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'TATF PLA.' BOARD
February 1950 E-794
United States Department of Agriculture
Agricultural Research Administration
Bureau of Entomology and Plant Quarantine
TESTS WITH ACRYLONITRILE-CARBON TETRACHLORIDE
AND HYDROGEN CYANIDE AS FUMIGANTS FOR
INSECTS IN CIGARETTE TOBACCOS
By C. 0. Bare and Joseph N. Tenhet
Division of Truck Crop and Garden Insect Investigations
Flue-cured and Turkish tobaccos are attacked in storage by two in-
sect pests, the cigarette beetle (Lasioderma serricorne F.) and the
tobacco moth (Ephestia elutella Hbn.). A new commercial fumigant has
been developed which is composed of acrylonitrile and carbon tetrachloride
(50-50 by volume). With material supplied by the manufacturers and in
cooperation with several tobacco companies, tests have been made to
compare this fumigant with hydrogen cyanide.
Laboratory tests.--Replicated laboratory tests were made in 33-cubic-
foot chambers, at atmospheric pressure and 70-82 F., and the exposure
period was 72 hours. The toxicity of acrylonitrile-carbon tetrachloride
to large unprotected larvae of the cigarette beetle and the tobacco moth
was roughly comparable to that of hydrogen cyanide. Against large
larvae of the tobacco moth hydrogen cyanide was the more effective at
very low dosages. At 2 or 3 ounces per 1,000 cubic feet the new fumigant
seemed to be slightly more effective; but 4 ounces of hydrogen cyanide
killed all moth larvae, whereas 6 ounces of acrylonitrile-carbon tetra-
chloride was required for a complete kill (table 1). It will be noted that
31 to 4 ounces per 1,000 cubic feet of the new fumigant killed all unpro-
tected cigarette beetle larvae.
In other replicated laboratory tests at summer temperatures (70-
95 F.) approximately 28 ounces of acrylonitrile-carbon tetrachloride
per 1,000 cubic feet with a 48-hour exposure or 32 ounces with a
24-hour exposure killed all cigarette beetle larvae to a depth of 9
inches in bales of Turkish tobacco (table 2).
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Tests in commercial chambers.--Tests were conducted in 5,000-
cubic-foot atmospheric chambers to determine the effectiveness of this
fumigant under semicommercial conditions. As would be expected, it
was found that the gas did not pt-netrate hogsheads of flue-cured tobacco
so readily as it did the less dense bales of Turkish tobacco. These tests
were made at temperatures of 70o-85 F. A 16-inch oscillating electric
fan was operated in the chamber for 1 to 2 hours at the beginning of
each test to prevent stratification of the gas. A 72-hour exposure gave
better penetration of hogsheads of tobacco than a 48-hour exposure. With
a 72-hour exposure a dosage of 20 ounces per 1,000 cubic feet gave com-
plete kill of cigarette beetle larvae to a depth of 9 inches in bales of
Turkish toba(_co. However, at no dosage or exposure was complete kill
obtained to such depths in hogsheads of flue-cured tobacco. A dosage of
32 ounces per 1,000 cubic feet with a 72-hour exposure gave a mortality
f k.igarctte beetle larvae of 72 percent at 9 inches in hogsheads of
tobacco, as compared with 36 percent at the same dosage of gas but with
a 48-hour exposure.
Tests in v.;, rehouses.--In 1947 and 1948 three large warehouses of
flue-cured tobacco in hogsheads were fumigated with acrylonitrile-carbon
tetrachloride. Two of them had a capacity of 280,000 cubic feet, and one
of 600,000 cubic feet. In all fumigations the exposure period was 72 hours
and the temperature range was 65o-90 F. Electric fans were operated
for the first 4 to 5 hours to prevent stratification of the gas. By means
of an air compressor the gas was introduced into the buildings through
copper tubing permanently installed for fumigation. The acrylonitrile-
SaIrbon tetrachloride mixture was in high pressure cylinders of the type
used for hydrogen cyanide, and was under carbon dioxide pressure.
However, air pressure was required to force the fumigant into the
building. The mortality of test insects used in these experiments is
qhown in table 3.
