So why are you traipsing through the jungle collecting dung beetles I hear you asking? Well, good question. Sometimes when I couldn’t breathe and my legs were giving way and I thought I was going to die I asked myself the same thing.
But then I’d remind myself that I’m contributing to 10+ years of extensive data that might help to conserve this area – something that is very much worth it.
There are lots of reasons why scientists like to study dung beetles:
Easy to Catch
Dung beetles are not the sharpest tool in the shed. If you leave poo somewhere, they’ll go for it. Regardless of if there’s a gaping big hole in the ground, a slippery funnel or conspicuous plastic plate. Different species of beetles have different life histories and behaviours, and hence use the poo in different ways. Some eat the poo, some bury it, some live in it, some raise their babies in it. Poo plays important and varied roles for all dung beetles.
Pretty much wherever there are animals producing poo, there are dung beetles. Scientists like studying animal groups that are found in lots of different places because it allows for comparisons between areas to be made.
For an invertebrate group, the taxonomy of dung beetles is pretty well known, as they have been well studied across the globe. This is great, because it means unlike a lot of insects, where you’d be constantly recording new, undescribed or unidentifiable species, we know exactly what we are catching, which makes our results more useful for biodiversity estimates.
Dung beetles do a lot for our environment! Without them, we’d be knee deep in poo. No one wants that. A famous example of the power of dung beetles happened in Australia, where a selection of 29 foreign dung beetle species were introduced to help tackle the immense quantities of livestock dung that native beetles weren’t evolved to handle. The accumulation of cattle dung was creating a breeding ground for flies, which were reaching plague proportions. It was a major success, with fly numbers dropping by more than 80%!
As well as the aesthetic benefits of dung removal, it also helps to suppress parasites and disease, aid in seed dispersal, aerate and fertilise soil. A pretty impressive list of achievements for such a tiny animal!
Dung beetles are environmental indicators, which means that the health of their populations can be used to assess the broader health of ecosystems. Since they are easily affected by changes in the environment, fluctuations in their abundance and distribution can be a good measure of the impacts of environmental change.
Something new and exciting that is being done with dung beetles is gut analysis. By looking at the DNA of the dung inside a beetle, you can figure out what animals are living in the area. We collected lots of live samples, which we then killed using strong ethanol to preserve the DNA. That DNA will be analysed to see what big mammals are around in Cusuco. We know that there are jaguars, tapirs and several types of cats, but nobody ever sees them. The results of this study might help give us a better understanding of the distribution and abundance of these rare animals.
As I mentioned in my last post, we collect the beetles using pitfall traps. Ours are made with some super high tech materials – two red plastic solo cups, a plastic plate, and a dung ball. A dung ball you ask? Where do you buy those? Unfortunately for us, we had to make them by hand! Every morning, locals would deliver horse poo to us on their motorbikes from the nearest town, Buenos Aires. We made the balls by putting a bit of poo in the middle of a muslin square, wrapping it up and tying it with string. Whenever we had school students we’d get them involved, which got mixed reviews as you might imagine.
The first time we visited a site, we’d need to set up the trap by digging a hole for the cups to go in, and poking in some sticks to hold the plate over the top. Then we’d tie our precious dung ball to a stick and dangle it over the opening of the cup. We did two different types of trapping – live and dead. When we did live trapping it was for the gut DNA analysis, so we’d have a funnel and some dirt in the cup to prevent the beetles from escaping. When we did dead trapping we’d have to lug big bottles of killing fluid on our hikes to fill the cups with.
And there you have it. Probably more than you’ll ever need to know about dung beetles. Hopefully you have a bit of an appreciation of how hard the field work was now, but also how important!