Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/1/2017
Publication Date: 4/18/2017
Citation: Cervantes, F.A., Backus, E.A. 2017. Understanding feeding behavior of Lygus spp. through electropenetrography. Presented at the 2017 International Heteroptera Symposium, April 18-20, 2017, Seaside, CA.
Technical Abstract: Electropenetrography (EPG) is a novel technique that allows real-time study of heteropteran feeding. Lygus hesperus and L. lineolaris (Hemiptera: Miridae) are economically important pests affecting production of cotton in the western and mid-southern USA, respectively. Direct-feeding damage caused by lygus varies in severity with age stage of the insect. Young nymphal lygus are cell-rupture feeders performing laceration and maceration of plant tissue before ingestion. However, it is presently unknown whether adult lygus feed in similar fashion. The main goal of this study was to identify EPG waveforms representing feeding behaviors performed by pre-reproductive, adult L. lineolaris and L. hesperus and to define biological meanings of waveforms based on histological correlations. A 3rd-generation AC-DC EPG monitor was used to study feeding of lygus adults on pinhead (<3mm) cotton squares. Recordings used DC or AC applied signal at input impedances ranging from 106 to 109 Ohms. EPG waveforms also were correlated with insect damage on cotton squares via histology. Results led to construction of an EPG waveform library to: 1) characterize waveforms, 2) identify electrical origins, and 3) hypothesize biological meanings. Three main waveform types were characterized: CR (cell rupturing, which includes stylet laceration, watery salivation but no sheath salivation), T (transition), and I (ingestion). Histological correlation of CR waveforms revealed that lygus did not reach vascular cells (either phloem or xylem), but feeding induced localized secretion of histologically stainable, putative tannins, probably marking the location of secreted watery saliva. Waveform I strongly resembles ingestion waveforms in other heteropterans, and was correlated with removal of macerated plant tissue, saliva and tannins.