History of Research at the
U.S. Department of Agriculture and Agricultural Research Service
A biological control agent, nuclear polyhedrosis virus, killed the beet
armyworm at top.
past 100 years, scientific approaches to insect pest control have run a gamut
from the naively simple to the technologically complex. But the underlying spur
to these diverse research efforts has been a single immutable fact: The
successful production and storage of the world's agricultural cropsand
the effective protection of humans and livestock against insect-carried
diseasesdepend upon the sustained control of hundreds of varied and
adaptable insect pests.
So, even after a dynamic century of discovery
and innovation, the earnest quest for safe, economical insect control methods
still continues. Much has been accomplished...and yet, so much more remains to
be done...if agriculturists are to have the means available to defend against
the predations of these widespread and destructive pests.
The storm clouds of World War II had broken
wide open over Europe, and the U.S. Army needed help with a big problem that
came in a tiny package.
It is a sad fact of life that where there are
people crowded into unsanitary conditions, there are likely to be body
lice...and in the wake of those lice often comes typhus. Thus it was for the
refugees of war in the Europe of the early 1940's.
Fortunately for the suffering Europeans, U.S.
Department of Agriculture scientists had begun some special research in 1942 at
Orlando, Florida, at the request of the U.S. Army, which was worried about the
welfare of its troops as well as civilians.
Twenty-five men at Orlando bravely allowed
themselves to be infested by some of the research station's colony of 75,000
lice in tests seeking an effective control against the vermin.
Those volunteers did not squirm in vain.
Within 4 months, Formula MYL was developed, and soon millions of 2-ounce cans
of the powder were on their way to American and Allied troops.
The human guinea pigs at Orlando weren't the
only ones contributing to the effort. Edward F. Knipling, retired director of
the Entomology Division of USDA's Agricultural Research Service, recalls how
chemical companies sent in hundreds of samples of their wares to be checked for
possible use against not only lice, but also mosquitoes, ticks, fleas, and
View other related
Egg-Citing Insecticidal Protein in Corn
Pill" Dooms Pesky Caterpillars
So it was that
a packet of DDT arrived at the Orlando lab in early 1943 from the Geigy Co. in
We put it in a test for body lice, and
its lasting properties were at least twice those of the powder we'd
developed, Knipling says. It appeared to be quite safe, and in a
matter of months we recommended its use by the military. Millions of men,
women, and children were soon dusted for lice in the war theaters.
Then we tested it for every other
insect we were working onhouse flies, mosquitoes, bedbugs. It gave
fantastic results on practically everything.
The phenomenal results with DDT
stimulated industry in the United States, Great Britain, and probably other
places to look for related types of chemicals, says Knipling. By
the late 1940's, there were several other encouraging insecticides available:
benzene hexachloride, chlordane, toxaphene, aldrin, dieldrin, to name a few of
the chlorinated hydrocarbons.
The modern age of agricultural chemicals had
begun...to the detriment of many years of research on other alternatives.
For even before the 1940's, humans had not
been entirely helpless against insects. By the time the term biological
control was coined in 1919, scientists had already been pursuing the
practice for several years.
Researchers still argue about how biological
control should be defined, but one simple explanation is that it is the use of
parasites, predators, and pathogens to combat unwanted invaders in
cropswhether those invaders are insects, weeds, or even plant diseases.
An early hero of biological control was C.V.
Riley, head of USDA's Division of Entomology upon its establishment in 1881.
Prior to his USDA postwhile still Missouri's state
entomologistRiley made the very first international shipment of an insect
natural enemy when he sent specimens of a predaceous mite to France to control
grape phylloxera there.
A one-sixteenth-inch long silverleaf whitefly, Bemisia argentifolii.
