Physical control of grain insect pests
Methods of controlling insect pests that don’t use insecticides include
High temperature
In the past, grain dryers have been used to help with disinfestation. Variables including temperature, time, and type of dryer are difficult to manage and may affect end-use quality of grain. As a result, insect control using high temperature may produce variable results. Only use a grain dryer if you need to dry grain fast.
After you apply heat treatment using a grain dryer, immediately cool grain so that it does not overheat, spoil and cause a new insect infestation.
Low temperature
Producers and grain handlers can use ambient cold air to prevent and control infestations.
Stored product insect pests don’t generally feed or reproduce at temperatures below 18°C. Lower temperatures can kill insect pests. For example, grain kept at -5°C for 12 weeks will control stored insect pests at all life stages.
You can lower the temperature of stored grain by:
- mixing and transferring infested grain from one bin or pile to another
- transferring part of the crop to a truck or small pile to expose it to low air temperature and leaving it to cool before returning it to the bin
- aerating the bin
Aeration systems cool grain and reduce moisture migration.
| Constant grain temperature (°C) | Time period required for disinfestation (weeks) |
|---|---|
| -5 | 12 |
| -10 | 8 |
| -15 | 4 |
| -20 | 1 |
Time and temperature effects in relation to insect growth activity or death, text version
- Death to insects occurs in minutes
- Between approximately plus 50 and plus 60 degrees Celsius or approximately 122 and 140 degrees Fahrenheit.
- Death to insects occurs in a day
- Between approximately plus 38 and plus 50 degrees Celsius or approximately 104 and 122 degrees Fahrenheit.
- Slower growth period for insects
- Between approximately plus 35 and plus 38 degrees Celsius or approximately 95 and 104 degrees Fahrenheit.
- Maximum growth period for insects
- Between approximately plus 25 and plus 35 degrees Celsius or approximately 77 and 95 degrees Fahrenheit.
- Slower growth period for insects
- Between approximately plus 13 and plus 25 degrees Celsius or approximately 55 and 77 degrees Fahrenheit.
- Death to insects occurs in week or months
- Between approximately minus 5 and plus 13 degrees Celsius or approximately 23 and 55 degrees Fahrenheit.
- Death to insects occurs in days, or months if acclimated
- Between approximately minus 15 and minus 5 degrees Celsius or approximately minus 5 and plus 23 degrees Fahrenheit.
- Death to insects occurs in minutes
- Between approximately minus 25 and minus 15 degrees Celsius or approximately minus 13 and minus 5 degrees Fahrenheit.
Pneumatic conveyer
Cyclone-based grain pneumatic conveyers (also called pneumatic grain auguers or grain vacs) can control insect infestations. The percussion effect (grain kernels colliding) created by the cyclone kills insects. The style of pneumatic conveyer and the class and physical condition of grain may affect this method. High grain volumes can reduce the effectiveness of this method.
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