Effects of paracoprid dung beetles (Coleoptera : Scarabaeidae) on the growth of pasture herbage and on the underlying soil

Field and greenhouse experiments were conducted to determine effects of three paracoprid dung beetles, Copris ochus (Motschulsky), Copris tripartitus Waterhouse and Onthophagus lenzii Harold, on the growth of pasture herbage and physical characteristics of the underlying soil. Treatments consisted of beetles plus dung, dung only and controls with neither dung nor beetles present. In the field in 2001, higher herbage yields were obtained with O. lenzii >= C. ochus = C. tripartitus >= only dung = control after 5 months. The air permeability of soil at a depth of 10 cm was highest when C. ochus was present (0.56 cm h(-1)), and lowest in the control (0.38 cm h(-1)). However, no significant differences were found among treatments in air permeability at 20 cm. In 2002/2003, the presence of all three species of dung beetle together was associated with higher herbage yields and with higher percentage nitrogen content than the control. In the laboratory, the presence of C. ochus and C. tripartitus was found to increase significantly the total crude protein in grass shoots and total digestible nutrient, compared with the control. The digestibility, dry intake and relative feed value of perennial ryegrass were highest where feces had been buried by O. lenzii. Acid detergent fiber was low in all treatments. The data suggest that the tunneling of paracoprid beetles improves the physicochemical characteristics of soil and increases the feed value of herbage by mixing and incorporating organic matter into the soil.