Riley was the
guiding force behind one of the United States' earliest and most notable
successes in biological control: importation in 1888-89 of the Vedalia beetle,
Rodolia cardinalis, from Australia into California to battle the
cottony-cushion scale, a pest threatening California's then-fledgling citrus
The road to biological control looked wide
and smooth in those early years. USDA explorations in Europe and Japan
beginning in l905 turned up natural enemies of the gypsy moth and brown-tail
From 1905 to 1918, USDA's Bureau of
Entomology imported parasites and predators of the elm leaf beetle, alfalfa and
clover leaf weevils, and sugarcane borer. In 1919, the department established a
laboratory at Auch, France, to simplify the search for natural weapons; a
second laboratory was established in Japan in 1922.
Biocontrol scored big again when a USDA
scientist, Samson R. Dutky, developed a way to produce spores of Bacillus
popilliae, bacterial milky spore disease, to provide effective suppression
of the Japanese beetlethe first commercial microbial pesticide.
But gradually, interest waned. Research
papers published on biological control equaled in number papers on insecticide
research in 1915; by 1925, papers on insecticides outnumbered those on
biocontrol three to one.
The events of World War II chilled biocontrol
progress even further, according to Clarence H. Hoffman, who worked with
Knipling and later served as director of ARS' Entomology Division.
There was always recognition of
biological control, but I think it wasn't widely pursued as much as
insecticides because when pesticides came along, they were so potent and so
cheap, says Hoffman, now retired.
When DDT came in, everything exploded.
Found to be effective against over 500 pests, it was recognized as a real
Maize weevil, Sitophilus zeamaise.
DDT set off a whole series of investigations to get related compounds.
The chemists had a field day.
Chemical companies began putting a lot
of emphasis on developing insecticides for agriculture and other
purposes, adds Knipling.
They came up with a class of
insecticides called organophosphate compoundsmalathion was one, and
methyl parathion, and several othersthat, from the standpoint of insect
control, were even more effective than the chlorinated hydrocarbons that had
looked so good.
In the post-World War II years and into the
era of the Korean War, ARS continued cooperating with the chemical industry in
evaluating pesticides, Knipling recalls.
Most of the companies by then had their
own screening programs and didn't just send us everything on their
shelves, he says. They'd only send us the promising ones to
evaluate. But we did not do a whole lot of trying to develop new chemicals;
industry did that.
Besides, Knipling adds, there was already
trouble on the horizon.
By the early 1950's, it was becoming
quite clear that, useful as these insecticides were, there were a lot of
problems with their extended use, he notes.
Wildlife biologists were becoming
concerned with effects on wildlife. Chemicals were upsetting nature's balance,
killing the natural biocontrol agents along with the pests.
People were finding residues in meat
and milk by the early l950's, and while we were controlling some types of
insects, the overall insect problem continued to be about the same, year after
year. So there were good indications that insecticides alone wouldn't be the
Aedes (Ochlerotatus) sp. mosquito on human skin.
Coulson, now an entomologist in ARS' Insect Biocontrol Laboratory at
Beltsville, Maryland, was still a college student in 1949-50, when he landed an
unusual summer job: feeding DDT to quail and pheasants in experiments at the
U.S. Fish and Wildlife Service's Patuxent Wildlife Research Center at Laurel,
Even then, scientists were concerned
about its getting into the food of game birds and were studying the effects of
that, Coulson recalls. Scientists were also aware of what was
happening with development of pesticide resistance among insects.
And even earlier, in 1947, Clarence Hoffman
had worked on a research team in Pennsylvania testing the widespread effects of
aerial applications of DDT against forest insects.
We were looking at how much you could
use and be safe, using from 1 to 5 pounds per acre. Hoffman says. I
tell you, those 5 pounds per acre were really destructive. We entomologists
were the first to find that birds were very vulnerable to DDT.
Among those in the scientific community who
saw the handwriting on the wall was ARS' Knipling. He recalls that he began
making shifts in ARS' entomology research program to do more on biocontrol,
host plant resistance, changes in cultural practices, and pest attractants.
