Evaluation of the role of dung beetles and adaptive multi-paddock grazing in reducing horn fly populations in Oklahoma

Dung beetles (Coleoptera: Scarabaeinae) consume cattle feces, thereby improving soil fertility, controlling filth fly populations, and enhancing pasture production. It is estimated that dung beetles provide up to US$33 billion in ecosystem services annually. Oklahoma is second in U.S. cattle production for pastured based cattle; however, ranchers suffer substantial production losses from horn flies, Haematobia irritans L. (Diptera: Muscidae). Horn flies feed on cattle, causing stress and discomfort to the animals, and result in losses of about $1.75 billion annually to U.S. production. Various techniques have been used in cattle operations to mitigate this pest, including the Adaptive Multi-Paddock (AMP) system. This system involves concentrating large numbers of cattle on small paddocks and moving them frequently. Our study was conducted at two different locations in Ardmore, Oklahoma where we compared dung beetle abundance and diversity and horn fly numbers between a conventional cattle operation and an organic ranching operation with AMP. Dung beetle sampling was performed using above-ground traps (litter box traps) baited with pig dung and in-ground traps (pitfall traps) also baited with pig dung. Sampling was conducted monthly from May to September, with four replicates of each trap per area. Fly populations on cattle were estimated by taking pictures of the cows' sides and counting the flies using a grid. We found more dung beetles associated with organic AMP and similar fly numbers at both sites. The results suggest that dung beetles can help provide fly suppression when AMP is utilized as an alternative to conventional pesticides.