[Focus On Public Health] Implementing A Mosquito Control Program

The emergence of West Nile virus in the United States in the past few years has turned the image of the mosquito from an annoying nuisance into a deadly threat. Allen Wooldridge, president of Adapco Inc., Sanford, Fla., said he believes this is an opportunity for pest management professionals to expand their businesses.

"Towns and residential areas are demanding mosquito control. The public perceives that any bite could cause a problem. The media has helped to nurture this perception," he said. Wooldridge and Jeffrey O’Neill, Northeast regional manager of Wellmark International Zoecon Professional Products Division in Schaumburg, Ill., gave a presentation at January’s National Pest Management Association’s conference, "Emerging Business Opportunities in Pubic Health." The conference was held Jan. 16-18 in New Orleans, La.

Many larger municipalities and counties have started to outsource mosquito control work, which may be a new market for many pest management professionals. "It actually takes a very minimal monetary investment to get started," Wooldridge said, "but it takes a commitment to train and learn about the mosquito, its life cycle and its habitat." He suggested that PCOs talk with manufacturers and distributors to learn proper application techniques. In addition, many state mosquito control associations sponsor training courses that are a valuable training resource for PCOs.

O’Neill added that cautionary wording should be used when dealing with clients. "PCOs shouldn’t say they can ‘kill’ mosquitoes. They should say that they will reduce the exposure of potential biting and potential diseases," O’Neill said. "Using the word ‘control’ implies eradication and should be avoided."

"Mosquitoes are flying insects. They move and reinfestations can occur," Wooldridge added. He stressed that customers should be kept informed of the procedures the pest management firm uses, and that communication helps the customer understand the difficulty in dealing with mosquitoes.

KNOW THE ENEMY. In order to be successful, pest management professionals must understand the four stages of the mosquito life cycle and apply proper products or prevention methods, based on observation and identification.

FIRST STAGE: EGGS. The adult female can lay about 150 eggs in or near water. In residential settings, rain gutters, bird baths, unfiltered swimming pools (with or without tarp coverings), tree holes and even hoof prints in pastures provide the necessary environment for eggs to hatch into adulthood. In commercial accounts, drains, flat roofs, drainage ponds (without fountains), old tires, or any receptacle that retains stagnant water can become a breeding ground. Even a rainfall measuring ½ inch is adequate for eggs to survive for seven days. Eggs can also become dormant in mud, but revive with a sustaining rain. This could lead to a major infestation, when millions of eggs hatch at the same time.

During this stage, prevention is the key, experts say. PCOs should recommend to customers to dispose of containers that collect rainwater because the stagnant water is the ideal breeding site.

SECOND STAGE: LARVAE. This stage usually lasts three to seven days, and the larvae progresses through four phases within this stage, known as instars. The mosquito larvae are sucking air, but during the fourth instar, their mouthparts fall out.

At this stage, larvacides and IGRs (insect growth regulators) are most effective. "Also available are oils and surface-active films that have very low rates of application," Wooldridge adds. "A new technology being explored is the use of sound to kill mosquitoes. It’s basically a sonar blip that explodes the larvae’s air bladder." (Larvasonic equipment is sold by New Mountain Innovations.)

THIRD STAGE: PUPAE. In this stage, which lasts one to two days, the pupae have developed "horns" on their heads to breathe. IGRs are most effective at this stage. Growth regulators produce an incomplete development by preventing the cells from dividing. The result is a hybrid that starves to death because it is trapped in a cocoon.

Pupae emerging from the cocoon need calm water, because they must stand up. In a commercial account, a fountain can be added to a pond to force rippling, which will drown the mosquitoes.

FOURTH STAGE: ADULT. After emergence, both the male and female will feed on flower nectar for energy, but only the female bites and sucks blood. This allows her to create eggs. The species of the mosquito determines the distance it can fly, but the majority of species only fly up to two miles from their breeding site. The typical life span of an adult is two weeks, but it can live up to two months, and a female can produce multiple, separate broods.

CONCLUSION. The two most effective measures for adult mosquitoes are barrier controls, which target them when they rest on foliage, and overall spraying. Most mosquitoes fly during the evening hours, and spraying is most effective at that time. An exception is the tiger mosquito, which flies during the day. "Surveillance techniques, such as light traps and landing counts, will show PCOs the numbers of mosquitoes they’re up against," Wooldridge says. "The PCOs need to take the specimens back to their office and identify them. They should talk with suppliers to learn about the tools available.

"PCOs must remember there is a high level of accountability and they need to have good record-keeping. They must keep track of how much product they used, when and where they used it, and the results," he said. "They will be looked at with different eyes, as a defender and protector of the public health because of West Nile virus. They should enter this market fully aware of the liability that they accept when they assume responsibility for defending the public’s health."

The author is a freelance writer from Cleveland, Ohio. She can be reached via e-mail at dtaylor@pctonline.com.