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Control insects in the bin

For decades, farmers have
aerated their grain bins to maintain the quality of stored grain by keeping it
cool while at the same time managing pesky insects.

Few studies performed
recently, however, have looked at whether the direction of airflow is better
from above or below as a way of using temperatures 60˚F. or lower to control
insects in the bin.

To determine this, USDA
entomologist Frank Arthur and agricultural engineer Mark Casada experimented
with bins cooled with one of two types of aeration: suction and pressure.

Suction Vs. Pressure

The difference between the
two systems is how the air is pushed or pulled through the bin. Suction
aeration reverses fans to pull air from the top downward. Pressure aeration
uses fans to push ambient air from the bottom of the bin upward.

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Conducting two
eight-month-long trials, the researchers, who work at the ARS Center for Grain
and Animal Health Research in Manhattan, Kansas, used six metal bins with
perforated floors and storage capacities of 1,250 bushels of wheat. Stored
insects examined included the rice weevil, the lesser grain borer, as well as
the five pictured above (from left to right): the red flour beetle, the rusty
grain beetle, the hairy fungus beetle, the saw-toothed grain beetle, and the
foreign grain beetle.

The study revealed that
during the summer, suction aeration cooled the upper portion of wheat, also
referred to as the surface zone, more quickly than pressure aeration.

That difference also correlated
to fewer insect pests. For example, in suction aeration-treated bins, 662 rusty
grain beetles and 772 red flour beetles were found in surface-zone traps
compared to 3,290 and 8,210 beetles, respectively, in pressure aeration-cooled
bins.

According to Arthur, because
the surface zone is where insects initially infest grain after flying in from
outside, suction aeration’s rapid cooling of the grain’s surface zone is
definitely advantageous.

Both researchers say
larger-scale studies are needed and note that one potential benefit of suction
aeration could be reduced use of phosphine to control insects.
Phosphine-producing materials have become the predominant fumigants used for
treatment of bulk-stored grain throughout the world.  

Learn More

ARS Information Staff

301/504-1638 |
www.ars.usda.gov/is

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