social insects
edyong | March 18, 2010
One night of passion and you're filled with a lifetime full of sperm with no need to ever mate again. As sex lives go, it doesn't sound very appealing, but it's what many ants, bees, wasps and termites experience. The queens of these social insects mate in a single "nuptial flight" that lasts for a few hours or days. They store the sperm from their suitors and use it to slowly fertilise their eggs over the rest of their lives. Males have this one and only shot at joining the Mile High Club and they compete fiercely for their chance to inseminate the queen. But even for the victors, the war…
awild | March 4, 2010
Who's that odd ant out?
While in sunny Florida last summer (ah, sunshine! I vaguely remember what that looks like), I spent an hour peering into a nest of little Dorymyrmex elegans. These slender, graceful ants are among Florida's more charming insects.
Every few minutes, though, the flow of elegant orange insects out of the nest was interrupted by a darker, more robust ant: Dorymyrmex reginicula. Who was this interloper?
Dorymyrmex reginicula is a temporary social parasite. Mature colonies behave pretty much like normal ants. Workers guard the nest, forage for food, and tend the larvae.…
awild | February 22, 2010
Zootermopsis soldier termite, jaws at the ready.
If you think of termites as pasty white squishy things, here's one that'll jar your preconceptions. Zootermopsis dampwood termites of western North America have large soldiers- over a centimeter long- that are muscular and well armored.
Soldiers are deployed not against predators but against other termites, as colonies within a single rotting log fight when they encounter each other. Those jaws are ideal for slicing through an enemy queen, for example, or for protecting their own.
Photo details: Canon mp-e 65mm 1-5x macro lens on a Canon EOS…
awild | February 9, 2010
Figure 1. Relationship between normalized metabolic rate and body mass for unitary organisms and whole colonies (from Hou et al 2010)
The notion that insect colonies and their constituent individuals are analogous to multicellular organisms and their constituent cells has been a controversial idea for decades. Is it useful, for example, to think of an ant colony as a single individual? Do superorganisms really exist as coherent entities? Or do insect colonies function more as aggregations of individuals?
Last week, PNAS published the first application of empirical methods to test the…
awild | January 20, 2010Let me preface this post by saying that Christian Peeters is one of my absolute favorite myrmecologists. If lost in a remote African jungle and stalked by ravenous leopards, for example, Christian is the first ant guy I'd pick to help get me out of the predicament.
Having said that, this paper in Insectes Sociaux is so bad I nearly gouged my eyes out and ran around in little circles screaming and flailing my arms.
Nonetheless there exist extant ants with relatively simple societies, where size-polymorphic workers and large queens are absent. Recent phylogenies show that the poneroid…
razib | January 18, 2010Mathematical support for insect colonies as superorganisms. Click through for the scatterplot.
awild | October 19, 2009
Formica obscuripes
Trophallaxis- the social sharing of regurgitated liquids- is a fundamental behavior in the biology of most ant colonies. One ant approaches another, asks for a droplet of food, and if her partner is willing the two spend anywhere from a few seconds to several minutes in what is best described as a myrmecological french kiss. The behavior is so central to the life of ants that the insects have an entire stomach, separate from their digestive gut, devoted as a reservoir for social sharing.
Although the act involves a transfer of food, it would be a mistake to think of…
awild | September 8, 2009
Crematogaster lineolata queen with a retinue of workers. (Vermillion River Observatory, Illinois)
This weekend we took a trip with some entomology students to the Vermillion River Observatory. The astronomical function of the observatory has long been abandoned, but the site remains as a lovely nature reserve and one of the closest patches of decent forest habitat to where we live in Champaign-Urbana.
The acrobat ant Crematogaster lineolata was one of many ants we encountered, and in this nest the queen was right up near the surface. She lingered long enough for me to get a few shots…
awild | March 4, 2009Achenbach, A., Foitzik, S. 2009. FIRST EVIDENCE FOR SLAVE REBELLION: ENSLAVED ANT WORKERS SYSTEMATICALLY KILL THE BROOD OF THEIR SOCIAL PARASITE PROTOMOGNATHUS AMERICANUS . Evolution, Online Early, doi: 10.1111/j.1558-5646.2009.00591.x
Abstract: During the process of coevolution, social parasites have evolved sophisticated strategies to exploit the brood care behavior of their social hosts. Slave-making ant queens invade host colonies and kill or eject all adult host ants. Host workers, which eclose from the remaining brood, are tricked into caring for the parasite brood. Due to their high…
awild | February 28, 2009Those of you who were into ants in the early '90s might remember SimAnt, a simulation game where you control the decisions your ants make to steer a colony to dominance over a competing species in a suburban lawn.
