Integrated Pest Management of Purple Loosestrife

On Tuesday, June 12th, forester Lukas Hyder, volunteer Eddie Matthews, and I went out to Catlin Marsh to find and capture the Galerucella leaf-feeding beetles. These beetles are used as a biological control agent for the invasive purple loosestrife plant (Lythrum salicaria). Between May and July the females lay up to 500 eggs on the leaves and stems of the loosestrife. When the eggs start to hatch they feed on growing shoot tips and flower buds. When there is a high abundance of larvae on a plant, it can cause the plants to defoliate. Loss of shoots and buds reduces the growth of the purple loosestrife and its ability to flower and produce a seed. Also without leaves, photosynthetic capability is reduced, which will eventually kill the plant. Using these beetles as a means of reducing purple loosestrife is preferred over using herbicides, which is expensive and can cause adverse effects to the environment.

Galerucella Leaf-feeding Beetle

In preparation for this project White Memorial has been growing several potted loosestrife plants. When we noticed the beetles starting to breed, we went out to capture them. In order to get an even ratio of male to female beetles we tried capturing beetles that were in the process of breeding. Then every ten beetles that were caught were placed into a holding jar. On our first try of Catlin Marsh we were able to capture approximately 70 beetles. We brought the beetles back to the museum, and each vessel of ten beetles were released onto a potted loosestrife plant, which was then canopied with a light fabric covering. The beetles will remain on the plant for about a month and a half or until they lay eggs and the larvae begin to emerge. Once the first new adults start to emerge it is time to take the pots to a wetland that is infested with purple loosestrife. At the wetland the fabric covering will be removed from the plant and the beetles will be released. Released adults feed on leaves for a few weeks, but disappear around mid-August to overwinter in the soil near their host plant. Galerucella leaf-feeding beetles were introduced to Connecticut in 1996; they primarily feed on purple loosestrife. If purple loosestrife is left unchecked, it can become a serious issue because the plant’s rapid growth can crowd out native species, therefore reducing biological diversity.

Purple Loosestrife (Lythrum salicaria)
The potted loosestrife covered with fabric
after the beetles were added.

1 comment:

Marlow said...

Excellent report Erin! Thank you for explaining how the the project will work-- looking forward to seeing how Galerucella leaf-feeding beetles eliminate the purple loosestrife population, eventually:-).