In 5 years, we'd shifted from 80
percent of our effort being on insecticides to probably not more than 50
percent, he says. We were recommending to USDA and others that
there should be more effort on biological control and other alternative
methods, but our appropriations were not increased.
Richard S. Soper, now the ARS national
program leader for biocontrol, recalls Knipling's spreading the word in the
I can remember when I was a graduate
student at Cornell and he came by and spoke to us, says Soper. Dr.
Knipling changed policy, going from the treadmill-like screening of
insecticides and pesticides to looking at a different approach.
False "eyes"-twin white, football-shaped markings behind the
head-show this to be an Asian multicolored lady beetle, Harmonia
Knipling's campaign got a healthy boost from the publication of the book
Silent Spring, written by Rachel Carson, that sounded a widespread
warning about the environmental drawbacks of chemical use.
'Silent Spring' got me involved in
biocontrol, notes Soper. I was writing a graduate thesis on
woodboring beetles, and the best control I found was a fungal pathogen. When
'Silent Spring' came out, everyone was concerned.
Her book probably did more than
anything else to gain public attention and convince the budget people that
these pesticides had caused problems and we needed to look more at biological
controls, adds Knipling.
But if those who held the purse strings
needed convincing, many scientists did not. Ed Knipling was already well
on his way to developing nonchemical control methods when 'Silent Spring' came
out, Hoffman says.
USDA research on biological control and other
alternatives to chemical insecticides boomed in the 1960's. New labs sprang up
in Columbia, Missouri; Gainesville, Florida; and Fargo, North Dakota. Plant
breeders concentrated more effort on developing plants with the natural ability
to resist or tolerate pest attacks.
It was almost a complete shift80
percent of our effort was on alternatives to chemicals to control
insects, says Knipling.
The successes were impressive, and led to
significant savings for farmers. In 1986, it was calculated that biocontrols
against the alfalfa weevil netted savings of about $48 million annually; a
later report put the benefit even higher, at $88 million in 1987 dollars. And
the price tag for the research was a mere $1 millionfor a ratio of return
on investment of about 50 to 1. Savings from biocontrol of another pest, the
pea aphid, were calculated in 1984 at about $36 million annuallyon
In a book he is currently editing on the
first century of USDA's biological control research, Coulson writes that since
1953, USDA's classical biocontrol program has saved growers several hundreds of
millions of dollars annually, largely as a result of reduced cost of pesticide
applications. This would put total grower savings from biocontrol during the
past two decades at about $2 billion or more.
surprising that, today, thoughts often tend to turn to biological controls as
weapons against the relentless invasion of pests. But biological controls, for
all their virtues, are no panacea, warns Coulson.
We get a new major pest in this country
about every 3 years, he says. Biocontrol alone will have a hard
time keeping up.
In fact, one of the chief criticisms of
biological control is that it moves too slowlyand does too little. Even
its strongest supporters acknowledge that natural biological agents will not
adequately control every insect and that they take time to work.
Our goal isn't 100-percent control or
at least, it shouldn't be, notes Soper. The goal is to produce a
crop economically. You only have to bring the pest population levels below the
economic thresholdthat point at which the farmer starts to lose money
because of the pest.
Farmers in the future should go one step
further, says Knipling, to a concept he calls total population
management. This entails widespread, coordinated attacks on populations
of the major pests at the precise time when such attacks will damage them most.
But even that won't allow a total farewell to
chemicals, Knipling warns.
We'll always need insecticides,
he says. In the United States alone, there are probably 1,000 different
insects a year that cause a little bit of damage somewhere.
But probably 100 of those insects cause
damage year after year across a much wider area. It's those we should plan to
control in an ecologically sound manner before they become an even bigger
problem.By Sandy Miller Hays, ARS.
"20th Century Insect
Control" was published in the July 1992 issue
of Agricultural Research magazine.
Send comments or questions about this historical timeline to