Honey Bee Medicine for the Veterinary Practitioner. Группа авторов

including that which attaches the leg to the thorax (Figure 3.2). Each joint is restricted to motion in only one plane, but this constraint is overcome as each of the six joints in the leg move in different planes, thus enabling considerable dexterity and agility (Snodgrass et al. 2015). Each leg segment is named as shown in Figure 3.2, so the honey bee has six femurs, six tibias, etc.

In addition to locomotion, the honey bee uses her legs to carry pollen back to the hive. Specialized “pollen baskets” called corbiculae are found on the modified tibia of each hind leg. The bee uses her front and middle legs, as well as specialized brushes and combs on her hind legs, to remove pollen collected on hairs covering her body. She packs the pollen into her corbiculae for transport back to the hive. These so‐called “pollen pants” can be seen on bees returning to the hive; they are an important observation when monitoring hive activity. Bees also carry propolis (a resinous mixture of bee saliva, wax, and botanical material) in their corbiculae (Snodgrass et al. 2015) (Figures 3.7 and 3.8).

The honey bee's antennae are critical information‐gathering organs, so they require regular cleaning and maintenance. The bee's front legs each possess an antenna‐cleaning notch that is lined by a tiny comb‐like structure (Figure 3.5). The bee scrapes the ipsilateral antenna free of pollen and other debris using this tool (Figure 3.9).

Figure 3.7 (a, b) Magnified view of the corbicula (pollen basket) on the lateral side of the hind leg (yellow arrow). The honey bee uses her front and middle legs to place pollen on the bristles (pollen brush) of the medial side of the leg. Then, using the pollen rake and pollen press on the opposite leg, she packs the pollen into the corbicula (Snodgrass et al. 2015).

      Source: Photo courtesy of Cynthia Faux.

Figure 3.8 Honey bee foraging on prairie spiderwort Tradescantia occidentalis with pollen loaded into her corbiculae.

      Source: Photo courtesy of Zachary Y. Huang.

Figure 3.9 Antenna cleaner.

      Source: Photo courtesy of Jamie Perkins.

Abdomen

The abdomen of the queen is greatly elongated compared to that of the worker honey bee, in order to accommodate the sperm contained within her reproductive tract. The male honey bee, the drone, has a more rounded, plump appearance than the worker. The abdomen terminates in a cavity containing the opening of the rectum (anus) and, in female bees, the sting apparatus (Figure 3.10).

Figure 3.10 Stinger of a worker honey bee. The queen's is barbless.

      Source: Photo courtesy of Jamie Perkins.

Figure 3.11 Circulatory and respiratory system.

      Source: Illustration by Patrick D. Wilson.

Circulatory and Respiratory Systems

      Insect “blood” is called hemolymph, as it is devoid of oxygen‐carrying cells. Delivery of oxygen and nutrients to, and collection of waste products from, the tissues and organs is accomplished by diffusion in an “open” circulatory system. (Figure 3.7) A single hemolymph vessel lies along the dorsal midline. Hemolymph flows into openings within this region, called the heart, and is pumped cranially through the thoracic region (aorta) toward the head. Hemolymph leaves the aorta and flows back toward the caudal thorax and abdomen, where it re‐enters the circulation. Hemocytes within the hemolymph play a role in the insect's immune system (Snodgrass et al. 2015).

The respiratory system of the honey bee begins with a series of openings called spiracles along the lateral sides of the bee. These openings lead to thin‐walled air sacs and then to a complex of tubes called the tracheal system. The air sacs allow air to be moved through the system by abdominal contractions. Oxygen is thus delivered to the tissues by diffusion (Snodgrass et al. 2015; Vidal‐Naquet 2015) (Figure 3.11).

Nervous System

      As in mammals, the brain lies within the bee's head; however, in bees a ventral nerve cord exits the head and passes caudally through the ventral aspect of the thorax and abdomen. The peripheral nervous system extends from the ventral nerve cord (Figure 3.8) (Snodgrass et al. 2015).

Honey bees have a remarkable capacity for memory and learning. The mere fact that foragers leave the hive daily and return to tell their hive‐mates about their discoveries is amazing! (Figure 3.12).

Figure 3.12 Ventral nerve cord of the honey bee, shown in purple.

      Source: Illustration by Patrick D. Wilson.

Digestive and Excretory System

      The digestive system of the honey bee begins with the mouth, including the proboscis. The esophagus is long, passing through the head and thorax before it empties into the crop, or “honey stomach,” in the cranial portion of the abdomen. The abdomen of the bee visibly expands (see Figure 8.7) when the insect ingests fluids (water, nectar, or honey) and the crop fills (Snodgrass et al. 2015).

The crop is used for carrying resources to and from the hive. The proventricular valve between the crop and the next portion of the digestive tract, the ventriculus, prevents contents of the crop from passing further along the tract where it would otherwise be digested. The ventriculus or midgut