ScienceDaily, March 8, 2012
A new study in Science
suggests that thrill-seeking is not limited to humans and other vertebrates.
Some honey bees, too, are more likely than others to seek adventure. The brains
of these novelty-seeking bees exhibit distinct patterns of gene activity in
molecular pathways known to be associated with thrill-seeking in humans,
researchers report.
The findings offer
a new window on the inner life of the honey bee hive, which once was viewed as
a highly regimented colony of seemingly interchangeable workers taking on a few
specific roles (nurse or forager, for example) to serve their queen. Now it
appears that individual honey bees actually differ in their desire or
willingness to perform particular tasks, said University of Illinois entomology
professor and Institute for Genomic Biology director Gene Robinson, who
led the study. These differences may be due, in part, to variability in the
bees' personalities, he said. "In humans,
differences in novelty-seeking are a component of personality," he said.
"Could insects also have personalities?"
Robinson and his
colleagues studied two behaviors that looked like novelty-seeking in honey
bees: scouting for nest sites and scouting for food.
When a colony of
bees outgrows its living quarters, the hive divides and the swarm must find a
suitable new home. At this moment of crisis, a few intrepid bees -- less than 5
percent of the swarm -- take off to hunt for a hive.
These bees, called
nest scouts, are on average 3.4 times more likely than their peers to also
become food scouts, the researchers found.
"There is a
gold standard for personality research and that is if you show the same
tendency in different contexts, then that can be called a personality
trait," Robinson said. Not only do certain bees exhibit signs of
novelty-seeking, he said, but their willingness or eagerness to "go the
extra mile" can be vital to the life of the hive.
The researchers
wanted to determine the molecular basis for these differences in honey bee
behavior. They used whole-genome microarray analysis to look for differences in
the activity of thousands of genes in the brains of scouts and non-scouts.
"People are
trying to understand what is the basis of novelty-seeking behavior in humans
and in animals," who Robinson, who also is affiliated with the
Neuroscience Program at Illinois. "And a lot of the thinking has to do
with the relationship between how the (brain's) reward system is engaged in
response to some experience."
The researchers
found thousands of distinct differences in gene activity in the brains of
scouting and non-scouting bees.
"We expected
to find some, but the magnitude of the differences was surprising given that
both scouts and non-scouts are foragers," Robinson said.
Among the many
differentially expressed genes were several related to catecholamine, glutamate
and gamma-aminobutyric acid (GABA) signaling, and the researchers zeroed in on
these because they are involved in regulating novelty-seeking and responding to
reward in vertebrates.
To test whether the
changes in brain signaling caused the novelty-seeking, the researchers
subjected groups of bees to treatments that would increase or inhibit these
chemicals in the brain.
Two treatments
(with glutamate and octopamine) increased scouting in bees that had not scouted
before. Blocking dopamine signaling decreased scouting behavior, the
researchers found.
"Our results
say that novelty-seeking in humans and other vertebrates has parallels in an
insect," Robinson said. "One can see the same sort of consistent
behavioral differences and molecular underpinnings."
The findings also
suggest that insects, humans and other animals made use of the same genetic
"toolkit" in the evolution of behavior, Robinson said. The tools in
the toolkit -- genes encoding certain molecular pathways -- may play a role in
the same types of behaviors, but each species has adapted them in its own,
distinctive way.
"It looks like
the same molecular pathways have been engaged repeatedly in evolution to give
rise to individual differences in novelty-seeking," he said.
The National
Science Foundation, National Institutes of Health and Illinois Sociogenomics
Initiative supported this research.
Collaborators on
this study included researchers from Wellesley College and Cornell University.
Story Source:
The above story is reprinted from materials provided by University of Illinois at Urbana-Champaign.Note: Materials may be edited for content and length. For further information, please contact the source cited above.
Journal Reference:
- Z. S. Liang, T. Nguyen, H. R. Mattila, S. L. Rodriguez-Zas, T. D. Seeley, G. E. Robinson. Molecular Determinants of Scouting Behavior in Honey Bees. Science, 2012; 335 (6073): 1225 DOI: 10.1126/science.1213962
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