09/05/02 - University of Florida Develops New Mosqutio Laravicide
A new mosquito larvicide developed at the University of Florida's Medical Entomology Laboratory in Vero Beach is expected to be on the market under the brand name "Skeetercide" in time for the next mosquito season. The "Skeetercide" formulation is based on a naturally occurring mosquito hormone - "trypsin modulating oostatic factor" or TMOF - that is produced in mosquito ovaries and acts to control digestion of the blood ingested when a mosquito bites. When ingested by larvae as part of a mosquito control program, TMOF switches off the digestive system, effectively starving the larvae to death in 4-6 days.
After discovering the biological properties (the mode of action) of the active ingredient, the research team led by biochemist Dov Borovsky needed to develop a formulation that would be readily eaten by larvae and that would remain near the water surfaces where mosquito larvae eat. They found that yeast serve well for this purpose when bioengineered to include TMOF and bound with cellulose particles to produce granules that are stable in the water for about 20 days.
In lab tests, the hormone has been shown to kill all mosquito species tested and to be effective in salt and fresh water. The next step in determining efficacy is field testing, which will begin this month in salt ponds in Key West, Florida. TMOF is expected to be environmentally benign, since mosquito predators ingest it regularly with no evidence of side effects. Product developers say it poses no human health concerns and that it is "safe enough to use in drinking water containers." The product is being commercialized by a North Carolina company, Insect Biotechnology Inc., that holds the license to University og Florida patents.
Although the other commonly used mosquito larvicides are also classified by EPA as "reduced risk" pesticides, the development of TMOF is exciting news because the availability of alternatives is an important pest control strategy both for (a) staving off development of insect resistance resulting from exclusive and repeated use of any one product or method and (b) having products suitable for disparate conditions.
For example, Culex pipiens and C. quincquefasciatus (the northern and southern house mosquito species, respectively) tend to breed in polluted water where the larvicide Bacillus thuringiensis israelensis (Bti) is less effective.
Additional information on this larvicide is available on the Environmental News Network.