[Advisory Board] Pheromone Traps, a Monitoring Tool

In an earlier column (September/October 2009), I discussed the importance of pest monitoring programs, the role of pheromone-baited traps in monitoring stored-product insect pests, and two different strategies for using pheromone-based monitoring programs. The first strategy, discussed in detail in the earlier column, focused on pheromone traps as a detective tool to identify stored-product insect sources and hotspots and determine if a problem had been eliminated. The number and distribution of traps is changed in response to pest problems.

The second strategy, to be discussed here, focuses on pheromone trap use to evaluate long-term trends in pest abundance and effectiveness of a pest management program.

Integrated pest management (IPM) programs for the food industry include four components: three of management—pest prevention, avoidance and suppression; and a fourth of monitoring.

• Prevention involves tactics to keep pests out of a facility.
• Avoidance is the second line of defense if prevention is unsuccessful. It focuses on preventing pests that have entered a facility from becoming established and/or an established population from leading to food product infestation.
• Suppression is focused on finding and eliminating pest populations that have become established.
• Monitoring can be used to evaluate the need for and effectiveness of the three management components.

Food manufacturing quality control programs rely on monitoring, including data collection and trend analysis, to ensure control limits are not exceeded. Effectiveness can be readily evaluated with standardized monitoring, but many food facilities find it difficult to quantitatively evaluate their program due to a lack of good information. While most facilities do have some information on the pest situation, the quality of this data may be limited, and what is available may not be used to its full potential. This makes it difficult to quantify how effective an IPM program is overall, to prioritize tactics, perform cost benefit analysis, evaluate impact of alternative tactics, or develop practical management thresholds or control limits based on risk.

To measure the quality of an IPM program, you need a standardized system that generates information that can be accurately compared over time. Pheromone trapping programs have this advantage if used properly, although they do have some limitations and should not be used exclusively. The program needs to balance between trap placement where problems are expected, have occurred or have the greatest risk of infestation, with placement for obtaining good coverage of the whole facility. This coverage, to include external and entry point placement, is important because past trends in insect activity do not always predict future activity, and outside activity can help with the interpretation of patterns of activity inside the facility. Maintaining a consistent trapping program, with traps similar in number and position from year to year, enables ongoing capture patterns to be more accurately compared.

Generated data can then be used to calculate the average trap capture and graph trends over time, look for differences in pest abundance and distribution in different areas, determine seasonal patterns in activity, and look at spatial patterns in distribution to identify problem sources and enable early detection. Through better understanding of the patterns, realistic management goals can be developed and the success of the programs determined. Understanding unique long-term patterns in both internal and external pest activity is important for laying the baseline from which management strategies and goals can be developed and success evaluated.

As an example, my colleagues and I recently conducted a detailed analysis of multiple years of red flour beetle pheromone trap monitoring data. From the data, we were able to evaluate the variation in beetle capture over time and captures in relation to seasonal differences and pest management tactics.

Comparing before and after implementation of an enhanced IPM program showed that the average trap capture of red flour beetles declined by approximately 90 percent, documenting the benefits of the management change. In addition, the data trends showed that the time of year that fumigations were conducted had a major impact on the rate at which beetle captures increased—thus revealing that adjusting the time of year that treatment was applied could improve the benefit-to-cost ratio. We were also able to evaluate the level of change in average beetle captures over time and use this to develop risk thresholds for implementing specific management tactics.

Documentation of pest management program effectiveness is likely to become more important in the future. As such, pheromone trapping programs can provide an important source of information on pest populations, with new and exciting opportunities continuing to increase the effective use of this information for IPM improvement.