Dung beetles are intriguing insects, widely recognized for their association with animal waste. While their name suggests a straightforward diet, their consumption process and the specific types of matter they consume are more nuanced. These beetles play a significant, often unseen, role in ecosystems globally by processing organic material. Their feeding strategies reveal a specialized and adaptive approach to their environment.
The Main Course: A Preference for Dung
Dung beetles primarily favor the droppings of herbivorous mammals. This choice stems from the rich composition of herbivore dung, which contains a significant amount of partially digested plant material and nutrient-dense fluids. Animals such as cattle, horses, and elephants do not fully break down all plant matter, leaving behind a valuable food source.
Adult dung beetles primarily feed on the liquid component of this excrement, teeming with microorganisms like bacteria, yeasts, and protozoa. These microscopic organisms provide a substantial source of protein and other assimilated nutrients for the beetles. Their specialized mouthparts allow them to filter out larger, indigestible plant fibers, effectively concentrating the microbial-rich fluid for consumption.
While some dung beetle species occasionally consume fungi, decaying leaves, or even other insects, the majority rely on readily available and nutritionally accessible herbivore dung. Carnivore dung, in contrast, offers less undigested plant matter and different nutrient profiles, making it less appealing for most dung beetle species.
Methods of Consumption
Dung beetles are categorized into three main functional groups based on their distinct methods of consuming and processing dung.
Rollers, also known as telecoprids, form a portion of dung into a spherical ball and then push it away from the original dung pile. They transport this ball to a suitable location, often a soft patch of soil, where they bury it for food storage or as a chamber for laying eggs.
Tunnelers, or paracoprids, dig tunnels directly beneath the fresh dung pat instead of rolling dung away. They then pull pieces of the dung down into these subterranean tunnels, burying it for later consumption or for reproductive purposes. This method ensures the dung remains fresh and protected underground.
Dwellers, termed endocoprids, are the least active in terms of dung relocation. These beetles simply live within the dung pile itself, or directly underneath it, consuming it where they find it. Females often lay their eggs directly within the dung pat, allowing their offspring to develop within the food source.
What Dung Beetle Larvae Eat
The diet of dung beetle larvae differs from that of adult beetles, as their food is provisioned by their parents. Adult female dung beetles prepare a “brood ball” from dung. This ball is crafted and often buried underground, serving as a nursery and food source for the developing offspring.
A single egg is typically laid inside each brood ball. Upon hatching, the larva, often described as a grub, begins to consume the surrounding dung from the inside out. This enclosed environment provides a safe, consistent food supply throughout its larval development until it pupates and emerges as an adult. The larvae are bulk feeders, consuming the solid dung material, which is a contrast to the adults who primarily consume liquid.