1-Introduction

Characteristics and Diversity of Insects

• Insects are:

  • Diverse – Many species exist in various habitats.

  • Abundant – They occur in high numbers worldwide.

  • Important – They impact our daily lives significantly.

Organismal Diversity

• Species Count:

  • Insecta: 751,000

  • Higher Plants: 248,400

  • Other Arthropods: 123,400

  • Fungi: 69,000

  • Mollusks: 50,000

  • Protozoa: 30,800

  • Algae: 26,900

  • Fish and lower Chordates: 18,800

  • Flatworms: 12,200

  • Roundworms: 12,000

  • Earthworms and Friends: 12,000

  • Jellies and Friends: 9,000

  • Birds: 9,000

  • Reptiles: 6,300

  • Echinoderms: 6,100

  • Sponges: 5,000

  • Monera: 4,800

  • Amphibians: 4,200

  • Mammals: 4,000

• Estimation: 10 – 30 million additional insect species remain to be described.

Abundance of Insects

• Statistics:

  • 9/10 of all living species are arthropods.

  • 8/10 of all living species are insects.

  • 2/3 of insect species belong to four major groups:

    • Beetles (Coleoptera)

    • Flies (Diptera)

    • Ants, Bees, and Wasps (Hymenoptera)

    • Butterflies and Moths (Lepidoptera)

  • For every person on Earth, there are approximately 175,000 individual insects, equating to about 525 trillion in total.

Insect Biomass

• Estimates:

  • Ants comprise about 10% of the animal biomass.

  • Termites also make up about 10% of the animal biomass.

Definition of an Insect

• Common Characteristics:

  • Three body parts:

    • Head

    • Thorax

    • Abdomen

  • Six jointed legs

  • Two antennae

  • Exoskeleton (external skeleton)

Insects and Their Impact

• Daily Life:

  • Insects are influential in many daily life aspects.

• Afflictions:

  • Destroy food and materials:

    • Clothes moths

    • Cheese skippers

    • Silverfish

    • Termites

    • Carpenter ants

  • Destroy body tissues:

    • Bot flies

    • Head lice and pubic lice

    • Brown recluse spiders

  • Annoying or irritating:

    • Bee stings

    • Ant bites

    • Transmit diseases such as:

      • Eastern Equine Encephalitis (EEE)

      • Western Equine Encephalitis (WEE)

      • Dengue Fever

      • Yellow Fever

      • West Nile Virus

      • Malaria

Insect Benefits

• Useful Products:

  • Silk

  • Honey and beeswax

• Medical Uses:

  • Maggot therapy

• Forensics:

  • Forensic entomologists use various techniques to determine time of death based on insect activity.

• Pollination:

  • Essential for the reproduction of many plants.

• Biological Control:

  • Includes natural pest control methods using parasitoids.

• Research:

  • Insects like honey bees are integral to genetic studies.

• Food Sources:

  • Insects are food for many animals and can be consumed by humans as well (e.g., rosted crickets).

Reasons for Insect Diversity

• Physical Characteristics:

  • Striated muscles

  • Haemocoel

  • Tracheal system

  • Evolution of wings

• Reproductive Potential:

  • High fecundity and short generation time.

• Complete Metamorphosis:

  • Allows adaptation to different niches at various life stages.

• Early Land Invasion:

  • Insects were among the first land animals, leading to their diverse adaptations.