Soybean and Bees

Nectar, aroma and fidelity of pollinators
The importance of olfaction in recruitment of forager honeybees has been well documented
(Von Frisch, 1967; Johnson and Wenner, 1970). Honeybees have large numbers of antennal
placoid sensilla, which are the principal chemoreceptors for floral aromas (Lacher,
1964). Antennal amputation has indicated that the acuity of scent perception in honeybees
varies with the number of intact sense organs on the antennal segments (Ribbands, 1955).
Indeed, it has been suggested that olfaction plays a more important role in forager recruitment
than the dance maneuvers observed in colonies (Johnson and Wenner, 1966; Johnson,
1967; Wenner, 1967; Wells and Wenner, 1973).
Gonzáles-Teuber and Heil (2009a, b) referred that the origin of FN scent is linked to the volatiles
released by the petals, which are absorbed and rereleased by the nectar. However, a
wide array of VOCs occur in the nectar of wild tobacco (Nicotiana attenuata), and many of
these compounds have not been detected in other flower parts, suggesting that in certain
species nectar emits its own scent, as referred by Kessler and Baldwin (2007). Like other nectar
compounds, these volatiles serve to both attract pollinators and protect from nectar robbers
such as ants (Kessler and Baldwin, 2007; Janzen, 1977).
Kolterman (1969) concluded that scent was more important in conditioning honeybees than
color, form, or time of day. Manning (1957) observed that honeybee discrimination was greater
with a change of scent than with a change of flower pattern or shape. Boren et al. (1962)
and Pedersen (1967) suggested that odor was partially responsible for differential foraging
by honeybees on selected clones of alfalfa, while Kriston (1969) found that honeybees could
be conditioned to scents resembling floral aromas more quickly than to nonfloral aromas.
Contrarily to soybeans, production of floral volatiles in alfalfa has been extensively studied
so, in the absence of specific data for soybeans, it is important to verify what happens with
alfalfa, which belongs to the same botanical family Fabaceae. Emanation of volatiles from alfalfa
flowers follows a daily cyclic pattern, which is controlled by photoperiodically induced
rhythms (Loper and Lapioli, 1971). Honeybee selection among flowers from seven clonal
lines of alfalfa, presented in bouquets for three consecutive days, was consistent from day to
day (Loper and Waller, 1970). Flower aroma differences were indicated as a possible basis
for this selection. Loper et al. (1974) observed that honeybee selection of 28 alfalfa clones appeared
to depend on quantity and quality of floral volatiles. The terpene ocimene has been
identified as the major volatile component of alfalfa flowers (Loper et al., 1971). Myrcene,
limonene, and linalool have also been identified as components of alfalfa flower volatiles
(Loper, 1972) and olfactory discrimination by honeybees has been demonstrated with these
compounds (Waller et al., 1972, 1973, 1974).
SoybeAn and bees
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