Caution: not for Entomophobes
Dr Greg Sword of the School of Biological Sciences is developing 21st century solutions to a problem that has afflicted humankind since the dawn of civilisation.
Tearing along bush tracks in a 4x4 truck, guided by satellite, ready to face down an adversary that has stalked the world for
millennia: this is field ecology, Hollywoodstyle. But Greg Sword laughs off the “bugbusting” premise of his recent foray into the
“We’ve just filmed a documentary for [pay TV channel] Animal Planet called Swarm Chasers and they were trying to make it like
something from the movie Twister,” he says. “They were out to make us look a lot more exciting than we really are but, in a way, our job is like that. We get the GPS coordinates, we drive out into the desert; we look for locusts. The really funny thing was that the sound guy was terrified of bugs. We had a lot of fun with him.”
Sword is a world-renowned expert on orthoptera, the group of insects including the cricket, the grasshopper and the locust,
the infamous eighth of the ten plagues visited on Egypt in the Old Testament’s Book of Exodus.
“Humans have been observing locusts for the entirety of recorded history,” says Sword, who heads the School of Biological
Science’s Molecular Ecology Lab. “We’re much better at it now, but we’re still not that great at controlling them. Although we are making tremendous progress in understanding why locusts swarm and move the way they do.”
Only recently, he explains, have scientists begun to discover some of the mechanisms behind the locust’s instinct to swarm in
sky-blackening numbers that can extend into the hundreds of millions – sometimes billions – and lay waste to enormous tracts
There is also another – rather more gruesome – driver of swarm behaviour, says Sword: cannibalism.
“It turns out that the locusts are constantly trying to nibble on each other,” he says. “Typically they are concentrated in areas where the resources are being depleted very quickly and at times like that, the next best thing, nutritionally speaking, is your neighbour. So they constantly nibble and keep moving to avoid being nibbled on and at the same time they are nibbling on the ones in front. It’s a chain reaction, a forced march.”
Sword is particularly interested in the mechanics of swarm motion. Figure that out, the reasoning goes, and controlling an
outbreak becomes much easier.
“We get the impression that these swarms are all of one mind or have some kind of master plan or destination in mind,” Sword
explains. “But it turns out that isn’t the case at all. Each locust is only interacting with locusts within about 12 centimetres around
it. So they are only responding to things in a very local environment. But when you have these local responses happening millions and millions of times over, you get what is called an emergent property: the group takes on a certain shape, a direction.”
And if that direction can be predicted, says Sword, farmers and agencies such as the Australian Plague Locust Commission will be better prepared to deal with the potentially devastating effects of a swarm.
Investigating the collective dynamics of a swarm requires a great deal of inter-disciplinary collaboration. Physics, mathematics and robotics may all come into play at some point and all are areas of great strength on campus, says Sword.
“There is a body of mathematical theory that tells us how large groups behave and you can apply the same techniques – some of which have been developed in statistical physics – to model the motion of a swarm.”
Sword’s team is also collaborating with the Australian Centre for Field Robotics (based in the University’s School of Aerospace,
Mechanical and Mechatronic Engineering) to develop cutting edge insect tracking technologies.
“We are working on developing unstaffed aerial systems – surveillance drones – equipped with incredibly sensitive cameras,” says Sword. “We’re developing little reflector tags that only weigh a couple of milligrams that can be attached to some of the insects. The aerial drone will have a high powered strobe and a digital camera timed to it that will pick up the little flash from the tag, which allows us to get movement data in real time on tens or even hundreds of individuals.”
Sword has devoted much of his career to developing an intimate understanding of grasshoppers, crickets and locusts, a passion that began during childhood while collecting bugs and snakes in the deserts of the American southwest. “I always knew I was going to be a scientist,” he says.
Undergraduate studies in ecology in Arizona, led to doctoral work in Texas and postdoctoral studies at Oxford, and fieldwork in
West Africa, home to the plague locusts of Exodus 10:12-15.
Compared to its African or North American cousins, the Australian plague locust is “a puny little creature”, says Sword, who grew up in Arizona, where grasshoppers can grow as big as a man’s thumb. “The Australian plague locusts are about the size
of your pinky nail.” When Aussie locusts swarm, however, they do so spectacularly. In 2008, one swarm was estimated to be
nearly 6 kilometres long.
“Australia has three swarming locust species and unlike species elsewhere, the Australian plague locust, in particular, swarms pretty reliably,” says Sword. “If you want to study swarming behaviour in any given year, this is the best continent to do it.”
General donations to the Sydney Development Fund help to support research projects like Greg Sword’s.
Words: Jason Blake