Sterile Insect Techniques, GE mosquitoes and gene drives

Hanson, J,  GeneWatch,  2017.

One of the great temptations in any field is to promote your solution to a problem as the only solution. The recent application of gene drives to sterilize mosquitoes that transmit malaria or viruses like dengue and zika is an example of this tendency to first develop a technology and then look for applications that might justify its use.; ; For at least 70 years, scientists have been trying to sterilize insects to prevent them from spreading disease, especially mosquito-borne diseases like malaria, dengue and zika, an approach known as “sterile insect technique.” Sterilizing some insects with irradiation has been successful in preventing their reproduction.[1] In the 1950s, it was used to rid the southeastern U.S. of the New World screwworm Cochliomyia hominivorax (Coquerel), a deadly parasite of livestock. During the next 43 years the technique was used to eradicate this screwworm from the U.S., Mexico, and Central America. Currently, the largest use of Sterile Insect Technique in the U.S. is for the control of Mediterranean fruit fly. Irradiated bollworms are also being released to control cotton boll weevils, and irradiated coddling moths are being released to help protect apples and pears.[2] Interestingly, Rachel Carson, in Silent Spring, warned that using the Sterile Insect Technique to control a population of insects that could rebuild from neighboring islands or other populations was especially challenging. Talking about a SIT effort to control houseflies in the Florida Keys, she wrote:; ; “In a test on an island in the Florida Keys in 1961, a population of flies was nearly wiped out within a period of only five weeks. Repopulation of course followed from nearby islands, but as a pilot project the test was successful….; ; One of the problems of sterilization by radiation is that this requires not only artificial rearing but the release of sterile males in larger number than are present in the wild population. This could be done with the screw-worm, which is actually not an abundant insect. With the housefly, however, more than doubling the population through releases could be highly objectionable [to the local people].”[3]