Naturespeak A naturalist's view of the world

May 23, 2008

No, It’s a Good Thing

Filed under: Uncategorized — wykes @ 3:18 pm

  The Purple Loosestrife is a beautiful flowering plant that hails from across the pond in Europe. As a garden plant, their slender magenta inflorescences add a special hue and a certain amount of verticality to the cultured garden-scape. Their long summer bloom time adds to their potential charm. After that glowing introduction, you’d think that the sight of a bunch of leaf hungry beetles reducing one of these plants to the vegetative equivalent of Swiss cheese would be a bad thing – a gardener’s nightmare. Truth is, the scene pictured above is a good thing.

  Like so many other garden plants, domestic Loosestrife escaped over the white picket fences and ran rampant over the landscape. By the mid 1990’s these aggressive aliens found their way into nearly every marsh in the Midwest. Lacking any New World pests, they were able to aggressively dominate and began to choke out the native flora and destroy wetland habitats. Many of our local marshes were reduced to pure plots of purple summer haze.

  The ‘strife was well on its way to becoming a grim ecological reaper of doom. It appeared that we mortals were powerless against it (Even Batman and Superman were rendered neutral in this affair). Thankfully, the solution finally came in the form of a 1/8th inch beetle called the Gallarucella, or Loosestrife, Beetle (here, take a look see). Researchers spent the better part of the last decade divining what the natural homeland enemy of the Loosestrife was and came up with this humble little bug that ate ONLY Purple Loosestrife. It was crucial to establish that this critter would not turn to other plant species if it was going to be considered as a control agent. Gallarucella passed the test with flying colors.

  To make this long story short, the beetle was introduced throughout the Midwest. Many individuals, and institutions (mine included), participated in rearing beetle populations and releasing them into ‘strife infected environs.  The effort turned out to be very successful and the Purple plague was nipped in the bud.

  It has been many years since I released any beetles at Lake Erie Metropark. The beetles have taken over the situation on their own and require no more assistance from us – as the scene above illustrates.

  This time of year, the adult beetles are emerging from their pupas. They immediately assemble on the new Loosestrife shoots and begin eating holes into the leaves. Soon, the like minded, and well fed, beetles get together and mate. Eggs are laid, larvae are hatched, and feeding goes on. The larvae burrow into the growing shoot of the plant and eventually kill the new growth. By the time the next generation of beetles come out later in the summer, the weakened loosestrife are barely able to maintain their growth, leave alone attempt any flowering. They become stunted, malnourished and eventually die.

  The other part of this good news story is that the Loosestrife plants are not totally destroyed. They continue to hold on and sprout, but they do so as peasant villagers within the eco-system and not as conquering despots.  This insures that Loosestrife beetles will always have food resources in order to maintain their purple policing duties. In the near future, the gardener will be able to once again enjoy this plant as a domestic, but will need to keep it sprayed just like the other plants.

  It is time to pause and honor the power of the meek and mighty Gallarucella.

1 Comment »

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    Comment by love songs — April 30, 2011 @ 9:01 am

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