whose
expertise is in the population biology of
invasion, is collaborating with Smith on

Agricultural Research/June 2000

ALB infestation in
Chicago: before,
during, and after
cleanup. The only
means of control
available is to
identify which
trees are infested,
cut them down,
and chip them
into tiny pieces.
Such an approach
can turn a
with tree-lined
streets into a
barren landscape.




&* *,^ ^ -j


his studies of ALB colonization behavior
and population dispersal.
Using molecular markers, Hopper and
Smith are working to determine the
genetic structure of ALB populations in
China. By comparing the beetles' genet-
ics, they plan to show whether beetles
tend to stay in the same tree or move
often between trees and to provide
additional evidence about how far the
beetles move. This information will be
used to determine sampling procedures
for ALB in the United States.

Natural Enemies

In 1999, Smith, working with Yang
Zhong-qi of the Chinese Academy of
Forestry, initiated studies of the known
natural enemies of ALB and other close-
ly related longhorned beetle species in
China. They want to evaluate known nat-
ural enemies of ALB in China, as well
as find and evaluate new ones, with an
emphasis on parasites of egg and early
larval stages.
Smith also plans to search for and
evaluate natural enemies of wood borers
indigenous to the United States that may
be potential biocontrols of ALB as well.
Besides this ongoing research, Smith
says studies are planned that will address
questions of host-tree preference and
suitability for larval growth and develop-
ment. These efforts will involve many
researchers and organizations, including
APHIS, Penn State University, Univer-
sity of Illinois, State University of New
York-Syracuse, and the Chinese Acade-
my of Forestry, to name a few.-By
Hank Becker, ARS.
This research is part of Crop Protec-
tion and Quarantine, an ARS National
Program (#304) described on the World
Wide Web at http://www.nps.ars.usda.
gov/programs/cppvs. htm.
Michael T Smith is at the USDA-ARS
Beneficial Insects Introduction Research
Laboratory, 501 South Chapel St., New-
ark, DE 19713-3814; phone (302) 731-
7331, ext. 41,fax (302) 737-6780, e-mail *

Agricultural Research/June 2000

Predicting a Fat's Behavior in

Food Products

improving shelf life and minimizing off-flavors in marga-
rines, shortenings, and cooking oils is important to both
food manufacturers and consumers. But accomplishing this
isn't easy because fats are complex mixtures of molecules.
What food manufacturers need is a way to predict how
fats-specifically those known as triglycerides-will act in
food formulations and during storage. Currently, food manu-
facturers use trial and error during the early phases of product
development, which is time-consuming and costly.
Now, ARS researchers in the Food Quality and Safety
Research Unit at the National Center for Agricultural Utilization
Research (NCAUR) in Peoria, Illinois, have developed an
analytical technique to help food manufacturers shave months
off product development.
The new technique is a scientific mouthful-reversed-phase
high-performance liquid chromatography (HPLC)/atmospheric
pressure chemical ionization (APCI) with mass spectrometry
(MS). It sounds complicated, but HPLC/APCI-MS can actually
simplify identification of triglycerides.
"It's faster, more accurate, and less time consuming than
normal chemical analysis," says ARS chemist Gary R. List,
who leads food quality and safety research at NCAUR. The
technique can identify 35 to over 100 triglycerides in 2 hours
and helps researchers correlate triglyceride composition with
the physical properties it imparts to food: melting range, mouth
feel, and reaction to refrigeration.
ARS chemist William E. Neff and Florida-Atlantic Univer-
sity researcher W. Craig Byrdwell (formerly with ARS)
perfected HPLC/APCI-MS in the laboratory. Previously,
researchers used a one-dimensional system of liquid chroma-
tography, which allowed them to see a single peak indicating a
"But seed oils are a complex mixture of triglyercides, with
compounds that overlap," says Byrdwell. "Mass spectrometry
allows us to see signature masses for each individual triglycer-
ide so that even if they overlap, they can still be identified
without being confused. This method is also helpful in evalu-
ating seed oils with modified fat compositions, like sunflower
or soybean, because there is no standard reference for the chem-
ical composition of these oils."
"Using APCI-mass spectrometry is an easier way to work
the puzzle," says Neff. "It can be used to break fat molecules
into a few large pieces so that we can clearly identify their
composition. We can see triglycerides intact before they break
down to form decomposition products during storage or high-
temperature frying."
What happens to oils during frying? ARS food technologist
Kathleen A. Warner in Peoria says, "they break down under
high temperatures, which causes them to turn dark and have
an unpleasant odor."

To help understand what these breakdown compounds are,
Warner and Neff used simple oils such as triolein and trilinolein
as model frying oils. The information from the simple oils will
provide a comparison to other breakdown products in more
complicated oils such as sunflower and corn oils.
Warner gets feedback about the oils' taste and smell from
trained sensory panel members. She and Neff send frying oils
to Byrdwell for APCI-MS analysis of the triglyceride decom-
position products. The data are then compared with the obser-
vations of sensory panel members.
Oils may someday be designed not only to resist formation
of the negative byproducts, but also to produce desirable fla-
vors. The ultimate goal of this research: to provide consumer
products that last longer on the shelf and withstand frying better
to provide more healthful, better tasting foods.-By Linda
McGraw, ARS.
This research is part ofNew Uses, Quality, and Marketability
of Plant andAnimal Products, an ARS National Program (#306)
described on the World Wide Web at http://www.nps.ars.usda.
gov/programs/cppvs. htm.
Gary R. List, William E. Neff and Kathleen A. Warner are
in the USDA-ARS Food Quality and Safety Research Unit,
National Center for Agricultural Utilization Research, 1815
N. University St., Peoria, IL 61604; phone (309) 681-4011
[List's ext. 6388, Neff's ext. 6392, and Warner's ext. 6584], fax
(309) 681-6679, e-mail
neffwe @ mail. ncaur.

