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AN UPDATE ON THE BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE IN MASSACHUSETTS BETH SUEDMEYER A late summer drive in Massachusetts rarely deprives one the opportunity to sight a sea of pink-purple in a roadside wetland habitat. Many people admire the beauty of the scene without further consideration, but a wetland scientist inevitably has some concern and perhaps wonders how that biological control for purple loosestrife they heard about is working. The Purple Loosestrife Biocontrol Project (the “Project”) in Massachusetts, initiated in 2000 and coordinated originally by the Wetlands Restoration Program (“WRP”) and the Association of Massachusetts Wetland Scientists (“AMWS”), has grown in recent years and shows much promise. This article describes the history of the Project, the results of ongoing monitoring, and the plans for Project implementation in the future. ous testing, beginning in 1986 in Europe and later in the U.S., identified the most effective host specific insects for controlling purple loosestrife. In 1992, three species of insects were approved by the USDA for importation to the U.S. for use in biocontrol of L. salicaria: two leaf-eating beetle species, Galerucella calmariensi and G. pusilla, and a root-mining weevil, Hylobius transversovittatus. In 1994, two additional species were approved, Nanophyes marmoratus and N. brevis, both flower-feeding beetles that reduce seed production. (2) The Galerucella are most commonly used due to their success in control and ease of rearing, releasing, and monitoring. These European insects are considered ideal agents for biological control because they depend on purple loosestrife as a larval host and easily survive North American climates to produce naturalized generations in the wild. It is the adult stage that over-winters in the ground and emerges to mate and lay eggs in the spring. Figure 1 depicts the life cycle of Galerucella beetles. Hylobius has also been effectively used, but is more difficult to inoculate and monitor for impacts to root mass. Since 1992, releases of Galerucella and Hylobius in the northeastern U.S. have been closely monitored and show positive results for the control of purple loosestrife. Treatments have occurred in all of the New England states, including Massachusetts, where beetles were first released on National Wildlife Refuges (Great Meadows NWR and Parker River NWR) in the mid1990s. Both Connecticut and Vermont have volunteer-based projects and have conducted releases at hundreds of sites. In as little as two to three years, biocontrol treatments can have a dramatic impact on purple loosestrife infestations. While these specialist herbivorous insects will not eliminate purple loosestrife, they have been shown to reduce the density of purple loosestrife by up to 90% and allow re-establishment of native wetland vegetation. During laboratory studies to determine the specificity of Galerucella to L. salicaria, the beetles fed on few other plant species even if given no other choice. Three species fed upon when beetles were given no other choice were: invasive multiflora rose (Rosa multiflora), water willow (Decodon verticillatus), and winged loosestrife (Lythrum alatum) (the later two are closely related to L. salicaria). However, when given a choice between L. salicaria and native relatives, the natives were avoided. In the field, occasional “spill over” beetle feeding on nontarget plants has been documented, but no significant damage to non-target plants has been reported. Research concluded that the chosen control agents are highly host-specific and do not pose a significant threat to native flora, and minor risks of collateral feeding on nontarget species are greatly outweighed by the ecosystem benefits achieved through control of purple loosestrife. (3) continued on Page 12 PURPLE LOOSESTRIFE INVASION: SMALL BEETLE, LARGE TASK There is general agreement among scientists that invasive species disrupt the natural processes of ecosystems, and studies have indicated that dense populations of purple loosestrife (Lythrum salicaria) decrease wetland diversity and richness, affecting the quality of wetland habitat. The invasion of purple loosestrife into wetland ecosystems alters important biochemical and hydrological processes, thereby threatening many species. In an ecosystem where it has no natural controls, purple loosestrife has adapted quickly to become a dominant wetland species that out-competes native plants for resources, uses nutrients more efficiently, produces millions of seeds per plant, and takes advantage of opportunities to become established in disturbed and low fertility soil. Based on its rapid spread, projected range, and severity of impact, L. salicaria was identified as one of the most harmful non-indigenous species in the United States. (1) Exploration