Predation of immature and adult Empoasca fabae (Harris) (Hemiptera: Cicadellidae) by three species of predatory insects

Relatively few studies have examined predation of Empoasca fabae (Harris) (Hemiptera: Cicadellidae), an important insect pest of alfalfa (Medicago sativa L. Fabaceae). In this laboratory study, we quantified rates at which E. fabae adults and nymphs were attacked by three predatory species: Coleomegilla maculata (Degeer) (Coleoptera: Coccinellidae), Chrysoperla carnea Stephens (Neuroptera: Chrysopidae), and Orius insidiosus (Say) (Hemiptera: Anthocoridae). Individual predators and E. fabae were held in a feeding arena for 24 hours (individual fava bean plants Vicia faba L. (Fabaceae) enclosed within dialysis tubing). Adult C. maculata attacked 4.2 nymphs and 1.6 adults at the high-prey density (15 E. fabae nymphs or 10 adults per cage) and 2.0 nymphs and 0.6 adults at the low-prey density (5 E. fabae nymphs or 3 adults per cage). Orius insidiosus attacked twice as many E. fabae nymphs than adults at the high density (2.9 versus 1.2). In contrast, similar numbers of nymphal and adult E. fabae were attacked by C. carnea larvae (4.6 versus 3.5, 1.2 versus 0.8; at high - and low-prey densities, respectively). Of the three predatory species, C. carnea larvae attacked the most E. fabae nymphs and adults. These predatory species may play a role in maintaining low population densities of E. fabae in alfalfa.