BIOLOGICAL CONTROL OF PURPLE LOOSESTRIFE: AN ENVIRONMENTAL SUCCESS STORY

SMALL STAND OF PURPLE LOOSESTRIFE...

...I'M NOT SEEING MUCH OF IT AROUND BAYFIELD ANYMORE!

Sunday, 8:30 AM.  56 degrees F, wind ENE, light to moderate.  The sky is overcast and the east wind made for a chilly walk with Buddy at the beach earlier this morning.  The humidity is 86% and the barometer now stands at 30.07" and is trying to decide where it is heading.  No porch-settin' today, I am afraid.
   Purple loosestrife, Lythrum salicaria, in the loosestrife family, the  Lythraceae, is a European native long used as a garden perennial and now escaped into the wild, where it has become an invasive nuisance which over-competes with native wetland vegetation.  There was a time when it was so pervasive that it appeared to be taking over many of our Wisconsin cattail marshes and was present in every roadside ditch.  Beautiful as it may be, it became too much of a good thing.
   Efforts to control it have been many, including herbicides and mechanical destruction, but it wasn't until biological controls were introduced (several European weevils and beetles and their larvae that feed on loosestrife roots, leaves or flowers) about twenty years ago that progress was made.  I can attest  that since these controls were introduced into our local loosestrife populations  the once very large areas occupied by purple loosestrife have receded significantly, and it is becoming much less obvious in the Bayfield area.
   Biological control of loosestrife or any other plant population is a complicated and expensive undertaking, but it is ultimately more effective and environmentally neutral than chemicals and mechanical eradication.  In Wisconsin and elsewhere much of the hands-on work has been done by volunteers and school groups, although the effort needs professional planning and guidance.  The following paragraphs are quoted from the Wisconsin Department of Natural Resources web site:

 "The DNR and University of Wisconsin-Extension (UWEX), along with hundreds of citizen cooperators, have been introducing natural insect enemies of purple loosestrife, from its home in Europe, to infested wetlands in the state since 1994. Careful research has shown that these insects are dependent on purple loosestrife and are not a threat to other plants. Insect releases monitored in Wisconsin and elsewhere have shown that these insects can effectively decrease purple loosestrife's size and seed output, thus letting native plants reduce its numbers naturally through enhanced competition."
   "A suite of four different insect species has been released as biological control organisms for purple loosestrife in North America and Wisconsin. Two leaf beetle species called "Cella" beetles that feed primarily on shoots and leaves were the first control insects to be released in Wisconsin, and are the insects available from DNR for citizens to propagate and release into their local wetlands. A root-mining weevil species and a type of flower-eating weevil have also been released and are slowly spreading naturally. The Purple Loosestrife Biocontrol Program offers cooperative support, including free equipment and starter beetles from DNR and UWEX, to all state citizens who wish to use these insects to reduce their local purple loosestrife."
   "The length of time required for effective biological control of purple loosestrife in any particular wetland ranges from one to several years depending on such factors as site size and loosestrife densitys. The process offers effective and environmentally sound control of the plant, not elimination in most cases. It is also typically best done in some combination with occasional use of more traditional control methods such as digging and herbicide use.
   "Though purple loosestrife is almost certainly here to stay in Wisconsin, we should be able to efficiently protect our wetland ecosystems from domination by purple loosestrife by simply restoring some of the natural checks and balances that can result in diverse, healthy environments."

   One of the virtues of biological control of plant and other invasive populations is that complete eradication of the target population is neither necessary nor desirable, as the biological agents being utilized need a residual host population to maintain their own numbers.  It is not like trying to eliminate every dandelion in a lawn, which creates a monoculture that itself is unnatural and therefore vulnerable to other destructive agents.  Biological controls seek a natural balance, which in the long run is the most economical and least intrusive of efforts.
   I often criticize the environmental bureaucracies, both federal and state, for being overly controlling and intrusive in our society.  The biological control of purple loosestrife is, however,  a very positive story.