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Phoenix-Made Moths Could Help Protect California Nut Industry

(Photo by Annika Cline - KJZZ)
Earl Andress holds a tray of navel orangeworm containers.

The pink bollworm used to be the bane of cotton farmers. But you won’t find any of these tiny caterpillars in cotton fields today.

The U.S. Department of Agriculture said this is the last year it’s checking fields before it’ll officially declare the pest eradicated.

That’s partly thanks to a USDA facility in Phoenix that mass-produced sterile bollworm moths and released them into the fields, reducing population. It’s the only facility of its kind, and it’s now setting its sights on doing the same with a new pest, the navel orangeworm. 

You might think the navel orangeworm is a threat to the citrus industry. 

“Yeah, that’s what I thought,” said Eoin Davis, the director of the Pink Bollworm Rearing Facility.

“It’s not particularly a pest of concern to the citrus industry.”

This caterpillar is wreaking havoc on the nut industry, maturing inside the shells and eating the nut meat. When they become moths they’re not a threat anymore. That’s why growers are interested in using sterile navel orangeworm moths to cut down the numbers. Davis said it’s similar to how the cotton industry paid for the bollworm project.

“The navel orangeworm project is a hundred percent funded by the pistachio industry,” Davis said.

They might not see returns on that investment for a while. This isn’t something that happens overnight. It could reduce costs long term. David Haviland is with the Integrated Pest Management program at the University of California and said the costs of dealing with this pest right now are huge.

“On every acre of almonds or pistachios in California, growers will spend two, three, sometimes $400 on an acre just doing what’s called mummy removal,” he said.

Mummy removal is clearing out all the leftover nuts after harvest, which are prime real estate for moths to lay their eggs. That’s one strategy of many. Farmers also use pesticides Haviland said are expensive and a paperwork nightmare.

“If the growers can use the sterile technique to actually avoid pesticide use altogether, that would be an ideal situation for both the farmer as well as for the consumer that’s concerned about how their food is produced,” Haviland said.

A work in progress

A climate-controlled, windowless room at the rearing facility is home to some of the bollworm moths left. Earl Andress is an entomologist with the facility. He pulled out a tray of six plastic containers, each about as big as a margarine tub.

“With the pink bollworm, you get 3,000 from each one of these cells,” he said.

There's about 840 containers— we’re standing in a room of more than 2.5 million bollworms. That’s nothing compared to what they used to produce.

“At the peak we were producing well in excess of 28 million a day,” Andress said. 

It was more than twice what they expected. They created a really efficient system. The orangeworms are proving more difficult. Andress said they like their space.

“Our production is a 25th of what it is with pink bollworm,” he said.

So, it costs more to produce, and you need more of these moths to be effective.

“The navel orangeworm is a very very strong flier,” said Bob Curtis with the Almond Board of California. “The question then becomes how much area can you release into.”

Until they have more answers, Curtis and some others in the nut industry aren’t sold yet on the sterile release method.

“There’s other work in the field that needs to happen,” said Eoin Davis.

The facility is sending a shipment of navel orangeworm moths to California next month “to see how well these things disperse when you release them, how easy they are to recapture, other things of that nature,” Davis said.

Then they’ll understand better what they’re up against. 

“One of the things the pink bollworm program taught us over the years is that you don’t know what your breakthroughs will look like until you make them,” Davis said.

Annika Cline was a producer for KJZZ's The Show from 2014 to 2019.