ANN ARBOR-The itty-bitty beetles haveemerged from a season of rest as voracious and prolific as expected. The beetles dine on an exclusive diet of purple loosestrife (Lythrum salicaria) to devour and control the damaging invader of wetlands across the country where mowing, burning, flooding and herbicides have failed. The University of Michigan’s Matthaei Botanical Gardens is part of a national research program on the biocontrol of the vibrant but damaging purple loosestrife. With more than 35,000 beetles released since the program began, leaf damage to the purple loosestrife is becoming more evident. For the past five years the Botanical Gardens has been monitoring the progress of the beetles released into its wetland area. By establishing 30 permanent plots (six times more than required by the national program), staff at the Gardens is able to monitor the populations of both the beetle and the plant species in the plots. This spring’s census shows a good steady growth in the beetle population. The beetles got off to a slow start during the first few years after their initial release, being found in less than 10 percent of the monitoring plots. However, in 2002, beetles or egg masses were found in more than two-thirds of the plots that contain loosestrife.

“I’m having an easy time finding the beetles and their larvae, as well as feeding damage,” said Brian J. Klatt, interim director of the Gardens. Increased feeding damage not only harms the individual plant, but also reduces the number of seeds that each plant produces, thereby reducing its spread. Wetlands vibrant with the blooming purple loosestrife may be a joy to look at, but with this invasive species crowding out native plants, wetlands are becoming unhealthy and showing less diversity in both plant and animal inhabitants. Home gardeners may be aware that nurseries no longer sell purple loosestrife, but they can and do offer its acceptable non-invasive cousin Lysimachia, which comes with a yellow or white blossom. For more information, visit http://www-personal.umich.edu/~jessymil/loosestrife.html and http://www-personal.umich.edu/~nlacros/otherans.html.
 

http://www-personal.umich.edu/~jessymil/loosestrife.htmlhttp://www-personal.umich.edu/~nlacros/otherans.html