Insect Birth Control

A brief report in the New York Times discusses the discovery of something that biologists knew was there and at work in social insects colonies, but had never conclusively identified - the fertility-suppressing pheromone that queens give off to keep the other workers in the colony sterile, and thus non-reproductive. Yes, this handy pheromone keeps the ovaries of other ants or bees from properly developing.

Cooperation in the superorganism/colony isn't just by simple consent, but rather a negotiation of a variety of  priorities and sometimes competing interests - at least from the point of view of natural selection...

AY

Master of the Killer Ants

If you've ever found yourself watching Nova on PBS, then perhaps you've seen this episode about the Mofu people in Cameroon who get help from army ants to protect their homes and crops from termites.

Watch the full episode. See more NOVA.

into the Field (literally)

This week's class found us among at the Field Museum in the company of its the 14 million or so insect specimens and its abundant exhibits.

We visit the current The Romance of Ants exhibit about the life and work of the assistant curator there, Dr. Corrie Moreau. Luckily Alexandra Westrich who illustrated the graphic novel that is the centerpiece of the exhibit was also there to show us around.

After that as well as a tour of some of the more charismatic insects in the collection (yes, there are walking stick insects as long as your arm) lead us to then see some of the creatures at work - to the bird collection where dermestid (flesh eating) beetles were busy cleaning a variety of different skeletons, including a primate skull (!)

As you can see from the photos, it these tiny beetles live in a odorous environment to say the least...

Corrie then  talked about the work her and others do in the Pritzker Molecular Biology labs, including sequencing the DNA of the ants from far and wide: Madagascar, Australia, and perhaps most exotic of all - Florida.

It was an excellent visit. We didn't get to see all 14 million specimens, but we made a dent with a least a few hundred - no doubt the best ones.

AY

 

bee brainz

This is a recently published article about how bees use advanced math to determine the shortest path from food source to food source. I posted it because it reminded me of what we learned about how ants use trigonmetry to find their way back to their nest. Interesting!

http://http://www.sciencedaily.com/releases/2010/10/101025090020.htm

hymenopteras

i am most fascinated with hymenopteras. mainly because of ants. i think ants are crazy. you dont mess with ants or they will mess you up by the tens of thousands. they build cities underground that we have no clue about, and they take on anything they can eat. im also terrified of hymenopteras. bees, wasps, and hornets. i havent been stung many times in my life, but the times i have were very unpleasant.

love, jeff pak

Colony collapse

A team of entomologists and military scientists have discovered a possible explanation for the 'colony collapse' that has affected 20-40% of bee colonies in the U.S.

article can be found HERE.
-Emily

Ant Death Spiral

Ants are colonial insects, meaning they are very social, and function more as a group and rarely as individuals. They seem to be exceedingly loyal to their colony, and some ant species will literally run themselves to death by exhaustion. When these ants become separated from the greater swarm, they will literally follow each other in circles until they all die. This action produces a breathtaking "hurricane" of ants that continues until no ants are left standing.

Video:

Bites Recruit Wasp Workers
March 27, 2006
By Joel Schwarz, University of Washington

If you think you’ve got a bad boss, one who loves to chew people out, or if you work with backstabbing co-workers, be thankful you are not a wasp.

If you were, chances are your nestmates might bite you to communicate that it is time to leave the nest and forage for the colony, according to research by a University of Washington animal behaviorist. Biting is a way that workers in a colony of the social wasp Polybia occidentalis recruit new foragers to gather water, food and building material in a time of need, said Sean O’Donnell, a UW associate professor of psychology.

O’Donnell previously found that biting appears to be an important way of regulating the division of labor among these insects. Now, in the March 2006 issue of the journal Animal Behaviour, he describes an experiment in which he artificially removed active foragers from four wasp colonies to see how new foragers are recruited.

He found that biting was directed at certain individuals, who previously hadn’t left the nest, to induce them to begin foraging. The rate of being bitten increased by an average of 600 percent for these recruited foragers, while biting rates did not increase for other workers.

“The fact that biting was specifically directed at recruited foragers shows that biting is the mechanism that the colonies used to activate new foragers,” said O’Donnell. “With no water, food and building material coming in to the nest, the colonies needed to ramp up their foraging workforce. This study shows that these biting interactions play a central role in recruiting foragers and that biting has a role in communication that affects task performance in a colony.”

To study the wasps, O’Donnell first collected and anesthetized an average of about 300 workers from each of the colonies. He then marked each wasp’s thorax with a color-coded system that made it possible to identify individuals and returned the insects to their nests. A day later, all foragers returning to a nest were removed for at least two hours and until none arrived for at least one hour of continuous monitoring.

“The rate of foraging slowed down and stopped completely, placing stress on the colony because materials the colony needs, primarily food, are not coming in. So the colony needs to recruit new workers to make up for the loss,” O’Donnell explained.

On the final day observers watched each colony, noted the behavior of the marked individuals to see which insects were foragers, and recorded all biting interactions.

O’Donnell said the biting did not always provoke an individual to begin foraging immediately, noting the biting seems to have a cumulative effect. Some insects were bitten multiple times for hours before leaving the nest to forage.

“Going off the nest to forage, where they are exposed to all kinds of stresses and dangers, is probably the biggest change these animals face in their lives,” he said.

O’Donnell plans future studies to learn what determines which members of a colony are doing the biting and which are being bitten. He suspects that biting recipients are recognized based on something chemical on their body surface, as well as by an age component.

O’Donnell and other scientists study social insects looking for clues about how social behavior evolved and how it is maintained since there are elements that are shared among all social animals. Social aggression is one such characteristic that is almost universal among animal groups ranging from insects to primates including humans.

The National Science Foundation funded the research, which was conducted in Costa Rica.

Press Release © 2005, Joel Schwarz, University of Washington

“Polybia wasp biting interactions recruit foragers
following experimental worker removals,” Sean O’Donnell, Animal Behaviour, Volume 71, Issue 3, Pages 709-715 (March 2006) (published online February 7, 2006)

Sean O’Donnell, University of Washington

Video of Polybia nest

Back to Research 2006


Polybia occidentalis recruits new forager (marked with pink) with a bite.

Photo © 2006 University of Washington


Polybia occidentalis workers

Photo © 2006 University of Washington