18.104.22.168. Collecting nectar from honey bees
Honey bee foragers collect nectar from flowers. This nectar is stored in their impermeable crops for transfer back to their hives. The crop can greatly expand for storage and it has been shown that workers can carry crop loads close to their own body mass (Nicolson, 2008). By inducing bees to regurgitate, full nectar loads can be collected (Roubik and Buchman, 1984; Roubik et al., 1995; Nicolson and Human, 2008; see the BEEBOOK paper on methods for behavioural studies (Scheiner et al., 2013) for the latter method).
- Capture honey bees visiting flowers on the plant of interest or at the entrance of hives on their way back from nectar gathering.
- Compress the thorax of individual bees gently dorsoventrally to obtain nectar to induce regurgitation of the content of the honey stomach (Roubik and Buchman, 1984). This should be done within 10 min of capture, to prevent the honey bee using her stomach load as fuel.
- Collect the liquid nectar from the mouthparts in micro capillary tubes through capillary action.
- Measure nectar volume.
Volumes (µl) are determined from the column length in micro-capillary tubes (length 75 mm/75 ml).
- Measure nectar concentration with a pocket
refractometer (e.g. Bellingham and Stanley Ltd, Tunbridge Wells, UK) by placing a drop of nectar
onto the prismatic surface of
the refractometer (through capillary action). Concentration is measured as %
w/w sucrose equivalents.
- Bees are not killed.
- Non-invasive method as far as the hive is concerned.
- Honey stomachs
may contain nectar from the hive used as fuel for flight, which could dilute
the nectar collected (Roubik
and Buchmann, 1984; Nicolson and Human, 2008).
- It has been shown that nectar concentration can be changed during flight back to the hive (Nicolson and Human, 2008).