So I’m not sure about all of you, but I think my main activities outside the house since March have mainly included escaping*1 into nature! Mainly surfing the local beaches in LA, hiking on some local trails, and two multi-day backpacking trips in the Sierras.
Since I love these treks so much, I recently took some youth, instructors and parents from a local South LA educational program*2: https://www.theknowledgeshopla.com/programs on a nature hike yesterday. I decided to take them to the Los Leones trail – since its only a 30 min drive, not too strenuous and is a fairly short hike (if your want it to be). The hike is 2.6 miles round trip if you decide that your end game goal is the bench overlooking the Pacific Palisades, Santa Monica and the ocean. You can however go much further!
In addition to cape ivy- another invasive plant that we found and that I hadn’t previously known about was the invasive black mustard plant! (see the yellow flowered plant below)- not only is it destructive to native flora and fauna but it can also serve as kindle for Autumn fires in California- yikes! Read more here
Originally one of my aims was to show all of the participants how to use iNaturalist so that they could all try to identify the flora and fauna while on the hike, and after the hike in their own backyards/neighborhoods. They all had downloaded the app onto their phones before coming to the hike- however one short sight I had is that we did not have very good cellular service.. ha (oops!).. So instead I tried to tell them a bit about what I knew (without the help of iNaturalist) and we also took a lot of photos (above) for post-hike identification (Ive tried to identify a lot of these in the captions above!).
I think overall everyone had a lot of fun. After the group nature hike, I ended up taking the trail for a couple miles further to enhance the workout factor!
*Footnotes! (or how about some Footloose?!) Dang I just gave away my age….
*I will admit that I should not be using the word ‘escape’- see this great essay by William Cronon -since nature is technically all around us all of the time.. take that fly that is on your windowsill or maybe even on your arm right now! I think in this sense that we should all appreciate both proximate and distant nature, and take extra care of our immediate surrounding nature-so that we never feel like we need to escape to wilderness.
TheKnowledgeShop works in conjunction with Stem54.. and these two educational youth programs and their leaders- including Yolande Beckles and Dr. Michael Batie are truly making an amazing difference in the South LA community and Beyond! Check them out!
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’.
Me, standing in a thick blanket of Cape ivy near Los Leones trail in Topanga State Park
Kirsten Sheehy, Research technician at the UCSB RIVRLAB inspecting the best place for the first release of the biocontrol agents- the gall-forming flies
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.
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.
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.
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.
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.
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)
Photo by Joyce Gross, UC-Berkeley
Photo by Tony Northrup
Photos of nutria from left to right by Joyce Gross at UC Berkeley and Tony Northrup.
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.
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