How does an intersex bee behave?
In the
neotropical forest of Barro Colorado Island in Panama, an unusual bee hatched:
half male and half female. The Smithsonian Tropical Research Institute students
and scientists working on nocturnal, socially flexible Megalopta bees at BCI
recognized it as a gynandromorph: a rare condition that results in the
expression of both male and female characteristics.
The bee's left
side was male-like, with a long antenna, a delicate, pointed mandible, and a
slender, naked left hindleg, all typical male characteristics. But the right
side was female-like, with a shorter antenna, a stout, toothed mandible useful
for digging a nest, and a robust hindleg plumose with branched hairs for
transporting pollen. It also had a sting, pointing outward from the female half
of the body.
The first
discovery of a Megalopta gynandromorph was made in 1999. STRI staff scientist
Bill Wcislo found a M. genalis that exhibited the same condition in Barro
Colorado. The recent discovery is the first report of gynandromorphism in the
closely related bee species Megalopta amoenae.
Given the
singularity of the occurrence, the group decided to describe an aspect of the
bee's behavior that hadn't been previously studied in gynandromorphs: circadian
activity, an internal process that enables organisms to clock their daily
activities, and for bees and other pollinators to coordinate their foraging behavior
with the availability of floral resources. The observations were led by former
STRI intern Erin Krichilsky, a student from Cornell University.
They found
that the gynandromorph's activity started earlier in the day, compared to the
male and female bees, but that its highest intensity periods most closely
resembled the behavior of females. These results were recently published in the
Journal of Hymenoptera Research.
"It is
impressive that even though there has been intense sampling of Megalopta at STRI
for nearly 30 years, only two gynandromorphs have ever been found," said
Krichilsky. "This really exhibits the rarity of these creatures. Finding
the M. amoena felt like striking gold or winning the Darwinian lottery."
For the
research team, cases like these are intriguing, not only because they help
determine the frequency and distribution of gynandromorphs globally, but also
because the insects may exhibit odd or novel behaviors. Ultimately, their
unusual activity patterns could potentially lead to new evolutionary paths.
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