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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.
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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
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)
Bagged Grain • Torpedo (spear) sampler • Coning and quartering • Boerner divider and other dividers (sample reduction) • Sieving (check efficiency)
Sieve Samplers Inclined sieve
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
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
Bait-Bag Traps Netlon netting (8x16 cm) Aperture 2 mm Brown rice-60 gram
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
Automated counts of insects in grain (OPIsystems.com) Stormax Insector
(a) (b) 51.3 cm (c) (d) OPI Systems, Calgary, Canada
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!