Thanks to Brilliant for supporting this SciShow video! As a SciShow viewer, you can keep building your STEM skills with a 30 day free trial and 20% off an annual premium subscription at Brilliant.org/SciShow.
You probably don’t spend a lot of time thinking about dung beetles, but maybe I can convince you that there’s a lot more to them than just poop. It turns out that they are helping us out by doing everything from improving agricultural yields to fighting climate change. So put a clothespin over your nose and let’s get to know the little guys a little better.
There are a few distinct types of dung beetle and they live all over the word, often much closer to home than you may expect. The first are rolling dung beetles, the classic ones you might picture from nature documentaries or ancient Egyptian iconography. As you’d guess, they create dung balls and roll them. These balls are known as brood balls, and are actually an offering, usually by the male dung beetle to the female. They serve as both food for her, and food for her offspring, as long as it’s accepted.
We also have tunnelers. They’re dung beetles that create tunnels of varying depth directly below the dung pile itself to feed dung into for either themselves, their mate or their offspring. If you’ve ever lifted up a cowpatty and seen pockmarks in the ground below, that’s the work of tunnelers. Other varieties are ones that simply live in the dung pile itself, and some are even kleptoparasites, meaning they steal the dung of other individuals as their entire survival strategy.
That’s not the flattering picture I promised you, but all of these guys are performing some seriously important services by digging around in poo. For one thing, dung beetles can regenerate poor quality soil. Areas in South Africa once used for mining have soil that is infertile, heavily compacted, and lacking in useful nutrients and minerals. In short, you’d struggle to grow anything there. But when researchers gathered up dung beetles from farmland and added them to this type of soil, those soils grew significantly more plant life, and had more nutrients as well.
On top of this, dung beetles also increase water absorption in the soil. Tunnelling dung beetles drill down into the soil to lay eggs, and the young break it up even more when they emerge. That makes the soil more porous, so it holds more water. The tunnelers can get down to over 100 centimeters, and in just 48 hours, dung beetles can create an effect that lasts for six months. More water being absorbed means less runoff and potential flooding, and it’s better for plant communities too.
All that churning of the soil leads to a lot of mixing in the sediment. But of course, dung beetles don’t just dig and burrow; they also bury their brood balls. All this digging and dung mixing don’t just result in plants being able to grow where they couldn’t before. It can often lead to more, larger, and healthier plants as well. Look… it’s fertilizer. Nitrogen is an important nutrient for plants, and it can be lost to the atmosphere thanks to ammonia gas escaping from livestock dung. When dung beetles bury it, that nitrogen stays in the soil instead. Plants grown with dung beetles are more nutritious and productive. In fact, a few studies have suggested that dung beetles can actually outperform chemical fertilizers in improving plant yields. Many studies have been done in laboratory settings, often with a single species of dung beetle or plant. However, dung beetles often function best in big, complex communities with multiple roles played by multiple species, meaning the effect in the wild could be more significant. Dung beetles not only bury balls full of seeds, but they also help protect them from predators or pathogens, disperse them, and select areas of soil that are better for the plant to grow in. Additionally, they may reduce greenhouse gas emissions, as a study from Finland in 2016 found that dung beetles in cow pastures can reduce methane. In countries where cattle are grazed more on pasture, this effect could be more important. Australia is a case study for the ability of dung beetles to clean up our messes, as 53 species were introduced in the 1700s and 23 survived, transforming the soil, encouraging nutrient flow, and limiting the influence of pests.
It’s incredible that these tiny bugs can help us with humanity’s largest problem, as they work with miniscule molecules that get out of balance in the climate crisis. To help make the idea of a molecule a little less abstract, there’s a Brilliant course called “Molecules” made in partnership with MinuteEarth. Brilliant is an interactive online learning platform with thousands of lessons in science, computer science, and math, made with a diverse set of experts from researchers at MIT, Princeton, and Stanford, to expert communicators like MinuteEarth and Kurzgesagt. They are giving these learning tools to you for free for your first 30 days of use, and after that you can take 20% off an annual premium Brilliant subscription by clicking the link in the description or going to Brilliant.org/SciShow.