Dung Beetles: Underground Allies

Dung beetles are important allies. Most beef producers are aware of these insects but few realize the range of benefits that they provide. About 30 species are important managers of livestock manure in the eastern US. These usually dark brown or black beetles and their grub-like larvae work out of sight to provide pasture management and pest management services that generally go unnoticed. Adults use their flat, shovel-like front legs to bury nutrient-rich manure that will serve as food for their developing larvae. Without dung beetles, manure pats would deteriorate very slowly, reduce productive pasture area, provide undisturbed breeding sites for pasture flies, and enable passage of intestinal parasites within herds.

Dung Beetle Services

Nutrient recycling – A significant proportion of the nutrients consumed by cattle is excreted in their manure. Using their strong sense of smell, dung beetles quickly detect and fly to fresh manure and immediately begin move it down into the soil. This helps to reduce nitrogen loss that can occur through ammonia volatilization and enables mineralization by soil microorganisms.

Soil mixing, aeration, and permeability – Several dung beetle species dig underground tunnels with expanded brood chambers where their larvae will develop on stored manure. These beetles bring large amounts of soil to the surface during the excavation process. Their tunnels allow oxygen and water to penetrate more deeply into the soil.

Improved plant growth – Dung beetle activity has a positive impact on plant growth. Studies have reported increased height, greater biomass, and higher protein levels and nitrogen content in plants grown in soils worked by dung beetles compared to sites where the insects were excluded.

Suppress internal parasites and pasture flies – Eggs of most internal parasites pass through the manure and ultimately the infective larvae are ingested by grazing animals. Aeration by burrowing beetles allows dung to dry more rapidly, resulting in death of many of their eggs. Burying or dispersal of manure affects pasture flies, too because it denies them the fresh cow manure that is their only breeding site.

Preserving pasture land – Most ruminants will not graze close to manure pats of their own species. If left to weather away, lingering cattle manure can reduce available grazing area by 5% to 10% per acre per year.

Managing for Dung Beetles

Some pesticides used to control internal parasites and pasture flies can affect dung beetle development or survival. However, there are management practices that will help to reduce adverse effects. Use fecal egg counts to determine when internal parasite control is warranted. Unnecessary treatments can contribute to resistance problems and may affect dung beetles. When deworming is needed, read product labels carefully. Some pass through in forms or at levels that can affect dung beetle development or survival. Insecticides used for pasture fly control can be excreted at levels that affect dung beetles. Use insect treatment guidelines to prevent unneeded treatment. When fly control is needed, limited use of oilers or forced-use dust bags can provide the protection needed with least harm to dung beetles. ~ Dr. Lee Townsend, UK Extension Entomologist, full article published in Grazing News.

Other Grazing News articles of interest: Annual Lespedeza for Grazing and Tips for Managing Grazed Forage Crops