The North American Invasive Species Management Association’s 5th Annual Weed Biocontrol Summit will be held virtually on December 5, 2024, from 11:00 am – 3:00 pm CST. The Biocontrol Summit communicates the latest in classical weed biocontrol research to North American invasive plant managers and educators and aims to connect researchers and on-the-ground practitioners. This year, the NAISMA Classical Biocontrol Committee is highlighting the role weed biocontrol can play in managing invasive aquatic plant species throughout North America. Our invited aquatic weed management and biocontrol experts will share updates in biocontrol development and innovative tools for improving integrated weed management.

Agenda Details

Sixty Years of Aquatic Weed Biological Control
Biological control of aquatic weeds started sixty years ago and has achieved significant milestones. As new applications and approaches have emerged, the research community has used these methods to improve results and outcomes. Moving forward, maintaining host specificity should continue to be a primary focus of all biological control research.
Alfred Cofrancesco, Advisor To The Technical Director For Environmental Engineering and Sciences, US Army Corps of Engineers Engineer Research and Development Center

Inundative biological control is the key to successful control of water hyacinth
Implementing biological control in systems with a history of chemical and mechanical control can be challenging. We implemented inundative biological control on a nutrient-enriched impoundment by fostering a community of practice. More than half a million biological control agents were released between 2018 and 2024 through the collective efforts of professional and private stakeholders. We show that bridging the boundaries between the research and public sector can strengthen biological control efforts, enabling successful and sustainable management of water hyacinth
Julie Coetzee, Professor, South African Institute for Aquatic Biodiversity.

Innovations and developments for biological control of water hyacinth
Despite nearly five decades (or more) of dedicated efforts to control water hyacinth (Pontederia crassipes), it continues to expand its range and negatively impact freshwater ecosystems throughout the tropics and subtropics. While several biological control agents have been released and cause significant harm in terms of biomass reductions, in all invaded regions, this impact is insufficient for control. Herein we present new research on changing paradigms (e.g., using planthoppers inundatively), and development of integrated methods in Florida.
Melissa Smith, Research Ecologist, USDA-ARS Invasive Plant Laboratory

Opportunities for improving biological control of giant salvinia (Salvinia molesta) in subtropical and temperate regions
The salvinia weevil (Cyrtobagous salviniae) has been used in the United States as a management tool for several decades. Releases of weevils have led to successful control during the summer months. However, its effectiveness varies significantly even across short distances, limiting its overall impact. This presentation explores new strategies to enhance the management of salvinia. We will discuss new remote sensing technologies for early detection and monitoring of salvinia infestations, as well as opportunities for using mass-rearing weevils in augmentative biocontrol. We hope to motivate a discussion on improving the consistency of giant salvinia management across diverse climatic regions.
Rodrigo Diaz, Dane Shackelford, and Victoria Ayala, Associate Professor, Department of Entomology, Louisiana State University

Implementation of biological control for introduced Phragmites in Canada
Two European stem boring moths, Archanara neurica and Lenisa geminipuncta, were approved for biological control of introduced Phragmites in Canada in 2019. To date the focus has been on development of operational protocols to rear, release, and monitor the biological control agents and more than 30,000 insects have been released at 50 sites in Ontario. Insect damage has been detected at over 90% of the release locations with negative impacts on introduced Phragmites at release points. For sites that are two- or three-years post-release, damage has been observed each year, indicating initial biocontrol agent overwintering and reproduction. This talk will review the current status of the Phragmites biological control program in Canada and outline ongoing experimental work to scale up the release program.
Rob Bourchier, Research Scientist, Agriculture and AgriFood Canada

Biological control of flowering rush: a new management approach on the horizon.
Flowering rush (Butomus umbellatus) is an aggressive freshwater invasive plant that rapidly colonizes and infests wetlands, lakes, rivers, and irrigation ditches across temperate North America. Three potential biocontrol agents have been identified and are under study. The highly host-specific leaf/rhizome weevil, Bagous nodulosus, was petitioned for field release in Canada and the United States in 2022. It was approved for release in Canada and was approved in the U.S. in October 2024. Pre-release monitoring, rearing, and release strategies are underway in Ontario, British Columbia, Montana, and Washington. Moving into the implementation phase of the biocontrol project offers exciting future opportunities for flowering rush management.
Jennifer Andreas, Professor, Washington State University

