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Have zebra mussels met their match?

The biopesticide Zequanox was applied in a barrier in Deep Quarry Lake in DuPage County, Illinois. (Photo by Kevin Irons, Illinois Department of Natural Resources)

Will Zequanox be the "silver bullet" in stopping zebra mussels?

A new study shows promising results, according to Marrone Bio Innovations, the company that manufactures the biopesticide.

Zequanox was highly effective at controlling invasive zebra mussels in Deep Quarry Lake located in DuPage County, Illinois, the company reported last week.

Zequanox, the industry's only environmentally compatible molluscicide, was applied within barrier systems in three locations throughout the lake.

Results showed that treated sites experienced an average mussel mortality of 97.1 percent compared with 11.2 percent mortality in the control (i.e., untreated) sites.

In the study, funded in part through a grant from the Illinois Department of Natural Resources, three sets of paired treatment and control sites were set up within the lake to evaluate the effectiveness of Zequanox.

Zequanox was so effective at controlling the invasive mussels that the study concluded after just one month.

The study also showed that the application of Zequanox had no impact on water quality and no adult or juvenile fish mortality was observed 24 hours after product application.

"Zequanox has proven to be a powerful tool for controlling invasive mussels in 'in-pipe' applications such as cooling water systems. This study shows the product can be equally as effective in open waters," said MBI Director of Water Technologies Sarahann M. Rackl, Ph.D., P.E. "This successful study represents MBI's next step in our commercialization efforts for Zequanox in natural water bodies, and we're excited about expanding into this new market, where there are currently no other environmentally compatible treatment options."

Zebra mussels were first discovered in Deep Quarry Lake in 2009 and have since developed a well-established population within the lake.

Because of their ability to reproduce quickly and in large numbers, invasive mussels can rapidly take over water systems they invade, outcompeting native species for food and space.

Invasive mussels also clog boat engine intake systems, causing the motors to overheat, and coat boat hulls, resulting in costly damage to paints and coatings. In addition, their thin, sharp shells cause painful cuts and wounds, and when the shells of deceased mussels wash ashore, they can ruin recreational beach areas.

Zebra mussels have been found in several Douglas County area lakes, including Alvin, Brophy, Carlos, Cowdry, Darling, Geneva, Irene, Jessie, L'Homme Dieu, Long Prairie River, Taylor, North Union, Stoney, Victoria and most recently, Miltona.

Currently, there are no commercially viable alternatives for treating invasive mussels in open water bodies without harming other species.

"We are very pleased with the outcome of this study," said John "Ole" Oldenburg, director, Office of Natural Resources, Forest Preserve District of DuPage County. "The mortality rates as a result of Zequanox applications were impressive and the use of anchored barriers proved to be an excellent method to isolate and treat mussels within specific areas of the lake."

The study was implemented in partnership with the Illinois Department of Natural Resources, Southern Illinois University (SIU), Forest Preserve District of DuPage County, PLM Lake and Land Management (PLM) and Marrone Bio Innovations.

Additional open water testing with Zequanox was performed earlier this year by the U.S. Geological Service in collaboration with scientists from New York State Museum at Lake Carlos, Minnesota and Lake Shawano, Wisconsin.

Further testing will be conducted in early 2013. EPA approval for using Zequanox in natural water systems is currently in process.


Marrone Bio Innovations, Inc. (MBI) is a leading global provider of natural products for pest management (biopesticides) and plant health. Used in agriculture and water applications, MBI's products control weeds, plant diseases and pests while managing pest resistance and promoting the health of natural ecosystems. MBI is addressing the water market with Zequanox, a possible solution for controlling invasive aquatic mussels in fresh waterways and is developing solutions for the control of algae and aquatic weeds. MBI's products for the agricultural market include the biofungicide, Regalia, and the broad-spectrum bioinsecticide, Grandevo. MBI has three-dozen patents pending in the U.S. and globally.