Beetles
on the Loose!
The Purple Loosestrife Biomonitoring
Control Project
The
Beautiful Invader:
Click to Enlarge
|
Purple
loosestrife, Lythrum salicaria, is an aggressive
invader of North American wetlands, lakes and rivers.
Once established, purple loosestrife can become the
dominant vegetation, forming mono specific stands
that significantly reduce biodiversity and degrade
habitat quality.
Of primary concern is that purple loosestrife displaces
native plants eliminating food and shelter for wildlife
and other species. While strikingly beautiful in flower,
dense stands of loosestrife also impair recreational
use of wetlands and rivers, impede water flow in drainage
ditches and invade right-of-ways, requiring costly
management efforts. Purple loosestrife is a widespread
and serious problem, affecting both coastal and inland
wetlands, lakes.
Viable
solutions for managing this invasive weed by conventional
means (water level management, burning, herbicides,
direct digging, cutting) have proven to be extremely
difficult and is impractical on a large scale. An
alternative is the biological control of purple loosestrife
by introduction of natural enemies from its
native range.
Three
species of plant feeding beetles Galerucella calmariensis,
G. pusilla and Hylobius transversovittatus
(a weevil) show promise in the control purple loosestrife
in the U.S. and Canada (Blossey, et. al, 1994, Scudder
and Mayer 1998). Native to Europe, these insects have
undergone extensive testing since 1986 to determine
their safety and effectiveness (i.e. remain specific
to purple loosestrife), receiving USDA approval in
1992. Since then, these insects have been released
in 27 U.S. States and all the Canadian provinces.
The Galerucella leaf beetles feed on bud, leaf and
stem tissue causing defoliation and prevention of
flowering/seed production.
Click to Enlarge
Hylobius Weevil
|
Continued
defoliation leads to plant death. Recent results from
Ontario, Minnesota, Michigan, New Hampshire, New Jersey,
Connecticut and in Massachusetts and other release
sites indicate that the Gallerucella beetles can have
a dramatic impact on purple loosestrife infestations
in as little as three years (Michigan State University,
1999). In Southern Ontario, introductions of Galerucella
spp. Reduced above ground biomass from 2,000g/m2 to
less than 20g/m2 in four (4) years (The Ontario Biological
Control Program, 1998).
Additional
studies found that at high Galerucella densities (200
larvae/plant), plants were entirely stripped of all
green tissue and seed production was prevented (Butterfield
et. al, 1996).
While these natural enemies cannot eliminate purple
loosestrife, experts believe that in combination they
are capable of reducing the density of purple loosestrife
by 90% over most its current range. Reducing purple
loosestrife density will allow re-establishment of
native wetland vegetation.
The
Massachusetts Wetlands Restoration Program (MWRP)
released 10,000 Galerucella calmariensis and
G. pusilla in 2000 in Walpole. An additional
2,000 beetles were introduced in June 2001. Other
successful releases in Massachusetts include Parker
River Wildlife Sanctuary in Newburyport who released
beetles in 1996, 97 and 98 and now have no evidence
of loosestrife left in the release site. They are
continuing their program.
The
Project:
Click for Life Stages
of
Galerucella Beetle
|
As
a nonprofit partner of the Corporate Wetlands Restoration
Partnership (CWRP), the Association of Massachusetts
Wetland Scientists (AMWS) is expanding these efforts
which began with the establishment of a comprehensive
Biocontrol Program for Purple Loosestrife consisting
of propagation of the Galerucella beetles and long
term field monitoring (training began April 2001).
The Project has been presented to the Invertebrate/Biocontrols
Group of the Massachusetts Executive Office of Environmental
Affairs who have approved the propagation and release
of the beetles to control purple loosestrife in the
Commonwealth. It is also authorized by the USDA, APHIS,
PPQ (United States Department of Agriculture, Animal
and Plant Health Inspection Service, Plant Protection
and Quarantine) who are bringing the beetles in under
their own permit for The Program.
Participants
in the 2001 Program include: Wetland Scientists, Entomologists
from three County Mosquito Control Programs plus two
schools (a Middle School and a High School). Teachers
are provided with a comprehensive curriculum, designed
in Michigan, to be used in educating the students
about the importance of wetlands in addition to being
an active part in the project as propagators and host
release sites where appropriate. It is our long-term
goal to expand the program throughout Massachusetts
by establishing a network of CBC (Cooperative Biological
Control) sites such as schools, watershed organizations,
scout troops, garden clubs, etc.
Also
included in the Project, to run concurrently, is a
comprehensive loosestrife data collection survey.
It is our long-term goal, in conjunction with MWRP,
to establish a statewide database of loosestrife populations
to determine sites suitable for future releases of
Galerucella.
Financial
Support:
AMWS
has committed funds for 2001 to establish the propagation
program, which for this year includes the training
program, held on April 21; and provides a complete
propagation kit to scientists from AMWS and selected
others interested in propagating the beetles. Partners
for Wildlife and the Corporate Wetlands Restoration
Partnership are also providing additional funding.
[Home]
[Who We Are] [Latest
News] [Workshops]
[Newsletter] [AMWS
Forum] [Join AMWS] [Job
Shop] [AMWS Library]
[Contact]
|
