Standard methods to estimate strength parameters, flight activity, comb construction, and fitness of Apis mellifera colonies 2.0

Figures & data

Table 1. Pros and cons of two variations of an objective mode for establishing honey bee (Apis mellifera) colonies of uniform initial strength.

Method	Pros	Cons
Classical (section Classical objective mode)	1. Results in colonies with initial populations of adult bees normalized for genetics and pathogen load.	1. Disease and parasite legacy effect in brood, although normalized, is nevertheless sustained into the experimental period.
	2. Results in colonies with brood of all stages, accelerating colony growth.	2. Because brood of all stages is present, progeny turn-over from new experimental queens is correspondingly delayed.
	3. Results in maximized colony uniformity regarding initial adult bee populations.
Shook swarm (section Shook swarm objective mode)	1. Does not require use of a customized cage to house common pool of bees.	1. Because adult bees are not normalized, between-colony variation in genetics and pathogen load remains at pre-experiment levels.
	2. Sustains colony-specific identity from pre-experimental to experimental period.	2. Because colonies begin broodless, colony growth is delayed.
	3. Because of #2, drift is not a concern and it is not necessary to move experimental colonies from the source apiary.
	4. Because all brood is removed and replaced with frames of foundation, disease and parasite legacy effect is minimized.
	5. Because of #4, if Varroa destructor control is an element of experimental design, the initial broodless period provides an ideal opportunity to treat for the mites.

Figure 1. Investigators pre-stocking experimental hives with equal numbers of brood combs, honey combs and caged honey bee (Apis mellifera) queens in preparation for receiving worker bees from a common cage.

Figure 2. A frame with a grid in dm² (1dm² = 0.01 m²) is used to visually sum the surface area of honey bee (Apis mellifera) brood. Photo credit: Benoît Droz, Swiss Bee Research Centre, Agroscope.

Figure 3. Nucleus honey bee (Apis mellifera) colonies are small enough to be weighed directly in the field, bypassing the need for intermediate hive-specific cohort cages.

Figure 4. A ventilated cage made to hold a large common heterogeneous mixture of honey bees (Apis mellifera) for starting experiments.

Figure 5. Honey bees (Apis mellifera) are transferred from the common cage to hive-specific cohort cages by use of cups or scoops.

Table 2. Surface area of some regionally common frame types and expected honey bee (Apis mellifera) density when a frame is fully occupied by worker bees.

Region	Local frame type	Number bees per fully-occupied side	Surface (cm^2) per side of frame	Bees (cm^2)	Ref	Worker cells (cm^2)
North America	Deep Langstroth	1215	880	1.38	^a	3.7^c–3.9^d
North America	3/4s	910	655	1.39	^a
North America	Western	785	565	1.39	^a
North America	Shallow	640	461	1.39	^a
Europe	Swiss	1200	930	1.29	^b	4.0^e
Europe	Dadant	1400	1130	1.24	^b	4.0^e
Europe	German normal	900	720	1.25	^b	4.0^e
Europe	Langstroth	1100	880	1.25	^b	4.0^e
Europe	Zander	1000	810	1.23	^b	4.0^e
South and Central America	Jumbo for brood chamber (modified Dadant)	1980	1130	1.75	^f	4.1–4.7^g
South and Central America	Jumbo for super (modified Dadant)	920	520	1.77	^f	4.1–4.7^g
Africa	We are not aware of published methods for determining bee numbers and cell density with Apis mellifera in Africa. However, these bees are ca. 3% smaller than African bees in South America^h, so it is reasonable to apply this conversion to the values given above for South and Central America.

^aBurgett and Burikam (1985).

^bImdorf and Gerig (2001).

^cHarbo (1993).

^dHarbo (1988).

^eImdorf et al. (1987).

^fGris (2002).

^gGuzman-Novoa et al. (2011).

^hBuco et al. (1987).

Figure 6. Mount where a comb is placed in a holder and the distance between the comb and camera is fixed to photograph its sides.

Figure 7. Outline of the method of Cornelissen et al. (2009). Flow chart of computer assisted image analysis applying ImageJ software. Step 2 can be skipped by making the photos in a fixed position at which the distance between camera and frame is constant.

Figure 8. Example of a datasheet for converting raw observer data into colony honey bee (Apis mellifera) population.

Figure 9. Example of a datasheet for converting raw observer data into cm² of open honey bee (Apis mellifera) brood cells (see section Subjective mode).

Figure 10. Example of a datasheet for converting raw observer data into number of open honey bee (Apis mellifera) brood cells.

Figure 11. Outline of method of Yoshiyama et al. (2011) for determining ratio of target surface: total comb surface. It is used with the OECD colour codes in Table 3.

Table 3. Colour and number-coding of cell contents of honey bee (Apis mellifera) combs according to the Organism for Economic Cooperation and Development (OECD, 2007).

Brood stages/stores	Colour	Number
Empty cells	Brown	0
Eggs	Blue	1
Young larvae (1–3 days)	Green	2
Older larvae (4–6 days)	Red	3
Pupae (capped brood)	Yellow	4
Nectar	Orange	5
Pollen/bee bread	Deep pink	6
Dead larvae/pupae	Dark salmon	7
Not characterized (nc)	White	8

Figure 12. Beehive activity monitor (including a Doppler radar) located above the entrance of a hive, with solar panels as energy sources (from Cunha et al., 2020 with permission).

Figure 13. A piece of cardboard with a square equal in size to 10 × 10 cells is laid over a patch of honey bee (Apis mellifera) brood. Percentage brood solidness is measured directly as (100 cells screened minus the number of empty cells).

Figure 14. A cross-shaped 10 × 10 cm transect intersects in the middle of a patch of contiguous honey bee (Apis mellifera) brood, and every cell along the transect is opened and assessed for visible disorders.

Table 4. Pros and cons of the objective and subjective modes for measuring honey bee (Apis mellifera) colony strength.

Method	Pros	Cons
Objective (section Objective mode)	1. More accurate. The method allows for high repeatability and reproducibility.	1. Labour intensive. The method requires of more steps, time, and resources.
		2. Invasive. The method can disrupt the colony; the complete deconstruction and reassembly of colonies disrupts social cohesion.
		3. The method requires movement of hives and colonies to a new location.
Subjective (section Subjective mode)	1. It requires less personnel compared to the Objective method. However, experienced observers are needed.	1. It is less accurate, as it relies on visual observations. However, the repeatability and reproducibility of the method is acceptable.
	2. Less disruptive than the objective method (section Objective mode). Allows for the maintenance of the adhesive cohesion and health of the honey bee colony.
	3. No relocation of the colonies is required.

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