Rodent Issues: Professional Analyses

By Lisa Lupo

Rats and mice have always been a grave concern in food processing facilities. They enter through structural gaps and openings; make their homes in and around food storage; and contaminate foods, packaging and food-contact surfaces with urine, droppings, and hairs. What do pest management professionals see as most problematic about these pests? What do they do and recommend for control? And how do they expect technology to impact service?

In 2016, PCT — the sister magazine of QA, conducted a survey of pest management providers on rodent activity and services, sponsored by Bell Laboratories. In this feature, we relay the key statistics (See Rodents Remain Problematic), with analysis of the responses and food-facility impacts from food processing pest control experts including McCloud Services Technical Director Patricia Hottel; Rentokil Director North America Commercial Pest Marketing Jeff Robbins; Industrial Fumigant Co. Staff Entomologist and Product Manager Jerry Heath; and Rollins Director, Quality Assurance and Claims Kim Kelley-Tunis.

1. Of survey respondents, 66% said that fall and winter were their busiest seasons for rodent control service. What does this mean for food manufacturers, especially this time of year? What should they be doing for prevention?

Kelley-Tunis: As the temperature drops, rodent activity increases, as rodents, just like humans, are looking to move into warmer areas with a stable food source during the cold winter months — and food manufacturing facilities provide just that. Prevention begins with a comprehensive and systematic pest management plan, detailing the methods the facility will use to prevent rodents from entering. This would include measures to identify and seal rodent entry points, as well as sanitation to prevent rodent access to food or water resources.

Hottel: Reviewing past service records can be valuable in determining and predicting the seasonal impact of rodents. For facilities that border agriculture fields, there can be an increase in rodent activity, especially mice, tied to harvest activities. More grain movement also can equate to greater spills and availability of food for rodents around processing and storage facilities. Thus, additional equipment may be required for monitoring and control, with increased monitoring and inspection for signs of rodents, followed by reaction to any indicated activity.

McCloud Services

Bell Laboratories

Heath: The single greatest preventive action one can take is exclusion — attending to openings, door thresholds, rail-shed track openings, etc. Sanitation and harborage elimination also are important, especially in the near outdoor areas. For example, leaves and litter blow around in the autumn, packing into piles in corners, etc., providing excellent harborage for rodents.

2. The most common rodent pest was said to be the house mouse, with Norway/roof rats second and third. How are these rodents best controlled?

Robbins: Because most rodents are attracted to food processing facilities for the same basic necessities: food, water, and shelter, reducing food sources can help reduce attractants. That means sealing garbage cans and ensuring contents are emptied regularly and diligently, quickly picking up any loose raw materials that may inadvertently be dropped, and cleaning any waste materials from all surfaces and flooring. Vegetation management is often overlooked, but reducing overgrowth and weeds can reduce potential harborage, and cutting back trees or branches that touch the building can eliminate the potential of a “super-highway” by which rodents can find entry into the roof and ceiling areas.

Kelley-Tunis: The best method for controlling both rats and mice is through exclusion, though that is often difficult to accomplish. Therefore, manufacturing facilities must rely on additional methods to help prevent rodents from entering and infesting their facility, such as maintaining a strict sanitation program that prevents rodent access to food, water, and shelter. This not only includes cleaning practices normally associated with a sanitation program, but also having a process to identify and correct potential problem areas in the facility that could promote a rodent infestation. Facility employees also should be educated on what they can do to help prevent an infestation.

3. How do control and prevention differ for mice and rats?

Hottel: Mice and rats are more similar than dissimilar when it comes to prevention, but control efforts will be different with a somewhat wider range of trapping tools available for mice. Behaviorally, there are differences in approaches to the three species. Controlling an elusive rat once it gets inside a facility can be one of the most challenging situations a pest management professional can encounter — and it is just one more reason for good prevention programs to keep rodents out.

Robbins: Mice are extremely curious, whereas rats are very cautious. Rats will avoid unfamiliar or new things in their normal paths. So, a cunning strategy is needed to allow a rat to become familiar with traps. Rats are also attracted to water as they need it daily, whereas mice can extract water from food. Therefore, water becomes an important consideration for rat control and prevention. Mice tend to build nests in hidden areas near food sources, so it is critical that food processors manage food storage areas to ensure entry is restricted. Thus, cutting off food supplies and utilizing well-placed traps are some of the best ways to eliminate mice.

4. The vast majority of PMPs said that, in their markets, the number of rodent infestations have stayed the same or increased. With all the control efforts going on, why do you think fewer than 5.2% have seen any decrease?

Hottel: Rats are a community problem. If cities lack the funding to support good community-based control programs, you will see more rodents tied to these areas. Although the rats which have migrated onto the processors’ property may be controlled, there is another set of rats ready to move in. Funding for some of these community programs has been decreased in recent years, and we have seen increases in rat activity in these areas as a result. Food-storage practices have changed over the years, such as the holding of product rejects in trailers for use in animal feed also can impact rodent, insect, and bird activity around a facility. Not only can these feed trailers be an area for rodents to get food, but we have seen cases where rodents were transported from the animal feed handler to the food processor. Storing product for animal feed minimizes waste going to landfills, but it can increase the time that food waste remains on a food processor’s site. Additionally, because that trailer is dealing with waste, it may not receive the level of scrutiny needed in checking for pest activity.

