Competition for herbage by Phaulacridium vittatum (Sjostedt) (Orthoptera:Acrididae) and sheep during summer drought

Wingless grasshopper (Phaulacridium vittatum_ populations inhabiting grassdominant sheep rangeland in the south-east of South Australia reached peak biomass in summer and possibly competed with sheep for available herbage when pastures were drying off. Laboratory studies indicated adult wingless grasshopper (WG) ate clover species at faster rates than other herbage species on the rangeland, while most dicotyledonous species were eaten at faster rates than grasses. the point of competition between WG and sheep is in respect to green clover. Calculated daily consumption rates of clover by WG indicate that for densities of 10 per m2, they have maximum daily potential consumption 0.85 dry sheep equivalents (DSEs) per ha and proportional consumption at higher densities. Field densities of 10–20 WG per m2 are common in some seasons on rangelands in southern Australia and may exceed 30 per m2 in patches. Competition for perennial clovers may occur during summer with a maximum potential value of 2.6 DSEs per ha in years when WG are generally dense (30 per m2).