[Cover Story] Biomonitoring for Rodents

Early in 2009, Bell Laboratories launched a new version of its Detex non-toxic monitoring rodent bait: Detex with Biomarker. Not too long after, Liphatech also released a non-toxic monitoring bait called No-Tox. Detex and No-Tox (see Fig. 1, page 28) are largely the equivalents of their toxic bait block counterparts, but without any toxicant. In other words, think of Contrac and Maki (respectively) without their anticoagulant toxicant, bromadiolone.

Non-toxic rodent monitoring bait blocks are not new. In 1995, Zeneca Professional Products launched a non-toxic monitoring bait, Census, as tool for rodent IPM. Census was similar to Talon WeatherBlok without the brodifacoum. The industry’s reception for Census ranged from applause to confusion to disregard. Apparently, disregard won out as Census failed to attract the industry’s interest and Zeneca discontinued the product. A couple of years later, Bell Labs introduced Detex (i.e., detecting rodents), the firm’s offering of a non-toxic monitoring bait. But similar to Census, Detex also did not sell and was discontinued. It seemed the structural pest management industry 15 years ago had little interest in the concept of proactively monitoring for rodent pests. But perhaps with the arrival of these two new monitoring bait products, combined with other technology, it’s a new day for this concept.

The purpose of this article is to re-examine the use of these new and more novel non-toxic rodent monitoring/tracking baits and to consider the numerous ways these baits can assist you in solving rodent infestations. These baits can help bolster IPM programs, reduce callbacks and provide another dimension of service. They certainly also meet the changing times when the world seems to be clamoring for "green" services.

Biomarkers & Blacklights. With the new Detex product, Bell Laboratories added a bio-fluorescent marker into the bait. When rodents consume Detex, they pass the bio-fluorescent marker in their scats (droppings). The addition of this bio-fluorescent changes everything in the concept of using these non-toxic baits. As you know, fluorescent materials are readily seen with a blacklight. When captured in a blacklight’s glow, the scats containing a bio-fluorescent marker become brilliant "glowscats." Consequently, the biomarker within Detex now enables the monitoring bait to also serve as a tracking bait (MTB).

What makes the concept of a bio-fluorescent monitoring/tracking bait so exciting and so promising is that just recently several new UV blacklights using LED technology have emerged within the industry (perhaps Bell Laboratories saw this coming?). These new LED blacklights are small (10 cm by 1.25 cm) and fit conveniently into shirt pockets or tool belts. But they are powerful. One model I tested to field-trial the bio-fluorescent baits (the Microlite UV by Falcon Innovations) is powerful enough to emit waves in the 370 nanometer range. But because of this light’s unique design, only items or spots that fluoresce under UV light appear. In other words, other surrounding items that would be illuminated under normal light (as produced with a flashlight) do not show. Even the faintest crumbles of the Detex Biomarker fluoresced brightly with this new UV technology. This one-two punch of MTB and UVL can reveal a whole new look into the world of structural rodent control.

Liphatech’s No-Tox bait also can be used as tracking bait although No-Tox does not contain a biofluorescent marker. Instead, No-Tox employs a reddish-pink dye additive. The color marker is passed in the rodent scats following feeding. In cases where scats are deposited in well-lit and/or exterior areas during the daylight hours, the red marker works well. For cases of night-time evaluations, or inspections for scats in shadowy corners, behind and underneath pallets and other low-lying objects in the dark basements of buildings and warehouses, the use of the black lights will locate and identify the glowscats even from a distance.

Regardless of fluorescent or red dye markers, both of these non-toxic baits are highly palatable to foraging rodents. I have installed them into bait stations in a few areas around New York City, both as standalones (i.e., just the MTBs) as well as installing them into bait stations containing conventional toxic baits. The rodents of NYC ripped the MTBs.

By installing highly palatable baits into bait stations (with or without the conventional toxic baits), once the rodents enter the stations, they are likely to feed. Of course, they begin scenting the station with their scats, urine and uro-genital secretions. Research has shown such scents may attract other local rodents to those "marked" bait stations, thereby enhancing or accelerating the take of toxic baits.

On-the-job tips. When new technologies "find one another," specialized tools and techniques often emerge. And this is true here with tracking baits and UV equipment offering potential help to analyze those occasional complex (and also the simple) rodent jobs. Consider the questions of the everyday on-the-job service professional conducting rodent work:

Along what paths are the rodents traveling from nests to food sources?

What are their ranges?

Are the rodents coming from the outside and invading the building along a particular wall, or through a specific opening?

The following is a list of the potential uses of MTBs for exterior and interior uses. It’s a good bet that as innovative professionals use MTBs, additional applications will be discovered.

