Small-scale observation on the effects of the burrowing activities of mole crickets on soil erosion and hydrologic processes

Soil-dwelling insects create continuous biopores when making their nests. Such burrowing activities alter soil structure and increase water infiltration. As fresh soil is brought onto the surface, sediments become available for erosion. Limited attention has been given to the ecological function of mole crickets on the Loess Plateau. In this study, the nest characteristics of adult and immature mole crickets (Gryllotalpa unispina) and their effects on soil hydrologic processes were investigated. Thin slurry of orthodontic plaster was used to fill the subterranean nests in the field to generate 3D renderings of the nest architecture. Dyeing and rainfall simulation experiments were conducted in a nest scale to quantify the effects of mole cricket burrows on the runoff and water infiltration on the slopes. G. unispina burrows consisted of horizontal and vertical parts. The mean diameter and depth of the vertical burrows created by adult mole crickets were 1.51 and 46.3 cm, which were significantly (P < 0.05) greater than those of immature ones (0.96 and 30.0 cm). Adult G. unispina exerted a more distinct effect on soil hydrologic processes than their immature counterparts. The horizontal burrows intercepted rainfall and promoted runoff reduction and infiltration, particularly in crusted soil. The mean amount of runoff in the crusted soil with adult nests (549.3 g) was significantly (P < 0.01) lower than that with no-nest (1039.6 g). Preferential flow in the nests resulted in high water content in the deep soil. In the semi-arid area, moderately improving the density of hypogeal animals and their nests might benefit to the soil moisture. However, the risk of soil erosion cannot be neglected.