Biology Reference
In-Depth Information
and nurse larvae; store food; and respond to adverse environmental factors.
Adult workers search for nectar and pollen at unpredictable sites, they learn
the celestial and terrestrial cues that guide their foraging trips over long dis-
tances and allow them to find their nest sites once again. Workers learn how
to respond to the changing position of the sun, to a pattern of polarized light
during the day, and to landmarks. Associative learning is an essential compo-
nent to foraging behavior and dance communication. Hive mates attending a
dance performance learn the odor the dancing bee carries and seek out that
same odor when they forage for food.
The complexity of bee behavior makes it an ideal organism to better under-
stand learning, especially odor responses (
Hammer and Menzel 1995, Ray and
Ferneyhough 1999
,
Menzel 1999
), as well as to analyze social behavior (
Bloch
and Grozinger 2011
). Associative olfactory learning in honey bees has sev-
eral features similar to higher forms of learning in vertebrates (
Grunbaum and
Muller 1998
).
11.5.5 Pheromones in Insects
Many insects use chemical cues as signals to find mates and molecular-genetic
methods are now used to study various aspects of pheromone-response behav-
ior. For example, genes are being identified that code for proteins involved in
the synthesis of
pheromones
(substances released by the body that cause a pre-
dictable reaction by another individual of the same species), the perception of
semiochemicals
(chemicals that influence insect interactions), and the process-
ing of the signals (
Krieger and Breer 1999, Mombaerts 1999, Tillman et al. 1999,
Field et al. 2000
).
Pheromone biosynthesis appears to use one or a few enzymes that convert the
products of normal primary metabolism into compounds that act as pheromones
(
Tillman et al. 1999
). For example, pheromones arise from isoprenoid biosynthesis,
or by the transformation of amino acids or fatty acids. Several genes encoding
the enzymes involved in transforming metabolites into pheromones have been
cloned and sequenced (
Field et al. 2000
). Three hormonal messengers regulate
production of pheromones by insects: juvenile hormone III, ecdysteroids, and a
neuropeptide called pheromone-biosynthesis-activating neuropeptide (PBAN).
The antennae contain olfactory organs (sensillae) that mediate pheromone
perception. Some receptor neurons on the antennae appear to respond to one
particular chemical (specialist neurons), but others appear to respond to a num-
ber of compounds (generalist neurons). Pheromones often are perceived in com-
bination with other chemicals, including plant volatiles.
