real-time flight info communication

Science 9 February 2007: Vol. 315. no. 5813, pp. 771 - 772 DOI:
10.1126/science.1136840

Perspectives BIOPHYSICS: Antennae as Gyroscopes R. McNeill
Alexander

Flying insects need to detect unwanted movements of their own
bodies, so that they can make any necessary corrections to
restore the status quo. They need to know, for example, when
their flight is disturbed by an eddy in turbulent air or by an
imperfectly executed wing beat. Dragonflies depend on sight for
this information. That works well in bright daylight but would
not be satisfactory in near-darkness because eyes cannot provide
precise information quickly in dim light. Moths active at night
need information about unwanted movements to maintain flight
stability, especially when hovering to collect nectar from
flowers. On page 863 of this issue, Sane and colleagues (1)
explain how a hawk moth senses its own rotations.

These researchers found that the moth's movement-detection system
depends largely on the Coriolis effect, which keeps spinning
gyroscopes stable. This effect is an apparent deflection of an
object viewed in a rotating frame of reference, seemingly
attributable to an apparent force. We already knew of the
importance of Coriolis forces for dipteran flies (house flies,
mosquitoes, etc.). Instead of having four wings like other
insects, dipterans have only two. Their hind wings have been
reduced to tiny club-shaped halteres (see the figure) that beat
at the same frequency as the fore wings. If their halteres are
cut off, these flies become unstable in flight and soon crash to
the ground. Pringle (2) explained how Coriolis forces on the
halteres inform flies of rotations of their bodies, enabling them
to fly stably. Sane et al. now find that hawk moths can do this
with their antennae, although detection of aerodynamic as well as
Coriolis forces may have a role.

…from:
SCIENCEWEEK
February 16, 2007
Vol. 11 - Number 7