Correlation of an Electrical Penetration Graph Waveform with Walking by Asian Citrus Psyllid, Diaphorina citri (Hemiptera: Psyllidae)

Abstract

The present study characterized and correlated 2 EPG waveforms, NP and Z, recorded when the Asian citrus psyllid (ACP) is walking/labial dabbing or standing still, respectively, prior to insertion of the stylets into the plant to begin feeding. The variable-voltage NP waveform was correlated with electrical contact caused by structures on the psyllid tarsus, such as tarsal claws or texture of the arolium, imaged using SEM. This conclusion is supported because covering the tarsi with smooth, clear nail polish abolished the electrical conductance. Despite walking by nail polish- treated insects, only the flat Z waveform (true baseline) was displayed. This is the first time that a walking waveform is detected for a sternorrhynchan hemipteran using the Giga8 EPG monitor. The walking waveform will be useful for numerous EPG studies of ACP.