Survey Results - Bins containing insects

North Dakota

• Wheat (25%)
• Oats (37%)
• Corn (84%)

U.S.

• Wheat (25%
• Oats (56%)
• Corn (80%)

Primary Stored Grain Insects

• Attack sound grain
  • Granary Weevil
  • Lesser Grain Borer
  • Angoumois Grain Moth

Secondary Stored Grain Insects

• Attack broken grain
• Contribute to heating
  • Red Flour Beetle / Confused Flour Beetle
  • Saw-toothed Grain Beetle
  • Indian Meal Moth
  • Rusty Grain Beetle

Damage from Stored Grain Insects

• Consumption
• Contamination
  • Insects
  • Insect fragments
  • Insect feces
  • Microorganisms
    • Aspergillus flavus
    • Bacteria
• Reduced market value
  • Example - Weevily wheat

Optimal Environmental Conditions

Temperature

• 70 - 95 ^oF

Grain Moisture

• 12 - 15%

Conditions That Contribute to Insect Problems

1. Large storage bins
2. Extended storage conditions
3. Long periods with warm ambient air temperatures
4. Harvest in early summer
5. High grain moisture
6. Over-filling
7. Inadequate aeration
8. Lack of monitoring
9. Improper sanitation and/or pesticide use

Suggested Bin Monitoring Techniques

• Grain probes
• Temperature monitors
• Insect traps
• Visual inspection

Stored Grain Insect Prevention Techniques

• Preharvest bin repair and cleaning
• Residual bin sprays
• Grain surface treatment
• Grain protectants

Residual Spray

• Applied to bin after cleaning
• Do not add grain within 24 hours
• Insecticides
  • Methoxychlor
  • Reldan
  • Tempo

Grain Protectants

• Grain is treated while filling the bin
• May be applied as a liquid or dust
• Insecticides
  • Actellic (corn & sorghum)
  • Reldan (cereals, except corn)

Surface Treatments

• Applied after grain is binned
• Insecticides
  • Dipel
  • Insecto

Grain Fumigation

• Vapors or gases kill the insects
• Concentration must be at toxic levels
• Requires several hours of exposure
• Application methods:
• Mixing with the grain
• Gravity penetration
• Forced distribution
  • Mechanical force
  • Air movement
  • Single pass
  • Closed recirculation
• Spot fumigation
• Important points
• Grain temperature must be >60^oF
• Bin must be tightly sealed
• Handle with extreme caution
• Never work alone
• Use proper protective equipment
• Isolate building from animals for >48hours
• Fumigants:
  • Aluminum Phosphide
  • Methyl Bromide

Reasons for Fumigation Failures

• Insufficient fumigant
• Inadequate storage structure
• Excess dockage
• High grain moisture
• High grain temperature

Effect of grain temperature & moisture content on residual activity of CYTHION insecticide

Moisture content (%)	60 oF	90oF
10	24	1-3
13	12	1

References:

North Dakota Agricultural Extension Service, North Dakota State University, Fargo, ND