Articles on forages, animals, and grazing systems
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Master Grazer Coordinator
821B W.P. Garrigus Building
University of Kentucky
Extension Forage Specialist
University of Kentucky
Phone: (859) 257-3358
Fax: (859) 323-1952
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. Dung beetle larvae use only 40% to 50% of the brood ball before pupating. The remainder is available to soil microbes, fungi, and bacteria.
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. This can mean reduced microbial contamination by runoff from rain events.
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 throughthe 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. The forage is palatable but the animals avoid it. If left to weather away, lingering cattle manure deposits can reduce available grazing area by 5% to 10% per acre per year. Losses may be greater in intensive grazing systems.
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.
Dung beetle biology and lifestyles
Dung beetles species have adopted one of three different main ways of using manure, which reduces the competition among species. They are dwellers, tunnelers, or rollers.
Male and female pairs of many dung beetle species cooperate to dig and provision underground chambers with manure that serves as food for their developing larvae, the only stage that eats dung. There is intense competition for this perishable resource so the insects must work quickly. Dwellers complete their entire life cycle in the manure pat. They do not dig much and do not make brood balls. They are small beetles with short developmental times.
Tunneling and rolling dung beetles tend to be larger and develop more slowly. Tunnelers burrow several inches beneath the manure, taking dung with them to widened brood chambers that will hold their developing larvae. Piles of soil next to a dung pat indicates that tunnelers are active in it. Rollers, also called tumblebugs, form dung balls that they roll some distance away from the pat and bury in the soil.
An understanding of dung beetle contributions and management practices that allow them to thrive will enable these unique allies to contribute to sound pasture and herd health programs.