Host Densities and Parasitism Rates in a Forest Defoliator Across a Rural-Urban Landscape

• Main Author: Nelson, Abigail J
• Format: Others
• Published: VCU Scholars Compass 2016
• Subjects: Lepidoptera; urbanization; population dynamics; trophic interactions; Population Biology
• Online Access: http://scholarscompass.vcu.edu/etd/4483; http://scholarscompass.vcu.edu/cgi/viewcontent.cgi?article=5465&context=etd

Fall cankerworm (FCW) outbreaks have recently increased in frequency and intensity in the mid-Atlantic region of the United States, especially around cities of Charlotte, NC and Richmond, VA. This study evaluated the effects of two landscape features associated with urbanization, impervious surface and forest cover, on population patterns of FCW and its parasitoids across eastern Virginia. Forest cover was positively related to parasitism rates while impervious surface was positively related to FCW abundance, suggesting that FCW outbreaks may be amplified in urban areas. FCW abundance declined over the two-year period of this study, but parasitism rate increased at most sites. Parasitism was highest at sites that experienced FCW outbreaks first, indicating that parasitoid populations are responding to moth abundances. It remains to be seen whether this outbreak was an aberrant occurrence, or represents a regime shift to more frequent defoliation in Virginia, similar to that in North Carolina urban areas.