Preliminary investigations of Aphodius species activity in cattle faeces treated with ivermectin

A.sphacelatus at densities of 0.5 and 1.0 beetle/g faeces caused significantly greater median percentage reductions (65.2% and 87.4% respectively) of Pilobolus sporangia than 0.1 beetle/g faeces (31%) in untreated cattle faeces. The median percentage reduction in sporangia due to beetle activity (48.4%) was significantly lower (P < 0.02) in faeces mixed with ivermectin at 1.0 ppm (wet weight) than in untreated faeces (88.4%). After treating a bullock with ivermectin (IvomecR Pour-On), the median percentage reduction in sporangia caused by beetles was significantly less (P < 0.05) on days 9 (78.9%) and 10 (76.9%) than in pre-dose faeces (86.5% and 93.8% respectively). In microcosms without beetles, sporulation of Pilobolus in cattle faeces from a heifer treated with ivermectin was significantly less on days 5, 10 and 15 after dosing. However, this difference was not apparent for days 5 and 10 after storage of faeces at 4 degrees C for 55 and 50 days respectively.