AC–DC Electropenetrography for In-depth Studies of Feeding and Oviposition Behaviors

Abstract

Studying the feeding, host damage, and transmission (i.e., acquisition, retention, and inoculation) of pathogens (plant and animal) by piercing-sucking arthropods is challenging. The piercing mouthparts are probed into opaque host tissues, precluding direct observation. This challenge was overcome by the invention of electropenetrography, or electrical penetration graph (both abbreviated EPG), the most rigorous method to identify arthropod feeding behaviors. However, until recently, most EPG research was restricted to studies of hemipteran plant pests, especially aphids and leafhoppers. Recent advances in EPG technology via the third-generation, alternating current–direct current (AC–DC) monitor (electropenetrograph) are opening new doors to expand the science into all types of arthropod feeding and oviposition. EPG can be used in three ways for the development of novel integrated pest management (IPM) tactics. First, in cases where the fundamental mechanisms of feeding/oviposition effects or pathogen transmission are unknown, EPG is instrumental in identifying mechanisms. Second, once the causes of damage or transmission are understood, EPG can be used to demonstrate the effects of insecticides, antifeedants, repellents, or other chemicals on specific feeding behaviors responsible for damage or transmission.Third, EPG can similarly identify the effects of resistant versus susceptible varieties of crop plants and animals, including transgenic organisms genetically engineered to express biopesticides or other genes. The purpose of this paper is to encourage new research avenues by 1) thoroughly reviewing history and electronic principles of EPG, culminating in the AC–DC electropenetrograph, 2) reviewing principles underlying biological meanings of waveforms, and 3) presenting a few examples of waveforms from new arthropod taxa.