Soybean and Bees

concentration on the open area was higher than the other treatments. The content of glucose
was not affected by the treatments, while fructose concentration was lower in covered
area without bees as compared to the other treatments.
Barella (2009) mentioned that Apis mellifera was the dominant species foraging on soybeans
(57%) in Barra do Bugre-MT, while Meliponini species represented 29% of total insects (not
necessarily pollinators) visiting soybean flowers.
Soybean blossoms have functional nectaries. Each flower of most cultivars produces only
slightly less nectar than alfalfa in northern regions of the USA, and sugar concentrations in
soybean nectars are 5-10% higher than those of alfalfa, when growing conditions are favorable
(Erickson, 1984b).
In the central United States, soybean nectar production and bee visitation occur between
9:00 am and 3:00 pm, each day. Soybean nectar volume per flower - greatest in warmer climates
- varies significantly among cultivars ranging from none to 0.2 µL / flower, with some
flowers having as much as 0.5 µL, noting that the honey stomach of worker honeybee holds
35 µL - 50 µL (Erickson, 1984a). This author examined soybean nectar and reported a mean
nectar sugar content of 37 to 45%. In Missouri and Arkansas, the total carbohydrate content
in soybean nectar varied from 301 µg/µL to 1,354 µg/µL of nectar and from 15 µg to 134 µg/
flower. He observed that floral sugar concentration increased, but volume decreased according
to the time of day and temperature. Nectar sugar ratios (i.e. fructose:glicose:sucrose content)
differ among soybean cultivars as well as with time of day within a cultivar.
Erickson (1984a) found no differences in carbohydrate content between purple and white
flowered cultivars, but registered that earlier in Wisconsin, nectar production appeared to
be most consistent in volume and carbohydrate content among white flowered cultivars,
hence they were judged more attractive for bees than purple ones. However, a later work
conducted in Missouri definitely dispelled this notion (Erickson, 1984).
Honeybee collection of soybean pollen is highly variable as is a cultivar’s ability to produce
quantities of pollen. Little soybean pollen may be gathered by bees in some areas. However,
soybean pollen may comprise over 50% of the total quantity of pollens gathered by many
bee colonies, on the studied areas, according to Erickson (1984). Soybean pollen pellets taken
from the corbiculae of foraging bees are easily recognized by their grey-brown color, small
size and compaction. A possible theory explaining the high soybean pollen share on bee´s
collection is the absence of flowering meliferous plants coinciding with soybean blooming,
partly due to the extensive crop cultivation along large areas.
92 SoybeAn and bees