Soybean and Bees

et al. (2003) conducted studies in 2001 and 2002 using two soybean cultivars, Pace (whiteflowered)
and DP3588 (purple-flowered), selected for their equivalent flowering dates. The
experiments utilized the dominance of purple flower color over white flower color to identify
natural cross-pollinations. In the first experiment, 12 rows of ‘Pace’ (white-flowered)
flanked on each side by four rows of ‘DP3588’ (purple flowered) were sown in the spring of
2001. Seeds were harvested by row from each of the ‘Pace’ rows and examined for natural
cross-pollinations in the next generation. In total, 73,512 potential hybrid plants were examined
and natural cross-pollination rates ranged from 0.41% at 0.9 m from the pollen source
to 0.03% at 5.4 m from the pollen source. These values were consistent with values previously
reported in the literature.
In a second experiment, seeds of ‘Pace’ and ‘DP3588’ were alternately sown 15.2 cm apart
within a row, in the same season of the previous study. At maturity, 167 Pace plants (whiteflowered)
were harvested and a total of 19,151 progeny were evaluated for natural crosspollinations,
expressed in the next generation. The progeny of 56 (33.5%) of the 167 parent
plants showed no evidence of natural crosspollination. The progeny of the remaining 111
plants exhibited natural cross-pollination rates ranging from 0.65 to 6.32% and averaged
1.8%. The maximum rates reported here are considerably higher than most previously reported
rates, according to Ray et al. (2003).
Relating to soybean pest resistance, there is a concern involving the potential negative impact
of the soybean proteinase inhibitor – a trait for soybean resistance to insects - and the
foraging strategy of honeybees, as referred by Sagili et al. (2005). Laboratory studies reported
disruption of the digestive physiology and learning behavior in individual honeybees treated
with Bowman-Birk inhibitor (BBI), a serine proteinase inhibitor expressed in some GM plants
(Dechaume-Moncharmont et al., 2005). These authors investigated possible behavioral
effects of this transgene on honeybees at the colony level, maintained in laboratory conditions.
A choice experiment, based on 150 free-flying individuals was set up, which performed
over 7,700 visits on the flowers. The mean number of visits per hour, the mean time spent on
the feeder and the interval between consecutive visits were not significantly different when
the feeding sucrose solution was mixed with BBI at 100 μg·mL –1 , a dose close to the expression
level in planta.
Soybean is not considered an anemophilous plant, ones that have cross-pollination mediated
by the wind. Yoshimura (2011) investigated the subject, using Durham pollen samplers
located up to 20 m from the field edge. In addition, the dispersal distance was assessed in a
wind tunnel under constant airflow and then it was compared with the anticipated distances
based on the pollen diameter. In the field, the maximum pollen density per day observed was
1.235 grains cm -2 day -1 at three observation points within 2.5 m from the field. Inside the field,
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