Over My Dead Body

Scientists have already enlisted blood-sucking leeches in their quest to monitor rare mammals. Now another team has suggested an equally icky way to track mammal numbers: by extracting DNA from carrion flies that feast on the animals’ carcasses. (Hat tip: Nature News.)

Researchers want to monitor mammal populations, but this is easier said than done. Tracking down nests or footprints is time-consuming, so scientists have turned to other methods such as camera traps. Recently, one team showed that leeches, which eat the blood of other animals, continue to carry their victims’ DNA for months. By analyzing the leeches’ DNA cargo, scientists could figure out which mammal species are present in the area and how common they are.

In a Molecular Ecology study, researchers tested whether blow flies and flesh flies could perform a similar role. The team caught flies at Taï National Park in Côte d’Ivoire and Kirindy Forest in Madagascar. Eighty-six flies were captured as they buzzed around the carcasses of known animals, and researchers could recover the DNA of those species from 63 percent of the flies. The team also found mammal DNA in about 40 percent of flies caught at random.

The insects carried DNA from about two dozen species, including pygmy hippo, little collared fruit bat, porcupine, and dwarf lemur. “Carrion flies therefore represent an extraordinary and thus far unexploited resource of mammal DNA,” the authors conclude. Roberta Kwok | 10 January 2013

Source: Calvignac-Spencer, S. et al. 2013. Carrion fly-derived DNA as a tool for comprehensive and cost-effective assessment of mammalian biodiversity. Molecular Ecology doi: 10.1111/mec.12183.

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