Biological Control of Aquatic Weeds

Nathan E. Harms U.S. Army Engineer Research and Development Center, Vicksburg, MS

March 2014- ASWM Workshop

US Army Corps of Engineers

BUILDING STRONG® Why USACE?

BUILDING STRONG® http://plants.ifas.ufl.edu Characteristics . Most are exotic . Disturbance specialists ► r-strategists ► For example - Hydrilla • Rapid growth rates • Broad tolerance ranges • Early maturation and reproduction (fragmentation) • Dispersal adaptations (fragmentation) • Long-term survival (tubers) . Often favorable environmental conditions ► Space ► Nutrition ► Lack of natural enemies

BUILDING STRONG® Underlying Factors- Biological

. Most problem species are non-native . Introduced with no competent herbivores and diseases ►“Natural enemies”

BUILDING STRONG® Hydrilla verticillata – U.S.

No damaging herbivores/ pathogens

BUILDING STRONG® Hydrilla verticillata – China

>110 Herbivore/pathogen species

BUILDING STRONG® What is Biocontrol?

Introduction, by man, of parasitoids, predators, and/or pathogenic microorganisms to populations of plant or pests.

BUILDING STRONG® Biological Control Two Approaches

• Classical Biological Control

• Inundative Biological Control

BUILDING STRONG® Classical Biological Control Important Aspects . Host-Specific Agents () ► target exotic plants . Release small numbers ► Population increase ► Expansion in distribution . Suppression is Key ► Long-term process ► Stress the target ► Bring into lowered equilibrium

BUILDING STRONG® Inundative Biological Control . Agents may not be Host- Specific ► ‘Bioherbicide’ . Release Large Numbers of Agents ► Population increase ► Creates Disease Levels . Mode of action ► Overwhelms Target ► Agents not self- sustaining . Not commonly used

BUILDING STRONG® Biological control . Minimize invasive characteristics/decrease competitive advantage . For example: ► Waterhyacinth weevils • Smaller height • Decreased flowering – less seeds • Less productivity ► Purple loosestrife agents • Reduced shoot/root growth • Fails to produce seeds

BUILDING STRONG® Challenges . How to define success ► Establishment ► Range Expansion agents ► Population Increase ► Impact • Change in species diversity/abundance • Biomass Decrease plants • Propagule Decrease ► Economic • Short/long term benefits . Long-term large scale monitoring needed ► Agent-caused declines? . Need demonstration projects . Hybrids!

BUILDING STRONG® Example: ‘Successional’ history of Caddo Lake, Texas

Waterhyacinth

American lotus

Brazilian elodea

Eurasian Giant watermilfoil salvinia

Hydrilla

BUILDING STRONG® BUILDING STRONG® Overseas research since 1990’s

BUILDING STRONG® Petitioner: • Consults with USFWS • Prepares petition for release or test plant list USDA-APHIS • Sends to APHIS-PPQ

TAG Executive Secretary: TAG • Establishes timelines • Sends petition to TAG members procedure TAG Members: • Review and Evaluate • Synthesize comments from subject matter experts Subject matter experts evaluate • Submit comments and recommendations

TAG Executive Secretary: • Logs and files comments and recommendations • Sends to Chair TAG petitioner: • Conducts more TAG Chair: research and • Consolidates recommendations • Resubmits petition or • Submits TAG recommendations to APHIS-PPQ, test plant list Petitioner, and others • Discontinues effort No • Or submits application Does TAG recommend release? to APHIS anyway Yes Petitioner submits application to APHIS-PPQ

BUILDING STRONG® Technical Advisory Group - TAG Make Recommendations Only

► Bureau of Land Management ► USDA, ARS ► Bureau of Reclamation ► USDA, APHIS ► Bureau of Indian Affairs ► USDA, NIFA ► Fish and Wildlife ► Forest Service ► National Park Service ► Documentation Center ► National Biological Survey ► Corps of Engineers ► Environmental Protection ► Weed Science Society Agency ► National Plant Board ► Representative for Canada ► Representative for Mexico

BUILDING STRONG® Plants and Their Agents

BUILDING STRONG® philoxeroides (Mart.) Griseb. (Alligatorweed)

► 1st Aquatic Biocontrol success ► Three agents released (1964-1971) • (Alligatorweed Flea Beetle) • Arcola malloi (Alligatorweed Stem Borer) • Amynothrips andersoni (Alligatorweed Thrips) ► Can be field-collected

BUILDING STRONG® Eichhornia crassipes (Mart.) Solms (Waterhyacinth)

Megamelus scutellaris (2010)

Neochetina eichhorniae "Mottled Waterhyacinth Weevil“ (1972)

. Acremonium zonatum . Alternaria eichhorniae . Cercospora piaropi . Uredo eichhorniae (rust) Neochetina bruchi Niphograpta albiguttalis “Chevroned Waterhyacinth Weevil” "Waterhyacinth Moth“ (1974) (1977)

BUILDING STRONG® >165,000 weevils released

BUILDING STRONG® Hydrilla verticillata (L.f.) Royle (Hydrilla)

•Four agents released since 1987 •Bagous affinis (1987) •Hydrellia pakistanae (1987) •Hydrellia balciunasi (1989) •Bagous hydrillae (1991) •Hydrellia spp. •Established • Damaging Stage •Feeds on Internal Leaf Tissues •Widespread U.S. Distribution •Operational •Current surveys in Northern China/ South Korea

BUILDING STRONG® 250 Hydrilla Only Current effect: F(1, 116)=.48237, p=.48874 Hydrilla + Natives Vertical bars denote 0.95 confidence intervals c 200

2 150 b

100 ab

a

TUBERS PER m PER TUBERS 50

0

-50

NO HERBIVORY HERBIVORYBUILDING STRONG® Salvinia molesta Mitchell (Giant Salvinia)

The image part with relationship ID rId7 was not found in the file.

• Cyrtobagous salviniae- “Salvinia Weevil” (1999) • Operational • Available from LAERF, TX Technology transfer- Knutson & Nachtrieb

BUILDING STRONG®

Giant salvinia in TX pond

BUILDING STRONG® Other Agents . Hydrilla (USACE, USDA-ARS, CSIRO, CAS) ► Exploratory surveys still ongoing . Eurasian watermilfoil (Enviroscience) ► Native milfoil weevil available commercially . Waterlettuce (USACE) ► One agent operational, one in quarantine . Purple Loosestrife ► Four agents released . Melaleuca (USDA-ARS) ► Four agents released in FL 1997-2008 ► Operational, two agents in quarantine . Arundo (giant reed; USDA-ARS) ► Two agents released in TX 2009-2011 ► Operational? One agent in quarantine . Phragmites (Cornell U, USACE) ► Four agents in quarantine

BUILDING STRONG® Take Home: . Biocontrol is a tool ►Shift the advantage away from the weed ►Should be combined with ecosystem management & restoration • Target the system, not just the plant! ►Evolving technology • Product of 50+ years aquatic plant management ►Long-Term • Realistic time-lines often 5-10 years

BUILDING STRONG® For more information: [email protected]

BUILDING STRONG®