Bull's-Eye!

Imagine tackling a difficult cockroach situation in an extremely sensitive commercial account: The environment provides everything a cockroach would want: In the 10,500-square-foot facility, there are lots of hiding places, plentiful food sources, the temperature is a constant 85°F, and the relative humidity is 85%. What's more, the customer won't tolerate large quantities of pesticide.

This situation isn't hard to believe. After all, PCOs have always been expected to reduce the risks that are posed by pests and pathogens, and increasingly, they are also being called on to reduce the risks posed by pesticides.

Now imagine eradicating the cockroach infestation while using an amount of pesticide equivalent to the size of a miniature candy bar, along with some corrective measures. You say it can't happen? It can, and it did.

Dr. Richard Brenner, research leader with the U.S. Department of Agriculture's Medical and Veterinary Research Laboratory in Gainesville, Fla., achieved this feat by analyzing how pests are distributed spatially. He is studying a new way to locate and eliminate pests that reduces the amount of pesticides used and therefore reduces pesticide exposure and the risks associated with it.

Brenner's work in the galley of a ship: Left, a contour map showing the number of cockroaches caught in each of 27 traps. Higher densities are depicted in red. From this data, a precision targeting map was prepared (right) showing areas harboring 75% of all the cockroaches. (Photos courtesy of the USDA Agricultural Research Service.)

 Brenner is working with the technique he calls "precision targeting," a science he first used in the mid-70s, when he was involved in a project analyzing the distribution of mosquito eggs on a flood plain near Decatur, Ill. In the project, the researchers found that the distribution of the mosquito eggs in the soil matched the distribution of foxtail, a common weed. The conclusion drawn was that the moist soil that fostered the growth of foxtail was the same environment preferred by female mosquitoes when laying their eggs. Subsequently, the group was able to achieve 98% control of the mosquitoes by treating only areas of the flood plain where fox tail was present, which turned out to be only 2% of the 100 acres of land.

It's just this sort of scientific reasoning that has helped Brenner successfully apply the concept to urban pest management. As he explains it, precision targeting has a place in structural pest control because all infestations are spatial in nature. In most biological and ecological systems, objects have "spatial continuity." For example, blades of grass tend to occur together, as do trees, and even water. Pests, too, instead of being randomly distributed across a particular area, tend to aggregate, as some structural areas are more conducive to their survival and population growth than others. Samples of cockroaches or other pests taken close to each other may yield similar results, or similar numbers of cockroaches found.

REDUCING RISKS. With regard to pest control, Brenner defines precision targeting as a method of determining both qualitatively and quantitatively the precise distribution of whatever pest is being studied, whether it is cockroaches, fleas, termites, or stored product pests. Then precision targeting determines the distribution of the necessary treatment, and ultimately, that means distribution of risks.

Spatial analysis, upon which precision targeting is based, was first developed by mineral engineers who used it to help estimate how minerals were distributed underground. But over the years, Brenner says, spatial analysis has gone largely unnoticed. Precision targeting uses spatial analysis to draw specific maps depicting where objects are likely to be found, and can be used to find everything from roaches to radon, asbestos, gold, weeds anything in which the locations of observations are related.

At the core of Brenner's interest in precision targeting is its capacity to reduce risks, because by using precision targeting, pesticides can be applied "precisely and minimally." Such a proactive approach hasn't been taken before by the pest control industry. Instead, Brenner points out, the industry has used traditional statistics to evaluate treatment success. Traditional statistics assumes that pests are distributed randomly, and that one "observation" or sample taken has no relationship to another sample taken nearby. For example, pest control professionals will typically treat an entire structure and will then estimate that the treatment was, for example, 85% successful in the structure. But by using only traditional statistics, pest control operators are unable to pinpoint areas of potential infestation.

Spatial statistics and precision targeting, on the other hand, give PCOs a way to predict where the pest problems will be. Then treatment efforts can be directed to only those areas. Spatial statistics also indicates the total amount of whatever is being measured. It analyzes the spatial continuity of an infestation by the collection of samples, and then estimates the pest distribution elsewhere, based on that spatial continuity profile.

To implement precision targeting, a PCO might lay sticky traps around a facility and then check them a few days later to count how many cockroaches were caught at each trap. After analyzing the location and numbers of cockroaches of each trap in comparison to all other traps in the room, "contour maps" are constructed which depict areas of equal densities of pests. The maps allow PCOs to visualize where the pest problems are actually occurring.

Coming up with the contour maps is "mathematically intense," says Brenner, but there are computer programs available that can be adapted to do all of the work and produce contour maps as output. With the software, the user takes samples and records the exact location of each. Laying traps is not necessary; the user simply must be able to document locations where specific numbers of pests have been identified. (The software Brenner has used is geared for the field of geology.)

