Eradicating Invasive Golden Mussels - Cap Radio Insight Interview

Golden mussels pose a growing threat to California’s waterways and infrastructure.

The tough little shellfish was first discovered in the Sacramento-San Joaquin Delta last year, the first time the species was detected in the country. Since then the golden mussel has spread to over 50 locations across California

State wildlife officials have implemented mandatory inspection and quarantine procedures at some lakes and reservoirs to prevent the mussels from taking hold in more areas, but the patchwork system leaves some lakes and areas unprotected.

Dr. Pam MarroneCourtesy of the National Inventors Hall of Fame

California has faced invasive mussels before, experiencing outbreaks of zebra and quagga mussels in recent years. And the ongoing threats have attracted some local attention.

Dr. Pam Marrone is the co-founder of the Invasive Species Corporation, a Davis-based company seeking to find environmentally-friendly solutions to control invasive species. The company created a product called Zequanox that successfully eradicates non-native zebra and quagga mussels, and is now adapting that product for the newest aquatic invader.

Marrone spoke with Insight Host Vicki Gonzalez about her experience in biocontrol, and her company’s work to get rid of the golden mussel for good.

This interview has been edited for length and clarity.

Interview highlights

You have a long history of scientific research and innovation. How did you get into this field? 

I grew up in southern Connecticut on a mini-farm, and there was a caterpillar called [the] spongy moth that would wipe out the forests. My father tried the first ever biological control, it's a bacteria that controls the caterpillars. He wasn't sure it worked but he was happy that it was good for the environment, and made my mother happy that he wasn't killing the bees and the ladybugs.

How do biocontrol products compare to chemical pest control?

Biocontrol products are made from natural substances or microorganisms. Just because it's natural doesn't mean it's safe, we have to prove it. But in general, there's been a 70-year history of biocontrol without any environmental or human health effects. So, these are well-regulated and shown to be safe.

They're biodegradable, don't harm humans, don't harm other organisms compared to synthetic chemicals, which can have a lot of toxic effects and [are] much more persistent in the environment than biologicals. 

What are some of the benefits and drawbacks of using biocontrols? 

One of the benefits is if you're a grape grower, you can spray in the morning and be back in the field in the afternoon. If you're a walnut grower and you want to export to Europe, you can spray right up to harvest and export without having to worry about it—there's all of the rules for chemicals. And we can improve soil health, increase biodiversity and help farmers increase the yields of their crops. And in the case of water pests, we can replace harmful chemicals with biologicals. 

Now one of the weaknesses is that they're so biodegradable you have to reapply them more often. A grape grower might spray a chemical and [it’ll last] three weeks, but with a biological microorganism… you need to spray it every 10 days instead. That could be seen as more costly by the farmers.

Your company name is the Invasive Species Corporation, that’s pretty straightforward. How did this get started? 

Novo Nordisk hired me back in 1990 to start up a company looking for natural solutions to control pests, and now we're three companies later with Invasive Species Corporation.

We had the opportunity to spin out a product called Zequanox which is a bacterium, a little microorganism that was found in a mussel-infested river in upstate New York. At my previous company we turned it into a product, and when the company was sold… they didn’t want this product, so we spun it out. Now we’re working on it for zebra, quagga and most recently, also for golden mussels.

Given your previous experience with invasive zebra and quagga mussels in California, what stands out to you about the spread of the golden mussel?

What is amazing to me is how quickly they've spread. But I guess that's because we have water infrastructure that can spread them, and that is faster than I’ve ever seen. I think it’s also a testament to this mussel. What we’re seeing compared to quagga and zebra is [it’s] tougher and harder to kill, and it withstands a lot more environmental conditions. When California Fish and Wildlife collected the golden mussels for us to test in the lab, we put it in the aquarium and it just thrived, where we have to really baby the quagga mussel.

Help us visualize how this eradication process could work for the golden mussel?

If it's a new microbe, we'd have to figure that out. But for Zequanox one six-hour treatment is enough to kill most or nearly all of the invasive mussels. The way it works is that we make Zequanox in a big vat, like you’re making wine and beer, but much faster. And then we harvest it and dry it into a powder… looks like powdered milk for the most part. We're developing a form of the product that could be in a pellet, so it would be suitable for big lakes.

It would be envisioned that we could put it on the bottom of the lake or enclose it in a dock where the mussels live and then treat it for six, eight hours, and then it would kill them. For pipes, we can just inject inside the pipe. Zequanox has been used for years to clean out irrigation pipes and power plants.

Is it just California that you're focused on for the Golden Mussel? I imagine it’s spread elsewhere in the world.

It invaded vastly into Brazil, Argentina, and Uruguay. In fact, the original tests on golden mussels were actually done in Brazil, that’s how we knew we actually had some activity on [them]. And then quagga and zebra mussels actually came from Eastern Europe, and they have invaded across all of Western Europe doing the same thing, gumming up power plants and industrial plants and wrecking lakes. 

We’ll be doing global work, but we’re focusing on the U.S. right now. We have a project with the U.S. Geological Survey to save an endangered fish, the whitefish, so fisherman can get that back again because the mussels have destroyed their habitat. We have a big project to rehabilitate parts of the Great Lakes with Zequanox, it’s pretty exciting. 

Is your field relatively new in the larger field of pest control?

Invasive species have been invading for decades, but because of global travel and the movement of people, it's gotten a lot worse. Invasive species are the second largest cause of biodiversity decline. They've caused $500 billion worth of damage globally every year. But, very few companies like ours are actually tackling this kind of biocontrol. 

Usually, you go to the place where the invasive species came from, you find a little predator and you bring that back. Very few are focused on the microbes like we are, so it’s pretty new.

When it comes to the golden mussel and Zequanox, when could this become a reality and get rolled out across the state? 

We're hoping to have something on the market next year if all goes well with the Zequanox. We'll start additional testing and non-target testing this year. We're going to move really fast because we know it's a really big problem.