Lecture Notes: The Success and Abundance of Insects

Introduction

• Hypothetical scenario: If insects became large and waged war on humans, humans would likely lose due to sheer numbers.
• Estimated 10 quintillion insects on Earth, vastly outnumbering humans (7 billion) by more than a billion to one.
• Insects constitute about 75% of all animal species on Earth.

Insect Species and Diversity

• Over 1 million known insect species.
• Many species remain unclassified.
• Insects possess huge genetic diversity, crucial for adaptation.

Factors Contributing to Insect Success

1. Reproduction
   • High reproductive rate; many species produce hundreds of offspring.
   • Rapid maturation allows quick reproductive cycles.
2. Adaptability to Environments
   • Inhabit diverse environments, including extreme ones.
   • Examples:
     • Flat bark beetles in -40°F.
     • Sahara Desert ants above 155°F.
     • Bumblebees at 18,000 feet.
3. Physical Adaptations
   • Exoskeletons act as armor, providing protection.
   • Small size allows habitation of small spaces and utilization of resources.

Ecological Niches

• Insects occupy many niches by using various resources:
  • Plant parts (roots, stems, leaves, seeds, pollen, nectar).
  • Other insects (e.g., wasps lay eggs inside paralyzed victims).
  • Blood (e.g., mosquitos and biting flies).
  • Feces (e.g., flies lay eggs, beetles use dung).

Metamorphosis

• Critical for resource utilization and avoiding competition within species.
• Example: Butterflies – caterpillars eat leaves, adult butterflies feed on nectar.
• 86% of insect species undergo complete metamorphosis.

Conclusion

• Despite their small size, insects are abundant and successful across the globe.
• Insects may be considered the true conquerors of the planet due to their unmatched success and adaptability.