Dung beetle activity correlates with reduced horn fly populations in Oklahoma

Ecosystem services provided by dung beetles (Coleoptera: Scarabaeidae include increasing soil fertility, expanding availability of forage, and reducing insect pests that affect livestock. The horn fly (Haematobia irritans L.) is the most economically significant cattle pest, causing more than 2 billion (USD) annual losses to the livestock industry. Horn fly population success relies on the availability of dung for egg laying; however, when dung beetles are present, this resource is reduced and decreases horn fly populations. Here, surveys were conducted on two ranches in Ardmore, OK from June to August in 2023 and 2024. Ranches differed by grazing management system (conventional and regenerative). Dung beetles were collected using non-lethal traps with pig dung as bait, and the horn fly population was estimated by photographing the animal's side and counting flies using imageJ™. Generalized linear models were used to analyze the relationship between dung beetle abundance and horn flies, with management type, month and year and cow ID as fixed effects. The model including dung beetle abundance, management, month, and year was best to explain the lower number of horn flies (adj. R² = 0.23). Overall, when more dung beetles were present, there were fewer horn flies. Although management type did not significantly impact horn fly populations in relation to dung beetle abundance the regenerative management practice had numerically higher dung beetle populations when normal precipitation occurred (2023). These results highlight the importance of dung beetles as a biological control of horn flies in cattle production systems.