Albany Pine Bush News

A Blunt Knapweed Flower Weevil in a Spotted Knapweed flower.

A Blunt Knapweed Flower Weevil in a Spotted Knapweed flower.

Last week was NY Invasive Species Awareness Week, a week dedicated to getting the word out about the threats posed by invasive species. At the Albany Pine Bush, visitors learned about invasive plants in the preserve and Field Ecologist, Amanda Dillon, took to the managed barrens around the Discovery Center, sweep-net in hand, to investigate the status of some very special insects. She was on the hunt for any of the 13 species of insects released at locations around the country over the past 40 years to help control invasive knapweed plants.

In the Albany Pine Bush, one species in particular, Spotted Knapweed (Centaurea stoebe), mostly occurs along the edges of hiking trails, with occasional patches scattered throughout the Preserve. Knapweeds are much more problematic in western parts of the country. There, knapweed can out-compete most of the native prairie species, creating large monocultures – areas where knapweeds are virtually the only plant species present.

Emergence hole in the seed head of a Spotted Knapweed plant. The small hole in this seedhead is the point at which a larvae of one of the seed-eating insects chewed its way out of the plant after consuming many of the seeds.

Emergence hole in the seed head of a Spotted Knapweed plant. The small hole in this seedhead is the point at which a larvae of one of the seed-eating insects chewed its way out of the plant after consuming many of the seeds.

They’re here! Dillon found not one, but three of the species of insects that biologically control the spread of Spotted Knapweed. The species she found included the Banded Knapweed Gall Fly (Urophora affinis), UV Knapweed Seedhead Fly (Urophora quadrifasciata), and Blunt Knapweed Flower Weevil (Larinus obtusus). While knapweed may never be totally eradicated from the Albany Pine Bush Preserve, these insects in combination with mechanical management and prescribed fire can give the native plants of this rare ecosystem a competitive advantage.

 

 

 

References:

Wilson, L.M., Randall, C.B., 2003. Biology and Biological Control of Knapweed. Forest Health Technology Enterprise Team, Technology Transfer. Available online at http://www.invasive.org/weeds/knapweedbook.pdf

Grace Barber @ 3:14 pm

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