Will Lee County Mosquito Control District be Utilizing Genetically Modified Mosquitoes?
While genetically modified mosquitoes (GMM) may be appropriate for some situations, it is not a likely option for Lee County at this time. There are factors which would make this control tool unsatisfactory for Lee County. To understand why genetically modified mosquitoes would work in some situations, but not in others requires some basic understanding on the method and what species of mosquito is being targeted for control.
Utilizing sterile insects as a control technique is not new technology. To use sterile insects for control purposes: the insects must be able to be mass produced in a laboratory, insects are then sterilized or altered to have a lethal gene not harmful to the carrier insect, the insects must be able to compete with the wild population for mating, the number of sterile insects released must be sufficient to overwhelm the native insect population, and there must be a barrier or buffer that minimizes the movement of insects from outside the sterilization zone.
A successful example of utilizing sterile insects to control a harmful insect is the screwworm fly erradication in the south east United States by the United States Department of Agriculture (USDA). The USDA began the program in Florida in 1958. A laboratory/factory in Sebring began rearing 75 million sterile screwworm flies per week. They released 75 to 300 sterile screwworm flies per square kilometer by airplanes. The flies were pushed out of the United States and a buffer area in Central America was created where sterile screwworm flies are continually released to prevent re-entry into the United States.The program has been successful and the last infestation in Florida was in 1959 and the last reported case in the United States was in 1982.
Researchers have been seeking to find a way to use sterile insect techniques in the control of mosquitoes. The company Oxitec has been a leader in this research. One of the benefits of using a sterile insect technique is that it focuses on the specific species to be controlled. Oxitec is working with the mosquito species Aedes aegypti, which is the vector of Yellow Fever, Dengue, Chikungunya, and Japanese encephalitis . For more information on Aedes aegypti go to: http://entnemdept.ufl.edu/creatures/aquatic/aedes_aegypti.htm.
Oxitec uses Aedes aegypti mosquitoes that have been genetically modified to require tetracycline in their diet in order to survive. The genetically modified male Aedes aegypti mosquitoes would be released to mate with native, female Aedes aegypti mosquitoes. The mosquitoes would produce nonviable larvae that would die due to the lack of tetracycline in their diet. Oxitec has successfully utilized genetically modified Aedes aegypti mosquitoes in the Cayman Islands, Brazil, and Malaysia and is currently working with the Florida Keys Mosquito Control District and seeking permission to test this technique in Key West.
Lee County Mosquito Control District would not select this method of control at this time for several reasons. The primary concern would be while sterile males are released, adulticide treatments for other species of mosquitoes would require extra coordination to prevent killing released GMM. This could be problematic if a salt marsh brood of mosquitoes hatched or if one of the other species of mosquitoes that can vector other mosquito borne diseases needed treatment.
A second concern for use of GMM in Lee County would be migration and reintroduction of Aedes aegypti mosquitoes from outside areas surrounding Lee County. A third concern would be that another mosquito species, Aedes albopictus, that shares the same habitat as Aedes aegypti would populate areas vacated by the Aedes aegypti mosquitoes. Aedes albopictus is a competent mosquito vector for mosquito borne disease and is currently not present in the Florida Keys.
A fourth concern is Lee County is geographically large compared to the other areas selected for use of GMM. Lee County would require significantly more GMM to be released in order to be successful.
Although Lee County Mosquito Control District views GMM as a viable control tool, Lee County Mosquito Control District is not considering the use of GMM at this time for the above mentioned reasons.