Endangered Beetles Hit the Dirt
For the first time ever, an endangered species has been released back into Missouri prairies. The American Burying Beetle may be back on its way to thriving, though in this beetle's world, thriving means living underground and feasting on meatballs.
The American Burying Beetle was once found in 35 states, but numbers have been on the decline. After its 1989 listing as endangered species, field surveys showed populations in only six states. Currently, the Center for the American Burying Beetle Conservation, headed by Bob Merz at the St. Louis Zoo, has bred thousands of the beetles after research into what caused their decline in the first place.
On June 5th, Merz and his crews released 300 of the beetles into Wah-Kon-Tah Prairie near El Dorado, Missouri. Burying beetles can live in both woodland and prairie conditions, which is what made Wah-Kon-Tah a good choice.
The Burying Beetle lives an interesting life. In addition to its striking black-and-orange coloring, the beetle is nocturnal and spends most of its time underground. They can grow up to an inch and a half long, and usually smell like the dead meat they consume. The beetle can detect carcasses of pigeons, rats, and mice from almost two miles away. When they finally arrive, they dig around the carcass and end up burying it, hence the name.
"They'll actually find a field rat or a bird, or even something as big as a carrier pigeon. Then they dig until it sinks down, and then they dig down in and make a cavity around the bird," explained Bill Graham, media specialist for the Missouri Department of Conservation and attendee at the release.
One of the most interesting things about the beetle, however, is its parenting style. Both the male and female feed their young, a rare quality in insects. The parents bury a carcass, then roll the meat into a ball that they protect from bacteria and fungi with their own bodily secretions. When the young hatch, the parents make a sound with their wings that attracts the larvae to their carefully crafted 'meatball.'
The beetles are also host to mites: phoretic mites attach themselves to the beetles, and when they arrive at a carcass, they debunk and eat the fly eggs that flies inevitably have already laid on it. The mites get transportation to food, and the beetles get a cleaned carcass. While the beetles are underground, there are very few mites on and around them. When they prepare to leave, it's a different story.
"The male leaves the brood chamber a few days before the female," explains Merz, "Right before he is ready to leave, hundreds or even thousands of mites come from the surrounding area for a ride to the next carcass. Sometimes it's so many that all you see is the two antennae and six legs of the beetle sticking out of a ball of mites."
The crew tried to mimic the natural conditions of the beetles' broods, digging holes and placing deceased pigeons for a 'starter home.' The broods were protected by a covering of chicken wire and stakes to keep scavenging mammals away.
There are several theories about the species' decline, including habitat fragmentation and light pollution, which may confuse the nocturnal animal.
"It's interesting to overlay a map of the beetle's former range onto a satellite image of North America at night," Merz explained. "There's a bright glow that pretty much covers the former range. More studies need to be done, but it's an intriguing hypothesis."
American Burying Beetles are classified as a non-essential, experimental population by the U.S. Fish and Wildlife Service. They are not allowed to be bought or sold, but other than that there are no land rules regarding their presence on private property, and they do not effect crops or livestock in any way.
"Basically this is sort of an experiment. Can they take this insect that hasn't been seen in a long time in Missouri, turn it loose in a place with protections in a natural ecosystem, and see it come back and rebuild a sustainable population?" Graham said.
Merz was humbled by the event and his team's involvement after working with the species since 2004.
"Missouri is not only the beetle's ecosystem, it's my ecosystem, it's every residents' ecosystem. When an entire species disappears from my ecosystem in such a short amount of time, personally, I want to do right by that species. It's a big responsibility... a humbling responsibility," he said.
The sites were checked on June 15th, ten days after the release the brood chambers were checked. Though some mammalian scavenging occurred, they found that about 70% of the broods they checked had larvae.
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St. Louis Zoo to Reintroduce the Endangered Burying Beetle (STL Today)