Wild Things

The weird and wonderful in the natural world

Sarah Zielinski

Wild Things

Wild Things

Bacteria make male lacewings disappear

green lacewing

Green lacewings can be infected with a bacteria that prevents the survival of any males, a new study finds.

Sponsor Message

It’s the perfect setup for a teen dystopian novel: Men start disappearing from the population as many women fail to give birth to living male babies. But for some insects, it’s real life, and when that plot plays out among green lacewings, bacteria are the masterminds behind it all.

A species of green lacewing, Mallada desjardinsi, can be found under street lamps near trees and bushes on the campus of Chiba University in Japan. While there are males, females far outnumber them. When Masayuki Hayashi of Chiba University and colleagues collected some of the tiny insects in 2011, they found 57 females and a mere seven males.

The researchers brought the insects into the lab; 34 of the females produced offspring. But again, the sex ratio was off. Of the 35 broods produced, 14 contained both males and females and 21 contained only females.

Many of the females that produced offspring, though, were infected with bacteria. The scientists discovered that all 21 that produced only females were infected with a species of Spiroplasma. In these broods, the females did lay eggs that included males, but these males died during the embryonic or larval phases. And treating females with an antibiotic that killed off the bacteria restored the survival of male offspring. The team reports their findings June 15 in PLOS ONE.

Invertebrates, unlike humans and other vertebrates, let some groups of bacteria proliferate within their reproductive cells, and these microbes can pass from mother to offspring (though not from father to child). For such a bacterium, males just aren’t that necessary, and so they’ve evolved to kill off the males. Male-killing Spiroplasma have been found before in moths, butterflies, ladybird beetles and Drosophila flies. But what’s weird about the green lacewings is that their Spiroplasma, a previously unknown species, is more closely related to Sprioplasma species that infect plants than those that infect other insects, the researchers discovered by creating a huge phylogenetic tree of the bacteria. For now, the scientists aren’t sure, but green lacewings may have picked up an ancestor of their Spiroplasma sometime in the past while feeding on flower nectar.

What will happen to a species in which the males are disappearing? It could lead to altered sexual behavior, since males would no longer have to try so hard to find females since they’d be so outnumbered, Hayashi’s team notes. But to find out, they suggest a deeper study of the evolutionary forces acting on this bacteria-insect pairing.

Or we could just wait for someone to write that dystopian novel.


Vultures are vulnerable to extinction

By Sarah Zielinski 8:36am, May 11, 2016
Life history makes vultures more vulnerable to extinction than other birds, a new study finds, but humankind’s poisons are helping them to their end.

Crocodile eyes are optimized for lurking

By Sarah Zielinski 2:28pm, May 6, 2016
Crocodiles hang out at the water’s surface, waiting for a meal. A new study shows their eyes are optimized for spotting their prey from this position.
Animals,, Oceans

Cause of mass starfish die-offs is still a mystery

By Sarah Zielinski 11:53am, May 5, 2016
Sea stars off the U.S. west coast started dying off en masse in 2013. Scientists are still struggling to figure out the cause.

Chemical behind popcorn’s aroma gives a bearcat its signature scent

By Sarah Zielinski 9:20am, April 28, 2016
Bearcats smell like popcorn. Now scientists now why: The chemical responsible for popcorn’s alluring scent has been found in bearcat pee.

How animal poop could be key in solving echidna mystery

By Sarah Zielinski 2:30pm, April 26, 2016
The western long-beaked echidna hasn’t been seen in Australia in 10,000 years. But DNA in scat could reveal its presence.
Animals,, Oceans

Scientists find a crab party deep in the ocean

By Sarah Zielinski 9:00am, April 18, 2016
A trip to check out the biodiversity off the coast of Panama revealed thousands of crabs swarming on the seafloor.

New species of tumbleweed is just as bad as its parents

By Sarah Zielinski 9:35am, April 12, 2016
Two species of invasive tumbleweeds hybridized into a third. A new study finds it probably will be invasive, too.

A sperm whale’s head is built for ramming

By Sarah Zielinski 7:00am, April 8, 2016
Computer simulations of a sperm whale’s head show that an organ called the junk may help protect the brain when ramming other whales — or ships.

Mama birds pay attention to more than chicks’ begging

By Sarah Zielinski 12:00pm, April 6, 2016
Whether a mama bird decides to feed her offspring depends on more than just who begs most — her environment is a big factor, a new study finds.
Animals,, Oceans

In the Coral Triangle, clownfish figured out how to share

By Sarah Zielinski 11:41am, April 1, 2016
In the Coral Triangle in Southeast Asia, an area of rich biodiversity, clownfish species often share anemones, a new study finds.
Subscribe to RSS - Wild Things