1. Rodent scats that are "marked" help the PMP discover three critical items: a) the high-activity trails of the rodents; b) the distances the rodents are traveling, and; c) possible zones in which the nests are located. In short, MTB scats provide the road maps for where to install traps and bait stations for maximum on-the -job efficiency.

2. By installing MTBs into bait stations on exterior areas (fences/walls), any MTB-marked scats seen in interior areas of a facility confirm the pressure of exterior rodents causing interior infestations. By installing MTBs in strategic placements, you can trace back the specific location or building direction from which the rodents may be originating. Suppose, for example, two different MTBs are used in two different areas around the exterior of a food plant or warehouse (i.e., Detex on the north and east walls; No-Tox on the south and west walls). Any MTB scats found inside the buildings, or within any interior mouse traps, can assist in pinpointing the possible origin of the rodents. Corresponding wall and/or door areas can be inspected to check for any structural breaches allowing rodents entry.

3. The areas around warehouses and food plants containing property line fence-rows at significant distances away from the building perimeter might or might not be home to commensal rats or mice — but they still must be monitored. With routine bait stations containing toxic baits, the baits will kill whatever small mammal happens upon the stations and feeds on the bait within. Many non-target small mammals (rodents and non-rodents) are important in the balance of those natural environments that can exist nearby our buildings (especially as we "urban sprawl" into undeveloped areas). Moreover, these same non-targets may be food to hawks, owls, foxes, coyotes and other wildlife species within the food chain. With non-toxic MTBs we can evaluate whether or not these mammals are making their way to the nearby structures, or remaining within their own "ecosystems" in their fields and other undeveloped areas. If it’s the latter, these non-target animals should not be victims of poorly designed rodent control programs that over-extend the zones requiring protection.

4. One of the best indoor utilities of MTBs is their installation into apartment complexes and large office buildings for mouse IPM programs. By installing MTBs into strategic floors or office areas (basements, suspended ceilings, suspect cubicles, etc.) and using backlights during subsequent service visits, the mouse population sources and reservoirs can be profiled. By focusing on these areas, callbacks can be reduced.

Recently, I installed MTB baits into the basement of a 12-story apartment complex in Manhattan. During the follow-up inspection three weeks later, I located a few "glowscats" in apartments on the first and third floors above the basement. Obviously, this confirms that the basement is serving as a possible mouse entry zone or replenishing source for the building. In such cases, property owners need to be shown such "smoking gun confirmation" to facilitate mouse-proofing the basement ceiling zones and wall penetrations from the outside leading into the basement. Or, at a minimum, the PMP should implement the most intensive mouse control efforts in the basement to stem off the severity of the upward migration.

5. The Detex BM product is particularly useful for confirming the activity of structural rodent burrows such as wall voids, floor voids and, in the case of Norway rats, exterior sidewalk and foundation wall burrows. For house mice in warehouses, Detex can be dropped into sub-slab cracks and crevices to determine whether or not mice are using these zones for harborage. During the spring of 2010, I was able to track the Norway rats’ use and movements below the sidewalks of Manhattan using Detex MTB (see Fig. 4, page 30).

6. Similarly, the Detex MTB can be installed into overhead ceilings spaces to allow for monitoring and tracking of the rodents’ use of the ceiling void. These voids are often overlooked in chronic indoor rodent infestations, which in turn results in expensive recurring callbacks.

7. Monitoring/tracking baits are a perfect fit for sensitive accounts when pesticides are not desired or allowed, but proactive rodent IPM programs are necessary. Consider the utility of MTBs in zoological gardens, pharmaceutical plants, animal-rearing facilities, schools, biotech firms and the like.

8. As more of the mega-corporate firms wish to increase their "green profile," the concept of using MTBs in those accounts fits this need perfectly.

Other Uses. The Detex Biomarker product also has uses against other cryptobiotic pests such as American cockroaches. This is because even the small the feces of cockroaches are illuminated under new blacklights. Often times, it is challenging to zero-in to where Periplaneta cockroaches are originating, or the location of their travel pathways (which if we knew, we could bait or treat). Are they coming from the attached sewer lines? Or from basement chases near steam pipes? By installing monitor/tracking baits in these areas, any cockroach frass that fluoresces in follow up services can provide trace-back to areas needing to be treated.

Some real-world research might indeed be exciting as to how the fluorescing MTBs have applications for this and other urban insect pests.

Summary. By using MTBs in routine pest management routes (i.e., installing MTBs in bait stations in many facilities), new insight of the behavior of the resident pest populations could be gathered. In short, monitoring/tracking baits can help us to be better detectives. Against the clever urban rodent pests, we need every detective tool and clue-gathering technique we can get.

The author is president of RMC Consulting, Richmond, Ind., and can be contacted via e-mail at
rcorrigan@giemedia.com.