October 16, 2010

October 16 - Cochliomyia hominivorax

The New World screwworm, Cochliomyia hominivorax, is a parasitic dipteran whose maggot larvae invade organs or tissues of living organisms in a type of infestation called myiasis. Attracted to wounds and sores, an adult C. hominivorax female deposits batches of 10 to 400 eggs onto the living tissue of warm-blooded vertebrates, even humans. Larvae feed and develop for 3 or 4 days and then drop off the host body to pupate in the soil, later becoming adult flies. Once prevalent throughout North America, this parasite was known for infesting livestock and causing major economic loss. Their damaging impact prompted the development of the Sterile Insect Technique (SIT) by Raymond Bushland and Edward Knipling in the 1950s. Male screwworm flies were sterilized by irradiation in the laboratory and released to mate with wild females. The females subsequently produced infertile eggs and over generations of sterile male release the population of C. hominivorax was greatly reduced. This control method was successful in eradicating the parasite from North America and much of Central America, leading former U.S. Secretary of Agriculture Orville Freeman to refer to the Sterile Insect Technique as "the greatest entomological achievement of [the 20th] century."

Contributed by Phil Scheibel.

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