Monday, December 11, 2006 - 10:11 AM

Correlations of electrical penetration graph (EPG) waveforms with beet leafhopper (Hemiptera, Cicadellidae) feeding behaviors

Candice A. Stafford, and Gregory P. Walker, University of California - Riverside, Department of Entomology, Riverside, CA

In the arid to semi-arid regions of North America, the beet leafhopper, Circulifer tenellus (Baker), is the only known vector of curly top virus, which causes major loses in a number of crops including tomato, sugar beet, and beans. Feeding behavior of beet leafhopper on leaves of young sugar beet and tomato plants was studied using a direct current electrical penetration graph (DC-EPG). Correlations between specific feeding behaviors and EPG waveforms were performed using a number of techniques. The main feeding behaviors of interest are ingestion of xylem and phloem sap. To elucidate which waveforms are associated with ingestion, EPGs and high magnification video of feeding leafhoppers were recorded simultaneously. These recording allowed us to determine which EPG waveforms are associated with production of honeydew. Honeydew production is indicative of ingestion from either xylem or phloem. To determine if xylem or phloem sap is being ingested during the waveforms in which honeydew is being produced, a high frequency radio microcautery device was used to sever the stylets. The portion of leaf containing the stylets was then examined histologically to determine placement of the stylet tips within the plant when the leafhopper was producing the ingestion waveform.

Species 1: Hemiptera Cicadellidae Circulifer tenellus (beet leafhopper)

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