Robbins: A number of factors have contributed to increased rodent populations. From the milder winters we’ve experienced that lead to longer reproductive cycles, to unusually long growing seasons with more natural food resources, rodent populations will thrive when supplies of food are plentiful and the environment is ideal.

Another factor is the general decline of natural predators, due to urban population sprawl. And because increased urban building can trigger rodent populations to spread, we’ve been seeing rodent populations increase in areas where they weren’t before. The roof rat, in particular, was previously a predominantly coastline problem. But industry research has shown that this rodent is now moving into new areas, gaining a foothold along transportation lines in the middle of the U.S. as well. Processors who have never had issues with roof rats may find themselves encountering these rodents for the first time.

Kelley-Tunis: Even though control efforts around facilities may have increased, the overall populations of rodents in the environment have not decreased. Our efforts only target those rodents that are trying to gain entry into our facilities, they don’t target the millions of other rodents that live everywhere else.

5. What do you find to be the best types of equipment or products, or combination of these, for rodent control — particularly in/around food processing facilities? Why?

Kelley-Tunis: Bait stations and traps, both single and multi-catch traps, remain the preferred method of control for rodents in and around a facility. These devices were designed to utilize the animal’s instinctive behavior against it.

Heath: In addition to baiting and trapping as the standards for rodent management service, facility staff efforts to maintain sanitation, eliminate harborage, and maintain the building for exclusion are important. This is an example of the partnership always necessary between service providers and food facilities. Fumigation for rodents is not very common, but it is sometimes necessary for quick resolution of a problem.

Robbins: There’s no roadmap to the “best rodent control” strategy because every facility is unique. The types of products being manufactured, geographic location, neighboring properties, climate — all can impact how and why rodents become a problem at a facility. The urgency with which issues need to be addressed also comes into consideration in choosing a control strategy. So, working with a pest control provider who understands the facility’s unique needs will result in the best program.

6. Do you rotate rodenticide products? Why/Why not?

Hottel: Flexibility is important, but different types and formulations of rodenticides should be tied to activity levels and purpose, rather than to a set calendar rotation system. There is a tradeoff between palatability and weatherability in baits. Some are formulated with increased weatherability but those same ingredients, such as wax content, can impact acceptance. This is a consideration and part of the selection process. If we are primarily in a monitoring mode, wax content may not be as critical a factor. Weather, such as spring or summer, is another consideration when bait melt or molding is more of a concern. Another consideration is activity; for example, if we want to determine if rodents are coming in from the exterior, baits or monitoring blocks with detection dyes would be selected.

Heath: Rotation of rodenticide products is not practiced quite as much as it should be. Products don’t need to be rotated as much for resistance management purposes as some would think, but rotating occasionally for a fresh taste, better palatability, etc., could help in many situations. Using soft baits in fall and winter and blocks in spring and summer when ant depredation is an issue makes lots of sense.

7. More than 75% of respondents see technology as able to help improve their ability to offer rodent control services. In what ways do you see it as helpful — or not?

Hottel: Technology and the way in which it helps us track and trend levels of activity is extremely helpful. It increases our ability to perform remote quality checks and direct technical support where needed. We look forward to remote monitoring devices and the role they will play in reducing the need for weekly inspections of traps and the ability to further customize programs to fit our clients’ needs.

Robbins: With the advent of the Internet of Things (IoT), technology certainly has a place in advanced rodent control strategies. Technology can be leveraged to help alert a facility to trouble, allowing problems to be quickly addressed and further control strategies implemented. Internet-connected devices will allow processors and their pest control providers to be notified when an individual trap or bait station experiences activity, allowing for resources to be dispatched as quickly as needed to determine the level of problem.

Electronic documentation (such as barcoding pest control devices) allows us to easily collect data on rodent infestations and our pest management program. This data can then be used to look at pest trends in a facility, such as which rodent pests are present during different months and rodent activity within specific areas of the facility over time. Knowing what the pest trends are in a facility allows us to make predictions about pest activity, where to focus pest prevention efforts, and any problematic areas to zero in on. As a result, pest control services for rodents can be highly targeted to specific pressures and the amount of rodenticide applications significantly reduced.

Kelley-Tunis: The continued advancement in technology will absolutely allow us to improve our rodent control offerings. In fact, the technology of the future will change what many rodent control programs look like.

8. In general, PCOs don’t feel that consumers really understand the health implications of rodent presence. Why is it important that management and workers in the food processing industry understand this?

Kelley-Tunis: It’s interesting, most consumers recognize that rodents do pose a health risk, but they think that these infestations tend to occur in areas where there are no control measures and poor sanitation exists. They don’t recognize that rodents can infest almost anywhere, especially a food manufacturing facility — even one with an already established control and sanitation program in place. Employees also must recognize that no place is immune from a rodent infestation and that little things, like closing a door or cleaning up any food debris, are important in keeping rodents out of a facility.

Heath: Consumers in general might not understand, but food processors are mostly very well attuned to pathogenic risks and audit standards/plant inspections where rodent activity evidence could be devastating to their business.

Hottel: Understanding the health implications can help increase support for sanitation programs by those who carry out the sanitation and exclusion efforts in the plant. Thus, it is critical to emphasize the amount of contamination that a single mouse can cause through its droppings, hairs, and urine. Linking that contamination to diseases such as Salmonella is equally important in gaining support to exclude and remove critical resources for these pests in the facility.

It is a pest management partnership and gaining support in that partnership on all levels leads to a more effective program.

The author is Editor of QA magazine. She can be reached at llupo@gie.net.