for a biocontrol option was initiated by the International Institute of Biological Control and conducted in association with the USDA Agricultural Research Service and the U.S. Fish and Wildlife Service. In its native Eurasia, 120 phytophagus insects were found associated with L. salicaria and 14 of these were considered host specific to the target plant. Rigor- Figure 1: Galerucella spp. life cycle. Credit: Vermont Department of Environmental Conservation. April 2007 * Page 11 This article was originally published in the April 2007 AMWS Newsletter and has been reprinted by the Wetlands Restoration Program for educational purposes with the permission of the AMWS Newsletter Editor. The article appears on pages 11 to 15 in Volume 61 of the AMWS Newsletter. Loosestrife (continued from Page 11) WRP PROJECT HISTORY The WRP Project was initiated in 2000 at a single site, Turner’s Pond, in Walpole. In order to expand the Project, WRP sought partners to help coordinate a volunteer effort. In 2001, a partnership was formed between WRP, AMWS, and local sponsors interested in controlling purple loosestrife in their communities. AMWS took the lead in identifying pilot sites, developing training materials, conducting trainings, and coordinating rearing, release, and monitoring activities with volunteers. Numerous AMWS and other volunteers reared beetles on purple loosestrife plants in backyard “pools” and then released the beetles at five pre-determined sites during the three years of this collaborative arrangement. Staff reductions and organizational shifts within both WRP and AMWS required modifications to the original approach to the Project. Since 2003, WRP has managed the Project without AMWS participation. Limited resources and uncertainty regarding the success of beetle production results prompted a scaling back of the Project to maintain and monitor existing release sites. WRP coordination has been an important factor for effective implementation of the biocontrol Project. WRP maintained the Project from 2003 to 2005 and facilitated releases at an additional three sites. In 2006, federal funding to support the MA Aquatic Invasive Species Plan was allocated to support a part-time position for the Project. This funding allowed for Project expansion, and releases were con- Biological control is long-lasting and relatively inexpensive. The costs of initial beetle collection, importation, and/or rearing, together with support of ongoing monitoring efforts, are significantly less than the expense of ongoing manual or chemical control options. Long-term control through conventional means, such as manual removal and chemical treatments, has proven difficult for this aggressive invasive that benefits from mass seed production, adventitious root system, and physiological efficiencies. ducted at six additional sites (see Figure 2). Refer to Table 1 for information and dates of releases at each treatment site. In 2007 the Project is focusing on expanding local rearing capacities through recruitment and training of school teachers committed to long-term rearing and releasing beetles and monitoring Project results. Interest and support for the Project continues to grow. Significant volunteer contributions have been, and will continue to be, integral to the Project. WRP has supported the program and solicited funds from the NiSource Environmental Challenge Grant and the ERM Foundation to purchase monitoring supplies and fund the field assistant position for two summers. Recently, the U.S. Fish and Wildlife Service’s Partners for Wildlife Program has also provided funding to purchase Project supplies and hire a seasonal field assistant. WRP is committed to maintaining the Project and continues to allocate a portion of staff time for Project management. In 2006, WRP produced a website for the Project: www.mass.gov/czm/wrp/ project_pages/loosestrife.htm. The website offers both a Project summary document as well as a more detailed guidance document that includes the complete protocols for beetle rearing and monitoring. The website and guidance document provide helpful information for those interested in learning more about the Project and how to get involved. continued on Page 13 PURPLE LOOSESTRIFE BIOCONTROL PROJECT IN MASSACHUSETTS Although Massachusetts got off to a slow start, partially due to initial opposition from the beekeeping community, there is now wide-spread acceptance and positive momentum to pursue biological control for management of purple loosestrife infestations across the state. The goal of the Project is to release biocontrol beetles in wetlands that have been degraded by purple loosestrife infestations to enhance the health, condition, and diversity of wetland habitats and native species. WRP focuses its efforts on: sustainable Project expansion, garnering public interest and support for biocontrol activities, continued