In the first warehouse the dosage was inadequate, and in this and
in the second warehouse some unknown factor reduced the effectiveness
of the fumigant. Perhaps the sheet-metal buildings were not so tight as
they were thought to be, or possibly the cinder floors were more
absorptive than was anticipated for a gas heavier than air. Nevertheless,
the penetration of the gas in these tests was superior to that obtained
with hydrogen cyanide, in previous tests under similar conditions. In
the third warehouse, a brick building with concrete floors, the penetration
of the gas and the mortality of test insects at depths of 5 to 9 inches,
above 90 percent at a 9-inch depth, were the best ever observed in
warehouse fumigation of flue-cured tobacco in hogsheads.
The effectiveness of fumigation in the third warehouse is further
confirmed by the weekly catches in suction light traps. Little build-up
of insect population was noted 3 months after fumigation with acryloni-
trile-carbon tetrachloride. In contrast, the average catch per trap
from six other comparable warehouses fumigated at about the same
ti;. with 16 ounces of hydrogen cyanide per 1,000 cubic feet showed a
much greater increase in tobacco moth population late in the summer.
Unfortunately for the experiment, the initial cigarette beetle population
in the warehouses fumigated with hydrogen cyanide was not appreciable.
The insect populations of these warehouses are shown in table 4.
Laboratory tests.--Tests were made at reduced pressure to determine
the minimum dosage of acrylonitrile-carbon tetrachloride that would kill
all cigarette beetle larvae in bales of Turkish tobacco. These tests were
conducted in a 33-cubic-foot steel chamber in which the air was exhausted
to a pressure of 28 to 29.6 inches of mercury. The exposure period was
3 hours, and temperatures ranged from 70 to 86 F. By means of the
customary steel test spikes (2), large larvae of the cigarette beetle were
placed in bales of Turkish tobacco (approximately 140 pounds each) at
depths of 1, 3, 5, 7, and 9 inches. Dosages tested were from 8 to 32
ounces per 1,000 cubic feet. All tests were replicated five times.
Table 5 shows that under the conditions of these tests the minimum
dosage which could be depended upon to produce 100 percent mortality
was 20 ounces per 1,000 cubic feet.
Tests in commercial chambers.--A series of tests in commercial
vacuum fumigation chambers of 1,082 cubic feet each was conducted in
the fall of 1946. Bales of Turkish tobacco and hogsheads of flue-cured
tobacco were fumigated in vacuum under commercial conditions. The
chambers were evacuated to a pressure of 28.5 to 29 inches of mercury.
The exposure period was 4 hours and the temperatures were below 70 F.
As shown in table 5, a dosage of 48 ounces of acrylonitrile-carbon tetra-
chloride per 1,000 cubic feet killed all cigarette beetle larvae to a depth
of 9 inches in bales of Turkish tobacco. However, a dosage of 64 ounces
per 1,000 cubic feet was necessary to kill all larvae to the same depth in
hogsheads of flue-cured tobacco.
In another series of tests in the same vacuum chambers in 1947,
acrylonitrile-carbon tetrachloride was approximately equivalent to
hydrogen cyanide in effectiveness. At tobacco temperatures of 42o-57 F.
and air temperatures of 31-64, a dosage of 2- pounds of acrylonitrile-
carbon tetrachloride, with an exposure of 4 hours, killed all cigarette
beetle larvae to a depth of 9 inches in bales of Turkish tobacco. However,
in a third series of tests under similar conditions, except at somewhat
lower tobacco temperatures (29-57), an occasional larva survived
dosages up to 4 pounds of acrylonitrile-carbon tetrachloride per 1,000
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Table 4.--Average numbers of tobacco moths and cigarette beetles
caught per suction light trap in a warehouse fumigated with
acrylonitrile-carbon tetrachloride and in six warehouses
fumigated with hydrogen cyanide. Wilson, N. C., and
Portsmouth, Va., 1948
Tobacco moths Cigarette beetles
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Effect of Acrylonitrile-Carbon Tetrachloride on Tobacco
Repeated tests were made to discover any possible effect of this
fumigant on flue-cured tobacco or on Turkish tobacco. Samples
fumigated and unfumigated tobacco of the same grade were submit'.
to leaf-tobacco experts. No effect upon the aroma, taste, or .ipc!pearnce
of the tobacco was noted. Immediately after fumigation a very faint odor
could sometimes be detected, but it vanished in less than 24 hours. A
chemical analysis was made for residues of acrylonitrile on fumigated
tobacco. The only method known of making such analysis was to pass
heated air over the tobacco and then analyze the air for free nitrogen.
Tobacco contains so much free nitrogen that the figures obtained were
Effect of Acrylonitrile-Carbon
Tetrachloride on Equipment
Acrylonitrile-carbon tetrachloride is corrosive to certain materials.
