|LUCINI, TIAGO - Federal University Of Parana Polytechnic Center|
|PANIZZI, ANTONIO - Embprapa|
Submitted to: Annals of the Entomological Society of America
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/12/2015
Publication Date: 1/21/2016
Citation: Lucini, T., Panizzi, A.R., Backus, E.A. 2016. Characterization of an EPG waveform library for redbanded stink bug, Piezodorus guildinii (Westwood) (Hemiptera: Pentatomidae), on soybean plants. Annals of the Entomological Society of America. 109:198-210.
Interpretive Summary: The redbanded stink bug is a major pest of soybean in both North and South America; in recent years, it has become the most important stink bug pest of soybean in southern Texas. Soybean seeds are damaged by saliva secreted during feeding. Varieties of soybean resistant to stink bug feeding must be developed, but the present inability to directly observe and measure such feeding hampers their development. The best way to alleviate this problem is to use electropenetrography (EPG) to record stink bug feeding. Studies were conducted using AC-DC EPG to record redbanded stink bug feeding behaviors on stem, leaves, and pods of soybean. Eleven different waveforms were characterized and their biological meanings identified via histological correlations with fed-upon soybean tissues. Five waveforms represented various types of salivation into leaf, stem, or seed tissues, while two represented swallowing of fluid from either seed tissues or xylem (water-conducting tubes). These new definitions of stink bug waveforms will allow future EPG studies to aid in development of soybean varieties that resist the feeding and damage caused by this insect pest.
Technical Abstract: Studies were conducted with the redbanded stink bug, Piezodorus guildinii (Westwood), using AC-DC electropenetrography (EPG) to record feeding behaviors on vegetative (stem and leaflet) and reproductive (pod) tissues of soybean, Glycine max (L.). P. guildinii is a major pest of soybean in the Americas; in recent years, its abundance has substantially increased in the southern United States, and it has become the most important stink bug pest of soybean in southern Texas. Eleven different waveforms were characterized and defined: Np, Z, R, Pg1a, Pg1b, Pg1c, Pg1d, Pg2, Pg3a, Pg3b, and Pg4, grouped into three different families, P, I, and N. Histological studies of intact stylets within salivary sheaths observed during Pg1b, Pg1c, Pg2, and Pg3 waveforms were correlated with specific stylet penetration sites. Np and Z waves were generated when the bug was moving or remained still on the plant surface, respectively. Waveform R occurred when the bug touched the plant surface with its rostrum (labium) before it started probing/stylet penetration into plant tissue. Waveforms Pg1a, Pg1b, Pg1c, and Pg1d (pathway phase – family P) occurred at the start of probing activities and represent stylet penetration deep into plant tissue and formation of a salivary sheath. Waveforms Pg2, Pg3a, and Pg3b (family I) represent the food-ingestion phase. Pg2 waveform represents xylem sap ingestion primarily on leaves and stems. During Pg3a, stylets were moving, lacerating deeply into pod tissue and partially retracting; during Pg3b, stylets were motionless inside the pod tissue. Pg3b occurred interspersed with waveform Pg3a. Waveform Pg4 (family N) represented short interruptions that occurred within waveform Pg2. The study demonstrated that P. guildinii, in addition to ingesting nutrients from the seed endosperm, also ingests from xylem vessels. These new definitions of P. guildinii EPG waveforms will allow future EPG studies to aid in development of soybean varieties that resist the feeding and damage caused by this insect pest.