Movement of Tribolium castaneum within a flour mill

• Marked red flour beetle found to move among flours within a flour mill.
• If adults moved between flours they tended to move downward.
• Heat treatments increased dispersal, but not movement between floors.
• Avoidance of heat treatments by moving to cooler floors was not detected.
• Red flour beetle populations on different floors can be interconnected.

The colonization of food processing plants by stored-product pests and their distribution within a facility depend, in part, on their dispersal ability. In this case study, we relied on self-mark recapture to evaluate the ability of Tribolium castaneum, the red flour beetle, to move among floors within a flour mill and the effects of a heat treatment on insect activity. Marking stations with pheromone and fluorescent powder were placed on each of five floors in the mill, and two techniques were used to recover marked individuals (trapping and direct collection of individuals from the floor). Considering both recovery techniques, T. castaneum was able to move among floors, but the majority of individuals remained on the same floor where they were marked (86%). Most individuals captured on a different floor were captured on a floor below the one they were marked (70%) and adjacent to it (87%). There was a spike in the number of beetles captured during heat treatment, but not an increase in movement of marked beetles between floors. These results suggest that the rate of heating was sufficient to prevent beetles time to move to cooler floors to escape heat. T. castaneum movement among floors needs to be taken into account when identifying sources of infestation and targeting pest management.