Sex Determination: An Introduction
Sex determination is the process by which the gender of an organism is established. This is often accomplished during fertilisation through the inheritance of specific genes that are typically located on a particular chromosome. This pattern affects the development of the body by regulating the metabolism of the cells and promoting the synthesis of hormones, both of which are necessary for the maturation of sexual glands and organs.
A person can develop the outward characteristics of one sex during embryological development while maintaining the genetic make-up of the other sex due to an imbalance in the number of hormones that are produced or their absence.
Mechanism of Sex Determination in Honey Bees
Haplodiploidy in Honey Bees
Honeybees use a haplodiploid sex determination mechanism. Males develop from unfertilised eggs as haploids, whereas females develop from fertilised eggs as diploids. Sterile diploid female bee and fertile diploid female bee, in which former one will act as a worker and latter one as a queen.
Johann Dzierzon, a Catholic priest, was the first to invent this method of sex determination in 1845.
The fertilisation or non-fertilisation of the eggs, rather than the presence or lack of sex chromosomes, determines sex in honeybees.
The male progeny of honeybees develops naturally from unfertilised eggs, which are haploid and have only one set of chromosomes.
Queens and worker bees are male or female and are produced from fertilised honey bee eggs, which are diploid and have two sets of chromosomes.
Number of chromosomes in honey bees: Diploid females have 16 pairs of chromosomes, or 32, whereas haploid males only have 16 single chromosomes.
How do Bees Reproduce?
All insects, including honey bees, begin their lives with eggs. During the winter, a queen establishes a new colony by depositing eggs in each honeycomb cell. Unfertilised eggs will hatch into drones, or honey bee males, whereas fertilised eggs will develop into female worker bees. The queen must lay fertilised eggs to spawn worker bees, who seek food and look after the colony for it to exist.
There is only one queen in each colony who mates at a young age and collects almost 5 million sperm. A queen bee only has one mating flight and accumulates enough sperm to lay eggs for the rest of her life. When a queen is no longer capable of laying eggs, new queens are tasked with mating and laying honey bee eggs. Honey bee eggs are about half the size of a grain of rice, measuring 1 to 1.5 mm long.
When the queen lays her eggs, she works her way along with the comb, inspecting each cell carefully before placing her eggs. A queen can lay up to 2,000 honey bee eggs in a single day, and the process of producing one egg takes only a few seconds.
A young queen systematically lays her eggs, laying each egg adjacent to its neighbours within a cell. Queens begin depositing their eggs in the cell frame's centre, allowing workers to place honey, royal jelly, and other larvae feed on the cell frame's outside edges. The queen, on the other hand, produces fewer eggs in a less structured pattern as she gets older. A mucous thread attaches a honey bee egg to the cell when the queen deposits it.
Conclusion
Honeybees use a haplodiploid sex determination mechanism. Males develop from unfertilised eggs as haploids, whereas females develop from fertilised eggs as diploids. Johann Dzierzon, a Catholic priest, was the first to invent this method of sex determination in 1845.
The fertilisation or non-fertilisation of the eggs, rather than the presence or lack of sex chromosomes, determines sex in honeybees. The male progeny of honeybees develops naturally from unfertilised eggs, which are haploid and have only one set of chromosomes. Queens and worker bees are produced from fertilised honey bee eggs, which are diploid and have two sets of chromosomes.
FAQs on Sex Determination in Honey Bee
1. What do you mean by parthenogenesis?
Parthenogenesis is a sort of asexual reproduction in which female gametes are developed without any male gametes being present to facilitate fertilisation. Insects like bees, wasps, and ants do not have sex chromosomes in their genomes. These organisms reproduce asexually through a process called parthenogenesis. There are also several species of plants, reptiles, and fish that are capable of reproducing in this way.
Some organisms, like crayfish, snakes, komodo dragons, and sharks, are capable of producing offspring both sexually and through the process of parthenogenesis. This type of parthenogenesis is referred to as facultative parthenogenesis.
2. What is the significance of parthenogenesis?
In honey bees, wasps, and other insects, parthenogenesis aids in defining an individual's sex.
It backs up the chromosomal inheritance idea.
Parthenogenesis eliminates variations in populations.
It is the most basic, stable, and straightforward method of reproduction.
Parthenogenesis is the process by which organisms become polyploid.
It aids in the creation of beneficial mutant characteristics.
A non-adaptive gene combination is regulated.
There are no races that are sterile.
3. What are the different sexes and castes of honey bees?
Honeybees come in two sexes, male and female, as well as two female castes. Workers, who are sterile diploid female bees and fertile diploid female bees are queens, who are fertile diploid female bees larger than workers, are the two female castes. Male honey bees, often known as drones, are larger than females and only appear in the early summer. The drones are stingless, whereas the workers and queens have stingers.
The spermatheca is a structure that queen honey bees use to store sperm and control the fertilisation of their eggs. As a result, queens might lay fertile or unfertilised eggs. Drones originate from unfertilised eggs, whereas fertilised eggs develop into females, which might be workers or virgin queens. Queen cells, which are larger than conventional vertical cells in the honeycomb, are where eggs destined to become queens are laid.
