Effects of intercropping on biological control of potato leafhopper, Empoasca fabae

The potato leafhopper is the key pest of alfalfa in the Northeast United States. To control this pest, farmers often use insecticides that are costly and detrimental to the environment. An alternative pest management strategy is intercropping, which can reduce herbivorous pests by making their host-plants difficult to locate, or by increasing the effectiveness of predatory insects.  We studied the effects of intercropping and predators on potato leafhopper abundance in a mesocosm experiment. Two crop treatments (alfalfa monocrop, alfalfa intercropped with orchardgrass) were crossed with three predator treatments (no predator control, Nabis americoferus, Coleomegilla maculata). There was no effect of C. maculata on leafhopper abundance. By the end of the first week, N. americoferus significantly reduced leafhopper abundance, but only in the intercropped alfalfa. These results indicate that intercropping alfalfa with orchardgrass may enhance biological control of the potato leafhopper by N. americoferus.