New experimental techniques for studying root herbivores

![CDATA[Many of the chapters in this volume illustrate the importance that root herbivores play in ecosystem processes in both applied and ecological contexts. In most cases, however, relatively less is known about belowground herbivores than their aboveground counterparts (Brown and Gange, 1990; Hunter, 2001). This is largely because root-feeding herbivores live in the soil, an opaque, tri-phasic medium, which makes them harder to study and perhaps a less perceptible part of terrestrial ecosystems. Conventional methods for studying root herbivores (reviewed by Dawson and Byers, Chapter 1, this volume) have proved successful for unravelling a number of aspects of belowground herbivory, but these techniques frequently still have a ‘black box’ characteristic to them. In this chapter, we focus on recent developments in non-invasive methods for studying root herbivores, both in the field (acoustic detection) and in the laboratory (X-ray tomography). We focus on these two non-invasive techniques because they seem to offer the most potential for investigating root herbivory, based on recent studies using a range of root feeders. Other noninvasive methods for studying subterranean herbivores exist (e.g. telemetric techniques reviewed in brief by Reynolds and Riley, 2002), but detailed studies concerning their usage remain scarce, and are therefore not covered in this chapter. We also restrict ourselves to discussing rootfeeding insects in this chapter because these techniques cannot yet be properly exploited for smaller root herbivores such as nematodes, and are probably inappropriate for larger root herbivores such as rodents.]]