Integrated parasite management and the pasture ecosystem: Optimizing outcomes for cattle health, soil health, and insect biodiversity

This study investigated integrated parasite management (IPM) used by grazing dairy farmers in the Northeast to understand impacts on pest flies, parasitic nematodes, beneficial dung insects, and soil health. Twenty-nine farms were enrolled in the study and grouped by grazing strategy, veterinary parasiticide use, and alternative treatments. Cattle gastrointestinal nematodes (GIN) were measured by fecal egg counts (FEC). Pest flies and coprophilous Diptera and Hymenoptera were collected using emergence traps. Dung inhabiting Coleoptera were measured using dung-baited pitfall traps. Soil samples were taken for soil health and bulk density analyses. Cattle managed using rotational and management intensive rotational (MIG) grazing had significantly lower GIN FEC than continuously grazed cattle. Grazing strategies did not influence pest fly abundances. Pyrethroids were the most effective for pest flies, however farms releasing parasitoid wasps also had reduced fly abundances. Dung inhabiting Coleoptera correlated with reduced pest flies and GIN FEC. Beneficial insects were negatively impacted on farms who used parasiticides. Continuously grazed pastures had higher beneficial insect abundances, however rotational grazing appeared to mitigate the negative impacts of pyrethroids on dung beetles. Pastures managed under MIG had lower bulk density and higher soil active carbon than continuous grazing. There were negative and neutral correlations between soil health indicators and insects utilizing dung on the pasture surface (Diptera and Aphodiinae dung beetles), but positive correlations between soil health and tunneling dung beetles (Onthophagus). These results highlight complex interactions between aspects of the pasture ecosystem, and trade-offs and synergies that must be considered for sustainable IPM.