Featured Research

from universities, journals, and other organizations

Why Locusts Abandon A Solitary Life For The Swarm

Date:
December 30, 2008
Source:
Cell Press
Summary:
By applying an old theory that has been used to explain water flow through soil and the spread of forest fires, researchers may have an answer to a perplexing ecological and evolutionary problem: why locusts switch from an innocuous, solitary lifestyle to form massive swarms that can devastate crops and strip fields bare.

Locusts on the move.
Credit: iStockphoto/Pawel Pachniewski

By applying an old theory that has been used to explain water flow through soil and the spread of forest fires, researchers may have an answer to a perplexing ecological and evolutionary problem: why locusts switch from an innocuous, solitary lifestyle to form massive swarms that can devastate crops and strip fields bare.

Related Articles


Their report, published online on December 18th in Current Biology, a Cell Press publication, concludes that once the insects' ranks grow to a certain threshold size, banding together prevents predators from moving from one patch of insects to the next and easily picking the bugs off one by one.

"A predator can only move continually across a landscape, consuming locusts as it goes, if there is a landscape-spanning pathway of connected, high-yielding patches containing locusts in abundance," said Andy Reynolds of Rothamsted Research. "If the locusts were to remain dispersed when their numbers become sufficiently high, then such predator-sustaining pathways would always exist. By grouping together, locusts can reduce the number of connections between patches, and there is a significant probability that the predator will locate too few locusts to sustain itself."

Locusts are a notorious outbreak pest, with the ability to increase sharply in abundance when conditions are right. They've also been of interest because of their remarkable ability to shift from a cryptic, solitary state to form migratory bands when their numbers grow. At such times, the insects not only behave differently, but the two "phases" also differ from each other in their physiology, color, shape, and many other traits—so much so that the phases were sometimes thought to be completely different species.

Despite the interest, scientists had no satisfactory explanation for the evolution of this behavior. Until now, that is.

In the new study, the researchers applied percolation theory—the study of how randomly generated clusters connect and behave—to the problem. The theory, so named from the way in which coffee flows through a percolator, is known to play a fundamental role in a diverse range of disorderly physical phenomena, but it had received rather little attention in ecological quarters, Reynolds said. Using the theory, they now show that it would be highly disadvantageous for individual locusts to continue indefinitely in a dispersed distribution as their population explodes. That's because the switch to a swarm disrupts the connections in the predators' network of tempting food patches.

The finding suggests that selection pressure from predators has been a key factor in driving the evolution of the insects' gregarious tendencies. And, they said, the theory will no doubt apply to other species and circumstances as well.

"We suspect that for any natural enemy that exploits patches of hosts, percolation theory warrants consideration as a generally applicable model underlying the ecology and evolution of aggregative behavior," Reynolds said. "For example, aggregation behaviors may have evolved in insects as an anti-parasite defense mechanism because by aggregating in groups, there is a greater probability that a parasite or pathogen will fail to breach the gap between infectious hosts."

The researchers include Andy M. Reynolds, Rothamsted Research, Harpenden, Hertfordshire, UK; Gregory A. Sword, The University of Sydney, Sydney, Australia; Stephen J. Simpson, The University of Sydney, Sydney, Australia; and Don R. Reynolds, University of Greenwich, Kent, UK; Rothamsted Research, Harpenden, Hertfordshire, UK.


Story Source:

The above story is based on materials provided by Cell Press. Note: Materials may be edited for content and length.


Cite This Page:

Cell Press. "Why Locusts Abandon A Solitary Life For The Swarm." ScienceDaily. ScienceDaily, 30 December 2008. <www.sciencedaily.com/releases/2008/12/081218122152.htm>.
Cell Press. (2008, December 30). Why Locusts Abandon A Solitary Life For The Swarm. ScienceDaily. Retrieved January 25, 2015 from www.sciencedaily.com/releases/2008/12/081218122152.htm
Cell Press. "Why Locusts Abandon A Solitary Life For The Swarm." ScienceDaily. www.sciencedaily.com/releases/2008/12/081218122152.htm (accessed January 25, 2015).

Share This


More From ScienceDaily



More Plants & Animals News

Sunday, January 25, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Florida Might Legalize Black Bear Hunting

Florida Might Legalize Black Bear Hunting

Newsy (Jan. 24, 2015) A string of black bear attacks has Florida officials considering lifting the ban on hunting the animals to control their population. Video provided by Newsy
Powered by NewsLook.com
Ebola Killing Large Portion Of Ape Population

Ebola Killing Large Portion Of Ape Population

Newsy (Jan. 23, 2015) Experts estimate Ebola has wiped out one-third of the world&apos;s gorillas and chimpanzees. Video provided by Newsy
Powered by NewsLook.com
Controversy Shrouds Captive Killer Whale in Miami

Controversy Shrouds Captive Killer Whale in Miami

Reuters - Light News Video Online (Jan. 23, 2015) Activists hope the National Oceanic and Atmospheric Agency (NOAA) will label killer whales endangered, allowing lawyers to sue a Miami aquarium to release an orca into the wild after 44 years. Jillian Kitchener reports. Video provided by Reuters
Powered by NewsLook.com
‘Healthy’ Foods That Surprisingly Pack on Pounds

‘Healthy’ Foods That Surprisingly Pack on Pounds

Buzz60 (Jan. 23, 2015) Some &apos;healthy&apos; foods are actually fattening. Fitness and nutrition expert John Basedow (@JohnBasedow) shines a light on the sneaky foods like nuts, seeds, granola, trail mix, avocados, guacamole, olive oil, peanut butter, fruit juices and salads that are good for you...but not so much for your waistline. Video provided by Buzz60
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins