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2023 California Invasive Species Action Week Lunchtime Talks

cdfa spotted lanternfly


Act Today to Protect Tomorrow

Invasive species are arriving in California with increasing frequency. The best time to stop them is before they arrive, and federal, state and local agencies are keeping their eyes out for new arrivals and threats on the horizon. When they do arrive, Early Detection and Rapid Response is critical to their management. Many detections are made by individuals not associated with any agency or university, and through community/participatory science programs, almost anyone can help to spot the next invasive. 

The 2023Invasive Species Lunchtime Talks all took place via Zoom Webinar from noon to 1:00 p.m. from Monday, June 5 through Friday, June 9. See below for more details and to view the recordings.


Monday, June 5


Rapid Response and Eradication of Caulerpa in California: Lessons learned

Presented by Rachel Woodfield

View recording here

This presentation provided an overview of infestations of marine algae in the genus Caulerpa, with a focus on introductions discovered in California.  The highly invasive strain of Caulerpa taxifolia was discovered in two lagoons in Southern California in 2000. Based on its aggressive nature and the displacement of native marine resources observed upon its discovery, it was recognized that the infestations potentially posed a major threat to coastal ecosystems, and recreational and commercial uses dependent upon coastal resources.  A rapid response plan was quickly developed, funding promptly secured, and C. taxifolia was successfully eradicated at a cost of over $7 million and 7 years. In 2021, Caulerpa prolifera was confirmed growing near the mouth of Newport Bay. Attempts to mount a similarly prompt and comprehensive response have been hampered by limited funding, as well as less government and public engagement. The presentation will discuss lessons learned and the importance of an immediate and sustained response when invasive species are detected early on.


Rachel Woodfield

Rachel Woodfield is a marine biologist with Merkel & Associates, Inc. (M&A) in San Diego, CA. She began her involvement in the field of invasive species studies when she found and reported the first known occurrence of the invasive seaweed Undaria pinnatifida in North America.  Later the same year she identified the first and only known occurrences of Caulerpa taxifolia in the Western Hemisphere. Working with the Southern California Caulerpa Action Team, she managed the development and implementation of all aspects of the successful rapid-response and eradication of C. taxifolia from the two infestation sites. With the discovery of a second non-native Caulerpa species (Caulerpa prolifera) in Newport Bay in 2021, Ms. Woodfield is again on the team attempting to eradicate it before it spreads throughout the bay or offshore. Her other work involves long-term monitoring of plant and animal communities in restored coastal wetlands in Southern California.


Tuesday, June 6

IRC Volunteers

Participatory Science as a Tool to Monitor Invasive Tree Pests

Presented by Dr. Beatriz Nobua-Behrmann and Hannah Vasilis

View the recording here

Invasive shothole borers (ISHB) are tiny invasive beetles that are responsible for the decline and death of thousands of trees in Southern California. Detecting infestations early is key for successful management of this pest and to prevent the spread to new areas, and participatory science could be a useful tool to identify infestation focuses and help monitor high-risk areas. However, we know that accurately identifying the presence of ISHB and other tree pests is challenging, even for professionals. Together with the California Naturalist program, we developed a participatory science project to evaluate how accurate volunteer observations are and to find out ways to improve it so we can use participatory science as a tool to monitor for this pest. Come learn about our journey, what we learned on the way, and how you can participate in this project and contribute to the local and state-wide efforts to monitor the presence of this invasive tree pest.

Bea Nobua Behrmann

Hannah Vasilas New


Dr. Beatriz Nobua-Behrmann is a University of California Cooperative Extension advisor for Orange and Los Angeles Counties, specialized in Urban Forestry. Her research background is in insect-plant interactions. She received her Ph.D. in insect ecology and her B.S. in Biology from the University of Buenos Aires, in Argentina. Beatriz’s research and extension program is focused on finding appropriate management strategies for urban forest pests that affect Southern California’s trees, like the invasive shothole borer beetles and the goldspotted oak borer.





Hannah Vasilis is the statewide invasive shothole borer survey and trapping coordinator with the University of California Integrated Pest Management program. As a coordinator for this program, Hannah offers her technical expertise on how to effectively monitor trees for the invasive shothole borers for a variety of audiences. She has been working in the fields of urban forestry and emerging tree pests with the University of California since 2016.


Wednesday, June 7

CDFA Truckee Inspection Center

Proactive Biological Control of Invasive Pests

Presented by Dr. Ricky Lara

View the recording here

Invasive insect pests pose an ongoing threat to California’s agriculture and natural resources. The best time to stop them is before they arrive. The California Department of Food & Agriculture (CDFA), US Department of Agriculture (USDA), and other organizations are on high alert to prevent the arrival of insects that have devastated other regions of the United States such as Emerald Ash Borer and Spotted Lanternfly. Emerald Ash Borer, which was recently detected in Oregon, has killed tens of millions of ash trees in the Midwest and East and has cost municipalities, property owners, nursery operators, and forest product industries many millions of dollars. Quarantine efforts for this pest proved ineffective and ended in 2021, and available resources are now focused on finding biocontrol agents such as parasitoid wasps that naturally prey on the insect. Spotted Lanternfly, another invasive pest that currently is plaguing the East Coast, would be a serious danger to California’s grape industry and other agricultural products. Human activity, such as movement of firewood, help these and other invasive pests to spread over long distances.

