EGPIC: An Automated Insect Census-Taker
In their Gainsville laboratory, entomologist Nancy Epsky and electrical
engineer Dennis Shuman test EGPIC probes. Displayed on the computer screen are
the total number of insect counts, time elapsed since the last count, total
time the probe was active, and status of the probe.
Stored grains, fruits, nuts, vegetables, and other foods are a smorgasbord
for rice weevils, sawtoothed grain beetles, and other insects that feast on
stored products. Insect infestations cause millions of dollars in annual stored
product losses and fumigation costs.
But the free lunch for these pests may soon be over. Scientists at
ARS' Center for Medical, Agricultural,
and Veterinary Entomology (CMAVE) in Gainesville, Florida, have developed a
high-tech system that exposes the gluttonous meal robbers.
The new pest detector, developed by electrical engineer Dennis Shuman, is
called the Electronic Grain Probe Insect Counter, or EGPIC.
"Low insect populations are difficult to detect in small samples, so a
much greater proportion of the grain needs to be sampled to accurately estimate
the size of an insect population," he says.
A probe trap is a perforated tube inserted into grain that insects crawl
into and then drop through into a reservoir at the lower end. Presently, probes
are left in grain bins for prolonged periods, until an inspector manually
removes and visually inspects them--a time-consuming and sometimes difficult
"These methods are expensive, so they are not repeated often. This
allows infestations to grow from undetectable to damaging levels in a matter of
weeks," says Shuman.
EGPIC is an enhancement of current grain probe trap technology. It uses an
infrared beam sensor to quickly, accurately, and economically record and
time-stamp insects as they drop through the probe.
Shuman says the probes can be located throughout a grain bin or elevator.
Their sensors can transmit insect counts back to a central computer via SMARTS,
a data transmission network Shuman designed and patented for large-scale
While current methods give only a snapshot of what's going on, EGPIC
provides a continuous moving picture of what's happening inside a storage
bin--and an accurate picture, having a 95 percent counting accuracy rate in lab
Best of All, It's Flexible
A live lesser mealworm adult drops through a cutaway-but operational-EGPIC
probe. The insect snapped its own picture in mid-fall when it intersected an
infrared beam, triggering an electronic flash.
Shuman's version has an adaptable design and can be customized, depending on
the type of stored product and storage environment. Environmental factors such
as temperature, humidity, noise and vibration, dust, and chemical pesticides
won't throw off its results.
Current traps require routine maintenance and have a finite life, since they
fill up with insects and have to be emptied or removed. To reduce this
maintenance, Shuman is working on a version that has a long, open-ended tube
below the sensor so insects can be counted and released lower in the
bin--virtually eliminating the need for trap servicing.
Monitoring stored-product insects is important mainly for two reasons:
Insect infestations can cause high damage and losses if left unchecked, and
they require costly chemical fumigation.
EGPIC allows companies to avoid or reduce insecticides. "General
practice has been to make scheduled pesticide treatments--independent of
knowing how big the problem is," says Shuman.
By accurately estimating the distribution of an insect population, companies
may not have to treat the entire bin. The new system allows them to target
treatments by knowing what is going on at any given moment.
This is a big advantage, considering the proposed worldwide ban on methyl
bromide, a widely used, highly effective fumigant used for stored product
insect control. The United States, in accordance with the U.S. Environmental
Protection Agency's Clean Air Act, plans a phaseout of methyl bromide by the
Currently, there is no single replacement for it. Companies will ultimately
have to use a combination of treatments, which could increase the cost of
fumigating. Pinpointing infestations and knowing their severity will allow
companies to better plan their fumigation strategies.
More EGPIC benefits:
- It requires minimal maintenance at sensing sites to permit monitoring at
- It's capable of sensing all different stored product insect pest species
at low densities.
- It's compatible with other grain management systems.
- It can be used without extensive training.
Shuman says EGPIC is ready for commercialization.
Eight copies of the prototype EGPIC system are being evaluated in lab and
field tests with different products, climates, and locations.
"We want to see if different conditions affect the system and, if
necessary, adapt the system to meet those conditions," says Shuman.
"Research with this new tool may also reveal new approaches to monitoring
pest population dynamics."
Entomologists Nancy D. Epsky and Richard T. Arbogast are each testing one of
the copies. "The biggest problem with traps is relating trap catch to the
population density," says Epsky, who works at CMAVE.
Epsky is evaluating the system's performance for detecting a broad range of
insects. "I'm going to look at insect
density and species and how they will affect the system. We're trying to take
all possible situations and determine if they have an impact on count
accuracy," she says.
For instance, Epsky thinks insect behavior may affect the trap count. She
says certain insects are more "grabby" and thus more likely to fall
down in pairs and to be counted as one insect.
Also, insect shape and size play a role and affect the size of a sensor's
output signal. "By analyzing this information and compiling guidelines,
the EGPIC system can be configured to discriminate between different insect
species based on their size," Epsky says. "We're hoping to fine-tune
the system, so we can more precisely determine what species is infesting the
Trap catch is also related to temperature and other characteristics of the
insect's environment, such as grain moisture content and the amount of open
space between grain kernels, says Arbogast, who is also based at CMAVE.
"These relationships must be defined, to maximize the value of EGPIC
for monitoring insect infestations in actual storage situations," he says.
Recognizing this, Shuman has incorporated automated temperature and humidity
monitoring into the overall system design.
Among other sites testing the prototypes are
Agricultural Research Service labs in
Manhattan, Kansas, and Fresno, California, along with researchers at Oklahoma
State University in Stillwater and at Montana State University in Bozeman.
A modified version of EGPIC called BICAP (Beneficial Insect Counting and
Packaging Device, patented) uses an EGPIC sensor head and cups on a
computer-controlled turntable to count and package mass-reared beneficial
insects more efficiently than by hand. Walt Disney World's EPCOT Center at
Orlando, Florida, has been using the system to count and package Opius
dissitus, a parasitic wasp reared in their laboratory as a biological
control for leafminer pests in gardens throughout Disney World.
"EGPIC is one step towards high-tech monitoring. Our focus continues to
be on innovative sensing methods for detecting insect infestations in and
around stored products," says Shuman.--By
Tara Weaver, Agricultural
Research Service Information Staff.
Nancy D. Epsky, and
Richard T. Arbogast are
with the USDA-ARS Center for Medical,
Agricultural, and Veterinary Entomology, 1700 SW 23rd Dr., Gainesville, FL
32604; fax (352) 374-5781.
[Shuman] phone (352) 374-5737.
[Epsky] phone (352) 374-5761.
[Arbogast] phone (352) 374-5719.
"EGPIC: An Automated Insect Census-Taker" was published in
the September 1998 issue of Agricultural Research magazine. Click here to see this
issue's table of contents.