Invasive Species Alert! Coypu River Rat (Nutria) confirmed in Los Banos, California

As some of you may have heard- the Bay-Delta (San Francisco Bay and the Sacramento-San Joaquin River Delta in California) is one of the most invaded estuaries in the world (Cohen and Carlton, 1998).

Yesterday, at the IEP Aquatic Vegetation Project Work Team Meeting, I found out that one more exotic species will likely cause harm to this important ecosystem (unless we can stop it of course!).

Details-David Kratville, a Senior Environmental Scientist at the California Dept. of Food & Agriculture, called in yesterday to inform all of us at the meeting that a Coypu River Rat / Nutria was caught by a trapper doing beaver control work near Los Banos California (just south of the legal Delta Boundary)

Photos of nutria from left to right by Joyce Gross at UC Berkeley and Tony Northrup.

Damage- This river rat,  Myocastor coypus, is an aquatic rodent native to South America and can cause massive damage to ecosystems and native species. Nutria consumes up to 25% of its body weight daily, and destroying additional plants and marsh area while burrowing for food. Nutria feeds primarily on marsh plants, including the base of the plants, and often dig through the soil for additional roots and rhizomes to eat. Additionally, nutria is known to carry many pathogens and parasites that threaten humans, livestock and pets such as: bacteria that cause tuberculosis and septicemia, tapeworms, a nematode (Strongyloides myopotami, resulting in a rash known as “nutria itch”), and blood and liver flukes. All of these pathogens can contaminate swimming areas and drinking water supplies.

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Strongyloides myopotami recovered from a feral nutria in Korea-Figure from (Choe et al. 2014)

History of Introduction- Although nutria was originally purposefully introduced for fur trade and control of aquatic weeds to Elizabeth Lake in Ca in 1899, and later in the 1930s in many other southern states- the damage from this species was soon recognized and eventually an eradication program in California was successful, with eradication announced in 1978. Unfortunately… it looks like this menace of a species is back.

What to do? –All is not lost at this early stage of detection. The best method at this point is to eradicate or relocate the current population before it grows (and hope that we don’t have too many gravid females in the area). Early control is key since nutria has a high population growth rate potential as they reproduce fast and all year round. If you spot this River Rat in California (see photos above), Immediately contact the CDFW Invasive Species Program to report your sighting ONLINE, by email to Invasives@wildlife.ca.gov, or by calling (866) 440-9530.  If this species is found in California, do not release it. More information on the current status of nutria near the Bay-Delta will be posted to this blog as I obtain further updates.

Additional information on nutria


Carter, J. & B. Leonard. 2002. A review of the literature on the worldwide distribution, spread of, and efforts to eradicate the coypu (Myocastor coypus). Wildlife Society Bulletin 30: 162-175.

Carter, J., Foote, A.L. & Johnson-Randall, A. 1999. Modeling the effects of nutria (Myocastor coypus) on wetland loss. Wetlands 19: 209. doi:10.1007/BF03161750

Cohen, A.N., Carlton, J.T., 1998. Accelerating invasion rate in a highly invaded estuary. Science 279, 555-558.

Choe, S., Lee, D., Park, H., Oh, M., Jeon, H.-K., & Eom, K. S. 2014. Strongyloides myopotami (Secernentea: Strongyloididae) from the Intestine of Feral Nutrias (Myocastor coypus) in Korea.  The Korean Journal of Parasitology,  52(5), 531-535. DOI:10.3347/kjp.2014.52.5.531


IEP (Interagency Ecological Program) Workshop 2017, Folsom, CA

This week I had the opportunity to attend and present at the 2017 IEP (Interagency Ecological Program) Workshop from March 1st to 3rd in beautiful Folsom, California: Conference Link.

IEP is a really cool program and group of people that have been focusing on cooperative ecological investigations in the San Francisco Bay Delta Estuary since 1970! I love this program since cooperation among different government agencies and academics is sometimes rare, but is absolutely critical in order to solve complex problems by combining resources and gaining ideas from multiple angles and viewpoints.  More about IEP here. 

This morning’s session was particularly exciting (disclaimer: I might be a bit biased!), Titled: “Into the Weeds: Lifting the Curtain from Aquatic Vegetation Ecology in the Delta”, with the session lead by one of my fellowship mentors: Dr. Louise Conrad (DWR).  Myself, Louise, and several others all gave presentations on the current state of invasive aquatic weeds in the Sacramento-San Joaquin and potential management implications (and of course including biological control!).

Also- while I was at the conference, I took myself on a running tour during the lunch hours as I’ve never been to Folsom, and it is a beautiful place. Here are some photos demonstrating the beauty and rich history in this cute town. You should definitely visit if you have a chance and plan to go outdoors!

Since I’m so close to Tahoe- Im going to go on a quick snowboarding trip on Saturday before I head back to the East Bay! Hopefully the storm holds off just enough to preserve my view of Lake Tahoe while boarding down the slopes!

If you build it, the weevils will come

Let’s face it – not everyday in the life of a scientist is filled with exciting and important discoveries. (And if this is not true for you – please share your secrets with me!)

Friday- My to-do list consisted of:

  1. Training a new undergraduate intern on processing frozen weevils (aka- smashing frozen weevils with plastic pestles in DI water) , and dissecting the weevil-mush (aka- homogenate) under phase contrast at 400x to look for microsporidia.
    • Footnote: Microsporidia by the way are hands-down the cutest parasites in the world. They are like little shiny hotdogs doing a waggle dance under the microscope. Then they become cooler if you imagine sunglasses on them. Ok.. I might be the only person that thinks this-  as several other researchers have voted for other parasites as #1 cutest…

Below is a photo of microsporidia (Nosema fumiferanae postvittana subsp.n.) from the Light Brown Apple Moth that I took during my PhD work. The mature spore form of the microsporidia in the weevil, Neochetina bruchi, look very similar under the microscope. .but so far I have not been finding high intensity infections … rather just 1-2 spores per slide for each weevil. Thus you can imagine it would be hard for a new intern to spot these little critters amongst all the other junk in a dissected bug.

 

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Photo from my PhD work on: Nosema fumiferanae postvittana, a microsporidian pathogen in the Light Brown Apple Moth (Epiphyas postvittana)

2. After training my new undergraduate intern, and a quick lunch- I proceeded to spend about the next 4 hours (can you believe that?! 4 hours?!) building a large cage for a bunch of weevils that an amazing technician brought back from the field for me. I had to build a large cage to make sure the weevils don’t fly off these plants and start eating other water hyacinth plants that were specifically being maintained as ‘healthy/clean’ for experiments.

The goal is to mass rear ~ 8000 weevils before February among these tanks and some others that I have going right now…. fingers crossed!

 

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Cage I built with tanks holding water hyacinth infested by the super hero weevil herbivore, Neochetina bruchi