Public Enemy No. 1 — Rodents

It’s an unappetizing thought for consumers and any facility that handles food products — the pitter-patter of paperweight feet above ceiling tiles, rub mark deposits along a miniscule crack, droppings. Then there’s the outright sighting — eek, a mouse!

Rodents are the No. 1 pest of concern among quality assurance professionals who participated in QA magazine’s annual State of the Rodent Control Market survey, sponsored by Xcluder. When asked to rate from 1 to 5 how much of a worry certain pests are, rodents and flies tied for first, ranking 3.2. And 67% have seen a rodent inside or outside of their facility.

The last thing any player in the food supply chain wants to invite into their facilities is rodents. “They can make products not sellable, and they can spread disease,” said William Hoffman, president and CEO of Hoffman’s Exterminating Co. in Mantua, N.J. “Plus, there is brand protection.”

Beyond food products, supplies and packaging are also at stake. “We’ve seen rodents get into non-food items, and with the cost of goods, you can’t afford to have supplies damaged or spoiled because of pests,” Hoffman said.

The souvenirs rodents leave behind are a substantial threat to food safety — excrement packed with microbes, viruses, bacteria and fungal spores that stay active for weeks, even months. “As they go about their days, they spread the potential for disease,” said Emory Matts, B.C.E., North American rodent technical manager at Rentokil, Carrollton, Texas.

It’s not a pretty thought.

“If a rat lives for one year, it can shed 1 million hairs,” Matts said. “That’s a lot of hair getting into the environment and food packaging and preparation surfaces.”

So, no wonder rodents are public enemy No. 1 and a palpable risk to the food supply chain — if there is not a stopgap rodent control and monitoring plan in place, that is.

Rodents, Behave

By nature, rodents are persistent. They exist to survive.

Aside from humans, rodents are the most successful mammal at doing this. “Their instinct is to survive, to feed, and they do nothing but try to figure that out,” Hoffman said. “They are not worried about the debt ceiling, taxes or going on vacation. We spend eight to 10 hours a day on how to get rid of them, and they spend 24 hours a day on how not to get caught.”

We know an awful lot about rodent behavior. Consider lab rat testing.

“They are really intelligent compared to most other pests,” Matts said. “They can be very secretive, get into areas you might not recognize, and they are nocturnal.”

Hoffman calls rodents stealthy. And their survival skills are passed from one fast generation to the next. (Mice breed monthly.) “If their parents are successful at getting into a facility and moving about the walls and ceilings without being caught, that behavior is learned and passed down,” Hoffman said. “Within six months, you can have six generations of rodents that have learned how to move about the facility.”

Shannon Sked, Ph.D., B.C.E., said, “They are learned animals.” As an entomologist, food safety specialist and director of fumigation at Western Fumigation in Parsippany, N.J., Sked has conducted research on rodent movement and population dynamics. “One of the things that is underappreciated with these animals is they communicate through a complex pheromone system using urine. So, if you think about that, they are basically urinating in all the areas they go, and if that happens on food or a food ingredient, consider it adulterated.”

Brave, New World

One behavioral variable that has shifted post-pandemic is rodent curiosity. Some research was conducted where rodent characteristics were observed in an environment with no “culling activity” or controls — and “environments where there were campaigns to get rid of them,” Sked said.

Neophilic (curious) rodents are brazen, more aggressive and not threatened by tools like snap traps. Neophobic rodents are scared of the new and the unknown. Not surprisingly, the rodents in facilities with no pest management plan in place were bold, and the ones in facilities with protocols and a concerted rodent mitigation plan were hesitant. “During COVID, everything was locked down, and those rodents that survived were very aggressive,” Sked said. “They survived in areas where there was less pest control activity occurring. So, we are left with a population that is very curious, and we are seeing more interaction. What that means for food processing companies is more sightings. They are not just staying in the places where pest control companies are used to dealing with them.”

This could be why among the QA professionals surveyed, 67% have seen a rodent inside or outside of their facility. Fourteen percent say there was an increase in rodent sightings in 2022 over 2021, 56% saw no change and 31% noted a decrease.

Another contributing factor: “Rodents move farther faster,” Sked said.

So does cargo when you consider same-day online ordering and the rapid transportation system that has evolved during the last decade. “Having an import of perishable mangos to Indiana in 24 hours is not unheard of,” Sked pointed out.

Climate change is spurring more rodent activity across the country. “We are seeing more humid, warm parts of the country that would be cooler and dryer in years past,” Sked said.

Well, rats! What does that mean for quality assurance professionals, aside from the reality that it’s likely they will have a rodent sighting?

“A pest control professional needs to work with the food safety team,” Hoffman said. “It’s like looking at an X-ray. You look at the image and don’t see anything, and the doctor looks at it and says, ‘Here’s the problem.’ That’s what pest control professionals do.”