A Beautiful Day for BioControl of Cape Ivy

Last Thursday on a typical sunny Californian day, I met up w/ researchers, Kirsten Sheehy (UCSB RIVRLAB), Bill Neill (Riparian Repairs) and Noa Rishe (California Department of Parks and Recreation) to romp around Topanga State Park in search of the invasive Cape ivy, Delairea odorata. As soon as we stepped foot onto the Los Leones trailhead we could see the vast entwined vines of this relentless invasive ivy climbing over and smothering all of the native species in its path, hence its nickname- the ‘California kudzu’.

Native to South Africa, Cape ivy was originally introduced into the USA in the 1850s for ornamental purposes due to its pretty green color with lush yellow flowers. However, looks can be deceiving as in some areas this invasive weed has reduced native plant species richness by 36%, and decreased native seedling abundance by 88% (see Alvarez and Cushman 2002). In addition to its detrimental impacts on native plants, this invasive weed also produces many chemical defense compounds (eg. pyrrolizidine alkaloids and xanthones), which make it toxic and unsuitable for foraging by resident mammals; and potentially detrimental to fish survival if substantial amounts of these chemical compounds end up in waterways. Aside from its toxins, this weed can interfere with nesting sites by many riparian-dependent birds. This invasive weed is also quite the ecosystem engineer due to its shallow root system contributing to serious soil erosion problems on hillsides; as well as potentially forming a serious fire hazard due to its dried out foliage hanging over native trees during the dry season.

Thus, there is a dire need to control the spread and growth of this menacing invasive vine. Invasive weeds can be controlled in several manners including herbicide chemicals, mechanical removal (via hand-labor or machines), and biological control. In classical biological control, a pest or weed’s natural enemies (for example, the insect herbivores of Cape ivy) are collected from its geographic place of origin, tested for target specificity and efficacy, and then released into the invaded region.

Successful biocontrol agents can reduce pest populations below threshold levels that cause problems for humans and native species. Once established, biocontrol agents can provide a sustainable, long-lasting management option as biocontrol agents are self-reproducing and self-distributing. Biocontrol agents will not eradicate every target pest or weed individual but this is actually a positive feature as it prevents population crashes of the biological agent and promotes the long term control of the weed. In sensitive or protected regions, biological control and hand-removal of invasive weeds are often the preferred method of control in order to reduce any negative impacts to the surrounding native ecological community.

 

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Kirsten Sheehy holding up a vial of the biocontrol agents, the gall-forming fly: Parafreutreta regalis

Hence, last Thursday was quite a monumental day as it marked the first release of the biological control agent for the control of the invasive cape ivy in the greater Los Angeles Region. The biological control agent in this case is the gall-forming fly, Parafreutreta regalis Munro (Diptera: Tephritidae), that has already been approved for release after undergoing intensive testing through the USDA-ARS to ensure that it only targets the invasive cape ivy, in order to prevent any non-target effects on local plants. Similar to its host plant, this gall-forming fly is native to the Cape Province of South Africa and is known to stunt the growth of Cape ivy in both the laboratory and in the field. Thus, it is expected that this biocontrol agent will reduce cape ivy’s ability to spread and climb, both which would reduce the smothering impacts of this invasive weed on native vegetation.

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Kirsten Sheehy releasing the super-hero gall-forming flies (Parafreutreta regalis) into a cage for biological control of the invasive Cape ivy

In two weeks from now Kirsten Sheehy and the UCSB RIVRLAB will come back to make sure that the galls are forming on the ivy before removing the cage. Once the galls have formed, these flies are pretty much on their own, continuing the cycle of injecting their eggs into new unsuspecting cape ivy hosts, and forming new galls that promote generation after generation of weed-controlling superheroes. Of course Kirsten will continue to make periodic new releases of adult flies in the SoCal region to increase the genetic variation of this fly to ensure the success of these new populations in the Los Angeles Region. The goals are to establish these super-hero flies in at least one site per coastal county in California to serve as ‘nursery’ sites for future regional releases. San Diego Co. is next up on this lucky-list of biocontrol study sites.

In addition to this beneficial fly, further biological control research on a stem- boring moth, Digitivalva delaireae Gaedike & Krüger (Lepidoptera: Acrolepiidae), is underway via the USDA-ARS (see Mehelis et al. 2015) and is likely to be approved for release in the near future. This stem-boring moth is actually expected to have an even greater impact on controlling Cape ivy, especially if it is combined with the impacts of the gall-forming fly. Once approved, we hope to add this additional superhero biocontrol agent in the SoCal Region in order to reduce the ecological crimes of the invasive Cape ivy villain. Stay tuned for the sequel.

In the mean time, if you would like to learn more, see the contact information, links and research articles below.

