Managing Invasive Purple Loosestrife
Purple loosestrife is an invasive plant that infests and threatens to destroy native ecosystems in our local wetlands. Loosestrife crowds out native vegetation, interferes with the natural food chain, and speeds up the progression of wetland conversion to field, ending wetland’s function as an area of water filtration and absorption during times of high precipitation. Researchers studied a select species of beetles from Europe to demonstrate their effectiveness as biocontrol agents, a natural enemy to loosestrife. In the early 1990’s, the United States began to successfully use these beetles (Galerucella sp.) to control purple loosestrife infestations.
Since 2008, NRWA has been working on a pilot bio-control project to manage loosestrife in our watershed wetlands. Galerucella beetles, which feed almost exclusively on loosestrife, were raised and released at 12 initial sites. NRWA and our trained volunteers have been monitoring the sites twice a year to evaluate the success of the beetles in controlling or reducing the loosestrife infestations. In many plots, the cover of loosestrife has been diminished. Monitoring has also shown that the beetles successfully winter over and migrate beyond the original release sites to other loosestrife infestations. The 12 initial beetle release sites are located in Ashburnham, Ayer, Groton, Leominster, Lunenburg and Pepperell. The first three years of this project were funded by the U.S. Fish & Wildlife Service.
Through grants from the Community Foundation of North Central Massachusetts and the Groton Garden Club, in the summer of 2011, NRWA and volunteers scouted several new sites for possible releases of beetles in the spring of 2012. NRWA has identified purple loosestrife infestation sites in Clinton, Groton, Harvard, Pepperell, and Shirley; and, following presentations by NRWA about the project, Conservation Commissions in those communities have given permission for beetle releases at the identified sites.