[Lawn Care Supplement] Resistance is not futile

It may seem that treating with insecticide is the lifeblood of the pest control business. But what happens when you treat and treat again — and the bugs still live?

The problem of insecticide resistance is an increasing issue in the pest control industry. Take, for instance, the case of the southern chinch bug’s (Blissus insularis) intractable dominance of St. Augustine grass. At PestWorld 2007 in Orlando, Fla., Eileen Buss, associate professor of entomology at the University of Florida-Gainesville, discussed the challenge of controlling this pest, which has developed resistance to every major chemical class used against it.

“We do the best job we can,” she said. “Application error, targeting the wrong species, using the wrong formula, these are things we can control and correct. But some things are uncontrollable — like insect resistance.”

APPLICATION ERROR. Buss suggests that pest control companies (that offer lawn care services) begin by reviewing the basics and ensuring the efficacy of controllable factors. For example, application error can be prevented by calibrating equipment and checking it for any problems. In some cases, perimeter areas may have been left untreated due to concerns about getting the product too close to landscaping or preventing any product from running off into public sewer systems.

Thatch control is another consideration when controlling turf pests. Buss says that lawn care specialists should assess the lawn’s thatch layer and modify an application as needed to ensure that the chemical penetrates the thatch.

“We really need more thatch management,” she said. “Getting rid of excessive thatch can stress insects’ habitat and knock back their populations naturally.”

TURF DAMAGE. Properly identifying the cause of turf damage is another key. In fact, pests may not be the culprits at all. Is there scalping near the edge of the pavement? Is the lawn being mowed unevenly? Is there a dog repeatedly using that part of the yard? Does the turf show signs of drought stress? These are all questions that need to be asked, Buss said.

Some homeowners need to be educated about proper irrigation, and in-ground sprinkler systems need periodic maintenance to ensure that water coverage is even. “If the damaged area is very uniform, then it’s probably not due to bugs,” she said.

Not only does irrigation affect the turf’s general health, but it is often crucial to the proper activation of insecticides. Clients should be instructed about the need for adequate watering after application and should be warned against over-watering, which can wash some chemicals away before they have a chance to work.

Finally, lawn care specialists need to sample the turf and correctly identify the pests in order to treat them effectively. “There’s no substitute for just getting down on the ground and looking for the bugs,” Buss said.

Chinch bugs live in grass sheaths, so it is critical to examine the bottom leaf sheath for evidence.

In a paper she published on the topic of chinch bug resistance, Buss writes, “Part of the difficulty in dealing with this pest is that one generation may develop in four to six weeks during the summer. Any insecticides used to treat turfgrass will likely kill most nymphs and adults, but the eggs will survive, nymphs will hatch and the infestation will continue. Thus, damage may become visible again within two to three months of treatment. Encroachment from neighboring lawns is also a possibility.”

INSECTICIDE RESISTANCE. If all controllable factors are accounted for, then Buss said the problem indeed may be insecticide resistance. This is more of a challenge seen in greenhouse and nursery environments, but resistance is increasing among turf pests and may develop when the same insecticide is applied repeatedly, allowing the insects an opportunity to adjust and survive chemical onslaughts.

The Insecticide Resistance Action Committee (IRAC) maintains a Web site, www.irac-online.org, that is filled with news and other resources for specialists dealing with resistant pests. IRAC defines resistance as “heritable change in the sensitivity of the pest population that is reflected in the repeated failure of a product to achieve the expected level of control when it’s used according to label recommendations for that pest species.”

“Resistance has been documented to every insecticide ever developed,” Buss said. Insects may change their behaviors in order to avoid the chemical, develop new metabolic functions that allow for faster breakdown of the chemical, develop an insensitivity to the chemical through the traditional target site, or have reduced penetration through the insects’ skin.

SOLVING THE PROBLEM. So what can be done to manage the problem? Buss admits that the ready solutions may not be attractive to homeowners who want a thick, green lawn. “You may want to skip applying the chemical for a while so that the less resistant bugs can breed with the resistant ones and dilute the gene pool. But no one really likes the idea of letting non-resistant bugs survive,” she said.

Rotating insecticides is another approach, and Buss advises technicians to become familiar with the active ingredients and their chemical classes in order to create a rotation strategy. The IRAC Web site provides information on various classes of insecticide.

Even with a well-considered Integrated Pest Management plan, eradication is an unrealistic goal, Buss said. She said that continued monitoring is important, and because of product and environmental limitations, no insecticide can provide 100 percent kill.

“Finally, when you have an insecticide resistance problem, inform your local county extension agent,” she said. “We may have information that can help you plan your attack.” 

The author is president of Compelling Communications, which offers marketing and customer service to help customers attract more clients.