3.2.2.3. Determining honey bee hygienic responses to SHB eggs and young larvae.

  1. Following the methods outlined in sections 3.2.2.1. and 3.2.2.2., expose reproductive SHB adults to brood comb. They will breed, and the females might oviposit in capped brood cells.
  2. Mark the cells (see section 3.2.2.2.).
  3. Use a pin to put small holes in brood cell cappings as a positive control (Ellis et al., 2004d).
    When pin-pricking, the holes should be made around the cap perimeter to avoid damaging the developing bee within the cell.
  4. Mark capped brood cells with no perforations in the cappings and/or side walls as negative controls (Ellis and Delaplane, 2008).
  5. Return the frame containing the perforated brood cells to the centre of the nest cluster.
    Consequently, the brood section returned to the colony in step 3 will be investigated and attended to by worker bees. Honey bee workers that possess heightened hygienic responses can detect SHB eggs/young larvae present in capped brood cells, uncap the cell, and remove the brood and/or SHB eggs/larvae (Ellis et al., 2003a; 2003c; 2004d; Ellis and Delaplane, 2008).
  6. Leave the frame containing the test section of brood in the nest for a predetermined amount of time.
    Ellis et al. (2003c) left the brood in the colonies post exposure to SHB for 48 hours. However, worker bee hygienic response to the capped brood neared 100% in all test colonies so Ellis and Delaplane (2008) lessened the brood time in the colony to 24 hours in subsequent tests to look for colony differences in hygienic responses.
  7. After the 24 hour period, remove the frame from the colony.
  8. Replace the marked acetate (see section 3.2.2.2.) on the corresponding frame and align to the section of brood.
  9. Consider hygienically removed the marked brood cells having perforated cappings/side walls the day before that no longer contained a developing bee.
  10. Calculate the level of hygienic behaviour (or proportion of brood removed) as

# marked brood cells containing no developing bee after 24 hours exposure to adult bees
total number of marked cells containing perforated side walls and/or cappings

The higher the proportion, the more hygienic the colony.