Western corn rootworm and maize growth under varying soil moisture conditions

Diabrotica virgifera virgifera LeConte, the western corn rootworm (WCR) is a major pest of maize. WCR larvae reduce water and mineral uptake of maize roots and cause a $2 billion economic loss annually. Drought is a serious natural hazard causing huge economic losses in most crops. The relationship between both soil moisture and WCR on maize is important and not well quantified. A greenhouse experiment was conducted to evaluate the interaction of soil moisture and WCR on maize and WCR. The experiment was a randomized complete block with treatments arranged in a 3×3 factorial (3 soil moisture levels × 3 WCR infestation levels). Root damage ratings were significantly greater in the well watered (saturated) treatment than the two reduced water treatments at both infestation levels. However, WCR larval recovery was lower for the saturated soils. Water potential was significantly higher under drought stress, but WCR infestation did not significantly affect water potential in this experiment. Shoot dry weight was greatest under saturated moisture conditions without WCR. As expected dry root weight was greater in the absence of WCR. Understanding how the combination of drought and WCR affect maize will be more important as additional drought traits become commercially available.