monitoring of treatment sites, reporting Project results, and strategic development to expand the Project and develop Project resources. Table 1: WRP biocontrol treatment sites. Site Name ^Great Hill Reserve ^Waring School Bolton Flats Chandler Pond Great Brook Farm Cutler Park Nashua River Rail Trail Third Herring Brook* ^Diamond School Stebbins Wildlife Refuge Lake Garfield Weir Hill Reservation Stony Brook Martins Pond Rice City Pond ^Turners Pond ^Ciriello Property Town Acton Beverly Bolton Boston Carlisle Dedham Groton Hanover Lexington Longmeadow Monterey No. Andover Norfolk Reading Uxbridge Walpole Woburn Collaborating Organizations Acton Conservation Commission, Acton Boxborough Regional High School Waring School Department of Fish and Wildlife Pond Association DCR No Nasties Stream Team, DCR Groton School YMCA Diamond School Local Land Steward Pond Association Trustees of Reservations Massachusetts Audubon, DCR Pond Association, Merrimack College Uxbridge High School Town of Walpole Private Landowner # Release Year(s) 2001, 2002, 2003, 2004, 2006 2001, 2002, 2003 2006 2002, 2003, 2004 2006 2006 2006 2003, 2004 2001, 2002, 2003 2000, 2001, 2004 2004, 2005, 2006 2006 2006 2002, 2005, 2006 2005, 2006 2000, 2001, 2002 2001, 2002 Number # of Beetles 35,000 10,000 10,000 15,000 3,000 10,000 Uncertain** 17,700 25,000 22,000 14,500 Uncertain** 7,500 Uncertain** Uncertain** 30,000 20,000 Notes: ^ original sites initiated by WRP and AMWS in 2000-2001 * treatment suspended due to prolonged flooding cumulative number of beetles over all release years DCR Department of Conservation and Recreation ** counts uncertain because of difficulty counting reared beetles Page 12 * AMWS Newsletter No. 61 Loosestrife (continued from Page 12) TREATMENT SITES Release sites are selected based on: the presence of a local sponsor that is willing to conduct the treatments and is committed to longterm monitoring, and on standard physical characteristics generally recommended for treatments in North America. Physical criteria include, but are not limited to: sufficient coverage of purple loosestrife to support released Galerucella beetles, reasonable access, lack of pesticide applications, and relatively stable hydrology (i.e., sites subject to abrupt flooding or drawdown are less suitable). nates with the Massachusetts Natural Heritage and Endangered Species Program (“NHESP”) and local Conservation Commissions during the review process for proposed release sites. GALERUCELLA SOURCES AND RELEASES WRP purchases beetles from the Philip Alampi Biocontrol Laboratory of the New Jersey Department of Agriculture for As of 2006, WRP has facilitated the release of rearing and direct release at an estimated 250,000 beetles at 17 sites in Mas- sites. The beetle price is cursachusetts (see Table 1 and Figure 2). Volun- rently eleven cents per beetle. teer organizations have been involved in beetle Recently, WRP also began colrearing, beetle release, and spring and fall site lecting beetles at sites where Figure 2: WRP biocontrol treatment sites map. monitoring. The five sites initiated under the beetle populations are well original WRP-AMWS partnership are indicated established for transfer to other sites. Sites up to the Cornell “Purple Loosestrife Monitoring to two acres receive at least 5,000 adult Protocol" (2003). At each monitoring site, a in Table 1. Galerucella, while larger sites may receive up minimum of five plots (one square meter each) to 15,000 beetles depending on beetle avail- have been established and are marked by eiREGULATORY PROCESS IN ther a PVC pipe or wooden posts. In general, ability and treatment history. MASSACHUSETTS one plot is placed at the beetle release site TREATMENT SITE MONITORING and the rest are placed at 10 to 20 meter inIn 2000, the Invertebrate/Biocontrols Group of tervals in multiple directions from the original the Massachusetts Executive Office of EnvironThe monitoring program is intended to detect release site. During both spring and fall monimental Affairs approved the propagation and release of Galerucella beetles to control purple the establishment and spread of the Galerucella toring, the number of stems, the percent covloosestrife in the Commonwealth on a pilot ba- beetles and their impact on purple loosestrife. erage of L. salicaria and Typha spp., as well as sis. Importation of the beetles is authorized by Monitoring is conducted in the spring to as- the identity and percent cover of all other plant the USDA, Animal and Plant Health Inspection sess the presence of all life stages of Galerucella species, are recorded. Additionally, spring moniService, Plant Protection and Quarantine Unit and in the fall to assess abundance and repro- toring counts the number of eggs, larvae, and under a permit issued to WRP. WRP coordi- ductive activity of purple loosestrife, according adult Galerucella beetles found in each