The Biology of Honey Bees: Pheromones

 

Groups are two are more people, animals, plants or organisms that interact with one another and collectively, have a sense of unity. One of the most profound observations of a group are honey bees. Honey bee colonies function as a highly intricate and intelligent group, but like all groups, they must communicate in order to really function as a group. Look at it this way, a colony consists of over 10,000 individuals. If these individuals did not communicate, the bees would likely perform random tasks, have too many foragers or nurses, the colony could not defend itself because only a few members would know of the danger, worker would defy queens and lay their own eggs, and foragers may have trouble finding their way home from a flight. These are many examples of why honey bees communicate, and why the colony would most likely fail without some semblance of communication.

 

While honey bees can communicate through other avenues, honey bees primarily communicate through pheromones. Pheromones are effective for a few reasons:

 

  1. Pheromones can be release by one individual, and spread to every member of the colony in a fast and consistent manner.
  2. Pheromones are chemicals, so they can change the behavior and/or physical characteristics of other bees. I go into more detail below.
  3. Pheromones can come in different types, properties, and characteristics, so bees can easily distinguish the differences.
  4. Pheromones seem to be the easiest form of communication for bees because they live in a small, high dense area. Thus, audible or other forms of communication may be less effective.

 

 

Honey bees primarily use pheromones as their method of communication. Pheromones are chemical signals released into the environment the can change the behavior and physiology of other colony members. I have included a list below:

 

Queen Mandibular

Queens release a pheromone called the Queen Mandibular Pheromone (QMP). This pheromone physically suppresses worker ovary development and attracts drones to mating sites. QMP is a great example of how a pheromone can both alter the physical and behavior characteristics of other colony members.

Picture1.png
Honey bee queen. The queen releases a pheromone called the Queen Mandibular Pheromone, which suppresses egg laying behavior. 

 

Alarm

Honey bees have two major alarm pheromones. Alarm pheromones often causes significant behavioral changes to exposed honey bees. For examples, alarm pheromones often make bees defensive and begin running to the colony entrance.

 

Brood Recognition

Larvae and pupae emit pheromones that actually cause physiological changes in worker bees! If worker bees are exposed to the brood pheromones, then their reproductive ovary development is inhibited and they cannot reproduce. This is why broodless and queenless colonies produce laying workers, because workers can now develop ovaries and begin laying unfertilized eggs.

 

Picture1.png
Capped and uncapped brood can release physiological and behavioral altering pheromones.

Drone

Drone, male honey bees, can also produce pheromones that impact the behavior of other males. Drones produce a pheromone called the Drone pheromone, a very original name! Ha Drones release this pheromone during mating flights, and it attracts other drones to the area. Effectively, the pheromone changes the behavior of other drones, and attracts them to the mating congregation area.

Picture1.png
Drone, male honey bees, can also release pheromones. Their pheromones typically attract other drones to mating congregation areas. 

 

Dufours Gland

The dufours gland releases pheromones within the vaginal cavity of queen honey bees. When queens oviposit eggs, the dufour gland covers the egg with a pheromone, which make these eggs more attractive to nursing bees. Thus, these nurse bees are more likely to care for these pheromone laden eggs. If these eggs do not contain the dufour’s gland pheromone, such as when laying workers produce eggs, than the nurse bees effectively take less care of these bees.

 

Egg marking

The egg marking pheromone is very similar to the pheromone described in the dufours gland section. The egg marking pheromone distinguishes eggs laid by the queens and worker, and effectively make queen laid eggs more attractive than worker laid eggs.

Picture1.png
This picture shows a queen laying an egg. When the queen lays an egg, she covers the egg with a pheromone to make it more attractive. 

  

Foraging

The foraging pheromone is one of the most important pheromones in the colony because this pheromone controls the number of nurses and foragers in the colony. The colony needs to have a certain number of nurse bees to care for brood and convert nectar to honey, but also a certain number of foragers to collect pollen, nectar, resin, and water. If the colony has too many nurses or foragers, the colony may effectively fail. Because of this, the foraging pheromone is very important. The foraging pheromone is released by older foragers, and inhibits “maturation” of nurse bees. As nurse bees get older, the characteristics and traits they have for brood care regresses. A great example of this is the nurse bees glands. Their glands for brood food shrivels and deteriorates as they mature. Without highly functioning glands, nurse bees cannot properly care for brood, and thus, they mature to become foragers. The foraging pheromone is a fountain of youth for the nurse bees because it physically alters and slows down this maturation process. Because of this, nurse bees can continue tending brood for a longer period of time. 

Nasonov

The Nasonov pheromone may be the most commonly known pheromone because it is the most visible. Beekeepers often notice bees release this pheromone at the hive entrance, as the bees stick their abdomen in the air to release the chemical. This chemical helps recruit and orient bees to the colony. Without the pheromone, foragers are shown to have a difficult time finding their colony when returning from foraging flights. The nasonov pheromone also orients swarming to their future home. When scout bees find a new home, they will release the nasonov pheromone around the area. When the colony swarms, they are immediately attracted to the new home, and can then easily orient to the new area.

