5.1. Subjective mode

This section describes a subjective mode for reporting quantity of any kind of colony resource stored in cells: open brood, sealed brood, honey, or pollen. The methods are similar to those described for measuring colony bee populations subjectively in section 4.2. The only difference concerns whether the investigator wants to report the resource in units of area (cm2) or number of cells. Authors have also reported resources in units of “frames,” but this is unnecessarily ambiguous and makes it harder to compare data to other studies. As mentioned before, honey is traditionally reported as weight (kg), and it is best to use queen excluders and pre-weighed honey supers as described in paragraph 8, section 4.1. However, if the investigator wants to report honey occurring in combs alongside brood it may be necessary to report it in units of cm2 or cells as described in this section. These methods for measuring brood, honey, or pollen are fundamentally the same for African bees, given that the investigator uses the region-specific multipliers in Table 2.

1. Estimates are carried out by no fewer than two observers, preferably each with a dedicated secretary who writes down numbers, or each fitted with an audio recorder.

2. A colony is opened and combs of bees sequentially removed. Each observer looks at one side of a comb, visually estimates the percentage of the comb surface occupied by the target resource, and records the number with the secretary or audio recorder. It is convenient to label frames 1-X, with each side indicated A or B. As described in the previous section, the observer is imaginatively sorting the resource into one contiguous mass and making a decision on the percentage surface area of the comb the contiguous resource occupies. This can be difficult in cases of spotty brood where widely separated cells must be imaginatively grouped together. It is to be expected that the accuracy of this mode is best when target resources are massed together in convenient contiguous patches.

3. Fig. 9 is a screenshot of an Excel datasheet demonstrating the conversion of raw data from two observers into cm2 of target resource, in this example open cells of brood. There are two fictional colonies, each with 5 North American deep frames, each with two sides. Columns D and E show the respective visual estimates of two observers for percentage comb surface covered by bees, and column F is the mean of the two. Column G converts the mean percentage surface occupied by open brood into area (cm2), using the surface area for one side of a North American deep frame from Table 2 (880 cm2). Rows 12 and 23 sum the area of open brood for each colony.

4. If investigators use colonies with different sized supers and frames it will be necessary to adjust calculations for the one-side surface area unique to each comb type. This would affect the area conversion factor used in Fig. 9, column G.

5. To report a resource in units of cells, it is necessary to multiply the cm2 of resource by the average cell density per cm2. This value varies by geography; conversion factors range from 3.7 - 4.7 (Table 2). It is advisable for investigators to determine this value for their local conditions. Figure 10 shows a modification of Fig. 9 taking the data from cm2 open brood to cells of open brood, using a conversion factor of 3.7.

Fig. 9. Example Excel worksheet for converting raw observer data into cm2 open brood. See 5.1., paragraph 3.

 Figure 9

Fig. 10. Example Excel worksheet for converting raw observer data into cells open brood. See 5.1., paragraph 5.   

Figure 10