Do predation and host plant quality interact to regulate soybean aphid?

Landis, D., A. Costamagna, K. Thelen, C. DiFonzo, M. O'Neal

Presented at the All Scientist Meeting (2003-09-12 )

The soybean aphid (Aphis glycines Matsumura) is an invasive species from Asia that has become a major pest of soybean in the US since its discovery in 2000. Prior research has shown that existing natural enemy communities contribute to A. glycines population regulation in Michigan soybeans and can result in effective economic control. The differential disturbance gradients represented on the KBS LTER site are likely to influence A. glycines population regulation via two mechanisms. First, 14 years of differential management on the KBS LTER site have created differences in generalist natural enemy assemblages that may regulate the ability of this invasive herbivore to successfully colonize these habitats via top-down influences. Second, by altering soil and nutrient conditions, treatment regimes may alter host plant phenology and nutritional quality through bottom up effects that may influence A. glycines intrinsic rate of increase. We present results from 2003 studies on the KBS LTER site that test three hypotheses:

1. Generalist predator communities do not differ among selected LTER treatments.


2. A. glycines establishment and population growth does not differ among the selected treatments.


3. There is no direct or interactive effect of predator community and agronomic practice on A. glycines population regulation in the selected treatments.

These studies provide a view of the ecological factors regulating A. glycines populations under a variety of relevant agronomic conditions in Michigan and provide information on practical management options.