Potential Effects of FQPA on Mosquito Abatement Programs in South Carolina

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Comments on Mosquito Abatement in Charleston County

Pat Wright, SC DHEC

October 1998

The Charleston County Mosquito Abatement Program uses malathion and Dibrom as two of its most important products for controlling adult mosquitoes and managing resistance. A third product is used as well. The loss of these would cause significant control problems and would be costly.

There is currently some resistance to malathion in some mosquito species. By using different products including malathion, resistance is being managed.

The loss of malathion and Dibrom would result in very few products being available. Only two products, Sumithrin and Resmethrin, would be available to use due to availability and environmental concerns. Resmethrin has not shown to be consistently effective in controlling Aedes taeniorynchus, a salt marsh mosquito that is the biggest pest mosquito from mid-June through mid-October.

With only two products to use, and one not consistently effective on the major pest mosquito, resistance management becomes very difficult.

Approximately 75,000 acres are treated by air with malathion per year and 600,000 acres with Dibrom through ground treatment. If other products are used, it will cost the tax payers of Charleston County a minimum of $100,000 per year plus the inability to manage for resistance properly.


TO: Bob Bellinger
Clemson University

FROM: Sue C. Ferguson
Richland County Environmental Health Services

SUBJECT: Potential Impact on Mosquito Control Services re: Loss of Organophosphate Insecticides

Pat Wright spoke with me and requested that I provide you with a few comments relative to the referenced subject. This is by no means an "in-depth" analysis, just those things that readily come to mind.

  • The Richland County Mosquito Control Program primarily uses malathion for its adulticiding activities. During the five year period 1994-1998, the program used anywhere from 219 gallons to 489 gallons per year, with the average usage approaching 400 gallons per year. The last time we purchased malathion in 12/97, we paid $25.75 per gallon including taxes and shipping. I contacted one vendor to obtain prices for alternative insecticides (permethrins, resmethrins, etc.) and the lowest price in a comparably sized container was $67.00 per gallon. If these products were applied at the same rate, the cost for our average yearly usage would be $26,800, an increase of 160%! Considering that our chemical budget is only $15,000/year including larvicides, we would not be able to provide our present level of service.
  • The malathion that we currently use comes in 55-gallon returnable/refillable drums. Should we not be able to use this product in the future, we would have to deal with the problems and costs associated with the triple-rinsing and disposal of containers.
  • The loss of the organophosphates would decrease our insecticide options should we have to address resistance problems associated with alternative products.

I hope these comments are along the lines of what you wanted. If you have any questions, please Email me or give me a call at (803) 748-4995.