The Effect of Host-Plant Resistance and Intercropping on the Potato Leafhopper in Alfalfa

The potato leafhopper is a significant agricultural pest of alfalfa, especially in the Northeastern United States. Alfalfa is a primary source of hay for dairy cows, and the damage done to the crop can ultimately result in lower quality hay and thus lower milk yields. Farmers spray pesticides on their crops to control insect pests which are effective, but can be environmentally damaging. Two alternative pest management strategies are intercropping and host-plant resistance. This study examines the effects of intercropping orchardgrass, which potato leafhoppers do not eat, with the semi-resistant strains of alfalfa which possess small hairs on the stem called trichomes that interfere with leafhopper feeding behavior. To determine the effectiveness of these planting treatments a nine acre field was planted with alternating treatments: susceptible alfalfa, resistant alfalfa, and resistant alfalfa intercropped with orchardgrass (n=8 for each treatment). Sweep samples were taken from the middle of each plot weekly and were processed in the lab to determine the abundance of potato leafhoppers in each treatment. As hypothesized, the abundance of potato leafhoppers in the susceptible plots was greater than in the resistant and intercropped-resistant plots