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United States Department of Agriculture

Agricultural Research Service

Pass The Mold

Hold the chemicals and pass the mold, please


Drawing of chemical flasks, bottles, and beakers holding colored liquids

Be glad you're not a sugar beet root maggot.

Scientists are experimenting with a nature-based way of making life miserable for this tiny crop pest.

Revolving dollar signAnd for good reason. The root maggot costs beet growers millions of dollars each year in crop damage and chemical insecticides.

About half of America's 1.5 million-acre beet crop is treated with insecticides. Without them, though, growers would have a tougher time stopping the maggot's costly sweet tooth.

Still, new weapons are needed, especially since beet crops supply about 35 percent of America's sugar for cereal, baked goods, sodas and other things you probably like to eat.

Now, relief could be in sight with a natural soil fungus, shown below. Scientists are testing it as an option to spraying chemicals.

Scanning electron micrograph (SEM): Highly magnified spore forms for the fungus Syngliocladium tetanopsis

It won't beat back maggot attacks as fast as chemicals. But the fungus could offer a safer way of getting the job done.

Unlike some insecticides, the fungus doesn't harm fragile beet seedlings, or helpful insects like ladybugs. That's the word from Chris Wozniak, a microbiologist at the U.S. Environmental Protection Agency.

In soils, a favorite fungus hangout is near sugar beet roots where maggots feed. That's also where Wozniak and coworkers first discovered the fungus.Drawing of beet plant above and below ground

This happened in 1994 when they were digging around for maggots in a North Dakota sugar beet field. At that time, Wozniak was with USDA's Agricultural Research Service (ARS).


Now, he and ARS scientist Ann Smigocki are looking for a commercial partner to help perfect a natural insecticide made from the fungus' spores. Smigocki works at ARS' Molecular Plant Pathology Laboratory in Beltsville, Maryland. It's about 45 minutes from Wozniak at EPA's Biopesticides and Pollution Prevention Division in Arlington, Virginia.

They say beet growers could coat the fungus-insecticide directly onto beet seed, or spray it into soils where maggots are lurking in wait.

Drawing of molecule model with elements in different colorsSome chemical insecticides now used short-circuit the nervous systems of crop-eating insects, like the root maggots. But the researchers' fungal fighter uses a different tactic, and it's not pretty.

Cartoon eyeglasses with whirling eyepieces If you had bionic eyes, you'd spy millions of the fungus' cigar-shaped spores attach onto a passing maggot. Soon after, the spores would drill into the maggot's body.

Sugar beet root maggot infected by Syngliocladium tetanopsis fungus.Once inside, they'd begin reproducing on the maggot's organs and tissues. Eventually, the fungus spreads to the maggot's outside. There, it can take on many forms, like slimy, amber-colored mold, or twisted horns poking out from the root maggot's body.

Yuck.

But don't worry, the fungus' main target is the root maggot--not people, animals or plants.

From what scientists have seen in the lab, 95 to 100 percent of newly hatched maggots die in 3 to 5 days. Older, bigger maggots take several weeks, but few escape.

In grapefruit as well as many other fruits, one female Mexican fruit fly can deposit large numbers of eggs: up to 40 eggs at a time, 100 or more a day, and about 2,000 over her life span.

It is a gruesome end, Wozniak admits.

But use of the fungus could help growers avoid costly losses, without resorting to chemicals.

Scientists also want to see if the fungus will zap certain pesky flies, like those that bug citrus.


By Jan Suszkiw, Agricultural Research Service, Information Staff


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Last Modified: 2/14/2011
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