Entomology Fundamentals: Course Overview

• The provided text offers a course outline and detailed study notes
• It covers core topics in entomology, from basic definitions to insect anatomy, physiology, and classification

Fundamentals of Entomology

• Entomology studies insects
• Course credit weighting of 1+1=2

Course Topics

• Introduction and history of entomology, including contributions from key scientists
• Study of the structure and function of insects
• Economic importance of insects, including harmful, beneficial and productive types
• Focus on nationally important pests and premier entomology research institutes

History of Entomology

• Entomology has roots in ancient texts like the Ramayana and Mahabharata
• The texts contain insect references like "Pipilika" (ant) and "Pathanga" (grasshoppers)

Key Historical Figures

• Prominent scientists include Aristotle, Carlous Linnaeus, Fabricious, and Charles Darwin
• Later contributors are Lefroy, Wigglesworth, Snodgrass, Pradhan, Runwal, Pruthi, and Ananthkrishnan
• Aristotle: Father of biological classification
• Carolus Linnaeus: Father of Taxonomy; publication "Systema Naturae"
• J.C. Fabricius: Danish entomologist; Published "Philosophia Entomologia”
• Snodgrass: Father of Insect Morphology; wrote Principles of Insect Morphology

Indian Contributors to Entomology

• TV. Rama Krishna Ayyar: Hand book of Economic Entomology for South India
• H.S. Pruthi: First Indian Imperial Entomologist
• Dr. M.S. Mani: Authored General Entomology
• Dr. S. Pradhan: Insect Pests of Crops; Father of Modern Applied Entomology in India
• B. Vasantharaj David and T. Kumara Swami: Authored Elements of Economic Entomology
• MRGK Nair: Insects and Mites of crops in India
• K.K. Nayar, N. Ananthakrishnan and B. Vasantharaj David: General and Applied Entomology

Entomology Institutes

• Key organizations include CAB (UK), IOBC (Trinidad), and the International Institute of Insect Physiology (Kenya)
• National institutes are the National Institute of Biological Control (Bangalore) and NCIPM (New Delhi)

Insect Dominance

• Insects are a dominant life form thanks to multiple reasons
• Insects are highly adaptable thanks to traits like flight
• Small size allows insects to exploit various ecological niches
• Exoskeleton provides protection, support, and flexibility
• Tracheal systems ensure efficient respiration
• High reproductive potential enables rapid population growth
• Complete metamorphosis reduces competition between life stages
• Defense mechanisms improve survival
• Hexapod locomotion provides stability

Insect Integument

• The insect body wall, or integument
• The integument forms its exoskeleton
• The integument has 3 layers in most insects
• Upper Cuticle
• Middle Epidermis
• Inner basement membrane

Insect Cuticle, the top layer of insect Integument

• Non cellular

• Has two regions

  • The upper region called Epicuticle

    • Chitin is absent in this layer, instead
    • Layer has Cement Layer for protection
    • Layer has Wax Layer for waterproofing
    • Layer has Polyphenol Layer providing resistance of acids
    • Layer has Cuticulin Layer is a growth and permeability barrier

  • The lower region called Procuticle

  • Layer has Exo and Endo Cuticle

  • The Exo Cuticle- is hardened as its full of Chitin and Sclerotin

  • The Endo Cuticle- is a flexible layer full of Chitin and Arthropodin

  • Pores are present in layers

• Cuticle Composition has two parts

  • Chitin is a nitrogenous polysaccharide, it’s the polymer of glucosamine and alkali soluble
  • Protein, made of Arthropodin, Sclerotin, and Resilin

• The Epidermis Layer has numerous functions

  • Secrete the Outer Cuticle layer
  • Break down old cuticles
  • Wound repairs
  • Looks superficial
    • made of
      • Dermal Glands making wax
      • Trichogen cells making hair
      • Moulting Glands secreting fluids
      • Peristigmatic glands around spiracles

Insect Integument Modifications

• Classifies as Cuticular Appendages and Cuticular Processes
• Cuticular appendenges needs a membrane joint
• Includes Seta/Macrotrichia hair structures
• Includes Spurs on insect legs
• Cuticular Processes includes non membrane articulations
  • Microtrichia fixed hair
  • Spines that are thorn like

Insect Moulting Process

• The moulting process is called Ecdysis, has complex steps
  • Apolysis, breaking old skin
  • Ecdysis, shedding Outer Layer
    • Triggered by Juvenile Hormone from Brain, and Moulting Hormones from glands

Insect Body

• The body is made of series of rings
  • Insecta body is broken in 3 tagmata
  • Head is 6 segments with mouth parts
  • Thorax is 3 segments and broken into
    • prothorax
    • Mesothorax
    • Metathorax segments
  • Abdomen has 11 segments with reproduction system

Insect Head

• The head has 6 segments fused as a forehead

  • Broken in 2, the Procephalon and Gnathocephalon

  • Attaches to thorax via cervix

  • Has Tentorium , to support brain

  • Functions include feeding

    • It has 2 components
      • Procephalon with the Pre and Antennary Segments
      • Gnathocephalon with the Intercalary, Maxillary segments Types of heads
    • Hypognatous, having a jaw, found in grasshoppers
    • Prognathous, having a same axis like beetles
    • Opisthognathous, mouthparts are between legs

Insect Head Sclerites

• It has sutures or large hardened body parts
  • Sutures provide support
• The head has
  • Labrum small lip top off mouth
  • Clypeus by front of clypeal suture
  • Frons is single face part
  • Gena connects mandible
  • Epicraniun is part extends to neck
  • Vertex above Frons
• key sutures includes
• Clypeolabral suture present
• Fronto suture present
• Epicranial suture Y shape has 2 arms known as weakness line splits skin during Ecdysis
• Occipital Suture U shaped

Insect Thorax

• It has 3 segment broken to prothorax, mesothorax segments
  • Helps moving the body by
  • Dorsum
  • Lateral Pleuron
  • Ventral Sternum

Insect Abdomen

• Its made 11 segmented
  • Segments are labeled uromenes
  • End has telson bearing anus
• 1st segments links metathorax forming propedeum
• Segment bears a spiracle
• Functions are repopulation and metabolic activity

Insect antennae

• It’s a paired sensory appendage from the Brain
  • Comes in two parts, the Scape and Pedicel
    • Then the Flagellum at joint of scrape creates auditories
  • Some types
    • Filiform
    • Setaceous
    • Mooniform
    • Pectinate
    • Bipectinate
• Helps to feel detect smells and detect dangers

Insect Mouth

• Includes the Mandible
  • For chewing and biting
• includes sucking too