Use of Radiography and Tunnel Castings for Observing Mole Cricket (Orthoptera: Gryllotalpidae) Behavior in Soil

Abstract

The behavior of mole crickets, serious pests of turfgrass, is poorly understood and has been rarely studied, predominantly because these insects dwell deep in the soil and are highly mobile. To better understand how the tawny mole cricket, Scapteriscus vicinus Scudder, and the southern mole cricket, S. borellii Giglio-Tos, behave in the soil, we used nondestructive x-ray techniques and wax and fiberglass resin castings to study the tunneling patterns and interactions of these mole crickets with their environment. Both species typically constructed Y-shaped tunnels to facilitate feeding and escape routes. Herbivorous tawny mole crickets tended to have more extensive and deeper tunnel systems than predatory southern mole crickets. Mole crickets maintained Y-shaped tunnels when subsoil density increased but often bent or terminated tunnels to avoid compacted areas. Both species maintained separate tunnels in the presence of other individuals of the same species. However, southern mole crickets exhibited more extreme separation, suggesting an avoidance behavior that may have been mediated by chemical, vibrational, or auditory cues. Although tawny mole crickets did not alter the shape of their Y-shaped tunnels in the presence of southern mole crickets, they sometimes would wall-off a tunnel, presumably in defense. Tawny mole crickets avoided contact with the entomopathogenic fungi, Beauveria bassiana (Balsamo) and Metarhizium anisopliae (Melchnikoff). This behavior suggests the potential of finding biologically active compounds that inhibit soil insect movement and could be used in the management of soil insect pests.