Soybean and Bees

Soybean yield, bees and
entomophilous pollination
In spite of being a cleistogamic, self-pollinating plant, not only the honey (domestic) bee
(Apis mellifera) but also other pollinating insects are found on soybeans. Monasterolo et al.
(2015) studied visitors on soybean flowers and the effects of pollinator visits on soybean reproductive
success, on a fragmented Chaco forest landscape in Argentina. Visitation rates
were assessed in relation to distance from the forest, comparing to soybean bee assemblages
with those on wild flowers in the nearby forest fragments. The authors also carried out an
exclosure experiment in order to assess the contribution of insect visits to soybean reproductive
success, as well as they also analyzed the relationship between visitor body size and
the distance from the forest to the visited flower.
Five species of bees, belonging to two families, were observed visiting soybean flowers, which
were also well represented in the forest. A. mellifera was the most abundant species, found on
soybean flowers at all distances from the forest. Instead, wild visitors displayed a turnover of
species throughout those distances. The smaller species were restricted to areas closer to the
forest, while the larger ones were often found toward the interior of the crop.
Total visitation rates were significantly and negatively affected by distance to the forest
(Monasterolo et al., 2015). All plant productivity variables measured in the exclosure experiments
were significantly improved in exposed flowers, duplicating the values observed
without the visit of pollinators, highlighting the forest role as pollinator reservoir for soybeans.
Bees and cross pollination on soybeans
Beekeepers have often reported that honeybees produce significant amounts of soybean
honey (Hambleton, 1936; Milum, 1940; Johnson, 1944; Pellett, 1947; Davis, 1952; Jaycox,
1970a; Pellet, 1976), indicating active foraging and nectar and pollen collection on
SoybeAn and bees
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