Irradiating And Eradicating The Tsetse Fly Scourge

http://www.forbes.com/sites/jamesconca/2015/04/02/irradiating-and-eradicating-the-tsetse-fly-scourge/

The International Atomic Energy Agency (IAEA), partnering with the Senegalese government and the United Nations FAO, used a radiation-based Sterile Insect Technique (SIT) to almost completely eradicate the tsetse fly scourge in the Niayes region of this West African nation. The tsetse fly is a bloodsucking insect that kills more than three million livestock in sub-Saharan Africa every year with the nagana wasting disease, sickens and kills over 75,000 people with the sleeping sickness, and destroys over $4 billion each year in agriculture. Senegal has 40,000 square miles plagued by this menace, but is only one of 38 countries infested with tsetse flies. Its Niayes regionwas selected for a SIT application because of its particular breed of cattle that produce more milk and meat than other cattle, but were being decimated by the tsetse fly. Infertility, weight loss, reduced meat and milk production, and fatigue so bad the cattle couldn’t pull a plough or carry any weight, the people of this region were suffering without the help of their essential animals. Not to mention the direct effects on humans themselves. The sleeping sickness affects the central nervous system causing disorientation, personality changes, slurred speech, seizures, difficulty walking and talking, and finally death.





A member of the common housefly family, the tsetse fly is a strange beast. It’s the only insect that bears live young and nurses them by lactation (Britannica). They have an unusual microbial symbiosis with the bacterium Wolbachia and have even exchanged and integrated DNA sequences with this pathogen to mutual benefit (Science). Wolbachia itself is a strange organism that is the most common reproductive parasite in the bioshpere (Wiki), having mutually evolved with many insects. Some insect species cannot reproduce, or even survive, without being infected with this bacteria.

But after only four years of using radiation to sterilize male tsetse flies, this region of Senegal is basically free of this torment.

“I have not seen a single tsetse fly for a year now,” said cattle farmer Oumar Sow (IAEA). “Before, we had to carefully select the time for milking.”

Loulou Mendy, a pig farmer, says, “Now, we can even sleep out in the open.”

SIT is a form of insect control that uses ionizing radiation to sterilize male flies. The males are mass-produced in special facilities, irradiated, and released in infested areas from the ground or by air. They mate with wild females, which then do not produce offspring, but also do not mate again.

It was thought that decoding the tsetse fly genome would offer the best chance of eradicating this scourge (NYTimes), but the simpler, easier SIT radiation technique has worked better than anyone could have imagined. The release of sterile male flies began in 2012, after a three-year period of pilot trials, training, preparation and testing. Radiation is working for many infectious insects on almost every continent on Earth (FAO/IAEA). In addition to tsetse flies, SIT has been applied to hundreds of species of fruit flies, moths, mosquitoes and screwworm flies. The outcome of this radiation technique is almost magic. Besides sleeping easy, the people in rural Niayes are looking forward to a 30% increase in their income this year.