Characterization of Biopores Resulting from Mole Crickets (Scapteriscus spp.)

Abstract

Soil organisms, particularly arthropods, create biopores as they move or tunnel. The abundance and burrowing nature of mole crickets, a common soil-inhabiting pest in the southeastern United States, will likely influence the hydraulic conductivity of soils. The objectives of this research was to provide additional insight into the biology of soil-dwelling insects and the ability of biopores to influence surface-to-groundwater infiltration, and to characterize the way two species (Scapteriscus vicinus Scudder and S. borellii Giglio-Tos) of mole crickets tunnel. These trials were performed in PVC arenas. Computed Tomography (CT) scans were taken of the arenas at the College of Veterinary Medicine at Auburn University, using a GE highspeed CT/i model computed tomography instrument. The scans were used to acquire 3-dimensional models of the arenas to best determine mole cricket tunneling characteristics in the soil. It was found that the only characteristic that was significantly different between soil types was the ability of the mole cricket constructs longer tunnels in the loamy sand compared to the clay loam. None of the other characteristics between the two species were found significant although the southern mole cricket was found to branch twice as much in the upper 20 cm of the arena than the tawny mole cricket. When comparing the adult and immature southern mole crickets, adult mole crickets displaced on average three times the volume of soil that the immature mole crickets displaced. Southern mole crickets construct significantly longer tunnels when turfgrass was not present. Throughout the experiments comparing mole crickets tunnel characteristics the total volume was significantly correlated with total length of mole cricket tunnels. The ability that mole crickets have to change the hydraulic conductivity of the soils was examined in field conditions as well as greenhouse trials. Field trials found there were significantly higher infiltration rates and lower runoff rates in areas infested with mole crickets compared to uninfested areas of Bermudagrass. In greenhouse experiments, the hydraulic conductivity of saturated soil was significantly greater in arenas with mole crickets or night crawlers compared to areas with no soil fauna. Also there were significantly lower saturation times in arenas when either mole crickets or earthworms were present compared to non-infested arenas. Field and greenhouse studies suggest that mole cricket tunneling activities may reduce runoff and erosion but, in turn, may facilitate movement of surface applied pesticides and fertilizers into groundwater.