Dung beetles, often recognized for their unique behavior involving animal waste, are a diverse group of insects found across almost all continents, excluding Antarctica. They are members of the Scarabaeidae family, commonly known as scarab beetles. Their distinctive interactions with animal feces have led to curiosity about how they process this material.
Different Ways Dung Beetles Handle Feces
Dung beetles use three primary strategies for managing animal waste. Roller beetles, also known as “tumble bugs,” shape a portion of dung into a spherical ball. They then roll this ball away from the original dung pile, often pushing it backward with their hind legs. This rolled ball, which can weigh 5 to 20 times the beetle’s own body weight, is buried away from competition.
Tunnelers dig tunnels directly beneath or adjacent to a dung pat. They transport pieces of the dung into these subterranean chambers. Tunnels can range from 6 inches to 3 feet deep, sometimes up to 1 meter, depending on the species and soil conditions. This method allows them to quickly incorporate large amounts of dung into the soil.
Dwellers are a third group that live and reproduce directly within the dung pile itself. Unlike rollers and tunnelers, dwellers do not significantly move the dung from its original location. They lay their eggs within the fresh, moist dung pat, and their development occurs within this environment.
Why Dung Beetles Need Feces
Dung beetles rely on animal feces for basic needs, primarily as a food source and a breeding ground. Both adult beetles and their developing young consume dung to obtain nutrients. Adult beetles primarily extract the liquid component of the dung for nourishment, while the more fibrous material is reserved for their offspring.
Feces serve as a nursery for dung beetle larvae. After mating, female beetles lay their eggs within the dung, often within specially prepared dung balls or masses. These “brood balls” provide a safe, nutrient-rich environment where the larvae hatch and grow. Larvae possess specialized biting mouthparts that enable them to consume the drier dung within their brood ball as they develop, eventually pupating and emerging as adults.
Beyond sustenance and reproduction, dung piles also offer temporary shelter for some species. The dung pat provides protection from predators and adverse environmental conditions. This underscores the central role of animal waste in the dung beetle life cycle.
Ecological Importance of Dung Beetles
Dung beetles contribute to ecosystem health through several processes. Their activity plays a role in nutrient cycling by burying animal waste, thereby returning valuable nutrients like nitrogen, phosphorus, and potassium to the soil. This rapid incorporation prevents the loss of nitrogen, with studies indicating that up to 80% of nitrogen in dung can be lost to the atmosphere if left on the surface, compared to only 20% when buried by beetles.
The tunneling activities of dung beetles enhance soil structure. Their burrows create channels that improve soil aeration and increase the ground’s capacity to absorb and retain water. This improved water infiltration reduces surface runoff and helps prevent soil erosion. The tunnels also facilitate deeper root growth for plants, benefiting pasture health and productivity.
Dung beetles are also important in the control of various pests. By quickly removing or burying dung, they eliminate breeding grounds for flies and other insects that can affect livestock and human health. For instance, a single cow pat can produce thousands of flies if left undisturbed, but dung beetle activity can reduce these populations, with some research showing up to a 99% reduction in certain fly species. This biological control reduces the need for chemical interventions.
Some dung beetle species also contribute to seed dispersal. As they process and bury dung, they inadvertently move seeds contained within the waste, both horizontally and vertically within the soil. This secondary dispersal protects seeds from predators and pathogens, influencing plant regeneration and growth.