Rhizedra lutosa, a natural enemy of Phragmites australis in North America

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Conference Proceeding

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Rhizedra lutosa (Hübner) (Lepidoptera: Noctuidae), native to Europe, was first found in North America in 1988 in southern New Jersey. The insect is reported to cause serious damage to Phragmites australia in the Netherlands, but it now appears to be relatively unimportant throughout central Europe. We are investigating this insect as part of an effort to characterize existing natural enemies of P. australis in North America toward a goal of biological control of this invasive plant. We trapped adults of R. lutosa with blacklights in Rhode Island, Massachusetts, Connecticut, New York, Delaware, and Maryland; we also found it in Ohio and Pennsylvania. R. lutosa larvae feed in stems and rhizomes of P. australis growing in dry sites. Based upon R. lutosa damage surveys and P. australia biomass measurements, we have determined that this insect does cause a reduction of plant growth in some sites, however, because of low moth densities, this effect is small. Despite spreading rapidly, R. lutosa densities do not appear to be increasing at sites we have investigated, and this insect does not currently appear to have much of an impact upon P. australia in North America.

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