4.7.2.3. Ensuring quality of bee collected pollen

Pollen traps are used in studies to measure foraging activity, identify pollen sources, analyse pollen for toxic residues, and to collect pollen for feeding studies. Dependent upon the intended use, steps should be taken to ensure the quality of trapped pollen. A heap of moist pollen is an ideal breeding place for small hive beetles (where they occur, see also the BEEBOOK paper on small hive beetle, Neumann et al., 2013)  and wax moths (see the BEEBOOK paper on wax moths, Ellis et al., 2013) and is very attractive to ants (Johannsmeier, 2001). Pollen quickly degrades and will start to become mouldy if it gets wet. Pollen should therefore be collected every day, cleaned of larger debris either by hand or by sieving through different sized sieves (see section 4.7.2.1.3., step 5) and be stored immediately as a frozen or dried sample to maintain quality. This is essential for samples collected for pesticide residue analysis, which should be stored on ice in coolers in the field and then frozen immediately to -20°C to prevent pesticide degradation until samples are processed.

Pros

- Pollen traps are a less invasive technique of collecting bee collected pollen.

- Easy to collect a large quantity of pollen.

- Pollen from certain plants is more suitable for collection because of their abundance and high yield.

- Pollen pellets are usually of single plant origin, but may occasionally be a combination from different species.

Cons

- Nutritional composition of pollen pellets may already be modified due to addition of nectar and glandular secretions added by bees.

- Pollen traps may reduce water and nectar collection because the congestion at the hive entrance slows the movement of foragers, which could stress the colony.

-Weaker colonies may be more stressed by pollen traps than strong colonies in an experiment, resulting in a confounding factor.

- If traps are left too long on hives there may be a reduction in brood rearing and honey production.

The BEEBOOK