In Part 1 of The Ultimate Road Trip, Scott Kleinschmidt chronicled all things termite-related on his journey from Brisbane to Darwin. Here in Part 2, he continues the commentary around Darwin and the second leg of his journey to Townsville.
Darwin is a termite-lover’s paradise. Mounds, mudding and damage can be found in almost every park, garden and front yard. In my previous roles with multinational companies, I had played ‘tour guide’ to numerous international termite researchers, who were blown away by the amount and diversity of termite activity in and around Darwin.
An enjoyable pastime is to spot sick looking palm trees in council sponsored beautification projects beside roads and in parks. A quick poke with a screwdriver will almost always uncover a healthy population of Mastotermes darwiniensis. Why the council persist with planting palm trees for this purpose is beyond belief (Figure 1).
Mastotermes would have to be my favourite termite, not just because I have conducted hundreds of trials on them over the last 20 years, they are just beautiful creatures. They have a voracious appetite and will attack almost anything (rose bushes, vines, fruit trees, rubber tyres, plastic, softer metals) – in trials with Coptotermes, where I would normally have to replenish feeder timber after six months, I have to replenish after only one month with Mastotermes! They are also the most ancient living termite in the world and are the closest link to their cousins, the cockroach.
I thought I had seen it all as far as Mastotermes attack was concerned, however on this trip I added another first. I noticed some suspicious mudding on an old coconut lying on the ground. Upon investigation, Mastotermes had eaten 95% of the husk material lying between the actual nut and the outer covering. I had never seen this before (Figure 2).
Of course, Mastotermes is not the only termite in town. Another interesting termite that builds a black, knee-high pointed mound at the base of a tree is from the genus Termes (Figure 3). Soldiers are very hard to find because there are so few in the colony. I persevered and found two soldiers, which I placed in a specimen bottle and stored in the glove box of my vehicle. Even travelling along the road with the radio on, I could hear the soldiers clicking their long slender mandibles. A closely related termite from Panama (Termes panamaensis) has recorded the fastest moving motion of any animal in the world. They can click their mandibles at 250 kph, killing their invading enemy with a single blow.
Our Australian relative has the same fast clicking mechanism, but no one has yet measured their speed.
As I had successfully completed the Darwin leg of my trial work, it was off to Townsville. Over the next two days I backtracked the 1700 km to Cloncurry. On the third day instead of turning south at Cloncurry to return to Brisbane, the road to Townsville continued east. This was the bit I was looking forward to; I was covering new ground to continue my observations on when and why the mounds would appear and disappear.
If you remember from Part 1, there were no obvious differences in vegetation or soil colour at the boundaries and the only noticeable difference was in the condition of the road. As soon as the mounds disappeared, the road became much rougher especially at creek crossings. When the mounds reappeared, the road was in much better condition.
Not long after leaving Cloncurry the mounds disappeared and stayed that way for the next 400km, including the towns of Julia Creek, Richmond and Hughenden. This section of road was also the roughest of any of the trip thus far.
Just past Hughenden the mounds re-appeared and stayed until reaching the coast at Townsville. The road also improved immensely. So the big question is why?
My first thought was height above sea level; lower areas would flood more often thus affecting both the termites and the road. Upon researching the heights above sea level of every town that I travelled through, there was no correlation at all.
The next option was soil type. When I overlaid a road map on top of a soil type map, it was a real Eureka moment. Exactly where I marked a boundary of mounds versus non-mounds, there was a change of soil type. Every section of highway that contained no mounds was found in the one soil type – vertosol (Figure 4).
Vertosols are a heavy soil with a high proportion of swelling clays, which form deep wide cracks when they dry out. The shrinking and swelling of vertosols can damage buildings and roads, leading to extensive subsidence. This would certainly explain the condition of the road surface.
But what about the termites? One could assume that building and maintaining an underground system of galleries or even building a mound would be extremely difficult in such reactive soils. I found the following reference in a book on soil ecology – “In northern and central Queensland, few mound-building termite species can tolerate the expansive nature of certain vertosols which shrink on drying and swell when re-wet. Mound-building termites are virtually excluded from these soils.” Riddle solved!
My thoughts now turn to economically important subterranean termites. The same vertosol soil type should also be a problem for species such as Coptotermes and Schedorhinotermes. That being the case, towns built on such soils, in theory, should have less termite activity; I have already started investigating this. Maybe an article for a future issue of Professional Pest Manager magazine.
Scott Kleinschmidt, Director, Australian Timber and Pest Research
Scott Kleinschmidt has been involved in termite research activities for over 30 years and after successful roles in the Qld DPI, Aventis, Bayer and BASF, he now runs his own consultancy business that provides research and development services to the pest management and timber preservation industries.