By Cassandra Willyard | November 9, 2010 | 12 Comments
Yesterday I shared a room with 3,000 buzzing tsetse flies – the bugs that carry the sleeping sickness parasite.
Tsetse flies live in Africa, but these guys are Yalies. They buzz and breed in racks of mesh cages on the 6th floor of Yale’s School of Public Health. (They also recite some Goethe – it’s the Ivy League, after all). By studying their inner workings, scientists like Serap Askoy hope to figure out how to stop them from spreading the parasite.
Three things you may not know about tsetse flies:
1. Female flies give birth to live babies (ok, you might call them maggots).
2. They produce milk for their maggots. Tsetse milk is similar to mammal milk, but the larvae only get to nurse inside the womb. After birth, they’re on their own.
3. And from the Annals of You-Must-Be-Joking, tsetse flies carry a bacterium called Wigglesworthia, named for the British entomologist who first described it: Sir Vincent Brian Wigglesworth. I’m not kidding. Wigglesworthia.
Tsetse flies don’t just have Wigglesworthia, they need them. The bacteria produce nutrients that enable the tsetse flies to reproduce. Female flies lacking these bacteria are sterile.
Wigglesworthia (it just makes me happy to write it) comes in two flavors: The first kind lives inside the fly’s cells in a special organ in the gut. The second kind floats freely in the space between cells in the female’s milk glands. When the baby maggot feeds, it ingests not only milk, but also a hefty helping of Wigglesworthia.
But, if you give a tsetse fly the antibiotic ampicillin, as these researchers did, Wigglesworthia dies. The antibiotic can’t penetrate the fly’s cells, however, so only the bacteria in the milk glands die. Thus mom fly, who still has Wigglesworthia, can have a baby, but her daughters, who don’t have the bacterium, can’t. They’re sterile.
How will this knowledge lead to the control of sleeping sickness? Yes, that would have been a good question for me to ask while I was standing in the tsetse lab. But I didn’t. So I can only guess. Perhaps we could promote tsetse fly sterility by hanging bags of ampicillin-laced blood in the African bush? (There’s a reason I’m not a public health policymaker).
Image credit: Cassandra Willyard