plot. Fall monitoring documents the height of the five tallest L. Table 2: Results at five initial purple loosestrife biocontrol treatment sites. salicaria and Typha spp. stems, the number of inflorescences, length of the terminal inflorescence for the five tallest purple loosestrife stems, the number of flower buds in a five centimeter portion of the terminal inflorescence for the five tallest stems, and the total number of inflorescences per plot. Both the monitoring and rearing protocols are included in the appendix of the “ WRP Purple Loosestrife Biocontrol Project Guidance Document ” available at the Project website. continued on Page 14 April 2007 * Page 13 Loosestrife (continued from Page 13) The current monitoring protocol has limitations. However, it can be efficiently implemented and is consistent with other monitoring efforts across the nation. Observations made inside five plots do not sufficiently capture conditions throughout the larger wetland system. If additional resources were available, more extensive monitoring could be conducted within treatment sites. Additionally, it would be helpful to have plots at several untreated reference wetlands to distinguish biocontrol effects from seasonal variations in purple loosestrife growth and vigor. RESULTS The site descriptions in Table 2, describe the basic observations at the five initial treatment sites where releases first occurred in 2000 to 2001. Data collected in the fall on loosestrife abundance and vitality at these sites is found in the charts in Figures 3A to 3C. Photo documentation is available for most sites and provides an important reference for change over time. Figure 4 demonstrates the striking contrast in purple loosestrife cover at a monitoring plot in Walpole. For sites where more recent releases have occurred, it is too early to draw conclusions. DISCUSSION Results at release sites have varied significantly, but all sites have seen beetle survival and effects on purple loosestrife. At several of the early release sites, the impacts have been obvious: beetles have thrived, reproduced, and moved to other areas, while the density and vigor of purple loosestrife has been diminished. Control of an invasive plant through biological means is a matter of balance; the beetles are not expected to eradicate purple loosestrife, but to remain in balance with it at low population levels so that native plants can be competitive. The Parker River National Wildlife Refuge (“PRNWR”) initiated biological control of purple loosestrife in 1996 by releasing 51,000 Galerucella beetles through 1999, as well as 1,800 Hylobius beetles in 1996 and 2001. The results of these releases at the PRNWR are informative of longer term biocontrol project results. Nancy Pau, Wildlife Biologist at the PRNWR, reports “Galerucella beetles caused a gradual decrease of purple loosestrife percent Page 14 * AMWS Newsletter No. 61 Figures 3A to 3C: Trends in purple loosestrife growth. Averages are for five monitoring plots for each site, graphed by year relative to release year. See Table 1 for information on release years. Percent cover and number of stems are estimated/counted for all purple loosestrife in each plot. Numbers of inflorescences are counted for five tallest stems in each plot. Missing bars indicate gaps in data. Black lines in the chart for Number Inflorescences represent true zeros (Lexington, Walpole, and Woburn). cover, density, and plant height. Six years after the last release of Galerucella beetles, we’re continuing to see effective loosestrife control. However, we’ve noticed an increase in purple loosestrife on the Refuge and a reduction of Galerucella eggs and larvae in the last two years, so we plan a release of Galerucella beetles in 2007 to augment the existing population.” continued on Page 15 Loosestrife (continued from Page 14) Meanwhile, it is speculated that the PRNWR released beetles are migrating successfully. Beetle populations have been observed at locations quite a distance from known release sites in the Essex County towns of Newbury, Rowley, Salisbury, and Gloucester. Beetle migration is anticipated and desirable. Beetles in New Hampshire are reported to have traveled up to 12 miles from release sites. WRP and NHESP staff observed Galerucella beetles and beetle damage to nearly every purple loosestrife plant at Crane Pond Wildlife Management Area in Georgetown in 2006. The source of the beetles is uncertain, although it is feasible that beetles traveled along the Parker River for up to eight miles to reach this site. While the beetles successfully found the purple loosestrife, no apparent adverse impacts were observed on other species, including Decodon verticillatus and Lythrum alatum. Another potential source of the Crane Pond beetles is a small release of Galerucella by a private individual that occurred near Crane Pond in 2005. WRP has heard of