PERSPECTIVES Summer 2000: Inside Story
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Inside Story

 


hom are you going to call when arthropods infest?
The Department of Entomology’s indoor Urban Entomology Program.

For immediate diagnoses and solutions, Dr. Mike Waldvogel, Extension specialist in entomology, works with the pest control industry and general public through county Extension centers to provide short-term solutions to pest problems. However, if a solution is not at the ready, Dr. Coby Schal, Dr. Jules Silverman and Dr. Ed Vargo step in to develop research-based answers.

The four are the core of the program. And all try to deliver solutions that will be as sustainable, as precisely targeted and as environmentally friendly as possible.

Photo by Sheri D. Thomas

In defining what is meant by “indoor urban entomology,” Schal says, “It’s defined by the people we serve. ‘Outdoor’ generally consists of production systems, production agriculture. The major commercial targets of outdoor urban entomology are the greenhouses, nurseries and commercial turf industries. The commercial component of indoor pest management is primarily the pest control industry. And both indoor and outdoor address the consumer in general, anyone who resides in a home, but the indoor component is really quite different from agricultural entomology and is related more closely to medical issues — such as allergies and asthma that can be aggravated by roaches — and environmental issues.”

Schal further explains that urban entomology refers to the entomology of structures. And the word “urban” notwithstanding, the struc-ture doesn’t have to be in the city.

“Structures facilitate the proliferation of certain pests,” he says. “It’s best to look at it in terms of the damage of pests. In a greenhouse, whereas aphids would be plant pests, cockroaches and termites would be structural pests.”

Getting rid of indoor pests can also impact other organisms in the local environment, according to Silverman, Charles G. Wright Professor of Structural Pest Management. “As urbanization increases, so will indoor pest problems, thereby increasing the demand for effective pest control strategies that create minimal environmental disturbance.”

Just when does an insect become a pest?

In agriculture, if it eats what you’re trying to grow, if it competes with humans, it’s a pest, says Schal. “To most people in urban areas, if it shares your home in an uninvited, unwelcome way, it’s considered a pest. Some spiders are very beneficial, but if a single spider appears inside, it’s a pest.”

“One ant may be too many in a home,” adds Silverman, whose research focus is household ants. “Economic thresholds are established in agriculture to determine the number of insects that a crop can tolerate before yields are substantially reduced. However, in the urban environment, aesthetic thresholds are frequently used when people make pest control decisions.”

Indeed, a well-tended lawn suddenly marred by an anthill or two can set a homeowner to what Schal calls “a tremendous over-application of pesticides. But humans like sterile environments. That means no insects.”

And in a world where most people think nothing of grabbing the nearest spray can or insect bomb and blanketing their environment with pest-killing chemicals, the urban entomology team members all have a common mission: to take out infestations without leaving chemical residues — targeting the pest instead of the environment.

ne of the important contributions of the Entomology Department’s structural pest management program, says Schal “is the development of tools for monitoring insect presence in order to decide where to apply the food-based bait or use other means for killing the insect in a targeted fashion. For example, we set traps to determine the numbers and location of infestations. A trap may catch less than 1 percent of the population, but it also tells us where and when to set the bait.”

Schal developed and patented a system using sex pheromones — chemical signals produced by the insects — to attract cockroaches, thus enabling the measurement of infestation levels and more controlled application of pesticides. “We can target the insect even better this way, because nothing responds to the pheromones other than the insect,” he says.

But when it comes to the use of chemical pesticides, you want them to do their jobs and disappear as quickly as possible.

For example, Vargo, whose focus is the social and spatial organization of termite colonies, explains that termites resurfaced as a major pest in the ’80s after a government recall of the termiticide chlordane. While an application of chlordane to the soil would kill termites and last for 30 years, Vargo explains, it was also dangerous to mammals, over time accumulating in fat cells as a carcinogen.

“While we had chlordane, there was no need for people to understand termite biology,” he says. “Now, industry needs a replacement for chlordane, and at the same time there’s government concern over the use of pesticides. So the new technology for termite control is use of baits: The termites take the bait and it spreads through the colonies as a slow-acting toxicant.”

However, he adds, the effectiveness depends on the spatial organization of termites underground — how many nests are in a colony, how they mix and exchange foods. All these are still areas of mystery, and all are important to the successful application of baits.

So in order to help define what a colony is and thus strengthen the effectiveness of colony elimination systems, Vargo has developed molecular genetic markers to distinguish groups from different colonies, track the colonies and map out spacial distribution in an area. “We can also use these markers to look at patterns of dispersal and reproduction,” says Vargo, who hopes to use this system to help identify and trace Formosan termites that are causing trouble in Louisiana and Hawaii and have been detected in 14 other states (including North Carolina).

Vargo is putting in a grant proposal to help in this effort and to look at the genetic relationships between different groups of termites in the United States.

