Pheromone Traps: A Detective Tool

Monitoring to ensure tolerances and target levels are being met is a critical component of food industry quality control programs. Pest management is a component of quality control programs and monitoring of pest populations is needed to ensure program effectiveness, but is often not used to its full potential.

If the sanitation/pest management program simply documents the procedures performed, but does not document pest populations, then we are only getting part of the story and limiting our ability to optimally manage pest populations.

Effective pest management programs are an information-intensive process, and professionals in the food and pest management industries need to have multiple high-quality sources of information from which to evaluate and optimize programs. As a scientist, I am biased by training and inclination to want conclusions to be supported by data, but all involved in pest management should want results of a pest management program to be well documented and this information used to determine the selection and targeting of man-agement tactics. While the process is challenging and does have a cost, there is also considerable potential for cost savings through more efficient programs and improved product quality.

Pest management programs for the food industry need to be focused on prevention, including preventing pests from entering facilities; eliminating newly established infestations as soon as possible; and, if pests are present within a facility, maintaining levels where the potential for product infestation is minimized.

Pheromone Traps. Pheromone-baited traps are a powerful tool in a stored-product insect management program, however, it must also be remembered that they are only one component; they need to be integrated with other sources of information; and there are a lot of misconceptions and misuse surrounding the traps.

Correct use of pheromone traps in a pest management program can fall into one of two general strategies—which can have overlap and can and should be integrated. They can be used:

• as a detective tool to find and eliminate problems after they arise.
• as an evalution tool to assess population trends, including early detection, in either focused problem areas or throughout the facility.

The first approach is discussed in this article.

When pheromone traps are used as a detective tool, it is typically in response to some sign of insect activity, such as infested product spillage or insect tracks in dust. The goal of this tactic is to identify the scope and nature of the problem. The tactic generally combines pheromone trapping with visual inspection and other sampling tactics.

To identify the scope and/or source of the problem, traps are placed around the area of activity. The traps are most effective and informative when placed in transects going out from the suspected problem area rather than set at random.

Through this approach, hot spots of insect activity can be identified and re-moved. Hot spots may be due to a localized infestation or because insects have moved into the area from some other source, such as a route of entry from outside. Once identified, intervention (such as sanitation, structural modification or insecticide treatment) should be implemented, and the traps monitored to determine results of the intervention. Once the problem is solved, the focused trapping program is typically removed.

Following are two examples of how we have used this program:

• In a warehouse attached to a food processing facility, we found high warehouse beetle trap captures in one trap location along a wall. No source of infestation was readily identifiable. By placing traps in surrounding areas, we identified the source of insects as being from an adjacent structure, with the insects moving through available openings into the warehouse. Removal of the source in a different room resulted in a drop in activity within the warehouse.
• At another location, insect activity was observed. Traps placed at different locations on that floor indicated almost all captures at one trap location. Subsequent visual inspection then revealed a place on a piece of equipment near the ceiling that was not being regularly cleaned, and in which a flour beetle infestation had developed. Removal of material and inclusion on a regular sanitation program eliminated the problem.

The strategy of using pheromone traps as a detective tool is a dynamic process that is useful for identifying and eliminating established pest problems, but it does not quantify pest activity in a way that can be used to document and evaluate the long-term impacts of management programs. A more stable monitoring program is needed to generate that information. In a subsequent column, I will focus on the second strategy and the benefits and limitations of other applications of pheromone trapping programs.