Detection and Monitoring of
Stored-Grain Insects
Bh. Subramanyam, Carl Reed, and Phil
Sloderbeck*
Department of Grain Science and Industry
*Department of Entomology
Kansas State University
Manhattan, KS 66506
sbhadrir@ksu.edu
2006 Grain Handlers Workshop
Detection
Looking for presence or absence of an
insect or an infestation (with respect to
your sampling device)
The type of device used and the number
of samples taken determine how good
you are in finding an insect or an
infestation
Monitoring
Tracking trends in insect numbers or
infestation levels over time
Helps you know when to take action
Helps you understand how populations
are behaving with respect to
environmental conditions
Helps you assess effectiveness of pest
management actions
Detection and Monitoring Require
Sampling
Counting all insects in a bin is difficult
Their distribution is unknown
It may take forever to count all insects
present
Time and money are limited
Sampling will help in making inferences
about the insects inhabiting a bin or silo
Infestation in Railcars
Wheat
21, 3 kg wheat samples/railcar were taken from 8
railcars (Perez-Mendoza et al., 2004)
They also had a lot of IDK
1024 insects were found in 7 of 8 railcars
3% of insects were found immediately after sample
collection
77.1% were found 7 weeks after sample incubation
Relevance to detection??
Relevance to fumigant efficacy??
In Concrete Elevators
 High insect density is within the top 3-4 ft and all of
the insects can be found within 40 ft from the top
 Discharge from spouts onto reclaim belt had more
insects than grain samples taken with a vacuum probe
 Fewer insects were found in treated empty bins and
the treatment effectiveness lasted 12 weeks
 Relevance: Understand where to sample!
Grain Sampling Methods: Absolute
Estimates
 Diverter-type
sampler
 Pelican
 Ellis cup
 Grain trier
 Vacuum probe
 Scoop
Diverter
Pelican Sampler
Ellis Cup
Grain Bulk
• Probe sampler
• Spear or trier
Vacuum probe for
bulk-stored grain
Insectomat
 Capable of processing
large samples
 Pass grain sample twice
for extraction of all
insects present (need to
check efficiency in
separating insects from
grain)
 Torpedo (spear) sampler
 Coning and quartering
 Boerner divider and other
dividers (sample reduction)
 Sieving (check efficiency)
Bagged Grain
Torpedo Samplers
Sieve Samplers
Inclined
sieve
Dividers
Absolute Estimates Are…
 More reliable estimates
 Pest management decision should be based on
absolute estimates
 Threshold for management: 1 insect/kg
 Time consuming, laborious, and expensive
Insect Sampling Devices: Relative
Estimates
Number of insects found in a trap
constitutes a relative estimate
There are many trap types
Sticky traps for
flying insects
For almond moths and
Indianmeal moths
Pherocon II traps
Pheromone lure
Traps for Crawling Insects
Provides a hiding place
Includes various designs
Can be used with pheromone lures or food
baits to enhance capture of species
Can capture multiple species
Corrugated Harborage Traps
Corrugated
Paper Traps
Bait-Bag Traps
Netlon netting (8x16 cm)
Aperture 2 mm
Brown rice-60 gram
Food-baited Traps
Traps for Use in Bulk-Stored Grain
Perforated metal or plastic probes or cones
inserted into grain bulks
Insects crawl through the holes and fall into a
collection tube or cone
Pitfall Cone Trap
 95 mm x 125 mm
cone-shaped
with holes
 Very sensitive
 For surface area
of the grain bulk
Probe traps
370 mm x 27 mm
Funnel and collecting tube
Can be inserted into the
grain bulk
Trap Retrieval is Critical!
Automated counts of insects in grain
(OPIsystems.com)
Stormax Insector
150
(a)
Flat grain beetle (n=2105)
Rusty grain beetle (n=1284)
Sawtoothed grain beetle (n=1620)
Lesser grain beetle (n=1387)
Numbers of Insects
100
51.3 cm
(b)
Red flour beetle (n=2432)
Rice weevil (n=1834)
50
(c)
(d)
0
0
10
20
30
40
50
60
70
80
90
100
Composite Adjusted Target Peak Amplitude
OPI Systems, Calgary, Canada
110
120
Relative Estimates Are…..
 Faster, cheaper, and easier than absolute methods
 Traps work 24 hours a day, 7 days a week
 Interpretation of numbers is difficult (biological and
environmental variable affect insect captures)
 Can be used to pin point problem areas
 Can be used to evaluate effectiveness of pest
management measures
Take Home Points
 Be a truck, railcar, bin, or elevator silo
 Take more samples than fewer samples
 More than 10 and less than 30
 Information from sampling can be used in 2 computer
programs (SGA and SGA Pro) to make pest
management decisions
 Without proper detection and monitoring of insects
you will treating more number of times than needed
or fail to treat when you really need to!