With the rate our world is changing and warming, there’s an urgency to cataloging and monitoring Earth’s diversity. Traditional efforts are often expensive and require many scientist- (and citizen scientist-) hours visiting remote lands that are often inaccessible.

But researchers are discovering other ways to monitor regional biodiversity and animal populations. Last year, Danish scientists found they could extract mammal DNA from leeches’ last blood meals. Now, German researchers are grabbing mammal DNA from widespread carrion flies.

Carrion flies (Calliphoridae and Sarcophagidae) feed on animal corpses, open wounds, and feces. While disgusting, the flies are widely distributed, found in diverse habitats and, perhaps most importantly, easy to catch. And since they don’t have acids in their guts like we do, scientists are able to retrieve viable DNA fragments from their stomachs.

For a recent study, published in the February 2013 issue of Molecular Ecology, the German scientists looked at carrion fly guts from two different forests—Taï National Park in Côte d’Ivoire, a rainforest, and the Kirindy Forest in Madagascar, a dry, deciduous forest. Among the mammals identified from the DNA fragments in the carrion flies were monkeys, lemurs, rodents, shrews, antelope, bats and even a hippopotamus. The DNA also revealed two bird species and one amphibian species.

Using deep sequencing technology, researchers are able to identify exact species, and hopefully at some point, they can glean information about population sizes and the spread of diseases.

The authors of the recent paper argue that with carrion flies and leeches performing their normal, albeit gross duties, perhaps scientists and conservationists can have entire armies of biodiversity monitors in the field.

Calliphora vomitoria image: JJ Harrison/Wikipedia

The Riverside flies are not alone. Scientists have known about flies’ love of beer since the 1920s. But Anupama Dahanukar, an entomologist at UC Riverside, wanted to know why so she headed to the lab.

She and her colleagues examined the feeding preference of the common fruit fly for the pale ale (the least sweet beer) and other products of yeast fermentation. They found that a receptor (a protein that serves as a gatekeeper) associated with neurons located in the fly’s mouth-parts is instrumental in signaling a good taste for beer.

The receptor in question is Gr64e.  When a fly settles on beer, Gr64e detects glycerol and transmits this information to the fly’s neurons, which then influences the fly’s behavioral response.

Once the group identified the receptor, NPR reports,

Dahanukar and [colleague Zev] Wisotsky even found the particular gene responsible for flies’ ability to detect glycerol. When they created flies missing that gene, and gave them the sugar water-beer choice, the flies went for the sugar water.

“Taste becomes important only after the fly makes physical contact with food,” says Dahanukar. “A fly first locates food sources using its odor receptors—crucial for its long-range attraction to food. Then, after landing on food, the fly uses its taste system to sample the food for suitability in terms of nutrition and toxicity.”

As often happens in science, Dahanukar’s discovery has left her with more questions than when she started this research. Her lab will work to answer them.]

“How do you get information from the chemical environment to the brain—not just in flies but other insects as well?” Dahanukar asks. “How is that information processed to give rise to appropriate behavior? How does feeding behavior change with hunger? These are some questions we would like to pursue.”

The research was published earlier this month in Nature Neuroscience.

Image: UCR Strategic Communications