14.2. Training bees to an artificial sucrose feeder in the field

Free-flying honey bees can be trained to forage on an artificial sucrose feeder in the field. In the following, one way is explained how bees can be prepared and trained to a sucrose feeder:

1. Fill a jar (e.g. a glass beaker of 250 ml volume) with a sucrose solution of a defined concentration (e.g. 30 % weight/weight; sugar diluted in water).

The exact sucrose concentration can be tested with a refractometer (e.g. N-50 E, Atago, Tokyo, Japan).

2. Turn the jar upside down on a 10 cm x 10 cm Plexiglas®-plate with radially engraved grooves (Fig. 37A).

The sucrose solution accumulates inside each groove and bees landing on the platform can easily access the food with their probosces without drowning in the solution (Fig. 37B).

3. To attract bees to the artificial feeder, place it directly in front of the hive entrance; the Plexiglas®-plate builds a bridge between the entrance of the hive and the feeder.

Thus bees can directly walk on the plate to the grooves filled with sucrose solution

4. Mark 5 – 10 bees continuously foraging on the feeder with a colour spot on the abdomen or thorax (see section 2.3.) for better identification.

5. Move the feeder successively away from the hive in 2-m steps every 15 min to the final destination.

Care should be taken that all marked bees are able to follow the moving food place; if a bee lost its track to the new location, the feeder must be returned to a former position until each single marked bee has found the food place again.

6. The marked bees will recruit new foragers to the feeder

7. The number of newly recruited foragers can be controlled by increasing the sucrose concentration of the feeder.

Increasing the concentration e.g. from 3 % to 50 % sucrose results in more bees being attracted to the feeder. Inversely, a decrease in concentration reduces the number of active foragers at this site.

Fig. 37. Training bees to an artificial feeder and selecting bees according to their sucrose acceptance in the field. A. Artificial sucrose feeder. B. Honey bee foragers drinking sucrose solution from the feeder. C. Schematic drawing of the sucrose feeder with decreasing sucrose concentrations (30 %, 10 % and 3 %) used for selecting bees with different sucrose acceptance thresholds in the field. Foragers visiting a 30 % sucrose feeder are individually marked with a colour spot on the abdomen or thorax. After 20 min the concentration on the feeder is reduced to the next lower concentration (10 %) and all individuals continuing to visit the feeder are registered. Again 20 min later, the sucrose concentration is reduced to 3 %. 20 min later, the sucrose concentration is increased again to 30 % sucrose. Bees visiting the feeder regardless of the sucrose concentration are assigned to the group with low acceptance thresholds. Individuals only foraging at the highest concentration are considered bees with high acceptance threshold.

1293PN revised Fig 37