THE EFFECTS OF DUNG BEETLES (<i>COLEOPTERA‐SCARABAEINAE</i>) ON THE FREE‐LIVING STAGES OF STRONGYLID NEMATODES OF THE HORSE

Abstract

SUMMARY Observations were made on the identity and activities of coprophagous arthropods in horse faeces at Moggill in southern Queensland. A number of families of arthropods were represented, but of these only members of the Scarabaeidae were involved in the dispersal of the faecal mass. Six species of indigenous dung beetles, all of the genus Onthophagus , utilised horse faeces as a food source. One of these, O granulatus , was present in large numbers, but it was unable to achieve complete dispersal of equine faecal masses. The introduced Afro‐Asian dung beetle Onthophagus gazella is also well established at Moggill, and uses horse faeces as a food source. Unlike the indigenous species, this beetle is able to achieve complete breakdown of the structure of horse faecal masses in one night, leaving the fibrous remnants on the soil surface. However, this level of activity was restricted to the warmer months, from November to March, with faeces remaining largely undisturbed for the remainder of the year. It was noted that heavy rain also reduced the activity of dung beetles. A comparison was made between the recovery of infective strongyle larvae from herbage near faecal masses exposed to dung beetle activity, and from control faecal masses from which beetles were excluded by insect mesh envelopes. Reductions in recovery of the order of 60% were recorded at the peak of O. gazella activity in summer, but since much less reduction occurred for the remainder of the year, it was concluded that dung beetles are of little benefit in the control of equine strongylosis, in the absence of other measures to reduce pasture contamination.