Schal notes that the Urban Entomology Program’s particular uniqueness makes it attractive to granting agencies. “There are six or seven other major university programs that deal with structural entomology, and we are one of the largest,” he says. “The other programs are excellent programs, but what’s unique to ours is that we have an excellent balance in extension, research and instruction, on the one hand, and on the other the excellent balance that we have between short-term (applied) research and long-term (fundamental, basic) research.

“Most urban entomology programs around the country are highly applied; they’re concerned with short-range solutions, funded mainly by industry. We don’t neglect the short-term problems — we address them very effectively — but we’re also concerned with the more distant horizon. We’re asking questions about where we’ll be 20 years from now. Those are the questions that federal granting agencies are more interested in, and that makes us more competitive for grants.

“That’s very much unique to our program, and I’m proud of that component. I hope we can maintain that.”

unding from the USDA is supporting Schal and his colleagues’ efforts in an Integrated Pest Management (IPM) program for the swine production industry.

“This is a huge, important industry,” says Schal, “and on many farms, the facilities where the pigs were being housed were terribly infested with cockroaches.”

The infestation was so acute in some places, recalls Waldvogel, that “you could open the door and cockroaches would come raining down on you.”

Clearly, says Schal, “We wanted to minimize cockroaches interacting with pigs. We didn’t want cockroaches crawling around pig manure and then being eaten by piglets. That results in transmission of disease.”

They have therefore developed a reduced risk type of program, Schal explains, “that uses a lot fewer insecticides than we did in the past and insecticides that are safer than we used in the past, with much less coverage of structures, yet with much better efficacy, much better results. We want to minimize the amount of insecticide that’s sprayed, especially in the food production system.”

One solution he developed for the swine facility infestation is biologically based. “We used an epizootic fungus, which kills cockroaches but is harmless to pigs, to humans and to the environment. It’s self-sustaining and low-input in terms of costs and chemicals required,” he said.

“That’s been a successful program. We’ve gotten a lot of cooperation and a lot of feedback from the swine production industry.”

This is a case when “it’s a short-term problem, but there’s no solution unless we conduct very applied research. That’s why we have a grant from the U.S. Department of Agriculture — to develop a solution,” Schal says. “In many other situations, we know the solution and it is disseminated to the public.”

Among the avenues of dissemination is the Plant Disease and Insect Clinic, a diagnostic center overseen by Plant Pathology and Entomology Extension, where people send insects for identification and management guidance. Likewise, county Extension centers receive high numbers of e-mail and telephone requests from home-owners and businesses for pest control information.

“World Wide Web has increased our notoriety, and it extends beyond this state,” Waldvogel says. “It’s not unusual for us to get requests from other states, which we refer to local experts, or from all over the world. For example, I recently was contacted about wood-infesting beetles by a man in Portugal.”

Waldvogel estimates the annual tally to be 1,200 to 1,300 requests for help. And their usual complaint? “Termites, easily,” he says.

Another public service endeavor that Schal points to is a program of Integrated Pest Management (IPM) for controlling insects in public elementary schools.

“We’re doing an entomological as well as an economic assessment of IPM programs as opposed to conventional pest control methods, such as spraying insecticides inside a classroom,” he explains.

IPM involves the use of infestation-measurement tools, then making decisions to apply pest control devices in a minimal, selected way — “not by broadcasting pesticide but by placing it in discrete locations,” Schal says. “We’re mainly using baits instead of broadcast insecticides.

“We went to several different schools documenting the differences between these two approaches.”

At the conclusion of this project, Schal, Waldvogel and their colleagues will develop a Web page for North Carolina schools to consult for a specific implementation plan and for guidance in deciding what is best for their school.

ooking at what’s ahead for the Urban Entomology Program, Schal says, “We constantly need to re-think our approaches. It’s important for us as a program to get together and redefine what we are all about and need to accomplish. We choose a research target within the insect (such as the digestive tract) that we hope will benefit pest control in the future. ”

Indeed, although Vargo sees immediate impacts as, for example, the four annually lend their expertise to the North Carolina Pest Control Technician School, he says his biggest impact as a member of the program “will be a long-term one — effectively providing basic information on controlling these pests.”

Silverman likewise sees his role as effective in the long-term. “There’s a need to develop a program focused on household ant biology, behavior and control,” he says. “There are a number of urban ant species that we know little about, and I believe there’s an opportunity to make a difference in their management with less reliance on pesticides.”

Among the program’s key accomplishments, prior to his arrival last year, he says, has been “the establishment of the best program focused on both basic and applied research on the German cockroach. I am developing this complementary approach for the household ant complex, as well.”

Waldvogel, who works with various public agencies, adds, “If you can solve a problem for an individual, I consider that a victory, especially if we come up with a solution that avoids use of pesticides. I guess I feel like we do a lot in terms of reducing problems associated with pesticides. And none of that would be possible without our county Cooperative Extension offices.

“We’re educating the public, telling people their pest control options.”

Vargo notes, “This program is making a big difference. If you look at the field of urban entomology, what’s been lacking is a sound scientific basis, a sound understanding of the biology of pest species. We have a good blend of basic science and are using it to find a more effective way of managing species.”

 

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