numerous other releases that have occurred in Massachusetts separate from the WRP Project. Such activity is encouraged, so long as it is conducted according to the WRP Guidance Document and is approved by NHESP and the local Conservation Commission. WRP would like to track information on such releases to help with planning for future releases. To effectively and efficiently control purple loosestrife over large regions, releases will need to happen strategically to cover areas which do not have a beetle presence. Results from early release sites indicate that successful suppression of purple loosestrife can be achieved through the use of biocontrols. However, monitoring data collected so far is not adequate to assess which types of replacement communities will develop at treatment sites. The long-term goal is to have a diverse native wetland plant community replace the once monotypic stands of L. salicaria. Monitoring must continue at all treatment sites to document whether goals are met and if adaptive management measures must be employed to repopulate native plants. Physical or ecological differences between sites may affect outcomes; some sites may be more conducive to beetle production than others, possibly due to abiotic ground conditions (e.g., soil type, moisture content, or pH) or biotic Figure 4: Photographic comparison of the Walpole site two and four years after initial treatment. Purple loosestrife dominates Quadrat #2 in 2002 (left) but is not present in 2004 (right), when native sensitive fern is the dominant plant. factors such as beetle predation at some sites. Beetles may move to other purple loosestrife areas if they find conditions are not favorable at the release site. While the results at the Acton site have not shown effects on loosestrife at that site, WRP received a report of Galerucella larvae and damage to purple loosestrife at a site approximately three miles from the release site. Likewise, at sites like Uxbridge and Reading, where flooding and high water fluctuations have been found, it is possible that beetles have been negatively impacted by those unfavorable conditions, and/or have migrated to other nearby loosestrife-infested sites. There are numerous opportunities for interested AMWS members to get involved in the Project, including: • Communicate information about the Project • • to inform the public and town officials of the options for purple loosestrife biocontrol; Volunteer to assist with routine monitoring or advising a school involved in rearing beetles; and When conducting wetland field work, monitor for beetle presence and damage, and report findings to WRP. WRP will be distributing beetle identification and reporting resources to assist volunteers with reporting their observations. STRATEGY FOR THE FUTURE More monitoring work is needed to determine the success of the Massachusetts Purple Loosestrife Biocontrol Project and to identify causes of variability of results across sites. Efforts will be made to locate new potential sites for release of biocontrol agents. Sites near major highways and rivers appear to be excellent dispersal routes for both the plant and the beetles, and may play a key role in future planning for strategic biocontrol releases. WRP plans to develop additional partnerships and support the expansion of treatment sites throughout the state. The Project will continue to use a volunteer-based model and will partner with schools and conservation organizations to help raise and release beetles and monitor treatment sites. Additionally, WRP is collaborating with government agencies and other partners to develop a long-range strategic plan for the biological control of purple loosestrife throughout Massachusetts. Ideally, regional centers would be established to coordinate the selection and monitoring of sites, as well as rearing and release of beetles. Existing WRP partners in North and South Shore regions have recently applied for grants that would support regional purple loosestrife biocontrol initiatives. REFERENCES U.S. Congress, Office of Technology Assessment. 1993. Harmful non-indigenous species in the United States. OTA-F-565, Washington, D.C., US Printing Office. (2) Malecki, R. A., Blossey, B., Hight, S. D., Schroeder, D., Kok, L. T., and Coulson, J. R. 1993. Biological control of purple loosestrife: A case for using insects as control agents, after rigorous screening, and for integrating release strategies with research. Bioscience 43(10): 680-686. (3) Blossey, B; Casagrande, R; Tewksbury, L; Landis, D.A.; Wiedenmann, R.N.; Ellis, D.R. 2001. Nontarget feeding of leaf-beetles introduced to control purple loosestrife (Lythrum salicaria L.). Natural Areas Journal 21(4): 368-377. (1) Beth Suedmeyer, Restoration Planner Wetlands Restoration Program beth.suedmeyer@state.ma.us 617-626-4921 www.mass.gov/czm/wrp/projects_pages/ loosestrife.htm April 2007 * Page 15