Using a "sniffing" apparatus, chemist William Neff determines the
odor intensity of each component of soybean oil while technician
Wilma Rinsch operates the equipment used to perform the test.

Agricultural Research/June 2000


Insecticides From Sugar?
Sugar esters tested by ARS and uni-
versity entomologists around the coun-
try could find use as environmentally
friendly insecticides. The esters are
lethal-almost immediately-to nearly
all the mites and soft-bodied insects such
as whiteflies, aphids, thrips, and pear
psylla that they contact. Then they
degrade into harmless sugars and fatty
acids. These sugar esters do little harm
to beneficial predatory insects and are
nontoxic to animals and humans. Some
are even approved as food-grade safe.
And because of how the esters work,
insect pests are not expected to develop
resistance to them anytime soon.
This is a control concept that origi-
nated about a decade ago. Now 4 years
of testing have shown the sugar esters to
be as good as-or better than-conven-
tional insecticides against mites and
aphids on apples; psylla on pears; white-
flies, thrips, and mites on vegetables; and
whiteflies on cotton. Like insecticidal
soaps, the esters kill insects by either
dissolving their protective waxy coatings
or suffocating them. ARS and AVA
Chemical Ventures of Portsmouth, New
Hampshire, have applied for a patent.
The company hopes to market the first
of these sugar ester compounds by the
end of 2000, pending U.S. Environ-
mental Protection Agency registration.
Gary J. Puterka, USDA-ARS Appala-
chian Fruit Research Station, Kearneys-
ville, West Virginia; phone (304) 725-
3451, ext. 361, e-mail gputerka@afrs.

Managing Blackberry
Rosette in the Southeast
New strategies for controlling rosette
disease in blackberries could open a new
market for small farmers. Rosette-or
double blossom-one of the most severe
fungal diseases of blackberries grown in
the southeastern United States, is caused
by the fungus Cercosporella rubi. Many
crops fall prey to this disease, which re-
duces yields and the quality of fruit.

Information used by growers to control
rosette originated in the 1930s and has
become outdated with the development
of new cultivars and changes in the dis-
ease itself. Rosette is one of the major
reasons southeastern farmers don't grow
this specialty crop, which can yield
$3,000 to $4,000 an acre.

sr'ciTT RAI n IF 777S-in1

A promising new spray schedule for
controlling blackberry rosette may inspire
more farmers to grow blackberries.
Few fungicides are registered for
controlling the disease, and benomyl is
the most effective one yet tested.
Researchers are evaluating some new
fungicides and are also looking more
closely at the pathogen and its mode of
A modified fungicide spray schedule
has already been found effective. It re-
quires making four applications of the
fungicide at 10- to 14-day intervals,
beginning about 6 weeks before the
berries ripen and continuing until 3 days
before harvest; a fifth application im-
mediately after harvest is also recom-
mended. Barbara J. Smith, USDA-ARS
Small Fruit Research Station, Poplar-
ville, Mississippi; phone (601) 795-8751,

Natural Product Helps
Insects "Bite the Dust"
Remnants of one of the oldest things
on earth-diatomaceous earth (DE)-
may help solve one of today's most
pressing problems: developing noninsec-
ticidal controls for insects in homes and
food-processing facilities. Consisting of
the dust of fossilized skeletons of micro-
scopic aquatic plants, DE is nontoxic to
humans. But it kills red flour beetles and
confused flour beetles-two of the food-
processing industry's worst insect pests.
It works by disrupting the insects' outer
covering, or exoskeleton, causing them
to die from rapid water loss.
Researchers have found that fluctu-
ations in temperature and relative hu-
midity can affect the performance of DE
products, which proved most effective in
controlling adult insects at higher tem-
peratures and lower humidities. In tests,
a 2-day exposure to DE at 80 F and 57-
percent relative humidity killed all red
flour beetles, while it took a 3-day expo-
sure to kill all confused flour beetles. DE
is a possible alternative to methyl bro-
mide, an ozone-depleting fumigant
scheduled for phaseout by 2005. Frank
H. Arthur, USDA-ARS Grain Marketing
and Production Research Center Man-
hattan, Kansas; phone (785) 776-2783,
.TI ,.t.;.. ",,, .

More than 450 research articles on the'
biology, taxonomy, and control of thistles
are mentioned in Thistles: Biology and
Control(ARS-150). This CD-ROM is a full-
text database with a picture section and
glossary. The database will be of use to
anyone concerned with the sludy or control
of thistles.
While supplies last, single copies of the
CD-ROM may be ordered at no cost via
mail or e-mail from Paul E. Boldt, USDA-
ARS, 808 Blackland Rd.,Temple,TX;

Agricultural Research/June 2000

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