Not all pheromones are alike, however. Honey bees use small and low volatile pheromonal signals. In short, these pheromones are not strong and only effect individuals in a small area. If the pheromonal odor was strong, then the pheromones may effect unintended individuals. Because honey bees live in a small and dense area, low volatile pheromones are a necessity. Thus, the goal of honey bee pheromones is to communicate between colony members, not necessarily with ALL colony members in a hive. Other organisms use pheromones with the goal of effecting and communicating all members of a group. These pheromones have a strong odor and are highly volatile.

Some pheromones are non-volatile, which means they do not become vapor and spread throughout the group. Honey bees use a non-volatile pheromone to distinguish nest members with non-nest members. Each colony has a specific mixture of oils called hydrocarbons and these hydrocarbons are similar to DNA because each colony has a specific mixture. When colony members interact, they spread these hydrocarbons to other members of the colony, so each member has the same mixture. But, the bees can use these hydrocarbons to determine whether or not the individual is a nest mate or not. For example, robbing bees have different mixture of hydrocarbons, so they are not easily accepted. For bees to become accepted to a foreign colony, other colony members must spread the right mixture of hydrocarbons to them.

I hope you enjoyed

Cheers!
Garett Slater

Washboarding: A Very Peculiar Behavior

IMG_7410
Honey bees washboarding

Many describe honey bees as a “superorganism” because thousands of bees function as a single unit. These thousands of bees perform several tasks for the betterment of the entire colony, including foraging, defending, brood caring and cleanliness for the entire colony. Each bee has their own task or role within a colony, and they must execute it for a colony to truly thrive and survive. However, in order to operate a highly-functioning organism, each bee must properly communicate and perform a panoply of behaviors. For example, colonies display hygienic behavior as a way to defend the colony from various brood disease. This is just one example, and washboarding may be another.

IMG_7415.jpg
Honey bees washboarding

Honey bees washboard for no apparent reason, which is fascinating considering humans have kept bees for several thousands of year. In reality, washboarding is an understudied behavior, which is perplexing because honey bees are a model for group behavior among scientific circles. When I say model for group behavior, I mean scientists study honey bees to understand social behavior and how groups arose. In short, honey bee behavior is highly studied! So why do we not know what washboarding it?

Before I explain why, I must describe washboarding. Washboarding honey bees look almost like they are bearding, yet they look much different than bees bearding. These bees gather outside the colony (but can bee seen gathered inside), and they rock back and forth. They seem to be lined up in rows, and spread across the face of the colony. The washboarding bees move their front legs frenetically back and forth, as if they were “scrubbing” clothes, thus the name washboarding. Some folks describe the washboarding behavior as a sweeping behavior because they move their front legs back in forth in an almost rhythmic movement. It is quite odd, so check out the video on my facebook page . I would add it to this blog but I cannot due to payment requirements. Ask to add to join the page to watch the video! But, many washboarding videos do exist online.

Washboarding was studied by Jeff Pettis of the USDA and Katie Bohrer. They believed washboarding was performed as a sort of general cleaning behavior, but the evidence does not point to that direction. But when they observed it,  they found a few things:

  1. Many wasboarding bees were between the ages of 15-25 days, with an average age of 13 days old.
  2. The behavior was most prevalent between 8:00 to 2:00 pm, but the behavior was observed at 9:00 pm.
  3. The behavior increased as the texture of washboarding surface increased. The researchers found that washboarding was more prevalant on rough surfaces like wood and slate, but less prevalent on smooth surfaces such as glass.
img_7396.jpg
Washboarding on the side of the colony

These were observations from the scientists, but beekeepers have anecdotal explanations for the behavior. Most beekeepers believe honey bees washboard immediately after a major honey flow, which is when it is often observed. While washboarding does seem to be associated with general cleaning, most research is needed to support this claim. I observed washboarding recently, on May 30th to be exact in Jamestown area ND. I talked to several commercial beekeepers in Minnesota, and they observed washboarding the same day. North Dakota and Minnesota have very different honey flows, so it may be due to a photoperiod or temperature cue. I have really only observed it in Late-May to Early-June, so this is my observations.

Washboarding is a very cool behavior, even though the function or purpose is unknown. Washboarding is one of the greatest mysteries of honey bees and I look forward to future research on the subject. Honey bees use behavior for a wide variety of reasons, and washboarding may be a necessary behavior for the survival of honey bee colonies. Either for the protection from pathogens and diseases, or as a signaling/communication cue. When I observed it, the bees seemed to be releasing a pheromone based upon what I smelt. But who knows… Hopefully this phenomenon will be solved soon so we can understand this fascinating behavior!

IMG_7414.jpg
More washboarding behavior, from the individual bee

 

I hope you enjoyed

Cheers!
Garett Slater