Scientists from the University of Bristol have found that dung beetles can help farmers by reducing the development and survival of parasites in cowpats that cause serious illness in cattle during the summer months.

The work, led by Bryony Sands from the School of Biological Sciences, involved using ‘artificial cow pats’ (which were made using faeces collected elsewhere); researchers added beetles to some pats and exposed them to varying simulated rainfall.

After two weeks, parasitic larvae were taken from vegetation surrounding the cow pats. The numbers of parasitic larvae found on vegetation around pats increased over the first six weeks, and remained high for at least ten weeks. At first, there were more parasites found around pats that were colonised by dung beetles as opposed to pats without beetles.

However, after eight weeks, fewer parasitic larvae were found around pats that were colonised by dung beetles. This pattern persisted for the rest of the ten week experiment, leading scientists to suggest that the beetles suppressed the development of parasites.

Although they appear to have beneficial effects, scientists found the beetles’ impacts can be easily overridden. In experiments with increased ‘rainfall’ (more watering of the pats), more parasitic larvae developing in the pats, whether or not beetles were present. The researchers said this shows that rainfall has a greater impact on parasite populations than beetle activity.

How beetles affect the presence of parasites

The researcher hypothesised that dung beetle activity ventilates cowpats, and this increased aeration improves the conditions for parasite eggs hatching out, but as parasite larvae require moist conditions to survive, and dung beetle activity dries cow pats out rapidly, they soon die off when beetles are present.

On average, almost 200 insects naturally colonised each cow pat, including 20 Aphodius dung beetles, which permanently live within dung.

Commenting on the discovery, Bryony Sands said, "Dung beetle conservation is vital for the welfare of our farm animals.

"The conservation of dung beetles on farmland today is extremely important for their role in dung degradation, nutrient cycling, pasture fertility, and because now we have seen that they can contribute to reducing economically deleterious livestock parasites on farms.

"These beetles may be important in cow welfare, as cows are severely affected by parasites found in their intestines."

Current control against parasites involves insecticide chemicals which the cows do not fully digest, resulting in contaminated cow pats, which potentially hurt beneficial insects like dung beetles.

Bryony Sands added, "These pats are toxic to dung beetles, even though these critters may provide natural control against the same parasites the chemicals are fighting. Controlling parasites is expensive, and these beetles could provide a natural way to keep cows worm-free."