After running contour maps, the PCO can see where areas of heaviest infestation are located. Situations encouraging pest entry or population growth can be corrected, such as door openings or gaps in furniture. The structure can also be chemically treated, with special attention given to the heaviest areas of infestation. After treatment, a second set of contour maps is run and compared to the original maps to show changes or shifts in the pest population. In this way, treatment successes or failures are documented. Precision targeting can be used for just about any pests, Brenner says, provided the normal control operation involves making a thorough visual inspection or trapping program.

"The advantage of spatial analysis," said Brenner, "is that it lets you know where the problems are based on a rigorous assessment of what your observations are." Spatial analysis also makes it easier for PCOs to practice true IPM. This is because effective IPM, Brenner explained, requires that technicians be well-versed in the pests' biology and behavior. But because of high turnover rates among employees, many firms find it difficult to provide continuity of treatment: Some employees have an extensive knowledge of pest biology, while others may not, and consequently some customers may receive a higher level of service than others.

Spatial analysis, meanwhile, points out where the pest problems are likely to be, and so relies less on the skill level of the pest control technician relative to the pest's biology and behavior. Instead, what becomes important is the number of observations made or the thoroughness of the sampling program.

WORK IN THE FIELD. Brenner's cockroach success story took place in a state-owned fruit fly rearing facility in Gainesville, which rears more than 20 million fruit flies each week. Facility officials asked Brenner to apply some of his research on precision targeting to try to solve their stubborn pest problem. The facility couldn't afford to risk having the flies contaminated by pathogens from cockroaches, but it also couldn't tolerate the use of pesticides, which might kill its stock of flies. A very proactive control approach was needed.

Brenner started out by placing 52 traps around the 10,500-square-foot facility. A few days later, he recorded the numbers of cockroaches found at each trap and identified them by sex and development stage. Contour maps showed that immature cockroaches were coming from the racks which held the fly rearing trays. The racks had holes in them for handles to be attached so the racks could be moved to the next room. This finding of immatures was critical to the pest management program because it identified where the female cockroaches were depositing their eggs. Knowing that the racks were moved from room to room, Brenner deduced that there was a high risk that this new generation of cockroaches was being spread to different areas of the building. The problem was solved by filling the voids with an expansive foam. Small indentations were left so the handles could still be hooked into the racks.

Meanwhile, the distribution of adults in the contour maps showed where the cockroaches were able to survive and where they were likely to end up. One problem area was identified near some of the doors in the facility. A close look at the doors revealed that many were rusted through and had holes in them. Cockroaches were living inside. To solve this problem, the doors were replaced with stainless steel units.

Sampling and contour maps produced several months later showed that the population coming from the movable racks was completely gone, but there was another problem area around a couple of floor drains. This puzzled Brenner because the species of pest being managed was the Australian cockroach, which is not a sewer dweller. Furthermore, large quantities of water were being flushed down the drains each day, which would seemingly provide an uninhabitable environment for the Australian cockroach. After removing the drain plate, Brenner found there was a hollow gap where cockroaches were harboraging, out of the way of the flushed water.

Now that the internal sources of pest infestation had been identified and eliminated, Brenner found that an open doorway used to bring in food supplies for the fruit flies was providing entry for cockroaches occasionally invading from a wooded area outside. This situation would never allow the facility to reach a total eradication, Brenner felt, and he convinced the officials to use small amounts of a USDA-patented pesticide bait stategically placed according to the precision targeting map. After seven consecutive nights of using the bait placed in souffle cups, the population was eradicated. Only one cockroach was found anywhere in the facility, using all 52 traps.

Now the facility sets traps once a month, but it no longer has to use 52 of them. Because of repeated use of contour maps, officials there have been able to narrow the areas of concern greatly. They now know where cockroaches are most likely to gain access to the building, as well as where the nearest harborage sites are located. Traps are needed only in these areas. For the past two years, with ongoing sampling, the use of contour maps, and baiting when necessary, the facility has achieved a level of control they are satisfied with. The facility is also spending less time and money on the control and is getting better results. "The amount of toxic bait that this rearing facility uses in a year," marveled Brenner, "is the equivalent of a bite-sized candy bar." What they do use a lot of, Brenner pointed out, is bait without toxicants. Used as an attractant, the bait has become a powerful monitoring tool that shows the officials where toxic bait should be used. Using precision targeting, the risks posed by both pests and pesticides have been reduced at the facility. "That immediately translates to any environmentally sensitive area," Brenner said. "Health care facilities, hospitals, nursing homes."

