Honey bees are remarkable creatures. They are social insects living together harmoniously in the same colony. The hierarchy of a single colony consists of different adult ranks: a queen, several drones, and a large number of workers—up to 20,000 to 80,000 workers in a hive.
The worker bees know how to collaborate to achieve a common goal by diligently performing their particular tasks. They gather food for their group, care for sick members, nurse the young, or keep each other safe and warm in their hive.
Honey bees also communicate with each other by using their senses. For example, they use an acute sense of smell and each other’s scents to receive and pass along messages to other bees.
Why is the sense of smell important for honey bees?
The sense of smell is important for honey bees to survive, reproduce, communicate, find a good food source and keep their hive safe. Honey bees (Apis mellifera) have 170 olfactory or ‘smell’ receptors, but only have 10 gustatory or ‘taste’ receptors (Kleopel, 2006). They use their extraordinary sense of smell to detect chemical signals, including pheromones from their surroundings.
A pheromone is a chemical substance used for communication within a group of animals from the same species. The term ‘pheromone’ derives from two Greek words: pherin (to transfer) and hormôn (to excite).
In the world of honey bees, the release of a pheromone triggers some changes in the physiology and behavior of other members in the same colony.
Depending on the duration of the impact, there are two types of pheromones in honey bees (Rong Ma et al., 2019):
- Primer pheromones: these pheromones cause slow and long-term changes. For example, some queen pheromones regulate large numbers of the workers’ genes and cause the delay from nursing to foraging for food.
- Releaser pheromones: these pheromones cause quick responses and short-term changes. For example, an alarm pheromone in honey bees triggers aggressive behavior by activating the expression of early genes in the brain of the workers.
Honey bees sense pheromones by using their body parts, such as their antennae. As the phase of the pheromones is typically volatile, the cells in their smell receptors are the ones that receive the chemicals. Volatile pheromones means these chemicals are easily evaporated or easily changed from a liquid phase into a gas phase—sometimes they even come with a specific odor.
Apparently, to us, an alarm pheromone released by bees smells like the aroma of bananas. This pheromone calls for other bees to come and protect their hive. Whereas, a pheromone produced by a new queen to attract drones, smells lemony.
What are the roles of pheromones in honey bees?
Honey bees uses their pheromones for many different purposes, such as aggression, kin recognition, alarm signaling, navigational and visual memories.
Below are some examples of pheromone roles:
To identify their nestmates
A worker bee carries a specific odor on the body surface, which is similar to other members from the same hive. This chemical signature, resembling an identification card, informs guard bees about the origin of the bee before entering the hive (Breed, 2014). In this case, the guard bees use a specific pheromone to screen a potential intruder.
To initiate nursing and foraging
A queen honey bee produces a mandibular pheromone to regulate large numbers of genes in the worker’s brain (Grozinger et al., 2003). As a result, this event triggers downstream behaviors of the bees, such as nursing or foraging. The most highly affected gene by the queen’s mandibular pheromone is Kr-h1 gene, which might play an important role in the transition to foraging behavior in honey bees.
To locate the queen
Honey bees use pheromones to locate their queen and form a coherent swarm (Nguyen et al., 2021), in which each member of the same group must keep track of what others do. First, the queen produces her pheromones to notify her location. But these pheromones only travel a limited distance, so the chemicals are unable to reach bees further away. To amplify the signal, the bees closer to the queen then display ‘scenting’ behavior.
‘Scenting’ behavior means the bees lift their abdomens to expose their pheromone gland, release their pheromones and then fan their wings to direct the smell toward other bees.
To locate their queen, bees in the same group demonstrate a series of cascading ‘scenting’ behaviors. As many as 6,600 bees can join in this action. This process is probably similar to the game of telephone—which involves whispering a word to your neighbor, and then she passes your message to the next person in the line.
There are many more fascinating behaviors of honey bees, including a special dance performance, or the waggle dance (below), to tell its nest mates where to find food.
Oftentimes, their behaviors can be easily missed, because honey bees are small and unnoticeable. Without doubt, despite their small size, honey bees are important for us.
Why are honey bees important?
Honey bees are important primarily due to their role as pollinators. According to the Food and Agriculture Organization, pollinators support agriculture production, particularly for pollination-dependent crops. These types of crops tend to be five times more valuable than the crops that don’t need pollination.
Honey bees also produce high-quality materials, including honey, royal jelly, pollen, propolis (bee glue), and beeswax for making candles and musical instruments. For many beekeepers around the world, even a small-scale production of honey has generated an income, such as those living in developing countries.
In 2006, scientists in the U.S. started to notice significant yearly declines in honey bee colonies caused by a variety of stressors (Nowierski, 2020). These stressors include parasites, diseases, pesticides, pollutants/toxins, nutritional deficits, habitat loss, effects of climate variability, agricultural production intensification, reduced species or genetic diversity, and pollinator or crop management practices. However, the good news is honey bee populations continue to recover after focusing efforts on their health.
In addition to honey bees, North America has approximately 4,000 native bee species, which are important pollinators for ecosystems containing native flowering plants or flowers that can only be pollinated by them. Without these types of bees, those plants will also disappear. However, a small portion of these native bee populations is at risk of extinction (Colla & Maclvor, 2016).
Unfortunately, honey bees compete with the native bees for pollen and nectar, so increasing their numbers outside the agricultural systems will affect the populations of native bees. Therefore, understanding the honey bee’s behaviors can potentially help direct efforts to manage the populations of honey bees and still protect the native bee populations.
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