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United States Department of Agriculture

Agricultural Research Service

Title: Video and Ac Epg Waveform Correlations of Homalodisca Coagulata Stylet Activity During Probing

item Backus, Elaine

Submitted to: Entomological Society of America Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: May 25, 2004
Publication Date: November 15, 2004
Citation: Joost, P.H., Backus, E.A. 2004. Video and AC EPG waveform correlations of Homalodisca coagulata stylet activity during probing. [abstract]. The 2004 ESA Annual Meeting and Exhibition. Available:

Technical Abstract: Glassy-winged sharpshooter (GWSS), Homalodisca coagulata (Say), is the main vector of Xylella fastidiosa, the casual bacterium of Pierce's Disease in grapevine. A detailed understanding of GWSS probing behavior is important because X. fastidiosa is acquired and inoculated when GWSS feeds. To further elucidate GWSS probing behavior we used the AC electrical penetration graph technique (AC EPG) and video to correlate GWSS probing behaviors with EPG waveforms in artificial diets. Three previously described waveforms, A1, B1 and B2, were correlated with GWSS stylet activity. Fascicle protraction, alternating mandible retraction and maxillary tip fluttering were correlated with subdivisions of the A1 waveform. Salivary sheath formation was also observed in A1. Waveform B1 was correlated with maxillary fluttering within the salivary sheath. Termination of the B1 waveform and maxillary fluttering occurred sometimes when the maxillae were inside the saliva sheath and always when the maxillae exited the salivary sheath. Waveform B2 was associated with stylet path branching within the salivary sheath. During B2, GWSS would "saw" a new stylet branch in the salivary sheath by rapidly retracting and protracting its stylet fascicle in a skewed direction from the original branch. Termination of B2 occurred when the styletd "sawed" through the salivary sheath.

Last Modified: 5/5/2015
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