REAL-WORLD APPLICATIONS. Using precision targeting in real world scenarios is still somewhat tedious for PCOs to do initially, but once the system is in place, monitoring and ongoing servicing is a "breeze," Brenner points out. One pest control firm, Sprague Pest Control, Tacoma, Wash., is achieving repeated success using precision targeting. Jeff Weier, technical director for Sprague, has employed the technique in a few accounts already, and he says in the near future the company may be using precision targeting in many more.

A scientist by training, Weier became interested in precision targeting when he first heard Brenner talk about the technique at a 1992 Whitmire conference. He was so impressed that he headed to the USDA research center in Gainesville where Brenner trained him in the procedures.

Weier has used the technique to control flying insects, Indian meal moths, cigarette beetles, German cockroaches, and various grain insects. Although this form of control costs customers more because of the front-end work involved in setting the system up, Weier has found that the program actually saves customers money in the long run. Furthermore, Sprague is able to achieve better results in less time, and pesticide usage is reduced.

Among the accounts in which Weier has employed the technique is a food warehouse, a facility of about 300,000 square feet, that was having an Indian meal moth problem. Weier first drew a map of the facility to scale and then placed 36 pheromone traps in the warehouse, noting their locations on the map. Upon checking the traps two weeks later and creating contour maps using Surfer, a software program manufactured by Golden Software of Golden, Colo., Weier noticed that the moth infestation was heaviest in the areas where the oldest food was stored. Some control measures were taken, including a limited application of pesticide and cleaning of old equipment and floor areas. Contour maps were again created after the treatment.

By comparing contour maps before and after treatment, Weier was able to identify sources of infestation, treat those sources, and document success to the customer.

"The initial map showed us where the infestation was probably located," Weier said, "and the second map showed us that we did, in fact, treat where we needed to." Weier now runs contour maps for the facility every two weeks as an ongoing monitoring system.

Periodic running and reviewing of contour maps is important because it shows where continued problems exist. It may show, for example, that roaches always turn up in one corner of a room. Continued monitoring of that spot, then, will tell the PCO the severity of the problem, and whether he or she should expand the treatment and observation area.

The first real-world consideration Weier has faced is trap density: He found it is not economically feasible to use the number of traps that Brenner uses in his research work. He also found that traps cannot be placed wherever the PCO wants them: They must be placed where they will not be moved or destroyed by day-to-day activity in the facility.

Brenner explains that the research community is in a better position to take numerous observations than pest control professionals working in the field, who are more limited by time and cost considerations. What researchers, working in concert with PCOs, must now do, Brenner says, is determine the optimal workable number of observations that should be made.

WHAT'S NEXT? Surfer, an off-the-shelf software program, sells for about $500. A version of this program suited to the pest control industry may be forthcoming: Golden Software is interested in customizing the program so it can be more readily used by PCOs. But using this or similar programs for pest control applications requires some in-depth training.

Brenner hopes to offer a training program for PCOs who want to implement the technique, and he is now in the process of setting up an "action team" of researchers and professionals who can further develop the use of precision targeting for a broad range of pest management concerns, in both urban and agricultural settings.

The tricky part of using precision targeting in pest control, says Brenner, is plotting the observations. To get the proper X and Y coordinates, a PCO must have a map or blueprint of the area to be analyzed. Then each trap location or observation must be marked on the map and given an X and Y coordinate, which is then input to the computer program. In order to compare maps over time, traps or observations should be maintained at the same locations, as their locations have already been entered into the program.

Brenner hopes to automate the plotting process, which is now somewhat labor-intensive. Under an automated system, instead of plotting coordinate points on a map, users would simply make visual observations while using a hand-held electronic device to identify their approximate global longitude and latitude.

Automation would reduce the chances for human error and would be less dependent on the PCO's skill level in plotting coordinates. A technician could use the initial contour map to identify the cause of the infestation and make corrections or apply treatment. Then the technician could go back a few weeks later, run another contour map, and analyze the results.

To help develop this global positioning technology, Brenner is now looking for a partner who would provide the specific engineering help required. He is also currently working with the Environmental Protection Agency, the Department of Defense, and members of the National Pest Control Association to develop this technology for the pest control industry.

To be sure, the technology for identifying approximate global locations from within structures is a few years off, says Brenner. Meanwhile, the concepts behind precision targeting are still very doable, even if they do require some front-end efforts in devising blueprints and plotting observations. What PCOs are left with is an informative tool that provides clues as to the causes of an infestation.

"Precision targeting allows precision in determining the spatial distribution of any parameter that you need to measure," explained Brenner. "This can be used as a tool to pick up incipient infestation, and it shifts pest management to a preventive approach instead of a reactive approach." With spatial analysis, a PCO can allocate resources where the likelihood of success is best, thereby reducing pesticide use while achieving an effective solution. PCT

Lisa Josof is associate editor of Pest Control Technology magazine.