UC maps genome of agricultural monsters

Joshua Benoit, an associate professor in UC’s College of Arts and Sciences, contributed to genetic studies of New World screwworms that feed on livestock and thrips, tiny insects that can transmit viruses to tomatoes and other plants.

It’s the latest international collaboration for Benoit, who previously unraveled the genomes of dreaded creatures such as bedbugs.

Just in time for Halloween, Benoit’s new study subject is no less creepy. The New World screwworm’s Latin name means “man-eater.” These shiny blue flies with pumpkin-orange eyes lay up to 400 eggs in open cuts or sores of cattle, goats, deer and other mammals. Emerging larvae begin gnawing away on their hosts, feeding on living and dead tissue and creating ghastly wounds.

“Sometimes you’ll see a deer missing a chunk of its head. The flies can cause small wounds to become massive injuries," he said.

Benoit's work demonstrates UC's commitment to research as described in its strategic direction called Next Lives Here. 

Benoit and his co-authors sequenced the genome of screwworms and identified ways of slashing populations by targeting particular genes that determine sex and control growth and development or even particular behaviors that help the flies find a suitable animal host.

A 2016 outbreak in the Florida Keys threatened to wipe out endangered Key deer before the USDA intervened, treating infected animals for parasites and releasing millions of sterile screwworms on the island chain until they disappeared.

“The U.S. still helps pay for control programs in Panama mainly because we don’t want screwworms coming back here. It’s the cheapest way to prevent potentially billions of dollars in damage,” Benoit said.

One possible way to cut costs would be to raise only male screwworms that are intended for release so the lab wouldn’t incur the huge costs of feeding female screwworms. UC’s genetic study could help scientists cull females before they hatch.

“So you’re left with surviving males. Then you sterilize the males and that would save a lot of money because you’d only have to raise the males for release,” he said.

Next, Scott said he wants to understand how the livestock-devouring screwworm Cochliomyia hominivorax evolved as a parasitic meat eater while similar species prefer carrion.

Benoit also contributed to a genomic study in the journal BMC Biology for an insect not much bigger than the dot over the letter i. Thrips, a tiny winged insect, are legion around the world and feed on a wide variety of crops, including soybeans, tomatoes — even cannabis. They can destroy crops both by eating them and transmitting harmful viruses.

In a study led by entomologist Dorith Rotenberg at North Carolina State University, researchers mapped 16,859 genes that helped understand the thrips’ sensory and immune systems and the salivary glands that transmit the viruses.

“The genome provides the essential tools and knowledge for developing genetic pest management strategies for suppressing thrips pest populations,” Rotenberg said.

Featured image at top: UC assistant professor Joshua Benoit and his students Elise Didion, Chris Holmes and Sam Bailey pose in his biology lab in January before the COVID-19 pandemic. Photo/Joseph Fuqua II/UC Creative + Brand