Posted on 06/02/2006 2:09:48 PM PDT by blam
How locusts decide it's time to swarm
19:00 01 June 2006
NewScientist.com news service
John Pickrell
Juvenile locusts marching in a swarm (image: Gabriel A Miller)
The precise moment at which a group of independently milling locusts loses its chaotic aspect and transforms into a highly aligned swarm has been pinpointed by researchers. The finding could provide a new weapon in the campaign to control the pests which devastate vegetation in Africa and Asia, with dire impacts on agriculture, health and economies.
Previous work has shown that solitary locusts can be induced to swarm when individuals in concentrated populations repeatedly touch each other on the hind legs. Swarms can form when flightless juvenile locusts congregate to form so-called “marching bands” on the ground.
To identify the critical mass of locusts needed for this to occur, Jerome Buhl and Stephen Simpson – at the University of Sydney, Australia, and the University of Oxford, UK,combined mathematical models of moving particles with observations of wingless desert locusts (Schistocerca gregaria) marching around a contained space.
The experiments showed that at low densities of just 2 to 7 locusts, the insects moved independently, while at slightly higher densities of 10 to 25 locusts they banded together, changing direction in unison, rapidly and spontaneously.
When more than 30 locusts were put together in the enclosed space (equivalent to 74 locusts per square metre), they adopted the aligned movement of a swarm after five minutes, collectively marching around the confined space until the experiment was ended 8 hours later. See a video of a 120-strong swarm travelling counter-clockwise here (3.3MB).
Locust commotion
By scaling up these densities to naturally occurring populations of locusts in Africa, for example, the team hopes to predict when a relatively harmless cloud of insects is growing dense enough to trigger a potentially devastating plague.
"The key to the control of these devastating swarms, is better understanding how they come together," Simpson told New Scientist. "We showed that at a critical density, these groups spontaneously start marching in a common direction.”
Gargantuan swarms of desert locusts can contain ten billion individuals and stretch over hundreds of kilometres. These swarms can have a massive impact on people – a 2004 infestation of in West Africa was the biggest since 1989, with harvest losses topping $2.5 billion, and pest-fighting costs of $60 million according to the UN. Finding new control solutions is a top priority.
Taking advantage
The new knowledge could help identify the best time to apply insecticide in order to have the greatest impact, the researchers suggest. The study appears in the journal Science (DOI: 10.1126 /science.1125142).
The study "presents the most detailed description yet of the behavioural mechanisms enabling social animals to form and maintain coherent large-scale groups", says Daniel Grûnbaum at the University of Washington in Seattle, US, in a related perspectives article in the same edition of Science.
"Species that take advantage of dense populations to form organised groups may benefit by more effective foraging, reproduction, migration and escape from predators," he adds.
Not true, they get together every so often in conventions and call themselves Democrats.
Gary Larson had a "Far Side" cartoon on this issue entitled "How Locusts Decide to Swarm."
He drew a whole group of locusts gathered together with one yelling "Let's fly over to Farmer Brown's - he's got crops galore!" and another locust saying "maybe we should think about it."
We need to introduce some Mormons and seagulls to Africa and that will take care of the problem. :-)
Ask Lucas
I was in Idaho for that. The BLM estimated there were 300 per square yard for miles and miles. Tons of them died. We had to plow our 5 acres to get rid of the smell.
I expect we'll see a slew of swarms (try saying that 5x fast) if there's ever a President Hillary Clinton.
Well, watching the MSM suddenly release a flurry of stories on the November "massacre" in Haditha right in time for Memorial Day gave me some clues as to how locusts swarm.
Darn. This is just a story about destructive insects. I thought it was going to be a peak behind the scenes at the MSM. I guess it is probably easy to confuse the two...
How Locusts Decide It's Time To Swarm
Congressional sessions are generally scheduled years in advance.
porn
Doogle
Simple. Cell phones.
Two words
Fried Grasshopper.
Pazuzu...
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