Forecasting and monitoring pea aphid (Acyrthosiphon pisum) pressure on the Palouse

The pea aphid Acyrthosiphon pisum is a sporadically serious pest of leguminous crops in the Palouse region of the inland Pacific Northwest. They damage crops by direct injury and more dramatically by vectoring plant viruses. Late summer and winter weather conditions on the Palouse prevent the Pea aphid from successfully overwintering in place; as a result the region is a sink. Pea aphid populations on the Palouse have been studied using a yellow pan trap network during the growing season beginning in May 2006 and continuing to the present, in addition a 27 year index of abundance has been established. Meteorological variables in both source and sink areas may act as predictors of the timing and magnitude of spring immigration of pea aphid alatae. Historical meteorological data has been compared with the 27 year index to examine the relationship between weather and seasonal abundance. Using data from the trap network the spatial and temporal dynamics of pea aphid populations established on the Palouse can be related to weather and landscape variables. The ability to forecast pea aphid abundance and distribution on the Palouse can enable producers to more effectively allocate resources in response to pest pressure.