Bacteria genes offer new strategy for sterilizing mosquitoes

wolbachia bacteria
STERILITY CULPRITS Wolbachia bacteria (red) effectively sterilize a male mosquito by infecting the insect’s testes (blue), shown at 100 times magnification. Now, researchers have identified genes that may be responsible for the sterility.

A pair of bacterial genes may enable genetic engineering strategies for curbing populations of virus-transmitting mosquitoes.

Bacteria that make the insects effectively sterile have been used to reduce mosquito populations. Now, two research teams have identified genes in those bacteria that may be responsible for the sterility, the groups report online February 27 in Nature and Nature Microbiology.

“I think it’s a great advance,” says Scott O’Neill, a biologist with the Institute of Vector-Borne Disease at Monash University in Melbourne, Australia. People have been trying for years to understand how the bacteria manipulate insects, he says.

Wolbachia bacteria “sterilize” male mosquitoes through a mechanism called cytoplasmic incompatibility, which affects sperm and eggs. When an infected male breeds with an uninfected female, his modified sperm kill the eggs after fertilization. When he mates with a likewise infected female, however, her eggs remove the sperm modification and develop normally.

Researchers from Vanderbilt University in Nashville pinpointed a pair of genes, called cifA and cifB, connected to the sterility mechanism of Wolbachia. The genes are located not in the DNA of the bacterium itself, but in a virus embedded in its chromosome.

When the researchers took two genes from the Wolbachia

6 Unexpected Consequences of a Solar Eclipse

Fear ye not, stargazer. That solar eclipse doesn’t mean that you’re going to die, that some higher force is about to smite you, or that demons are lurking in the coal shed. No, it means the Moon has passed in front of the Sun and blocked it out. At worst, it will be a bit colder and dark for a few minutes. But there are some unexpected consequences of a solar eclipse that you might not be aware of.


Animals rely on a day/night cycle in order to function correctly, and the sudden darkness can trick animals into switching their behavior to nighttime mode. Nocturnal animals such as crickets start chirping, mosquitoes come out to feed, and predators such as owls wake up and venture out of the nest. Other birds, such as geese, instinctively return to roost when the eclipse starts, only to pull a U-turn when it ends. Cicadas, normally very loud creatures, stop singing to conserve energy.

Other animals just freak out. Bees markedly increase activity. Squirrels too fear for food, and run around far more than usual. But, feel sorry for hippos. They get scared and hide underwater until it ends.


Eclipses were historically considered ill omens by many cultures, but few considered them so portentous as the ancient Chinese. Approximately 4000 years ago, two astronomers called Hsi and Ho were tasked with predicting solar eclipses in an effort to stay ahead of ill fortune. However, their solitude soon begat drunkenness, and they not only failed to predict an eclipse which occurred,…