It was the best of times, it was the worst of times: an update of the USDA’s alligator weed and exotic Ludwigia biological control programs in California
Alligator weed (Alternanthera philoxeriodes) and exotic Ludwigia species invade similar habitats in California. Biological control results in complete control of alligator weed in much of the southeastern US but multiple attempts to establish agents in California have failed. A combination of new cold-adapted biotypes of existing agents and testing new agents is expected to expand control of alligator weed in the weed’s northern distribution. In contrast, the most promising insects associated with Ludwigia species were imported and tested but none are sufficiently host specific for release in the US. Alternative options are being considered (inundation of native herbivores) but classical biological control does not appear to be well suited for the management of exotic Ludwigia species in western US.
Paul Pratt, Research Leader, USDA-ARS Invasive Species & Pollinator Health Research Unit

Mapping floating aquatic vegetation with remote sensing platforms
Remote sensing plays a crucial role in managing aquatic invasive species by facilitating ongoing monitoring and offering valuable scientific insights into the mechanisms of invasion. These components are essential for making informed, evidence-based management decisions, which ultimately improve the effectiveness of control strategies. This presentation showcases studies focused mapping invasive floating aquatic vegetation and understanding invasion mechanisms using remote sensing at different scales and sensor types.
Christiana Ade, Postdoctoral Researcher, NASA JPL

Using drones to assess natural enemy impacts in aquatic systems
Assessing the impact of biological control agents in aquatic systems is expensive, time consuming, and often dangerous. Drone-based remote sensing has potential to collect post-release impact data over a large area quickly, safely, and cost-effectively. We will demonstrate the effectiveness of this tool in the water hyacinth system.
Usman Mohammed, Master’s Student, University of Florida Indian River Research and Education Center

eNAS: a new database for eDNA surveillance data of non-native aquatic species
The US Geological Survey’s Nonindigenous Aquatic Species (NAS) database is the leading resource for tracking non-native aquatic species occurrences. Integrating environmental DNA (eDNA) data with traditional sighting records will create a more comprehensive dataset, offering a clearer understanding of invasive species spread. This presentation will cover the development of community standards for incorporating eDNA data into the database, as well as the implementation of this innovative surveillance tool for early detection of invasive species nationwide.
Dr. Wesley M. Daniel, Supervisory Fish Biologist, USGS’s Wetland and Aquatic Research Center

New targets: Parrots feather, yellow floating heart, European frogbit and water soldier
Aquatic weeds continue to invade water systems in North America, having negative socio-economic impacts as well as negatively impacting biodiversity and ecosystem functioning. This presentation aims to raise awareness and give a brief update on the progress of the biological control programs on four new targets. These include, parrots feather, Myriophyllum aquaticum, yellow floating heart, Nymphoides peltata, European frogbit, Hydrocharis morsus-ranae and water soldier, Stratiotes aloides.
Philip Weyl, Team Leader Weed Biological Control, CABI & Nathan Harms, Research Biologist, Aquatic Ecology and Invasive Species Branch, USACE

Update on water chestnut biocontrol
We will summarize the results of pre-release studies of Galerucella birmanica, the leaf feeding beetle being evaluated for biocontrol of water chestnut. In addition to reviewing the host-specificity of this specialist herbivore, we will touch on broader ecological relationships that we have investigating with this species.
Wade Simmons, PhD Candidate, Cornell University

Biological control of duckweeds: host specificity and impact of selected insect herbivores from Louisiana and California
Lemna minuta, native to North America but invasive in Europe, threatens freshwater ecosystems. Investigations in its native range identified two potential biocontrol agents: the weevil Tanysphyrus lemnae and the fly Lemnaphila scotlandae. Host-specificity tests revealed that their host range includes duckweed species native to Europe, rendering them unsuitable as biological control agents for L. minuta.
Dr. Flaminia Mariani, Louisiana State University