Ricky Lara

Dr. Ricky Lara is a Senior Environmental Scientist – Specialist with California Department of Food and Agriculture. He is a research entomologist by training. He specializes in the development of classical biological control programs targeting invasive arthropod species that pose a threat to specialty crop production in agricultural systems. Part of his research responsibilities include conducting foreign exploration for co-evolved natural enemies of invasive target pests and studying the host-specificity of candidate natural enemies in quarantine lab space to determine their environmental safety in future release areas. Some of his pest control projects have involved working with ambrosia beetles, stink bugs, and spider mites. His work is driven by a desire to better understand the ecological relationships in the natural world and a commitment to share these findings with the general public, research scientists, and farming communities through a variety of publications, extension/outreach events, and conference presentations.



Thursday, June 8


Early Detection and Rapid Response for Invasive Plants in California

Presented by Dr. Chris McDonald

View the recording here

Early Detection and Rapid Response is critical to management of invasive plants, but it can be a high risk, high reward approach. For example, Desert Knapweed (Volutaria) is a case study of missed detections and slow responses, coupled with a naturally fast spreading weed. Desert Knapweed is a highly invasive, noxious weed and A-rated pest by the California Department of Food and Agriculture. There are three known populations in North America, two of which are Borrego Springs and Chula Vista. While the Chula Vista site is small and well-controlled, Volutaria continues to spread in Borrego Springs. A single Volutaria plant can produce hundreds of flowers and thousands of seeds. As this plant spreads it threatens to reduce wildflowers and wildlife, and could become a pest for growers. Chris McDonald will share the Desert Knapweed experience as well as other examples where Early Detection and Rapid Response has proven more successful.

Chris McDonald

Dr. Chris McDonald is the Inland and Desert Natural Resources Advisor for the University of California Cooperative Extension in San Bernardino and San Diego Counties. His expertise is in managing plants in wildlands with an emphasis on managing difficult weeds.



Friday, June 9

Suisan Marsh

Rapid Spread of Invasive Aquatic Plants in the Changing San Francisco Bay-Delta Estuary

Presented by Dr. Brenda Grewell

View the recording here

Biological invasions by alien plant species are a global change factor linked to declines in native species diversity and ecosystem functions. On-going detections of new invasive alien plant species in waterways and wetlands of the San Francisco Bay-Delta Estuary continue to challenge ecological restoration goals. Rapid response actions to curtail these invasions are difficult given the swift dispersal and spread of buoyant, reproductive parts of aquatic plants with water currents. With global climate change, plant species in tidal marshes are being exposed to increasing salinity and longer inundation periods related to sea level rise and alteration of local watershed runoff and precipitation amounts and patterns. Despite extensive tidal wetland restoration plans for fish recovery, actions to prevent spread of invasive plant species in tidal sloughs and tidal wetlands of Suisun Marsh are largely overlooked. The distribution of some alien plant invaders in upper estuaries and tributaries were considered limited to freshwater, yet range expansions into Suisun Marsh and areas with higher salinity suggest a need to broaden our view of rapid response to include range-expanding populations. Climate-driven environmental variation can influence the fitness, establishment and invasive spread of alien plants, yet adaptive evolution may support their invasiveness. A broad vision of ecosystem recovery encompassing system-wide integrated weed and restoration management could advance efforts to achieve current and future conservation goals. 

Brenda Grewell
Dr. Brenda Grewell is a Research Ecologist/Botanist with the USDA-ARS Western Regional Research Center’s Invasive Species & Pollinator Health Research Unit at Davis. She serves as lead scientist for the USDA research team investigating integrated weed management and restoration strategies to protect water resources and wetland ecosystems in the far western U.S. She holds a Ph.D. in Ecology from University of California, Davis and is a research associate in the Department of Plant Sciences and the Center for Plant Diversity at UCD. Her research program focuses on invasive plant biology and ecology to understand controls over invader establishment, abundance, and impacts. Recent focal taxa have included invasive Ludwigia spp. (water primrose-willows), Spartina spp. (cordgrasses), Iris pseudacorus (yellow-flag iris) and Alternanthera philoxeriodes (alligator weed) in their native and naturalized ranges. This applied research contributes to improve risk assessments, weed management and ecological restoration approaches to support conservation of native flora, biological diversity, water resources, and recovery of wetland ecosystems in changing environments.