Project ID: 2005DE58B

Title: Biological Control of Purple Loosestrife: Preventing Wetlands Degradation by an Invasive Plant

Project Type: Research

Focus Categories: Wetlands, Invasive Species, Management and Planning

Keywords: None

Start Date: 05/01/2005

End Date: 02/28/2006

Federal Funds: $3,500

Non-Federal Matching Funds: $3,500

Congressional District: At Large

Principal Investigator:
Judith Hough-Goldstein

Abstract

Purple loosestrife (Lythrum salicaria) is a non-native invasive European plant that has spread throughout the northeastern US. It is considered a noxious weed in at least 23 states. Purple loosestrife invades American wetlands and chokes out cattails and other native wetland plants. It can form dense stands that are inhospitable to a large number of wetland animals. Mechanical and chemical methods are not feasible for controlling large stands of purple loosestrife, so scientists have introduced several biological control methods to American infestations in order to combat the plant’s advancement. Of the one hundred insect species that feed on purple loosestrife in Europe, four have been identified as having potential as biological control species while remaining safe for introduction into the US. These four include two species of leaf-feeding beetles, one root-feeding weevil, and one flower-feeding beetle. Several controlled releases have occurred throughout the US, including several sites within the state of Delaware. Once released, these species have caused dramatic reductions in some purple loosestrife stands and virtually no noticeable effects in others. At Flat Pond, near Lums Pond State Park, experimental biological control using 5,000 Galerucella calmariensis and Galerucella pusilla beetles was conducted during the summer of 2004. At the request of the Del Bay Retriever Club, Dr. Hough-Goldstein began this project in order to determine the effectiveness of biocontrol methods on halting the advancement of purple loosestrife there. At the end of the summer, Dr. Hough-Goldstein determined that the Galerucella beetles were effective in limiting purple loosestrife flowering. Because of this, the Del Bay Retreiver Club has decided to continue the project for the summer of 2005 with a much larger release—approximately 50,000 Galerucella beetles.

Progress/Completion Report PDF