4.1. Objective mode

This section is derivative of the references cited in section 3.1.

1. The day before the experiment is ended, each queen is found, caged with attendants, and returned to her colony. This will save a great deal of time the next day. Additionally, any hive cracks or gaps are sealed with duct tape to prevent bee loss.

2. The night or early morning before colonies are dismantled, the entrance of each colony is securely closed with a ventilated screen to trap workers inside.

3. Ending colony adult bee population is derived from net colony bee weight (kg) and average fresh bee weight (mg). Each screened whole hive is weighed in the field, then opened, all bees brushed off every comb and surface (usually into a temporary holding hive), and the hive re-weighed without bees. The difference in weight is the net weight of bees. A sample of ca. 300 live bees is collected into a pre-weighed or -tared container, weighed, the bees frozen or narcotized with cold or CO2, and counted to determine average fresh weight (mg) per bee. Net colony bee weight is divided by average fresh weight per bee to derive colony bee population. If the fresh bee sample is frozen or stored in alcohol, it can be used to later determine adult loads of diseases, varroa mites, or other parasites of the investigator’s choice.

4. Combs are labelled to preserve colony-specific identity and moved to the laboratory for further measures.

5. Number of brood cells is derived as described in section 3. using a grid pre-marked in cm2, visually summing the area of brood (Fig. 2), and converting area of brood (cm2) to cells of brood by multiplying cm2 by the average cell density per cm2 appropriate to one’s locality. This same method can be used to derive cell number of any comb resource of interest to the investigator;  honey, pollen, or empty cells.

6. Brood solidness is determined by placing a grid that delimits 100 cells over a section of sealed brood and subtracting empty cells to estimate percentage brood solidness (Fig. 6). This measure is repeated on different patches of brood to derive a mean of at least ten observations.

7. Alternatively to reporting comb resources as cells, many investigators report these resources empirically as total area (cm2).

8. In the case of honey, it is traditional to report this variable by weight (kg). In these cases, the investigator is aided with the use of queen excluders that restrict brood to the lower hive bodies. If supers are pre-weighed before adding to hives, the investigator can determine honey yield by simply weighing bee-free honey supers at the end of the experiment.

9. Visible brood disorders can be quantified by first selecting a relatively contiguous patch of brood in the late larval / capped stage (stage more likely to express visible symptoms), and overlaying on the patch a 10-cm horizontal transect and a 10-cm vertical transect intersecting at the centre (Fig. 7). Along each transect every cell of brood is examined under strong light and magnification for visible disorders, i.e., symptoms typical of American foulbrood, European foulbrood, sacbrood, or chalkbrood. The parameter is reported as percentage of brood expressing visible disorders.

Fig. 6. A piece of cardboard with a square equal in size to 10 x 10 cells is laid over a patch of brood. Percentage brood solidness is measured directly as (100 - no. empty cells).

Figure 6

 

Fig. 7. A cross-shaped 10 x 10-cm transect intersects in the middle of a patch of contiguous brood, and every cell along the transect is opened and assessed for visible disorders.

Figure 7