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Submitted to: Book Chapter
Publication Type: Book / Chapter Publication Acceptance Date: 10/18/2015 Publication Date: 12/30/2016 Citation: Backus, E.A. 2016. History, principles, and summary of applications of electropenetrography (EPG). In: Yan F.M., Wang M.Q., editors. Electrical Penetration Graph and Applications. Zhengzhou, China: Henan Science & Technology Press. p. 2-24. Interpretive Summary: Many devastating agricultural pests in the world are hemipteran insects that transmit lethal plant pathogens, such as Asian citrus psyllids transmitting the citrus greening bacterium, or green peach aphids transmitting Potato virus Y. Other hemipterans, such as lygus bugs, cause direct feeding damage to crops via enzymatic saliva. Developing novel, non-pesticidal tactics to manage hemipteran pests is facilitated by studying insect feeding behaviors that result in transmission or direct damage. However, studying feeding of hemipterans is challenging because piercing-sucking mouthparts cannot be directly observed while being probed into opaque plant tissues. This challenge was overcome by the invention of electropenetrography, or electrical penetration graph (EPG) monitoring, which produces measurable electrical waveforms as a representation of feeding behaviors. Today, EPG is extensively used for development of novel integrated pest management (IPM) tactics for hemipteran pests. This paper reviews: 1) electronic principles and history of EPG, especially development of the new, third-generation AC-DC monitor, 2) principles underlying biological meanings of waveforms, and 3) summarizes the ways that EPG can be used for both basic entomological research and applied improvements in insect pest management, using aphids (the best-studied system using EPG) as examples. Technical Abstract: Studying feeding, plant damage, and transmission (i.e. acquisition, retention, and inoculation) of plant pathogens by hemipteran insect pests is challenging. Hemipteran piercing-sucking mouthparts, the stylets, are probed into opaque plant tissues precluding direct observation. This challenge was overcome by the invention of electropenetrography, or electrical penetration graph (EPG) monitoring. Today, EPG is used in three main ways for development of novel integrated pest management (IPM) tactics for hemipteran pests. First, in cases where fundamental mechanisms of feeding damage or transmission of a plant pathogen are unknown, EPG is instrumental in identifying such mechanisms. Second, once feeding-related causes of damage or pathogen transmission are understood, EPG can be used to demonstrate effects of insecticides, antifeedants, or other chemical compounds on specific feeding behaviors responsible for damage or transmission. Third, EPG can similarly identify differential effects of resistant versus susceptible varieties of crop plants, including transgenic plants engineered to express biopesticides. The purpose of this paper is to: 1) review electronic principles and history of EPG, especially development of the new, third-generation AC-DC monitor, 2) review principles underlying biological meanings of waveforms, and 3) summarize the ways that EPG can be used for both basic entomological research and applied improvements in insect pest management, using aphids (the best-studied system using EPG) as examples. |
