February 17, 2015

A Dung Beetle's role in nature

Every organism has its role in nature but perhaps none are more important than the much loved dung beetle.  Its role as the bush sanitation engineer has raised its lowly profile to gargantuan proportions and every safari goer gleans as much pleasure from watching their ball rolling antics as they do from seeing the mighty elephant.  Dung beetles are split into 4 main groups dependent upon their egg laying strategy.  The telecoprid dung beetles are the most famous and are often seen rolling their disproportionately large trophies across the bushveld.

There are many different species but the most common behaviour seems to involve the male making a ‘food ball’, hoping that his architectural prowess will attract a potential mate.  Once a female has approved the construction of the dung ball the male rolls it to a suitable site (whilst the female hitches a free ride!) and sinks it into the ground where the pair then consume the ball and mate for the first time – not everybody’s idea of a romantic dinner-for-2 but the animal kingdom is full of variety!  

Whilst the female gestates her eggs, the male locates another deposit of fresh dung and fashions a ‘brood ball’ that he dutifully rolls back to his pregnant bride.  Such are this diminutive creature’s navigation skills, it can relocate the nest from over a mile away!  One can often see them scaling their mighty cargo to orientate themselves with the Sun, their specially adapted eyes even able to do so on cloudy days.

Once more he sinks the ball into an underground chamber and here the female lays an egg inside his mobile larder.  She then meticulously smoothes the outer surface, much like a plasterer would finish a wall, in order to harden the outer shell and cocoon her offspring.  It also prevents the dung within from drying out and thus ensures a good supply of food for the larva. The egg will hatch shortly and the young larva will spend the next few weeks systematically consuming the contents of the ball until it has absorbed enough nutrients to begin the process of pupation and ultimately emerge as an dung beetle.

Remains of "brood balls"
These grubs are however a great source of protein and are relished by all sorts of predators and even humans.  The biggest threat to a dung beetle larva is the honey badger and it is common to find the hollowed out remains of these brood balls littering the bushveld.  Many larvae reach adulthood however and their role in nature abounds.  Not only do they recirculate the nutrient rich dung, but play a huge role in seed dispersal, literally planting the many seeds that emerge undigested from the digestive tracts of many herbivores.  They also contribute massively in controlling parasite numbers as countless fly eggs are sunk into the ground along with these balls and thus never see the light of day.  Such is their ecological importance that Australia as imported dung beetles from Africa in an attempt to control the fly population in the country due to an excess of cattle dung – not a bad CV for one of the unsung heroes of the African bush! 

Wildlife fact and photos by: Ben Coley
Post a Comment