Mesophyll-Feeding by the Potato Leafhopper, Empoasca fabae (Homoptera: Cicadellidae): Results from Electronic Monitoring and Thin-Layer Chromatography

The probing behaviors of the potato leafhopper, Empoasca fabae (Harris), were studied using an AC electronic monitoring system. Observations on two artificial media (water-sucrose solution and agar-sucrose solution) and two host plants (alfalfa, Medicago sativa L., and broad bean, Vicia faba L.) revealed three waveforms correlated with probing behaviors: Ia, representing multiple-cell laceration feeding, the dominant waveform on both hosts; Ib, representing Single-cell puncture-feeding, ingestion of the contents of individual mesophyll cells; and Ic, ingestion with the insect's stylets held motionless. These results plus those from thin-layer chromatography of the host plants and insects show that the potato leafhopper, like many of its typhlocybine relatives, does not ingest strictly from the phloem but also from the mesophyll. However, the potato leafhopper uses a feeding strategy that does not produce leaf stippling; this strategy differs from that of other leafhoppers that ingest from mesophyll.