On the surface, a bee hive may seem to be bustling with activity. But beneath the buzz, millions of years of evolution are hiding. Bees are some of the most fascinating species of insects due to their incredible intelligence and important role in ecosystems. Their unique biology has fascinated scientists for years and continues to amaze society.
Bees Form Complex Social Relationships
Bees, along with other insects that belong to the order Hymenoptera (ants and wasps), form complex and valuable relationships with one another. Their interactions are so advanced that scientists consider their behavior to be eusocial, the highest level of interaction and communication exclusive to invertebrates and some mammals. For a species to be classified as eusocial, members must exhibit three things: cooperative brood care (organisms care for young that are not their own), reproductive division of labor (caste system where only certain members reproduce) and an overlap of generations.
Haplodiploidy — Weird Bee Biology
Most eusocial relationships arise from a biological mechanism driving the interactions. In the case of bees, this is known as haplodiploidy, where females develop from a fertilized egg and males develop from an unfertilized egg.
Before getting into the details of this bizarre mechanism, let’s break down the word “haplodiplody”: haplo- indicates a single set of chromosomes, so half the usual number found in a species; diplo- means a double set of chromosomes, or the normal number of chromosomes in a species. All animals have two pairs of each chromosome. Humans normally have 23 pairs of chromosomes found in every cell (46 total) — the only exception is in sex cells (egg and sperm) that have only 23. During fertilization, the two half sets combine to form one whole-set, diploid organism. All humans, male and female, are diploid. In bees, it’s a little different. Females are diploid, possessing an entire set of chromosomes. Males are haploid, having only half of the usual set.
All worker bees are female, offspring from the queen and a drone male. If a queen was not to mate and only to produce drones, the colony would quickly die — drones are notoriously lazy and not equipped with pollen-collecting anatomy or a stinger to defend the colony.
In bees, sisters are 75 percent related to each other. If a female bee had an offspring, she would only be 50 percent related to it because an animal can only pass down half of its genetic material. Because a female worker bee is more related to her sister than her child, theories suggest she would be more inclined to protect the kin that had more of her DNA. Therefore, it makes more sense from an evolutionary standpoint for only a small fraction of a population to reproduce — the queen. This close relatedness in bees likely caused the caste system to socially evolve, resulting in eusociality.
Because this topic can be pretty confusing, refer to this article for a more in-depth explanation.
Termites (order Isoptera) and naked mole rats are the only other animals besides Hymenopterans to exhibit eusocial behavior without being haplodiploid. The evolution of eusociality in these animals is theorized to arise from harsh living conditions that require the development of a reproductive and working caste system to complete tasks for the good of the colony.
A Strict Caste System
In a bee hive, a bee can be categorized as either a queen, worker or drone. A typical honey bee colony has one queen (the only reproductive female). She will mother all of the worker bees, who are all sterile females. The queen, using a special pheromone product from her mouthparts (queen mandibular pheromone or QMP), prevents her offspring from reproducing. Recent studies have been conducted in which the glands that produce this pheromone were removed, yet the queen still controlled the workers by other means. Researchers concluded that there must be pheromone redundancy where the queen produces additional chemicals that perform the same task as QMP. This fascinating discovery has led to further research initiatives to elucidate more about how a queen bee chemically manipulates her colony. If she, for any reason, stops producing these pheromones, some worker bees could develop into rival queens, resulting in a fight until all queens, except one, are killed.
Males are known as drones and essentially are only used for reproduction. The queen will conduct a mating flight, in which she circles around the hive alerting suitors of her presence. Using his large compound eyes (double the size of the queen or workers), a drone may easily spot her and attempt to mate with her. If a drone successfully mates with the queen, he will die while mating. A queen usually mates with eight drones during a single 30-minute mating flight.
Some Bees Know How to Bust a Move
Scientists have recently discovered that honey bees communicate using an incredibly advanced maneuver known as the waggle dance. Using a series of movements and shakes, a worker bee can accurately communicate the location of a point of nectar she recently discovered. She’ll reveal two things using her body language: direction of the nectar source and distance from the hive. Moving in a circle, she will vibrate her abdomen. The time it takes to complete one circuit indicates the distance from the hive, and the direction in which she waggles indicates the angle of the nectar in relation to the sun.
Check out this video to see the waggle dance in action.
Related > Why Do Bees Make Honey?
Tanner Felbinger is a current sophomore at the University of Florida. She’s an Entomology & Nematology major with a minor in Sustainability and plans to attend grad school for Entomology after she completes her undergraduate degree. At school, Tanner is involved in the Entomology Club, teaches group fitness classes at the campus gyms, and is an ambassador for the College of Agricultural and Life Sciences. She is an undergraduate research assistant in Dr. Phil Koehler’s Urban Entomology lab and focuses on control methods for bed bugs. When she’s not in class, Tanner enjoys being outdoors, listening to music, and practicing yoga.