Iron corrodes quickly; hence it is not satisfactory to use plain iron pipes
or containers. Galvanized iron and tinned iron stand up satisfactorily
for short periods. RUBBER TUBING CANNOT BE USED, AS ACRYLO-
NITRILE QUICKLY POLYMERIZES AND DESTROYS RUBBER. Stainless
steel tubing is most satisfactory for use in vacuum or atmospheric
chambers. Copper tubing has been used, with little or no evidence of
corrosion after 3 years. However, regardless of the fumigant used,
great care should be taken to blow out the piping system thoroughly
afterwards. Apparently it is the liquid fumigant that is corrosive, not
the vapor phase.
A compressor that had been in constant use for over a year in
connection with acrylonitrile-carbon tetrachloride fumigation of tobacco
was dismantled for repairs in the winter of 1948-49. Careful examina-
tion of all parts showed no corrosion of the steel.
Although the acrylonitrile-carbon tetrachloride mixture is not so
volatile as most fumigants and can be shipped in regular galvanized-
iron or tin drums, THE VAPOR EVOLVING FROM THIS MIXTURE IS
POISONOUS AND THE MIXTURE MUST BE HANDLED ACCORDINGLY.
In extensive tests with atmospheric and vacuum fumigation a 50-50
mixture of acrylonitrile-carbon tetrachloride, was found to be a satis-
factory fumigant for cigarette-type tobaccos.
In laboratory tests at atmospheric pressure, it was as effective as
hydrogen cyanide against cigarette beetle larvae, but less effective
against tobacco moth larvae. It showed unusual penetration, yet it aired
UNIVERSITY OF FLORIDA
10 3 1262 09239 0870
out rapidly. No injury to tobacco was noted. In commercial atmriospheric
cl-imbers at summer temperatures a dosage of 20 ounces per 1,000
cubic feet, with an exposure of 72 hours, gave complete kill of cigarette
beetle larvae to a depth of 9 inches in bales of Turkish tobacco. In hogs-
heads of flue-cured tobacco a dosage of 32 ounces with the same exposure
gave 100 percent mortality of cigarette beetle larvae at a depth of 3 inches,
99 percent at 5 inches, 86 percent at 7 inches, and 72 percent at 9 inches.
In large warehouses of flue-cured tobacco in hogsheads a dosage of
approximately 40 ounces per 1,000 cubic feet, with an exposure of 72
hours, gave excellent results against cigarette beetle larvae. In other
warehouses fumigation with hydrogen cyanide at 16 ounces per 1,000
cubic feet was less effective against the tobacco moth.
In small vacuum chambers in the laboratory the minimum dosage of
acrylonitrile-carbon tetrachloride to give complete kill of cigarette
beetle larvae in bales of Turkish tobacco was 20 ounces per 1,000 cubic
feet, with a 3-hour exposure and temperature of 73o-82
In vacuum fumigation in commercial chambers at temperatures above
60o F., a dosage of 48 ounces of acrylonitrile-carbon tetrachloride per
1,000 cubic feet, with an exposure of 4 hours, gave complete kill of
cigarette beetle larvae to a depth of 9 inches in bales of 'Turkish tobacco.
However, at lower temperatures (29o-50) 64 ounces per 1,000 cubic feet
did not give complete mortality in all tests. In hogsheads of flue-cured
tobacco at summer temperatures, 64 ounces per 1,000 cubic feet, with
an exposure of 4 hours, gave complete mortality of cigarette beetle larvae
to a depth of 9 inches.
No effect of acrylonitrile-carbon tetrachloride upon the aroma, taste,
or appearance of flue-cured or Turkish tobacco was noted.
In a study of the effect of acrylonitrile-carbon tetrachloride on
different materials, it was found that stainless steel is most satisfactory
for use in vacuum or atmospheric chambers; copper showed little or no
corrosion after 3 years; galvanized iron and tinned iron stand up for
short periods; but plain iron is not satisfactory. Rubber tubing cannot
(1) Reed, W. D., and Vinzant, J. P.
1942. Control of insects attacking stored tobacco and tobacco
products. U. S. Dept. Agr. Cir. 635, 40 pp., illus.
(2) ____ Livingstone, E. M., and Morrill, A. W., Jr.
1936. Apparatus for placing test lots of insects within parcels
of stored tobacco during fumigation experiments. U. S.
Bur. Ent. and Plant Quar. ET-83, 3 pp., illus. Processed.