©victor zastol'skiy | adobestock

“The pest control industry must adopt best practices in mosquito suppression management — techniques that achieve high customer satisfaction by being efficacious, economic and environmentally sound. If this doesn’t happen and quality mosquito control doesn’t occur or improve — then sooner or later you’re going to have legislative-mandated best practices standards. And you don’t want that.”

Those were the cautionary words of Dr. Grayson Brown of the University of Kentucky’s Public Health Entomology Lab as he conducted his segment of PCT’s annual mosquito control virtual conference.

Brown further defined the term “best practices” as “techniques that have generally been accepted as superior to all alternatives because they produce results superior to other techniques and help achieve our goal of mosquito suppression to ensure high customer satisfaction.”

According to Brown, there’s a high placebo effect with current mosquito control services. “So you have to be sure that you are actually suppressing these pests by operating an ethical business that provides efficacious, economic and environmentally sound service.

“Mosquito control is a rapidly growing service because the prevalence of mosquito-borne diseases in cities and suburbs will continue, as will news media reports about them. It’s quite important to initiate and utilize best practices and to explain them and educate your customers about them,” he said.

TWO BIOLOGIES COMPARED. As a general background for the webinar participants, Brown compared the biologies of two common mosquito species — Aedes and Culex — that are prevalent in the United States.

“The Aedes genus is responsible for transmitting viruses that cause dengue fever, Eastern equine encephalitis, LaCrosse encephalitis, chikungunya and Zika; while the Culex mosquito is the primary vector of the West Nile virus, Western equine encephalitis and St. Louis encephalitis,” he explained.

Aedes mosquitoes principally attack mammals and the Culex species preferentially attacks birds but is responsible for a few human bites,” Brown added.

CLEANER, STAGNANT WATER. “The Aedes adults bite during daytime and early evening hours, and (they) prefer cleaner water, while Culex mosquitoes are active late night and early morning hours, and are attracted to stagnant water.

“The resting sites for Aedes mosquitoes are found close to ground level (less than 10 feet above the ground), while the Culex species resting sites are higher, often more than 10 feet above the ground.”

In explaining how mosquitoes are attracted to people, Brown said that humans in a backyard, for example, give off carbon dioxide (CO2) plumes. “Studies have shown that mosquitoes can detect amazingly small concentrations of CO2 and once they do, they move toward the source of the plumes and bite their target,” he said.

SUPPRESSION SERVICE. So what should PMPs do when faced with an Aedes threat such as Zika? The answer, Brown says, is to contract with a good suppression service that uses best perimeter spraying practices with quality products to develop a good degree of protection.

“We’ve learned that mosquitoes have a short flight range and are susceptible because of their behavior. They’re extremely susceptible to perimeter spraying applications of a residual insecticide. Subacute dosages won’t necessarily kill them but will severely disrupt their ability to target and locate a host.”

SPRAYING PATTERN. The important thing about perimeter applications, he explained, is the pattern of spraying. “Start spraying close to the house and work around it. Target vegetation — but not grass or flowers. Go after thick bushes, or honeysuckle or ivy, and get way down deep. Spray underneath decks, crawlspaces — anyplace that’s cool, dark or humid. The mist blower will blow the mosquitoes away from the area and when they return they’re unable to penetrate the barrier created by the perimeter spray application.” Brown suggested PMPs spray with a quality synthetic pyrethroid and a can expect a 75-80 percent reduction of the mosquito problem.

PYRETHROIDS. Using other effective products when necessary is another best practice, Brown said. He discussed how insect growth regulators (IGRs) — chemicals that disrupt and impede the life cycle in the egg and larvae stage of development — are being used by some for mosquito treatments. The idea with an IGR is that if a mosquito can’t reach adulthood, it can’t reproduce.

There are a number of good pyrethroids on the market, Brown said. “In some of the early work we had done with a premium residual synthetic pyrethroid, we achieved about a 60 percent mosquito reduction over a six-week period. Now we are routinely getting more than 80 percent reduction over eight weeks with some of the formulations that are intended to maximize the duration of effect.”

GRAVID TRAPS. Brown also suggested that granular larvicides could be used in damaged gutters or other areas where standing water hasn’t been eliminated.

PMPs should consider crafting a handout that explains customers’ responsibilities to help curb mosquito populations. Residents may not be aware how standing water encourages mosquito breeding.
“Using gravid traps when needed is also recommended,” he said. “Use them when you get complaints of mosquito bites shortly after your treatment. Often, you’ll find homeowners in those circumstances mistaking fungus gnats or drain flies for mosquitoes. Gravid traps, which are simple and inexpensive devices, will help you identify the problem insect. They’re easy to use and available at hardware or big box stores.”

HOMEOWNER PARTNERSHIP. According to Brown, it’s worthwhile to have a handout for customers that highlights common larval breeding sites. He recommends using an environmental assessment form for this; some are available commercially. “Or you can create your own,” he said. “It should note inspection areas where larvae or adults can usually be found. This will help homeowners become cognizant of breeding areas, which is often information that they don’t know about. The form could also include a simple map showing which areas to treat or not to treat, and which areas to watch for mosquito activity.”

“Obviously, quality application treatment is an important part of best practices,” he said. “But another aspect is an awareness that homeowners have a responsibility in mosquito suppression and communicating those responsibilities to homeowners. That can go far in helping you achieve your goals. Residents must be responsible for ridding their areas of standing water that might be the source of larval breeding and that includes damaged gutters that are holding water. They should do their pruning of nearby foliage such as Japanese honeysuckle before you treat.”

Brown said the environmental assessment form also could be a useful reference in planning for return visits to customers. “Or if you need to send a different technician for that return visit, the form will be very helpful for that employee.”

The filled-out environmental assessment form, he said, could be included with other paperwork given to customers, such as bills or receipts. “It can help further inform and educate your homeowner customer — a very important best practice.”

The author is a PCT contributing writer.