Morphological Structure and Distribution of Hairiness on Different Body Parts of Apis mellifera with an Implication on Pollination Biology and a Novel Method to Measure the Hair Length

Abstract

Bees play a very important role in pollination, especially western honey bees, which contribute upwards of billions of dollars concerning crop pollination. Hairiness plays an important role in pollination success by transporting pollen, and pollen intake, but there is a lack of detailed studies on the morphological mechanisms. The hairiness trait is barely discussed in pollinator trait analysis because of the lack of systematic techniques used to measure hairiness. This paper reports a novel method that is used to measure the hair length of different body parts of a western honey bee through a stereomicroscope equipped with live measurement module software. Scanning electron microscope (SEM) was used to update the knowledge regarding the hair structure of a western honey bee. We explained different types of hairs, hair branches, and their distributions on different body parts, which are discussed in detail. A positive correlation was found between hair length and the number of branches on all body parts. Five types of branches were observed, and these branches vary with different body parts. Our study provides sufficient details about the hair morphology of the western honey bee and a new methodology for measuring hair length. This methodology will improve the knowledge about understanding the pollination efficiency of the western honey bee.

Keywords: evolution; hairiness; morphology of hairiness; pollination efficiency; western honey bee.

Figure 1

Body parts are used to remove hairs for analysis. (a) Pinned western honey bee, (b) dorsal thorax, (c) ventral thorax, the surface of the ventral thorax is shown in red circle. (d) face, (e) dorsal abdomen, (f) ventral abdomen, (g) foreleg, (h) mid-leg, (i) hind leg, and (j) dorsal thorax, red arrows indicate hair branches. (k–o) Photos taken from the slide by using the LEICA M165C stereomicroscope (Leica Microsystems Ltd., Heerbrugg, Switzerland), (k) hairs without any branch, and (l–o) with branches.

Figure 2

(a–g) Hairiness structure on the face, (b) the long branches and (d) short branches, (h–j) compound eye, hairs without branches are shown.

Figure 3

Hairiness structure on the thorax. (a–e) dorsal thorax: (a) hairs with very short branches, (b,d) short hair without branches, (c) long hairs with short branches, (e) short hairs with long branches. (f–h) Ventral thorax, two distinct forms of hairs were found on the ventral thorax: (f,h) short hairs with multiple branches, and (g) long hairs with short branches.

Figure 4

Hairiness structure on the abdomen. (a–e) Dorsal abdomen: (a–c,e) long hairs with short branches, (d1) short hair with multiple branches and (d2) short hair without branches. (f–i) Ventral abdomen, (f,h) long hair and short branches, and (g,i) short hairs with multiple branches.

Figure 5

Hairiness structure on the leg. (a–e) Coxa, short and thin hairs without branches, (b,c) very few branches at the end of the hair, (d) long hair with short branches. (f–h) Trochanter, (f,g) three forms of hair, including (f,h) long hairs with short branches, (g) short hairs with short branches, and (f) short hairs without branches, were found. (i,j) Femur, two different forms are found: one end with a triangular structure (i) and other ends with very short branches (j).

Figure 6

Hairiness structure on the hind leg. (a–d) Femur: (a,d) short hairs without branches (b,c), short hairs without branches and end with triangular structure. (e,f) Tibia, short hairs with small branches and hairs without branches. (g–j) Basitarsus, short hairs without branches.

Figure 7

Pollen of Alcea rosea (Malvaceae), attached to body parts of the western honey bee. (a) Whole body, and (b,c) close-up on the dorsal thorax.

Figure 8

(a) The results of hair length and the number of branches on legs, where: FLT, foreleg thorax; FLB, foreleg basitarsus; MLB, mid-leg basitarsus; MLT, mid-leg tarsus; HLB, hind leg basitarsus; FLF, foreleg femur; MLF; mid-leg femur; FLC, foreleg coxa; HLC, hind leg coxa; HLT, hind leg trochanter; HLF, hind leg femur; MLC, mid-leg coxa. (b,c) Thorax and face. p-value shows the significant difference. Treatments with the same letter are not significantly different (one-way ANOVA and Pearson correlation coefficient (r)). Tukey’s test showed that the length across all parts was significantly different, while branches show that treatments with the same letter are not significantly different (p > 0.05).

Figure 9

Scatter plots showing the correlation (95% confidence interval of the regression line) between hair length and the number of branches, (a) on the whole body parts, (b) the face and thorax, and (c) the legs.