sex determination in honey bee

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Introduction:-

The sex determination in honey bee is based on the number of sets of chromosomes an individual receivers. An offspring formed from the union of a sperm and an egg develops as a female (queen or worker), and an unfertilized egg develops as a male (drone) by means of parthenogenesis. This means that the males have half the number of chromosomes than that of a female.
The females are diploid having 32 chromosomes and males are haploid, i.e. having 16 chromosomes. This is called as haploidiploid sex-determination system and has special characteristic features such as the males produce sperms by mitosis shown in figure below, they do not have father and thus conot have sons, but have a grandfather and can have grandsons.
sex determination in honey bee
Sex determination in honey bee
Non-Allosomic genetic sex determination:– Non-allosomic genetic sex determination refers to systems where sex is determined by genes that are not located on sex chromosomes (allosomes). Unlike the well-known XY system in humans, these systems rely on specific genetic loci found on autosomes, the non-sex chromosomes. One example is the ZW system in birds, where males have ZZ sex chromosomes and females have ZW. Another instance is found in some fish and reptiles
where environmental factors can influence gene expression on autosomes to determine sex. These mechanisms highlight the diversity of sex determination processes across different species and illustrate how evolution has shaped reproductive strategies in complex ways.
Western honey bee
  • Genic balance or X/A Balance Theory of sex Determination:- Given by C.B Bridges. According to him, Y chromosome plays no role in sex determination of Drosophila and it is the ratio between number of X-chromosome and set of autosomes which determines the sex of fly.

Chromosome Constitution

X/A ratio

Sex Index

AA + XXX

3/2 = 1.50

Super female

AA + XX

2/2 = 1.00

Normal female

AAA + XXY

2/3 = 0.67

Intersex

AA + XY

1/2 = 0.50

Normal male (Fertile)

AA + XO

1/2 = 0.50

Female (Sterile)

AAA + XY

1/3 = 0.33

Super Male

It was concluded that X/A ratio of > 1.0 expresses super femaleness, 1.0 femaleness, below 1.0 and above 0.5 Intersexes, 0.5 maleness and < 0.5 supermaleness
sex determination in honey bee- haploidiploid sex-determination system
haploidiploid sex-determination system
Environmental Mechanism of Sex Determination:- In some organisms e.g.. Bonnelia sex is determined by the site where larvae differentiates into adult. The environmental mechanism of sex determination (ESD) is a fascinating process where an organism’s sex is determined not by its genetic makeup, but by external environmental factors
This mechanism is prominently seen in reptiles like turtles and crocodiles, where the temperature at which eggs are incubated dictates the sex of the offspring. For example, warmer temperatures might produce more females, while cooler temperatures produce more males. ESD can also be influenced by social factors, such as the presence of dominant individuals or population density, as seen in some fish species. This adaptive strategy allows species to optimize their reproductive success in varying environmental conditions, showcasing nature’s ingenious flexibility.
In honey bees, sex is determined by a haplodiploid system. Females (workers and queens) are diploid, having two sets of chromosomes (one from each parent), while males (drones) are haploid, having only one set of chromosomes from the mother.
The queen bee lays eggs that can be either fertilized or unfertilized. Fertilized eggs develop into diploid females (workers or queens), while unfertilized eggs develop into haploid males (drones).
In haplodiploidy, females develop from fertilized eggs with two sets of chromosomes (diploid), and males develop from unfertilized eggs with one set of chromosomes (haploid). This system relies on whether the egg is fertilized or not during oviposition.
Yes, worker bees can become queens if they are fed a special diet called royal jelly during their larval stage. This diet triggers the development of queen-specific characteristics and reproductive abilities.
The queen controls the number of males and females through selective fertilization of eggs. Additionally, worker bees can influence the rearing of new queens by selecting specific larvae to feed royal jelly.

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