Contact Information regarding UCSB RIVRLAB Biocontrol Research:

Dr. Tom Dudley: tdudley(at)msi.ucsb.edu

Kirsten Sheehy: kirsten.sheehy(at)lifesci.ucsb.edu

 Relevant Articles:

Alvarez and Cushman (2002). Community-level consequences of a plant invasion: effects on three habitats in coastal California. Ecological Applications. 12(5): 1434-1444. http://marbles.sonoma.edu/users/c/cushman/pdf/alvarez%20&%20cushman%2002.pdf

Mehelis, C.N., Balciunas, J., Reddy, A.M., Van Der Westhuizen, L., Neser, S., Moran, P.J. 2015. Biology and host range of Digitivalva delaireae (Lepidoptera: Glyphipterigidae), a candidate agent for biological control of Cape-ivy (Delairea odorata) in California and Oregon. Environmental Entomology. 44(2):260-276. doi: 10.1093/ee/nvu030.

Relevant Links:

California Department of Parks and Recreation: http://www.parks.ca.gov/?page_id=21576

UCSB RIVRLAB: http://rivrlab.msi.ucsb.edu/biocontrol/cape-ivy

USDA-ARS, Albany CA:

Acknowledgements: Additional thanks to Dr. Tom Dudley and Dr. Adam Lambert from the UCSB RIVRLAB and Danielle LeFer from California Department of Parks and Recreation for coordinating this momentous day, and to Dr. Patrick Moran, Dr. Scott Portman, Dr. Angelica Reddy, Dr. Chris Mehelis and additional researchers from USDA-ARS in Albany, CA for all of the rigorous testing of this weed and its biological control agents.

 

Invasive Weed Alert! Alligatorweed in the Delta and Suisun Marsh, California

I just received word from Louise Conrad (Department of Water Resources) that there have been recent sightings of Alligatorweed (Alternanthera philoxeroides) in both Suisun Marsh and the Tower Bridge marina in the east Delta. This is a new, noxious, weed to the Sacramento-San Joaquin River Delta system and we should all be on the look out (see photo above and below).

This invasive weed, native to South America, forms floating mats but it is rooted in sediment and has submerged, floating, and emergent forms. This invasive weed can survive a wide range of environmental conditions making it particularly threatening to both aquatic and terrestrial ecosystems.    For more information on this weed- please see: http://www.sms.si.edu/irlspec/alternanthera_philoxeroides.htm

In California, currently this weed has been documented near Grizzly Island in August, 2017 and from two other sites further up the Montezuma Slough channel in September.

The introduction point is unknown, but it is clear that this weed is in the Sacramento River and has now moved into Suisun Marsh.  Other naturalized locations can be expected.  A rapid response to the alligator weed in Suisun is warranted before this invasion compromises planned tidal wetland restoration projects.

On a related note, the invasive yellow flag iris (Iris pseudacorus), and  Ludwigia hexapetala  (Uruguayan primrose-wllow) are also spreading in these same areas and should be reported as well if found (see details for contact info below).

 

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High densities of Alligatorweed (Alternanthera philoxeroides), forming dense mats. Also called “Pig Weed”. Photo credit: http://www.discoverlife.org

KEY ACTION POINTS: If you find new populations of alligatorweed (or the other weeds mentioned above) please take photos, GPS points (can be via your smart phone), and a voucher specimen (if possible) to send/email to the State Taxonomist, Genevieve Walden, at CDFA Genevieve.Walden@cdfa.ca.gov

 

It is crucial to notify Genevieve Walden as we need to document the extent of the problem. If we are not able to control the spread of this weed immediately it will result in similar issues and problems resulting from Brazilian Waterweed, Water Hyacinth and Water Primrose.

What happens if this weed spreads you ask?


Biological control is a possibility, and in fact, one of the biological control agents, the alligatorweed flea beetleAgasicles hygrophila, has the distinction of being the first biocontrol insect released in the U.S. in order to combat an invasive aquatic weed!

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Agasicles hygrophila, Photo Credit: http://www.sms.si.edu/

Overall, management impacts on alligator weed by the alligatorweed flea beetle have resulted in a dramatic decrease in the amount of infested aquatic habitat since the insect was first released.

However, the most effective and easiest solution to combating alligatorweed in the California Delta and Suisun Marsh regions is to prevent it from spreading in the first place!

 

 

 

 

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 destroys 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- Nutria was originally purposefully introduced for the fur trade and control of aquatic weeds, first to Elizabeth Lake in California in 1899, and later in the 1930s in many other southern states. However, 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


UPDATE ON NUTRIA 2/16/18

Christine Joab provided this update on the state of the invasion of Nutria in California:

·         Over the last year they have reappeared in three counties (Merced, Fresno and Stanislaus County); so far 20 have been found in the state.

·         CDFW is calling on residents to help them track the animal to get an accurate count on the size of the latest infestation

·         If you find or observe Nutria in California, do not release it. Do not kill it either. Contact CDFW and let them handle it.

·         Immediately contact the CDFW Invasive Species Program to report your sighting by:

o   emailing Invasives@wildlife.ca.gov, or  

o   calling (866) 440-9530, or

o   completing and submitting an online Invasive Species Sighting Report:https://www.wildlife.ca.gov/Conservation/Invasives/Report


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!