Entomologists Say 3D Printing Key to Saving California Avocado Crop

The vast majority of American-grown avocados come from California, and the rest come from Florida and Hawaii. The domestic avocado market is worth $429 million, and all but $23 million of that national market comes from the Golden State.

Now scientists say a “beetle-fungus complex” has caused dieback and mortality to avocados and numerous agricultural and landscape ornamental trees in Los Angeles County.

The fungus Fusarium euwallaceae forms a symbiotic relationship with the polyphagous shot hole borer beetle, and together they add up to what’s known as Fusarium dieback (FD).

Dr. Akif Eskalen, an extension plant pathologist at the University of California, Riverside, says that’s bad news indeed, and that California isn’t the only locale in the world where plants suffer from the complex.

“This beetle has also been found in Israel, and since 2009, the beetle-fungus combination has caused severe damage to avocado and landscape trees there,” Dr. Eskalen says.

Dr. Eskalen says he first discovered the beetle-fungus complex in 2012 on avocado trees found in the backyards of Los Angeles County, and since then, his lab has conducted ongoing monitoring efforts in Southern California to address the problem.

“Our survey efforts show that this pest-disease complex is actively spreading in Los Angeles, Orange and recently San Bernardino, Riverside and San Diego counties,” Dr. Eskalen says.

It works like this: When the beetle burrows into the tree, it injects the host plant with the fungus carried in its mouth-parts. The fungus then attacks the vascular tissue of the tree and blocking the transport of water and nutrients from the roots to the key parts of the tree. The condition eventually causes FD and ultimately – the death of the tree.

To add insult to injury, the beetle larvae live in galleries within the tree while feeding on the fungus.

The beetle in question is thought to have originated in Southeast Asia, perhaps Vietnam, and at first researchers identified it as the Tea Shot Hole Borer. Following analysis of DNA evidence, it appears that it’s actually a species in the same genus.

Dr. Eskalen says FD has been observed in approximately 117 separate plant species in Southern California, and a good share of those are species generally found in urban landscapes including fully a third of the street trees in Southern California, avocado trees and nine other tree species native to California.

Now researchers at the University of California, Riverside are using 3D printing technology to accelerate the study of the beetle-fungus complex.

Dr. Richard Stouthamer, a professor of entomology at UC Riverside, says 3D printing has been key to fighting the battle against this insidious beetle-fungus complex. The researchers have used the technology to create traps for the beetles.

“Having these 3D printed traps available allows us to study the impact of insecticides,” Stouthamer says.

And a postdoctoral researcher at UCR, R. Duncan Selby, goes further. Selby says the capabilities of 3D printing allows researchers to design complex tools which would not be possible using traditional methods of fabrication.

“Entomology is reliant on trapping. The fact that 3D printing allows us to come up with prototypes very quickly is going to revolutionize how we study invasive species throughout America,” Selby says.

What do you think of this project at the University of California, Riverside aimed at using 3D printing to wipe out a species of invasive beetles which are threatening to destroy the avocado crops in California and Israel? Let us know in the 3D Printed Beetle Traps forum thread on 3DPB.com.