Sterile Insect Technique helped eradicate screwworm from US in 1960s. How does it work?

A first case of new human screwworm has been reported in the US. It has been observed that the parasitic flies feed on warm-blooded animals and pierce through them. If untreated, the infestation can lead to become fatal. Screwworm usually infests cattle and wild animals; it's rare to target humans. The recent case was reported in Maryland, but it surfaced after Brooke Rollins, Secretary of the Department of Agriculture, along with other government officials, travelled to Texas to announce plans to build a sterile fly facility, which would help ward off the pests. The disease was eradicated from the US in the 1960s using Sterile Insect Technique.

What is Sterile Insect Technique?

In a bid to eradicate the infestations, Rollins advocated the adoption of a plan which was used in the past. A sterile fly facility produces a large number of male flies and then sterilises them. They are later released to mate with the female flies, and this drastically reduces the population. This method was succesfull and effective in eradicating screwworm in the 1960s.

A sterile fly facility produces a large number of male flies and sterilises them - these males are then released to mate with wild female insects, which collapses the wild population over time. This method eradicated screwworm from the US in the 1960s.

In a letter written to Charles A. Stewart, Secretary-General Manager, Texas and Southwestern Cattle Raisers Association highlighted:

“The investigations showed that a normal female screwworm fly mated with a male which had been made sterile by exposure to X-rays or gamma rays produced infertile eggs. The information obtained supported the theoretical calculations that the introduction of a preponderance of sterile male flies into a normal population would result in a reduction in the numbers of the species simply because the sterile males would greatly reduce the production of normal flies.”

The letter further noted, “It was demonstrated in laboratory cages and small field tests that the continued introduction of sterile males would soon result in the complete elimination of the insects. The final crucial experiment was conducted by our research group on the island of Curacao in 1954 where the screv-vorm was eradicated by use of this technique.”

What are screwworms?

Screwworms are parasitic flies which feed on the host and, if untreated, can be fatal. The female flies lay eggs in wounds on animals. They usually do so on warm-blooded animals. And once the eggs hatch, the larvae then begin digging through the host animal's body. These parasitic flies are similar to maggots, and their activity seems like a screw being driven into wood. They usually feed on cattle and wildlife; infestations in humans is a rarity, but once they attack, it can turn fatal.