Brewer, M.J.
Presented at the ASM at Estes Park (2006-09-01 to 2012-09-23 )
The Kellogg Biological Station cropping system LTER presents an experimental framework to consider the importance of habitat affinity of aphid parasitoids and predatory flies as they adapt to utilizing an aphid invading the US Midwest field crop system. Within 3 yr of the invasion of Aphis glycines, the soybean aphid, we found a diverse group of resident parasitoids and predatory flies utilizing A. glycines as host/prey. Species diversity was similar to the community known to regulate A. glycines in its home range, but at the KBS LTER no greater than 1% parasitism of soybean aphid occurred, predation by flies was detected, and aphid outbreaks were pronounced. In 2004 and 2005, we measured habitat affinity of these aphid-specialists by placing sentinel A. glycines in soybean, other field crops, and noncropped vegetation at the KBS LTER. Overall, the predatory fly fauna utilizing A. glycines in soybean was about the same or only modestly lower in species number and abundance than in other habitats. In contrast, habitat affinity of the parasitoids was more pronounced as measured by differences in parasitoid abundance between the habitats. The habitat data bode well for predatory flies preying on A. glycines in soybean, but stronger habitat affinity of parasitoids likely presents additional challenges as they adapt to use of an invading species.
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