The Science Behind What We See, Part 1
On Thursday, January 19, the Northwest New Jersey Beekeepers Association had the distinct pleasure of hosting Jon Zawislak, an assistant professor of apiculture and urban entomology at the University of Arkansas. A beekeeper of over twenty years, much of his research involves trying to understand more about honey bees and their behavior. His presentation to the group focused on a type of chemical signal called pheromones.
More than likely you’ve heard this word thrown about in conversation when two people find instant attraction and chemistry. However, unlike humans, where research has been unable to demonstrate that we secrete chemical signals that elicit physiological or behavioral responses in another of our species, we know pheromones elicit the behaviors in our colonies that we witness as beekeepers. You may hear beekeepers refer to their bee colonies as “superorganisms,” and as you learn more about how pheromones affect the colony, you will understand why!
Whether you are in your first, your fifth, or even your twenty-fourth year as a beekeeper, like Professor Zawislak, trying to understand what is happening in a hive can sometimes feel a bit like solving a Rubik’s cube. However, what we are seeing as the behavior of the hive is only secondary to what is happening.
Like the absolute monarchies, people always assume the queen in a hive has all the control and the workers are her loyal minions. Unfortunately for queen bees, her workers (which the majority of the time she has laid herself) can overthrow her in a coup of sorts.
Queen Mandibular Pheromone (QMP) is the main regulatory factor in a honey bee colony. While it’s called “pheromone,” it’s not just one type. QMP is made of over eighteen major and minor components — and the composition changes over time as the queen matures and ages. The multiple pheromones she secretes serve as a meter for the workers to measure her health and effectiveness as a queen. She hits her peak at two to two and a half years. When her pheromones are no longer what the workers expect, they are triggered to replace her.
Say we use 100 to represent the amount of QMP produced by the queen. When a colony is an average size (60,000 individuals), the amount of QMP received by each of those workers is 0.0017. If the size of the colony increases to 80,000, the amount of QMP produced by the queen remains constant, yet the amount per capita drops to 0.0013. While that might not seem like a big difference, this drop in QMP received throughout the colony can promote supersedure, and then swarming.
Supersedure is how honey bees create queens. They find an egg laid by the queen which is less than four days old and feed it only royal jelly. They convert the regular cell into a queen cell, and the larva develops into a queen bee. A hive can create up to thirteen queen cells at a time. The new queen or queens hatch, and will leave with about half the hive’s population, which we call swarming. So while the queen is responsible for laying all the workers, they are unfortunately only “fair-pheromone” subjects.
Normal levels of QMP suppress worker reproduction. In a healthy hive with a normal-sized population, the queen is the only female in the hive to have fully developed ovaries. In the absence of QMP — if the queen fails, dies, or is removed — the ovaries of workers can become active. “Laying workers” will produce only drones, as workers have never mated, so all the offspring are haploid.
Without a queen laying fertilized (diploid) eggs, the worker bee population will decline over the six to eight weeks of a summer worker bee lifespan. A laying worker will increase the drone population, but drones do not mate with workers, nor do they forage for nectar or pollen. Unless the worker bees start raising a new queen, if there is no intervention from the beekeeper, the hive will collapse.
Professor Zawislak shared several more pheromones with the group and explained how they affect the hive. Keep an eye out for our next post which will discuss a few more in detail.