AC–DC electropenetrography: fundamentals, controversies, and perspectives for arthropod pest management

Abstract

Studying the intimate association of arthropods with their physical substrate is both important and challenging. It is important because substrate is a key determinant for organism fitness; challenging because the intricacies of this association are dynamic, and difficult to record and resolve. The advent of electropenetrography (EPG) and subsequent developments allowed researchers to overcome this challenge. Nonetheless, EPG research has been historically restricted to piercing–sucking hemipteran plant pests. Recently, its potential use has been greatly broadened for additional pests with instrument advances. Thus, blood‐feeding arthropods and chewing feeders, as well as non‐feeding behaviors like oviposition by both pests and parasitoids, are novel new targets for EPG research, with critical consequences for integrated pest management. EPG can explain mechanisms of crop damage, plant or animal pathogen transmission, and the effects of insecticides, antifeedants, repellents, or transgenic plants and animals, on specific behaviors of damage or transmission. This review broadly covers the principles and development of EPG technology, emphasizing controversies and challenges remaining with suggested research to overcome them. In addition, it summarizes 60+ years of basic and applied EPG research, and previews future directions for pest management. The goal is to stimulate new applications for this unique enabling technology. Published 2020. This article is a U.S. Government work and is in the public domain in the USA.

AC–DC electropenetrography unmasks fine temporal details of feeding behaviors for two tick species on unsedated hosts

“…EMG instruments necessitate higher Ri levels, extensive band pass filtering, and differential amplification to detect these tiny biopotentials, compared with EPG instruments. More information on EPG/EMG electronics is here 17 , 22 , 35 .…”

“…Although coordinated salivation processes are generally understood at a coarse time scale, from numerous molecular and biochemical studies 11 – 16 , the time-scale temporal dynamics of specific tick salivation and ingestion events are largely unknown. Until ‘normal’ tick feeding behaviors and tick-host interactions are delineated, including the temporal sequence of these events, it is nearly impossible to attain a clear understanding of how tick and TBP intervention methods alter tick feeding behavior and tick-host interactions 17 .…”

“…Waveforms can be correlated with highly specific behaviors, such as mouthpart movements, direction of fluid flow, salivation, ingestion, puncturing of specific cells, and pathogen acquisition/inoculation 22 . Three generations of major EPG technology designs have occurred, in parallel with advancements in electronics 17 , 22 . The first-generation (AC) monitors 18 , 20 (no longer manufactured); used high AC applied signal and fixed-low amplifier sensitivity (input resistor or Ri; 10 6 Ω).…”

“…EPG has been widely used in studies of feeding behavior/physiology of plant-feeding, piercing-sucking hemipteroid insects 17 , 22 . EPG has made possible virtually all present knowledge of the role of feeding in vector-mediated transmission of plant pathogens 22 .…”

“…EPG has made possible virtually all present knowledge of the role of feeding in vector-mediated transmission of plant pathogens 22 . In addition, EPG has been instrumental in gaining insights into and improvements in pest management 17 , such as: (i) targeting insecticide modes of action 23 , 24 ; (ii) improving host plant resistance 25 , 26 ; and, (iii) targets for RNAi 27 .…”