1. Introduction
In agricultural systems, knowledge of food web interactions is often limited due to the complexity of tritro phic relationships and the number of species involved (
Basco-
mpte and Melian, 2005
). Invasions of exotic species are
likely to profoundly a
V
ect the structure of food webs in
agroecosystems. The soybean aphid,
Aphis glycines
Mat-
sumura, a native of Asia, was
W
rst detected in the U.S. in
Wisconsin in July of 2000. Its range now extends through-