Heat treatments are being used to disinfest flour mills but there is no information on the utility of this technique to disinfest empty grain silos.
Researchers at USDA's Center for Grain & Animal Health Research (CGAHR) conducted field trials by placing live lesser grain borers, red flour beetles, or two psocid species inside containers with wheat and/or flour media and suspending those containers at different heights inside empty silos.
Propane heat was generated from commercial equipment and introduced into the bottom of the silos. When temperatures exceeded 122 F for at least 6 hours, complete mortality of all insects and life stages generally occurred.
The wheat inside the containers did provide some insulating effect from the heat. The lesser grain borer was more heat-tolerant than the red flour beetle, and one of the psocid species was more tolerant than the other. Most of the insect survival occurred in the containers that were in the top or midpoints of the silos.
Results show heat could be used to disinfest empty silos, but cleaning and sanitation prior to heat treatment might be necessary to maximize effectiveness.