Potato Leafhopper (Homoptera: Cicadellidae) Injury Disrupts Basal Transport of 14C-Labelled Photoassimilates in Alfalfa

The potato leafhopper, Empoasca fabae (Harris), is a key pest of alfalfa, Medicago sativa L., in part because of the leafhopper’s ability to disrupt upward translocation within phloem tissues. To determine if leafhopper injury also disrupts basal translocation necessary for regrowth and perenniality of alfalfa, we used radiolabeled 14CO2 to measure the basal transport of photoassimilates in injured and healthy plants. In one experiment, less 14C was transported to lower stem tissue of leafhopper-injured plants in comparison to the same tissue of healthy plants in early vegetative and early reproductive stages of alfalfa development. In a second experiment, less 14C was transported to lower stem, crown, and root tissues of injured plants in comparison to the same tissues of healthy, early reproductive plants. The disruption of basal transport caused by potato leafhopper may impact carbon storage and mobilization subsequent to defoliation, winter survival, and nitrogen fixation.