UPSC MainsZOOLOGY-PAPER-I201510 Marks150 Words
Q4.

Apis is known for social behaviour. Discuss.

How to Approach

This question requires a detailed understanding of the social behaviour exhibited by *Apis* (honeybees). The answer should focus on the caste system, communication methods (waggle dance), division of labour, and cooperative behaviours like foraging, nest building, and defense. Structure the answer by first introducing *Apis* and its social nature, then detailing the different castes and their roles, followed by explaining the communication mechanisms and finally, highlighting the benefits of this social organization. Use specific examples to illustrate the points.

Model Answer

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Introduction

*Apis*, commonly known as honeybees, are renowned for their highly developed social behaviour, a characteristic that sets them apart from most other bee species. This eusociality, a form of social organization characterized by cooperative brood care, overlapping generations within a colony, and a division of labour into reproductive and non-reproductive groups, is crucial for their survival and success. The intricate social structure of *Apis* colonies, involving thousands of individuals, allows for efficient resource management, effective defense against predators, and optimal environmental adaptation. Understanding this social behaviour is fundamental to appreciating the ecological role of honeybees and the challenges they face.

The Caste System in *Apis*

The social organization of *Apis* revolves around a distinct caste system, comprising three primary types of individuals:

  • Queen: The sole fertile female in the colony, responsible for laying all the eggs. Her pheromones regulate colony behaviour.
  • Workers: Sterile female bees that constitute the vast majority of the colony. They perform all the tasks necessary for colony survival, including foraging, nursing larvae, building and maintaining the hive, and defending the colony.
  • Drones: Male bees whose primary function is to mate with the queen. They do not participate in foraging or hive maintenance.

Division of Labour and Age Polyethism

Worker bees exhibit age polyethism, meaning their tasks change with age. This division of labour optimizes colony efficiency:

  • Young Workers (1-3 days): Cleaning cells and caring for larvae.
  • Middle-aged Workers (3-12 days): Building comb, receiving nectar and pollen, and guarding the hive.
  • Older Workers (12-20 days): Foraging for nectar, pollen, water, and propolis.

This sequential task allocation ensures that the colony’s needs are met at every stage of development.

Communication: The Waggle Dance

Honeybees communicate complex information about food sources through the famous “waggle dance”. This dance, performed by foraging bees upon their return to the hive, conveys both the distance and direction of a food source.

  • Waggle Run: The straight run portion of the dance indicates the direction of the food source relative to the sun.
  • Return Phase: The circular return phase provides information about the distance to the food source, correlated with the duration of the waggle run.

The intensity of the dance signals the quality of the food source. This sophisticated communication system allows the colony to efficiently exploit available resources.

Cooperative Behaviour and Colony Defense

Honeybees exhibit remarkable cooperative behaviours beyond foraging. Nest building is a collective effort, with workers meticulously constructing hexagonal cells from beeswax. Colony defense is also a coordinated activity. When threatened, worker bees will collectively attack intruders, utilizing their stingers (at the cost of their own lives). Alarm pheromones are released to alert other bees to the danger, triggering a defensive response.

Benefits of Social Behaviour

The social behaviour of *Apis* provides several advantages:

  • Increased Efficiency: Division of labour allows for specialized tasks and optimized resource utilization.
  • Enhanced Defense: Collective defense mechanisms protect the colony from predators and competitors.
  • Improved Climate Control: Bees regulate hive temperature through fanning and evaporative cooling.
  • Resilience: The colony as a whole can withstand environmental fluctuations and challenges.

Conclusion

In conclusion, *Apis* exemplifies complex social behaviour driven by a rigid caste system, age-related division of labour, and sophisticated communication methods like the waggle dance. This eusociality is not merely a behavioural trait but a fundamental adaptation that has enabled honeybees to thrive in diverse environments and play a crucial role in pollination and ecosystem health. The continued study of *Apis* social behaviour provides valuable insights into the evolution of sociality and the principles of collective intelligence.

Answer Length

This is a comprehensive model answer for learning purposes and may exceed the word limit. In the exam, always adhere to the prescribed word count.

Additional Resources

Key Definitions

Eusociality
The highest level of social organization in animals, characterized by cooperative brood care, overlapping generations within a colony, and a division of labour into reproductive and non-reproductive groups.
Age Polyethism
The division of labour in social insects based on the age of the individual, where younger bees perform tasks within the hive and older bees engage in foraging.

Key Statistics

Globally, there are seven recognized species of honeybees within the genus *Apis*. (Source: FAO, 2023 - Knowledge Cutoff)

Source: Food and Agriculture Organization of the United Nations (FAO)

Honeybees contribute an estimated $20 billion to the global economy through pollination services. (Source: USDA, 2019 - Knowledge Cutoff)

Source: United States Department of Agriculture (USDA)

Examples

Colony Collapse Disorder (CCD)

CCD, first observed in 2006, is a phenomenon where worker bees abruptly disappear from the hive, leading to colony failure. This highlights the vulnerability of *Apis* social structure to environmental stressors like pesticides and pathogens.

Frequently Asked Questions

What role do pheromones play in *Apis* social behaviour?

Pheromones are chemical signals that regulate various aspects of colony life, including queen control, worker behaviour, and alarm responses. The queen’s pheromones, for example, suppress ovary development in workers and maintain colony cohesion.

Topics Covered

ZoologyBiologyEcologyInsect BehaviorSocial InsectsEcology