The game is based, in part, on the optimality equations summarized in Oster & Wilson's 1978 text "Caste and Ecology in the Social Insects". The book lays out mathematical foundations for determining the investments a colony should place in workers, queens, and males in order to optimize Darwinian fitness over a range of ecological conditions. If you knew the equations,…
awild | February 17, 2009
Pheidole dentata, older worker with larva.
A study out in pre-print by Muscedere, Willey, and Traniello in the journal Animal Behaviour finds little support for a long-held idea that worker ants change specializations to perform different types of work as they age. By creating colonies out of different age classes in the ant Pheidole dentata, the researchers showed that older workers were good at pretty much everything, while younger ants performed only a few tasks, but did those less efficiently. Here is the abstract:
Age-related task performance, or temporal polyethism, is a prominent…
awild | February 14, 2009Who is supposed to read The Superorganism?
I can't really tell. While I'm enjoying Holldobler & Wilson's latest tome, I am perplexed at the book's target audience. The text switches between broadly anthropomorphic prose clearly aimed for a general audience and obtuse jargon digestible only by the experienced biologist.
I get the feeling that the authors- at least one of them, anyway- desired a technical book more along the lines of Bourke & Franks, while the marketing department at Harvard University Press wished to trade on the authors' name recognition with a glossy coffee-table…
awild | February 10, 2009 There's been a debate simmering among Argentine Ant researchers about the difference between the ant's ecology in its native South America and in the introduced populations. The heart of the disagreement is this: is the introduced Argentine ant dominant because its biology changed during introduction, or because the ecologies of the native and introduced ranges are different?
Like most scientific debates, some aspects are factual in nature while others are semantic. Sometimes the semantic and the factual become confused in a way that makes it difficult to tease the arguments apart…
jwhitfield | January 27, 2009Science is fun. Now, I know that someone telling you a thing is fun is usually a guarantee that it isn't. And I know that people who tell you science is fun usually do so in strained and pleading tones, and expect you to believe them because they have spiky hair and can play the harmonica. But it's true.
To see what I mean, read chapter 6 of the Origin, 'Instinct'. Despite, or because of, having its share of 'are you sure about that?' moments, it's a delight, because it shows Darwin doing the most fun thing in science: mucking about with reality, sometimes called experimentation.
In this…
awild | January 19, 2009
Camponotus discolor male, queen, and worker
Here's an image I should have taken years ago. It's a stylized shot of the different castes in an ant colony, perfect for a textbook illustration of the morphological distinctions among males, gynes, and workers. Better late than never, I suppose.
photo details: Canon MP-E 65mm 1-5x macro lens on a Canon EOS 20D
ISO 100, 1/250 sec, f/13, flash diffused through tracing paper
awild | January 12, 2009
Aphaenogaster cockerelli, Arizona
Here's a new study in Current Biology from Adrian Smith, Bert Hoelldobler, and Juergen Liebig:
Abstract: Cheaters are a threat to every society and therefore societies have established rules to punish these individuals in order to stabilize their social system [1â3]. Recent models and observations suggest that enforcement of reproductive altruism (policing) in hymenopteran insect societies is a major force in maintaining high levels of cooperation [4â6]. In order to be able to enforce altruism, reproductive cheaters need to be reliably identified. Strong…
awild | November 21, 2008 My copy arrived from Amazon the day before yesterday. I've not given it anything more than a couple cursory thumb-throughs, but I'm immediately left with the impression of schizophrenia.
The bits on social organization, behavior, communication, and levels of selection- mostly Bert Hoelldobler's sections- seem an engaging and modern review, while the chapters dealing with ant history and evolution- Wilson's area- are... How do I say this diplomatically? Rubbish.
The past ten years have brought immeasurable advances in our knowledge of ant evolution, both in breadth and detail. …
awild | September 27, 2008
Atta texana queen and worker
Ant queens are those individuals in a nest that lay the eggs. They're pretty important, of course, as without reproduction the colony dwindles and disappears.
Understandably, ant-keepers have an interest in making sure their pet colonies have queens. Conversely, pest control folks trying to get rid of ant colonies need to be sure that they've eliminated queens. Whether your interest is live ants or dead ants, I'll give some pointers in this post for recognizing queens.
In many species the difference between workers and queens is obvious. Consider the…
awild | August 29, 2008
Juergen Heinze has a must-read piece in the latest edition of Myrmecological News about how ant colonies are not often simple families as we like to think of them:
Abstract: The social systems of ants are far more variable than has traditionally been believed. In addition to variation in queen number and queen mating frequency, recent research has documented such bizarre phenomena as the parthenogenetic production of females from unfertilized eggs or genetic caste determination. All these affect the genetic structure of ant societies, and it appears that in a large percentage of species…