Spatial and Temporal Dynamics of Aphids (Hemiptera: Aphididae) in the Columbia Basin and Northeastern Oregon

Aphid species, such as the potato aphid, Macrosiphum euphorbiae Thomas, and the green peach aphid, Myzus persicae Sulzer, are routinely considered the most important pests of potatoes. Potato aphid, green peach aphid, and more recently, other aphids such as the bird cherry-oat aphid Rhopalosiphum padi L. have been identified as vectors of multiple plant pathogenic viruses in potatoes. Since 2006, an area-wide trapping network consisting of ∼60 sites was developed through collaboration between researchers, extension faculty, and stakeholders, to monitor aphid populations in the Columbia Basin of Oregon (Umatilla and Morrow counties) and in northeastern Oregon (Union and Baker counties). Over a 9-yr period (2006 to 2014), aphid specimens were collected weekly using yellow bucket traps and specimens were then identified and counted to determine population levels during the growing season (May-September). Thus, aphid population data were compiled and subjected to spatial and temporal distribution analysis. Weather data, obtained from an established network of weather stations located in the monitoring areas, were used in a nonparametric multiplicative regression analysis to determine which abiotic variables may impact aphid populations. Weather conditions were characterized using confidence intervals (CIs) established based on weather data from 1999 to 2005 for each environmental variable. Aphid populations were found to have a heterogeneous distribution in most years; a few sites had high aphid populations while low numbers were observed at most sites; aphids were also found to correlate with several abiotic variables, namely, elevation, previous season temperature, and previous season dew point.