Cell orientation characteristics of the natural combs of honey bee colonies

Abstract

The cell orientation characteristics of the natural combs of honey bees have received much research attention. Although natural combs have been shown to be composed of cells with three orientations-vertical, intermediate (oblique), and horizontal-the proportion of comb cells in these three orientations varies. Knowledge of the comb-building preferences of honey bees is essential for the installation of wax comb foundations, and clarification of the cell orientation characteristics of natural honey bee combs is important for beekeeping. The purpose of this study was to determine the cell orientation characteristics of natural combs of Eastern honey bees (Apis cerana cerana) and Western honey bees (Apis mellifera ligustica). Newly built combs were used to measure the orientation of hexagonal cells and calculate the proportion of cells in different orientations relative to the total number of cells. The number of eggs laid by queens in the cells of different orientations was also determined. The orientation of cells in the natural combs of Eastern and Western honey bees was determined based on the value of the minimum included angle between the pair of parallel cell walls and a vertical line connecting the top and bottom bars of the movable frame in the geometric plane of the comb: 0°≤θ≤10°, 10°<θ≤20°, and 20°<θ≤30° for vertical, intermediate, and horizontal orientations, respectively. Natural combs were composed of cells with at least one orientation (vertical or horizontal), two orientations (vertical + intermediate (oblique) or vertical + horizontal), or three orientations (vertical + intermediate + horizontal), and the proportions of combs with the three aforementioned configurations differed. Both Eastern honey bees and Western honey bees preferred building combs with cells in a vertical orientation. Queens showed no clear preference for laying eggs in cells of specific orientations. The results of this study provide new insight that could aid the production and cutting of wax comb foundations of Eastern and Western honey bees. Our study highlights the importance of installing wax comb foundations compatible with the comb-building preferences of bees.

Fig 1. Schematic of combs with cells in different arrangements and orientations.

Combs with cells that are (a) oriented vertically, (b) oriented horizontally, (c) oriented obliquely, and (d) arranged in a rosette pattern (i.e., cells on one side of the comb are oriented vertically, whereas cells on the other side of the comb are oriented horizontally).

Fig 2. Orientations of the cells, and the minimum included angle between a pair of parallel cell walls and a vertical line connecting the top and bottom bars of the movable frame.

Cells oriented in a (a) vertical, (b) intermediate, and (c) horizontal orientation.

Fig 3. Method for measuring the minimum included angle.

Fig 4

(a) The newly built Western honey bee combs of group A. The installation sequence of the wax comb foundation sheets was vertical, intermediate, vertical, and horizontal for each movable frame; (b) The newly built Western honey bee combs of group B. The installation sequence of the wax comb foundation sheets was intermediate, horizontal, intermediate, and vertical for each movable frame; (c) The newly built Western honey bee combs of group C. The installation sequence of the wax comb foundation sheets was horizontal, vertical, horizontal, and intermediate for each movable frame.

Fig 5. The cell orientation angle of honey bee combs.

(a) The frequency distribution histogram of the cell orientation angle of Eastern honey bee (A. c. cerana) combs; (b) The frequency distribution histogram of the cell orientation angle of Western honey bee (A. m. ligustica) combs.

Fig 6

Comparison of the proportions of cells in a vertical (V), intermediate (I), and horizontal (H) orientation in natural (a) Eastern and (b) Western honey bee combs. Asterisks indicate significant differences (P<0.05); “ns” indicates differences are not significant (P>0.05).

Fig 7. Natural Eastern honey bee comb with cells in a horizontal orientation.

Fig 8

Proportions of cells in different orientations in natural Eastern honey bee combs with (a) cells in vertical (V) and intermediate (I) orientations, (b) cells in V and horizontal (H) orientations, and (c) cells in V, I, and H orientations. Proportions of cells in different orientations in natural Western honey bee combs with (d) cells in vertical (V) and intermediate (I) orientations, (e) cells in V and horizontal (H) orientations, and (f) cells in V, I, and H orientations.

Fig 9. Natural Eastern honey bee comb with cells in vertical and horizontal orientations.

Fig 10. Natural Eastern honey bee combs with cells in vertical (outlined in red), intermediate (outlined in green), and horizontal (outlined in blue) orientations.

Fig 11. Natural Western honey bee comb with cells in vertical and horizontal orientations.

Fig 12. Natural Western honey bee comb with cells in vertical (outlined in red), intermediate (outline in green), and horizontal (outlined in blue) orientations.

Fig 13. Natural Western honey bee combs with cells in a rosette arrangement.

(a) Cells enclosed by the red rectangle are in a vertical orientation; (b) cells enclosed by the red rectangle are in a horizontal orientation.

Fig 14

Number of eggs laid by (a) Eastern honey bee queens and (b) Western honey bee queens in cells in vertical (V), intermediate (I), and horizontal (H) orientations. The acronym “ns” indicates that differences are not significant (P>0.05).