Using temperature to control grain insect pest infestations

Using high temperature

If you need to mechanically dry grain, heat produced by a grain dryer can cause mortality to insects. Expose insects to a temperature between +50°C and +55°C for approximately 15 minutes. Grain temperatures above +40°C will kill insects at all life stages.

Caution: After you apply heat treatment, grain must be immediately cooled so that it does not overheat, spoil and cause a new insect infestation. Energy costs for this method of control are high. Therefore, this is recommended only when you need to rapidly dry the grain.

Time and temperature effects in relation to insect growth activity or death

Using low temperature

Producers and grain handlers can use ambient cold air to effectively prevent and control infestations.

Stored product insect pests generally do not feed or reproduce at temperatures below +17°C. Lower temperatures can also be used to cause mortality. 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 are very effective at reducing grain temperatures, as well as reducing moisture migration. Read about using aeration to cool grain temperature.

This table shows how much time is needed to disinfest a grain bin by using low temperatures.

Disinfestation time periods required at low temperatures

Constant grain temperature	Time period required for disinfestation
-5°C	12 weeks
-10°C	8 weeks
-15°C	4 weeks
-20°C	1 week